CHAPTER Env-Wq 700
STANDARDS OF DESIGN AND CONSTRUCTION FOR SEWERAGE AND WASTEWATER
TREATMENT FACILITIES
Statutory
Authority: RSA 485-A:6, III
Revision Note:
Document #8590, effective 3-25-06, readopted with amendments
and redesignated former Chapter Env-Ws 700 titled Standards of Design and
Construction for Sewerage and Wastewater Treatment Facilities as Env-Wq 700
pursuant to a rules reorganization plan for Department rules approved by the
Director of the Office of Legislative Services on 9-7-05.
The prior filings for former Env-Ws 700 include the
following documents:
#757, eff 2-18-76
#2245, eff 12-31-82
#2670, eff 4-12-84
#4860, eff 7-5-90; EXPIRED 7-5-96
#6350, INTERIM, eff 10-5-96, EXPIRED
2-2-97
#6590, eff 9-26-97
#8434, INTERIM, eff 9-26-05, EXPIRES: 3-25-06
PART Env-Wq 701
PURPOSE AND APPLICABILITY
Env-Wq
701.01 Purpose. The purpose of this chapter is to protect public
health and the environment by establishing minimum technical standards and
requirements for the planning, design, and construction of sewerage and
wastewater treatment facilities, including solids handling and disposal
facilities.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
701.02 Applicability.
(a) Env-Wq 700 shall apply to any person that
designs or constructs new sewerage, wastewater treatment, or solids handling
and disposal facilities or any appurtenances related thereto.
(b) For purposes of proposed upgrades or other
modifications to existing sewerage, wastewater treatment, or solids handling
and disposal facilities or any appurtenances related thereto, the following
provisions shall apply:
(1) Env-Wq 702
relative to definitions;
(2) Env-Wq 703
relative to engineering design documents; and
(3) All
provisions of Env-Wq 704 through Env-Wq 719 that directly apply to the
system(s) proposed to be upgraded or modified.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
PART Env-Wq 702
DEFINITIONS
Env-Wq 702.01
“Annual average design flow” means the
entire volume of flow, including all infiltration and inflow (I/I), discharged
in one year, expressed as a daily rate.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.02
“Beneficial use” means “beneficial use” as defined in Env-Wq 802.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.03
“Biochemical oxygen demand (BOD5)” means the amount of oxygen
used by microorganisms in the biochemical oxidation of decomposable organic
matter under aerobic conditions over a 5-day period, as expressed in milligrams
per liter (mg/L).
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.04 “Clean
Water Act (CWA)” means the Federal Clean Water Act, Pub. L. 92-500 as amended
by Pub. L. 95-217, Pub. L. 95-576, Pub. L. 96-483, Pub. L. 97-117, Pub. L.
100-4, 33 U.S.C. 1251 et seq.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.05
“Collector sewer” means a sewer that serves the primary purpose of
collecting and transporting wastewater to the interceptor sewers.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.06
“Cross-country locations” means locations not otherwise defined as roadway
locations.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.07
“Department” means the
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.08
“Discharge permit” means a national pollutant discharge elimination
system (NPDES) permit or a
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.09
“Engineer” means the engineer of the owner, acting individually or
through duly-authorized representatives.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.10 “HS-20
loading” means the force imposed by a pair of 16,000 pound concentrated loads,
one located over the point in question and the other located 72 inches distant,
so as to simulate the tire loads of a truck.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.11
“Industrial waste” means “industrial waste” as defined by RSA 485-A:2,
VI, as reprinted in Appendix C.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.12
“Interceptor sewer” means a sewer designed to carry wastewater from
collector sewers to the WWTP.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.13 “Local legislative body” means “legislative
body” as defined by RSA 21:47, as reprinted in Appendix C.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.14 “Maximum daily flow” means the largest volume of flow anticipated to occur during a 24-hour period.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.15
“Maximum monthly flow” means the largest
volume of flow anticipated to occur during a continuous 30-day period,
expressed as a daily rate.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.16
“Minimum daily flow” means the smallest volume
of flow anticipated to occur during a 24-hour
period.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.17
“Minimum monthly flow” means the smallest
volume of flow anticipated to occur during a continuous 30-day period,
expressed as a daily rate.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.18
“Municipality” means a city, town, district, county, or other public
body created under state law and having jurisdiction over treatment and
disposal of wastewater.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.19
“National Electric Code (NEC)” means the National Electric Code as
adopted under RSA 155-A:1, IV and RSA 155-A:2, I.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.20
“Owner” means the municipality or private owner for which sewerage or
wastewater treatment facilities are designed or constructed.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.21 “Peak instantaneous flow” means the maximum anticipated instantaneous
flow expressed in gallons per minute (gpm).
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.22 “Peak hourly flow” means the largest volume of flow anticipated to occur during a one-hour period,
expressed in gpm.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.23
“Person” means “person” as defined in RSA 485-A:2, IX, as reprinted in
Appendix C.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.24 “Pressure sewer” means a system of individual
grinder pumps connected using small diameter collector sewers to grind, collect
and convey sewage to an interceptor sewer or a wastewater treatment plant.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.25
“Privately owned” means ownership by a person other than a municipality.
Source. (See Revision Note at chapter heading for Env-Wq
700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.26 “Roadway locations” means all
parking lots, traveled ways, and roadway shoulders.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.27
“Sewage” means “sewage” as defined in RSA 485-A:2, X, as reprinted in
Appendix C.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.28
“Sewer” means a pipe or conduit used to convey sewage.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.29 “Sewer
appurtenances” means components of a sewer other than pipe, such as manholes,
tees, wyes, chimneys, cleanouts, and siphons.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.30
“Sewerage” means a system of pipes, pumping facilities, and
appurtenances for the collection and conveyance of sewage and liquid wastes.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.31
“Standard scale” means the commonly used drafting scales of engineers and
architects including, but not limited to, 1:10, 1:20, 1:40, 1:50, 1:100, and
1/8 inch, 1/4 inch, 3/8 inch, 1/2 inch, 3/4 inch and 1 inch to the foot.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.32
“Standard dimension ratio (SDR)” means the ratio of outside pipe
diameter to pipe wall thickness, as used in the pipe manufacturing industry.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.33 “Total
suspended solids (TSS)” means solids that either float on the surface of, or
are in suspension in, water, sewage, or other liquids, and which are removable
by a 0.45 micron filter.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 702.34
“Wastewater treatment plant (WWTP)” means “wastewater treatment plant”
as defined by RSA 485-A:2, XVI-a, as reprinted in Appendix C. The term does not include conventional septic
tank and leach field systems as regulated under RSA 485-A:29.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
PART Env-Wq 703
ENGINEERING DESIGN DOCUMENTS
Env-Wq 703.01
Submittal of Design Drawings, Technical Specifications, and
Supporting Documentation.
(a) The owner shall submit design drawings,
technical specifications, and supporting documentation for proposed new or
modified publicly or privately owned sewerage and WWTPs to the department for
approval in accordance with this part.
(b) The owner shall submit design drawings,
technical specifications, and supporting documentation for any proposed sewer that
serves more than one building or that requires a manhole at the connection, and
for any proposed sewage pumping station that serves more than one building or
has a capacity in excess of 50 gallons per minute (gpm).
(c) All design drawings, technical
specifications, and supporting documentation submitted to the department for
review and approval shall be:
(1)
Prepared or reviewed by an
engineer licensed in the state of
(2) Stamped and
signed by the engineer who prepared or reviewed them.
(d) The
owner shall submit the following number of sets of plans, design drawings,
technical specifications, and supporting documentation:
(1) For state-
or federally-funded projects:
a. For initial
review, 2 printed sets; and
b. For final
review and approval, one complete
printed set, 2 additional printed copies of the cover sheet, and 2 electronic
sets submitted on 2 separate compact disks or DVDs; and
(2) For other
projects:
a. For initial
review, one printed set; and
b. For final
review, one complete printed set, 2 additional printed copies of the cover
sheet, and 2 electronic sets submitted on 2 separate compact disks or DVDs.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
703.02 Technical Specifications and
Supporting Documentation.
(a) Complete technical specifications and
supporting documentation for the construction of sewerage and WWTPs shall
accompany the design drawings submitted pursuant to Env-Wq 703.01.
(b) The technical specifications shall describe
the following information as applicable to the proposed project:
(1) All
construction information not shown on the drawings that is necessary to inform
the contractor of the design requirements and the quality of materials,
workmanship, and fabrication of the project;
(2) The type,
size, operating characteristics, and rating requirements of all mechanical and
electrical equipment;
(3) Laboratory
fixtures and equipment;
(4) Operating
tools;
(5) Pipe and
other construction materials;
(6) Special
filter materials;
(7) Sewer
appurtenances;
(8) Chemicals that
will be used as part of the wastewater treatment process;
(9)
Instructions for testing materials and equipment as necessary to meet
design standards; and
(10)
Performance tests for the
completed works and component units.
(c) The supporting
documentation shall include:
(1) An
explanation of the proposed boring and soil sampling methodology used;
(2) For
proposed new sewer connection, calculations showing the estimated current flow
in the sewer and in the downstream sewers and the impact of any proposed
additional sewerage flow to the sewer and subsequent downstream sewers;
(3) Design flow
and loading calculations, as applicable;
(4) A review of
existing inundation maps showing potential downstream impact of dam failures on
sewerage and WWTPs;
(5) Flotation
calculations for buried structures; and
(6) An
explanation of the methodology used to determine 25-year and 100-year flood
elevations applicable to the project.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 703.03 Design
Drawings.
(a) All design
drawings shall include the following information:
(1) A title
citing the project name, location and owner;
(2) The scale;
(3) The north
arrow;
(4) The name
and signature of the engineer, and the imprint or stamp of his/her New
Hampshire Professional Engineering license seal;
(5) The date of
the original issue and all revisions;
(6) The initials
of the designer, draftsperson, checker and responsible engineer;
(7) The
dimensions and relative elevations of all structures;
(8) The
locations and outlines of all mechanical equipment;
(9) The
locations and sizes of all piping;
(10) Water
levels;
(11) Existing
and proposed ground elevations;
(12) A
topographic map of the proposed project site;
(13) The date
and source of survey data; and
(14) Plan sheet
match lines for plan and profile views when more than one sheet is required for
the design drawings.
(b) The design
drawings shall be clear, legible, and drawn to a standard scale which permits
all necessary information to be plainly shown.
(c) The design
drawings shall not be larger than 24 inches by 36 inches in dimension.
(d) A vertical datum
shall be indicated and, if different from the national geodetic vertical datum
of the United States Geological Survey (USGS), its relationship thereto shall
be noted.
(e) For any test
borings:
(1) The
locations of the test borings shall be shown on the plans; and
(2) Boring logs
and soils sampling protocol shall be included in the specifications.
(f) The design drawings shall include plan views,
elevations, sections and supplementary views which, together with the specifications
and general layouts, provide the working information for the contract and
construction of the works.
(g)
The following information shall be submitted by the engineer:
(1) A
location plan showing the location of all parts of the project with respect to
municipal boundaries and the location and extent of the tributary area within
the project area;
(2) Detail plan
and profile sheets of all proposed sewerage;
(3) Details of
construction of manholes, siphons, and other sewer appurtenances;
(4) General and
detail plans for WWTPs and sewage pumping stations; and
(5) Technical
specifications for all proposed construction.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 703.04 Design
Drawings for Sewerage. Design
drawings for proposed sewerage shall, in addition to meeting the applicable
requirements of Env-Wq 703.01 through Env-Wq 703.03, include the following:
(a) Contour lines at 2-foot intervals and
elevation of existing and proposed project area;
(b) The locations of all streams and other surface waters within the proposed
project area, including their direction of flow and water surface elevations at
the time of survey;
(c) 100-year flood
elevations, if available;
(d) The boundary
lines of the municipality, sewer district, or other area to be sewered;
(e) The location,
size, and direction of flow of all existing and proposed sewers;
(f) Insets and
detail sections with the scale shown directly beneath their subtitles;
(g) Plan and profile
views in which the plan view is placed at the top;
(h) Plans clearly
showing the location of:
(1) All
existing structures affecting the project;
(2) Existing
and proposed sewer outlets or overflows; and
(3) All other utilities in the vicinity of the proposed
sewerage;
(i) The locations of
existing, proposed, and future sewerage as differentiated by appropriate
symbols or designations;
(j) All
topographical symbols and conventions as employed by the USGS;
(k) The horizontal
distance or stationing between manholes,
grades in feet per foot, and sewer sizes, types, and class;
(l)
All sewer appurtenances depicted by symbols and referenced by a legend,
with detail drawings of all sewer appurtenances accompanying the detail
sewerage plans;
(m) Profiles
indicating:
(1) All manholes
with manhole identification numbers;
(2) Existing
and proposed water main crossings with elevations;
(3) Siphons;
(4) Sewage
pumping stations; and
(5) In the case
of stream crossings, the elevations of stream beds, flow lines, and the type of
pipe;
(n) The sizes and
gradients of sewers, surface elevations, first floor house elevations, and
sewer inverts shown at or between each manhole;
(o) Profiles
including borings and groundwater level and, except for special details, drawn
to standard scales, indicated on each sheet;
(p) Finish grade
elevations;
(q) Elevations of manhole
inverts shown to the nearest 0.01 foot;
(r) All elevations
referenced to a standard datum that is indicated on the plans; and
(s) As specified by the engineer, any special precautions
or methods of construction necessary to prevent surface water pollution.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 703.05 Design
Drawings for Sewage Pumping Stations.
Design drawings for proposed sewage pumping stations shall, in addition
to meeting the applicable requirements of Env-Wq 703.01 through Env-Wq 703.04,
include the following:
(a) Existing sewage
pumping station locations and elevations;
(b) The location(s)
and elevation(s) of all proposed sewage pumping station(s), including
provisions for installation of future pump(s) if required to meet full
build-out of the service area.
(c) Test boring logs
and groundwater elevations; and
(d) 100-year and
500-year flood elevations, if applicable.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
703.06 WWTP Plans. Design drawings for proposed WWTPs or modifications
to existing WWTPs shall, in addition to meeting the applicable requirements of
Env-Wq 703.01 through Env-Wq 703.05, include the following:
(a) A location plan that shows the WWTP in
relation to the sewerage, including topographic features to indicate its
location in relation to streams and the point of effluent discharge; and
(b) Layouts of the proposed WWTP or proposed
modifications to an existing WWTP that include the following:
(1) Topography
of the site using 2-foot contours;
(2) Dimensions,
elevations, and location of all existing and proposed WWTP structures;
(3) Site
boundaries including areas reserved for future expansion and all buildings or
building lots within 600 feet of WWTP property;
(4) A process
and instrumentation diagram showing the flow of sewage, sidestream flows, and
sludge through the WWTP units;
(5) Piping,
including any arrangements for bypassing individual units and the materials
handled and direction of flow through pipes;
(6) Hydraulic
profiles showing the annual average, maximum day, and peak instantaneous flow
elevations;
(7) The high
and low water level elevations of the water body to which the WWTP effluent
discharges or is proposed to discharge, including the 25-year and 100-year flood
elevations;
(8) A summary of WWTP and unit process design
criteria, capacity, and sizing; and
(9) A description of any features not otherwise
covered by the technical specifications or reports.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 703.07 Sewer
Connection Permit.
(a) In addition to
any other local or state requirements, any person proposing to construct or
modify any of the following or any combination of the following shall submit an
application for a sewer connection permit to the department:
(1) Any extension of a collector or interceptor,
whether public or private, regardless of flow;
(2) Any wastewater connection or other discharge
in excess of 5,000 gallons per day (gpd);
(3) Any wastewater connection or other discharge
to a WWTP operating in excess of 80 percent design flow capacity or design
loading capacity based on actual average flow or loadings for 3 consecutive
months;
(4) Any industrial wastewater connection or
change in existing discharge of industrial wastewater, regardless of quality or
quantity;
(5) Any sewage pumping station greater than 50
gpm or serving more than one building; or
(6) Any proposed sewer that serves more than one
building or that requires a manhole at the connection.
(b) The applicant shall provide the following on
a sewer connection permit request form obtained from the department:
(1) The name of
the municipality;
(2) The length,
size, and location of the extension,
if applicable, and the connection to the existing collection system;
(3) The quantity or flow rate of the proposed
wastewater discharge;
(4) A request for department authorization to add
the proposed wastewater discharge to the municipal sewage collection,
treatment, and disposal system;
(5) A statement as to whether the receiving
sewerage and WWTP suffer from hydraulic surcharging or overloads;
(6) A statement as to whether the proposed sewer
connection meets with the approval of the appropriate local authorities;
(7) The signature and title of the municipal
official who is authorized to sign on behalf of the municipality; and
(8) Such additional information as may be required
under Env-Wq 305 for industrial wastewater discharges.
(c) The
applicant shall remit the permit review fee or design review fee in the amount
specified in RSA 485-A:4 with the sewer connection permit application and
applicable engineering plans.
(d) The department
shall issue a sewer connection permit or permit extension only if the receiving
WWTP and the receiving sewerage are, or will
be, capable of adequately processing the added hydraulic flow and organic load
at the time of connection.
(e) A sewer connection permit shall be valid for
3 years from the date of issuance.
(f) Upon written request by a permittee that
includes the information required by (b), above, the department shall grant a
maximum of one permit extension for 2 years from the date of issuance, if the
receiving WWTP and the receiving sewerage are, or will be, capable of
adequately processing the added hydraulic flow and organic load at the time of
connection.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 703.08 Project
Revision and Approval Requirements.
(a) For projects
that receive any state or federal funds, the owner shall obtain written approval
of the design plans and specifications from the department prior to bidding the
project.
(b) For all other
projects, the owner shall:
(1) Submit the design plans and specifications at
least 30 days prior to the anticipated start of construction, as per RSA
485-A:4, VI; and
(2) Obtain written approval of such plans and
specifications prior to commencing construction, as per RSA 485-A:4, IX.
(c) No deviations
from approved plans or specifications shall be made without prior written
approval from the department in accordance with this chapter. All deviations from the original approved
plans or specifications shall be reflected in the record drawings.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 703.09 Contract
and Bidding Requirements. Owners of
projects that may receive state or federal funds shall comply with all
applicable requirements of Env-Wq 500.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
PART Env-Wq
704 DESIGN OF SEWERAGE
Env-Wq 704.01 Type
of Sewerage.
(a) All new sewerage
and extensions of existing sewerage shall be designed as separated sanitary and
storm systems.
(b) Rain water from
roofs, streets, and other paved areas, and groundwater from foundation drains,
geothermal systems, and sump pumps shall be excluded from the sanitary sewer.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.02 Design
Period.
(a) Sewerage pipes
and structures other than pumping facilities shall be designed to accommodate
flows anticipated for the projected 50-year build-out of the project service
area.
(b) Sewerage pumping
facilities shall be designed to accommodate flows anticipated for the projected
20-year build-out of the project service area.
(c) Anticipated
flows shall be calculated using population projections based on historical
population data from the United States Census Bureau for no less than 20 years prior
to filing the application.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.03 Design
Flow Basis.
(a) For facilities
that were in operation on March 25, 2006, sanitary waste flows from
residentially-, commercially-, or industrially-zoned areas shall be measured.
(b) For proposed
facilities, sanitary waste flows shall be estimated on the basis of the
following:
(1) For commercial areas, recreational facilities
or industrial parks, as specified in Tables 3-3, 3-4, and 3-5 of Metcalf and Eddy/AECOM, “Wastewater
Engineering Treatment and Resource Recovery”, 5th edition, available as noted
in Appendix B, unless design for a lower flow can be justified based on actual
flow records or implementation of water conservation measures; and
(2) For residential areas, an average daily per
capita flow as specified in Table 3-2 of Metcalf and Eddy/AECOM, “Wastewater
Engineering Treatment and Resource Recovery”, 5th edition, available as noted
in Appendix B, unless design for a lower flow can be justified based on actual
flow records or implementation of water conservation measures.
(c) New sewerage
shall be designed to carry the peak hourly flow rate at full pipe capacity,
calculated as the product of the average daily flow rate for the service area
multiplied by a peaking factor. For
gravity sewers, an infiltration allowance shall be added in accordance with
(f), below.
(d) Peaking
factors for average daily flow rates in excess of 100,000 gpd shall be as
derived from Figure 2.1 of TR-16 Guides for the Design of Wastewater Treatment
Works, New England Interstate Water Pollution Control Commission, 2011 Edition,
available as noted in Appendix B. A
peaking factor of 6 shall be used for average daily flows less than 100,000
gpd.
(e) Design of interceptor sewers shall be based on the greater of the estimated future
peak contributory flow from the collection system served or 2.5 times the
estimated future average daily flow of the tributary system.
(f) Infiltration
allowance for the design of gravity sewers shall be as follows:
(1) For areas to be sewered in the future, an
infiltration allowance of 150 gpd per acre shall be used;
(2) For sewers under design, an allowance of 300
gallons per inch diameter per mile per day shall be made; or
(3) For sewers in use as of March 25, 2006
intended to be connected by the collector sewer or interceptor sewer under
design, infiltration shall be measured during high spring groundwater
conditions.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.04
Details of Design and Construction of Gravity Sewers.
(a) A gravity sewer
may be smaller than 8 inches in nominal diameter only if the sewer:
(1) Is constructed on a dead-end or cul-de-sac
street;
(2) Serves, or is planned to serve, no more than
10 residences;
(3) Has a
total estimated flow no greater than 2,000 gpd; and
(4) Has a nominal diameter of 6 inches and a
minimum pipe slope of 0.01 feet per foot.
(b) Sewers shall be buried
to a minimum depth of 6 feet below grade in all roadway locations and to a
minimum depth of 4 feet below grade in all cross-country locations.
(c) Sewers shall be
designed and constructed at such slopes as to prevent deposition of solids,
with a minimum flow velocity for design purposes of 2 feet per second when
flowing full.
(d) The minimum allowable slope shall be as set
forth in Table 704-1, below:
Table 704-1 Minimum Pipe Slope
|
Nominal Pipe Diameter (Inches) |
Minimum Slope (feet/foot) |
|
8 |
0.0040 |
|
10 |
0.0028 |
|
12 |
0.0022 |
|
14 |
0.0017 |
|
15 |
0.0015 |
|
16 |
0.0014 |
|
18 |
0.0012 |
|
21 |
0.0010 |
|
24 |
0.0008 |
|
27 |
0.0007 |
|
30 |
0.0006 |
|
36 |
0.0005 |
|
42 |
0.0004 |
|
48 and larger |
0.0003 |
(e) The slope requirements set forth in (d),
above, shall not be met by using sewers that are larger than required based on
design flow calculations.
(f) Sewers smaller than 48 inches in nominal diameter shall be laid with
straight alignment between manholes.
(g) When a smaller sewer joins a larger one, the
invert of the larger sewer shall be lowered sufficiently to maintain the same
hydraulic gradient. An approximate
method which may be used for securing these results is to place the 0.8 depth
point of both sewers at the same elevation.
(h) A reduction in the size of the outgoing sewer
from a manhole shall be allowed only on sewers larger than 24-inch diameter and only if the capacity of
the outgoing sewer is not exceeded.
(i) Where velocities
greater than 10 feet per second are anticipated, the design shall incorporate pipe anchors on steep sections and
eliminate the potential for hydraulic jumps.
Velocities shall be calculated based on the peak hourly flow and
hydraulic elements related to the depth of flow.
(j) Sewers on 15 percent slopes or greater shall
be securely anchored.
(k) Sewers crossing
streams or located within 10 feet of a stream embankment shall be protected
against erosion.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.05
Gravity Sewer Construction Materials. The technical specifications shall specify
the approved gravity sewer pipe and materials to be used on the project, as
follows:
(a) Ductile iron
pipe and fittings shall be certified by the manufacturer(s) as conforming to
the following standards of the American Water Works Association (AWWA) in
effect at the time that the pipes or fittings are manufactured:
(1) AWWA C151/A21.51 for ductile iron pipe, centrifugally cast in
metal- or sand-lined molds, for water, wastewater, and reclaimed water systems;
and
(2) AWWA C150/A21.50 for thickness design of
ductile iron pipe and with ASTM A536 for ductile iron castings;
(b) Joints shall be
mechanical type, push-on type, or ball-and-socket type as appropriate for the
specific application;
(c) Plastic gravity
sewer pipe and fittings shall be
certified by the manufacturer as complying
with the standards listed in Table 704-2, below, as in effect when the pipes
were manufactured:
TABLE 704-2 Plastic Pipe
|
ASTM
Standard |
Generic
Pipe Material |
Sizes
Approved |
|
D3034 |
Polyvinyl chloride (PVC),
solid wall |
8-inch through 15-inch (SDR
35) |
|
F679 |
PVC, solid wall |
18-inch through 60-inch
(T-1 & T-2) |
|
F794 |
PVC, profile, dual-walled
corrugated |
4-inch through 48-inch |
|
F1760 |
PVC, recycled,
non-pressure |
All diameters |
(d) Plastic sewer pipe shall have a pipe stiffness
rating of at least 46 pounds per square inch at 5 percent pipe diameter deflection, as measured by the
manufacturer in accordance with the ASTM D2412 standard in effect when pipe was
manufactured;
(e) Joint seals for PVC pipe shall be oil resistant
compression rings of elastomeric material and certified by the manufacturer as
conforming to the ASTM D3212 standard in effect when the joint seals were
manufactured, and shall be push-on, bell-and-spigot type;
(f) Concrete pipe
shall be certified by the manufacturer as
conforming to the AWWA C302 standard
in effect when the pipe was manufactured;
(g) Pre-stressed
concrete cylinder pipe and fittings shall be
certified by the manufacturer as conforming
to the AWWA C301 standard in effect when pipe was manufactured; and
(h) Joints for concrete cylinder pipe shall be made of oil
resistant elastomeric material and certified by the manufacturer as conforming
to the AWWA C301 standard in effect
when pipe was manufactured.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.06
Gravity Sewer Pipe Testing.
(a) All new gravity
sewers shall be tested for water tightness by the use of low-pressure air
tests.
(b) Low-pressure air
testing shall be in conformance with the following testing standards in effect
at the time the test is conducted:
(1) ASTM F1417 “Standard Test Method for
Installation Acceptance of Plastic Gravity Sewer Lines Using Low-Pressure Air”,
available as noted in Appendix D; or
(2) Uni-Bell PVC Pipe Association Uni-B-6,
“Low-Pressure Air Testing of Installed Sewer Pipe”, available as noted in
Appendix D.
(c) All new gravity
sewers shall be:
(1) Cleaned and visually inspected using a lamp
test and by introducing water to determine that there is no standing water in
the sewer; and
(2) True to line and grade following installation
and prior to use.
(d) All plastic sewer
pipe shall be visually inspected and deflection tested not less than 30 days
nor more than 90 days following installation.
(e) The maximum
allowable deflection of flexible sewer pipe shall be 5% percent of average
inside diameter. A rigid ball or mandrel
with a diameter of at least 95% of the average inside pipe diameter shall be
used for testing pipe deflection. The deflection test shall be conducted
without mechanical pulling devices.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
704.07 Details of Design and
Construction of Force Mains and
Pressure Sewers.
(a) Force mains for constant speed pumps shall be
sized to yield a cleansing velocity of 3 feet per second or greater at design
pump capacity.
(b) Force mains for variable speed pumps shall be
sized to yield a velocity of 2 feet per second or greater at average daily
design flow.
(c) Force mains shall be 4 inches or larger in
nominal diameter.
(d) Pressure sewers shall be 1.5 inches or larger
in nominal diameter.
(e) Minimum allowable pressure sewer pipe sizes
and corresponding flow rates shall be as set forth in Table 704-3, below:
Table 704-3:
Minimum Pipe Size and Flow Rate for Pressure Sewers
|
Number of Connections Served |
Estimated Peak Flow, gpm |
Minimum Pipe Size, inches |
|
1 to 3 |
15 |
1.5 |
|
4 to 10 |
20 |
2 |
|
11 to 30 |
30 |
3 |
|
31 to 150 |
90 |
4 |
(f) Pressure sewers for grinder pumps shall be
sized to yield a velocity of 2 feet per second or greater at design pump
capacity.
(g) To prevent air locking, force mains shall be
provided with an automatic air relief valve at each
(h) Force mains shall enter the gravity sewer
system at the flow line of the receiving manhole.
(i) Force mains shall be provided with a drainage
blow-off at each low point that:
(1) Has a
properly valved connection for a vacuum truck or other suitable containment
device; and
(2) Is
installed within a manhole structure that meets the design requirements of Env-Wq
704.12 through Env-Wq 704.17, with sufficient space for handling the displaced
waste without danger of pollution or health hazard.
(j) Force mains shall be designed in accordance
with Env-Wq 704.07, constructed with materials as specified in Env-Wq 704.08,
and tested as specified in Env-Wq 704.09.
(k) Pressure sewers shall be designed in
accordance with Env-Wq 704.07 and Env-Wq 704.20, constructed with materials as
specified in Env-Wq 704.08, and tested as specified in Env-Wq 704.09.
(l) Thrust blocks made from inorganic,
corrosion-resistant material shall be placed at all bends, elbows, tees, and
junctions.
(m) Force mains shall be designed to withstand
instantaneous hydrostatic pressures of at least 2.5 times the design total
dynamic head or at least 100 psi, whichever is greater.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.08 Force
(a) Force mains and
pressure sewers shall be constructed of ductile iron (DI), high density
polyethylene (HDPE), or PVC material.
(b) Force mains and
pressure sewers shall be treated as gravity sewers for purposes of foundation
bedding and backfill requirements.
(c) PVC pipe used
for force mains and pressure sewers shall be certified by its manufacturer as
conforming to the ASTM D2241 or ASTM D1785 standards in effect when the pipe is
manufactured.
(d) HDPE pipe used for
force mains and pressure sewers shall be certified by its manufacturer as
conforming to the ASTM D3035 standard in effect when the pipe is manufactured.
(e) If DI pipe is
used in an environment that could cause corrosion or other deterioration of or
damage to an iron pipe, or otherwise reduce the typical life expectancy of the
pipe, such as may occur with certain soil types, low pH levels, or water
conditions, the pipe shall be protected against corrosion, such as with
cathodic protection.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.09 Force
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.10 Grinder
Pumps for Pressure Sewers.
(a) A pressure sewer
system shall have at least one grinder pump at each building or residence that
is connected to the system.
(b)
The minimum capacity requirements for each grinder pump connected to a
pressure sewer system shall be determined based on hydraulic modeling of the entire pressure
sewer system and the main sewer to which the pressure sewer is proposed to be
connected.
(c) Grinder pumps
for pressure sewer systems shall be:
(1) Wet well type;
(2) Readily removable without manual
disconnection of piping;
(3) Rotating type with a stationary hardened and
ground stainless steel shredding ring with stainless steel cutters;
(4) Capable of reducing all components in typical domestic sewage,
including a reasonable number of foreign objects, including but not limited to
wood, paper, plastic, glass, and rubber, to a size that will pass through pump
passages and a 1.25-inch nominal diameter pipe;
(5) Positioned so solids are fed into pump from
the bottom in an upward flow;
(6) Capable of processing foreign objects without
jamming, stalling, or overloading;
(7) Accessible for maintenance and replacement;
(8) Installed within a manhole meeting the
requirements of Env-Wq 704.12 through Env-Wq 704.17 or in a tank meeting the
requirements of Env-Wq 704.10(d); and
(9) Equipped with:
a. Non-fouling sensing devices for high level
alarms;
b. A visible alarm light; and
c. An audible alarm.
(d) A grinder pump
tank shall consist of:
(1) A manhole meeting the requirements of Env-Wq
704.12 through Env-Wq 704.17;
(2) A reinforced concrete tank meeting HS-20
requirements;
(3) A high density polyethylene tank; or
(4) A fiberglass-reinforced polyester resin using
a filament wound process, layup and spray technique.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.11 Trench
Construction.
(a) Pipe
trench bedding material for excavation below grade shall be screened gravel or
crushed stone meeting the ASTM C33/C33M stone size No. 67 standard in effect
when the stone is used, available as noted in Appendix D.
(b) Subject to (c),
below, the pipe sand blanket material shall be graded sand free from organic
materials, graded such that 100 percent passes a ½-inch sieve and a maximum of
15 percent passes a #200 sieve.
(c) In lieu of the
sand blanket specified in (b), above, a stone envelope 6 inches thick
completely around the pipe using ¾-inch stone may be used.
(d) Pipe bedding
material shall extend from a horizontal plane through the pipe axis to 6 inches
below the bottom of the outside surface of the pipe.
(e) Pipe sand blanket
material shall cover the pipe a minimum of 12 inches above the crown of the
outside surface.
(f) Compaction shall
be in 12-inch layers for bedding and blanket materials.
(g) Backfill
material shall be compacted in no more than 3-foot thick layers to the ground
surface except for road construction where the final 3 feet shall be compacted
in no more than 12-inch thick layers to the road base surface.
(h) Trench backfill
material in roadway locations shall be natural materials excavated from the
trench during construction, excluding:
(1) Debris;
(2) Pieces of
pavement;
(3) Organic
matter;
(4) Top soil;
(5) Wet or soft
muck;
(6) Peat or
clay;
(7) Excavated
ledge material;
(8) Rocks over
6 inches in the largest dimension; and
(9) Any
material not approved by the engineer.
(i)
Trench backfill at cross-country locations shall be as described in (h),
above, except that top soil, loam, muck or peat may be used provided the
completed construction will be stable, and provided that access to the sewer
for maintenance and reconstruction is preserved.
(j) Backfill shall
be mounded 6 inches above original ground at cross country locations.
(k) Base course for
trench repair shall meet the requirements of Division 300 of the “Standard Specifications for
Road and Bridge Construction” of the
(l)
Where sheeting is placed alongside the pipe and extends below
mid-diameter, the sheeting shall be cut off and left in place to an elevation
not less than one foot above the top of the pipe and at least 3 feet below
finished grade.
(m) Trenches for
sewer pipes with slopes over 0.08 feet per foot, trenches for sewer pipes below
seasonal high ground water level, and trenches for sewer pipes downstream of
and within the hydraulic influence of waterways or wetlands shall have
impervious trench dams constructed every 300 feet to prevent potential
disturbance to pipe bedding and blanket materials.
(n) Precautions
shall be taken to avoid groundwater pooling at the surface by providing
drainage to a suitable outlet at catch basins or run-off swales.
(o) For trenches for
sewer pipes in ledge, excavation shall extend to at least 12 inches below the
bottom of the sewer pipe.
(p) All sewers shall
be marked using metal-impregnated marking tape or tracer wire that can be
located using metal detection equipment.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.12 Manholes:
General Construction Requirements.
(a) All component
parts of manhole structures shall have the strength, leak resistance, and space
necessary for the intended service.
(b) Manhole
structures shall have a life expectancy of at least 25 years.
(c) Manhole
structures shall be designed to withstand HS-20 loading and shall not leak in
excess of one gpd per vertical foot of manhole for the life of the structure.
(d) Barrels, cone
sections, and concrete grade rings shall be constructed of precast reinforced
concrete.
(e) Base sections
shall be of monolithic construction to a point at least 6 inches above the
crown of the incoming pipe.
(f) Horizontal joints between sections of precast
concrete barrels shall be of an overlapping type, sealed for water-tightness using a double row of an elastomeric or mastic-like sealant.
(g) Pipe to manhole joints shall be as follows:
(1)
Elastomeric, rubber sleeve with watertight joints at the manhole opening
and pipe surfaces;
(2) Cast into the
wall or secured with stainless steel clamps;
(3) Elastomeric
sealing ring cast in the manhole opening with seal formed on the surface of the
pipe by compression of the ring; and
(4) Non-shrink
grouted joints where watertight bonding to the manhole and pipe can be
obtained.
(h) Manhole cone sections shall be eccentric in
shape.
(i) All precast sections and bases shall have the
date of manufacture and the name or trademark of the manufacturer impressed or
indelibly marked on the inside wall.
(j) All precast sections and bases shall be
coated on the exterior with a bituminous damp-proofing coating.
(k) Manholes that are not replacing existing
manholes shall have a brick paved shelf and invert constructed to conform to
the size of pipe and flow. At changes in
direction, the inverts shall be laid out in curves of the longest radius
possible tangent to the center line of the sewer pipes. Shelves shall be constructed to the elevation
of the highest pipe crown and sloped to drain toward the flowing through
channel. Underlayment of invert and
shelf shall consist of brick masonry.
Inverts and shelves shall be placed after testing of the manhole.
(l) Replacement manholes where there is an
established line and grade through which the sewer enters and exits the manhole
shall have:
(1) A brick
paved shelf and invert constructed to conform to the size of pipe and flow as
required in (k) above;
(2) A precast
concrete shelf and invert with the shelf constructed to the elevation of the
highest pipe crown and sloped to drain toward the flowing through channel; or
(3) A
fiberglass insert with the shelf constructed to the elevation of the highest
pipe crown and sloped to drain toward the flowing through channel.
(m) When manhole
depth is less than 6 feet, a reinforced concrete slab cover may be used in lieu
of a cone section, provided the slab has an eccentric entrance opening and be
capable of supporting HS-20 loads.
(n)
The minimum internal diameter of manholes shall be 48 inches. For sewers larger than 24-inch diameter,
manhole diameters shall be increased so as to provide at least 12 inches of
shelf on each side of the sewer.
(o) In the flow
channel, a drop of at least 0.1 feet shall be provided between incoming and outgoing
sewers on all manholes.
(p) Slope across
manholes shall be the average slope of the incoming and outgoing sewers. Design shall include measures to prevent
hydraulic jumps across the manholes.
(q) Watertight
manhole covers shall be used for all manholes located in flood-prone areas as
determined by the municipality.
(r) Electrical
equipment installed or used in manholes shall conform to the National Electric
Code (NEC) adopted by reference in the state building code pursuant to RSA
155-A:1, IV, for installation in areas classified by the NEC as Class 1,
Division 1.
(s)
Precast bases shall be placed on a 6-inch layer of compacted bedding
material that conforms to the ASTM C33/C33M No. 67 stone standard in effect
when the stone is processed by the manufacturer, available as noted in Appendix
D. The excavation shall be dewatered
while placing bedding material and setting the base or pouring concrete.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
704.13 Manholes: Materials of Construction.
(a) Materials of construction for manholes shall
be as follows:
(1) Concrete
for manholes and concrete grade rings
shall conform to the requirements for class AA concrete in the
(2) Reinforcing for concrete manholes and
concrete grade rings shall be steel or structural fibers that conform to the
(3) Precast
concrete barrel sections, cones, and bases shall be certified by their
manufacturer(s) as conforming to the ASTM C478 standard in effect at the time
the barrel sections, cones, and bases are manufactured;
(4) The manhole
frame and cover shall provide a 30-inch diameter clear opening;
(5) The manhole
cover shall have the word “SEWER” in 3-inch letters cast into the top surface;
(6) The
castings shall be of even-grained cast iron, smooth, and free from scale,
lumps, blisters, sand holes, and defects;
(7) Contact
surfaces of covers and frames shall be machined at the foundry to prevent
rocking of covers in any orientation;
(8) Castings
shall be equal to class 30 and certified by their manufacturer as conforming to
the ASTM A48/48M standard in effect at the time the castings were manufactured;
(9) Brick masonry for shelf, invert, and grade
adjustment shall be certified by its manufacturer as complying with the ASTM C32 standard in
effect at the time the brick is manufactured, clay or shale, for grade SS hard
brick, with no more than 5 layers of brick for grade adjustment;
(b) Materials of
construction for manhole grade adjustment shall be as follows:
(1) Grade
adjustment rings shall be constructed with either Grade SS hard brick that has
been certified by its manufacturer as meeting the ASTM C32 standard in effect
at the time the brick was manufactured or reinforced concrete meeting the
requirements of this section;
(2) Grade
adjustment rings shall:
a. Be sized to the opening of the manhole; and
b. Not obstruct the access to the manhole.
(c) Mortar used in
manhole construction shall comply with the following:
(1) Mortar shall
be composed of Type II Portland cement and sand with or without hydrated lime
addition;
(2) Proportions
in mortar of parts by volumes shall be as shown in table 704-4:
Table 704-4: Proportions of
Cement, Sand, and Hydrated Lime
|
Hydrated Lime |
Sand |
Type II Portland Cement |
|
None |
4.5 parts |
1.5 parts |
|
0.5 part |
4.5 parts |
one part |
(3) Cement shall be type II Portland cement that
is certified by its manufacturer as conforming to the ASTM C150/C150M standard in
effect at the time the cement was manufactured;
(4) Hydrated lime shall be type S that is
certified by its manufacturer as conforming to the ASTM C207 standard in effect
at the time the hydrated lime was processed;
(5) Sand shall consist of inert natural sand that
is certified by its supplier as conforming to the ASTM C33 standard in effect
at the time the sand is processed by “Standard Specifications for Concrete,
Fine Aggregates”; and
(6) Concrete for drop supports shall conform to
the requirement for class AAA concrete of the
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.14 Manholes:
Steps. Manhole steps shall:
(a) Be permitted only at the request of the
system owner;
(b) Be manufactured of stainless steel, plastic-covered steel, or plastic;
(c) Be shaped so that they cannot be pulled out
of the concrete wall into which they are secured;
(d) Be certified by the manufacturer as meeting
the ASTM C478 standard in effect at the time the manholes were manufactured for
load carrying capacity and pull-out resistance;
(e) Not be secured with mortar;
(f) Be approximately 14 inches by 10 inches in
dimension;
(g) Have a drop section or raised abutments to
prevent sideways slippage off the step; and
(h) Have non-skid safety serrations on the foot
contact surfaces.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
704.15 Manholes: Placement. Manholes shall be located as follows:
(a) Manholes shall be installed at the end of each
gravity sewer, force main, and pressure sewer, at all intersections, and at all
changes in grade, size, or alignment.
(b) For gravity sewers only, in establishing a
maximum space between manholes, the engineer shall not exceed the distance that
can be cleaned by the cleaning equipment the owner already has on hand or
proposes to obtain. In no case shall the
distance between manholes be greater than the distances shown below in Table
704-5:
Table 704-5: Manhole Spacing Requirements
|
Sewer Diameter, inches |
Maximum Distance between Manholes, feet |
|
less than 15 |
300 |
|
15-30 |
400 |
|
greater than 30-48 |
500 |
|
>48 |
1,000 |
Source. (See Revision Note at chapter heading for Env-Wq
700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
704.16 Manholes: Drop Entry Construction Requirements.
(a) The invert of
the incoming pipe shall be no more than 6 inches above the invert of the
outgoing pipe unless a drop entry pipe is used.
(b) Sewer slopes
shall be adjusted to avoid differences in incoming and outgoing pipe inverts
greater than 6 inches unless a drop entry pipe is used. Invert differences greater than 6 inches and
less than 24 inches shall be eliminated by adjusting the sewer slope.
(c) A drop entry
pipe shall be provided for any sewer entering a manhole at an elevation of 24
inches or more above the manhole invert.
The drop pipe may be constructed internal or external to the manhole.
(d) The maximum size
limits and number of internal drop pipes within a manhole shall be as shown in
table 704-6, below:
Table 704-6: Size Limits and Number Requirements for
Internal Drop Pipes
|
Manhole Diameter |
Internal Drop Pipe Size |
Number of Pipes Required |
|
4-foot, 0-inch |
8-inch or 10-inch |
1 |
|
5-foot, 0-inch |
15-inch |
1 |
|
8-inch or 10-inch |
2 |
Source. (See Revision Note at chapter heading for Env-Wq
700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.17 Manholes: Testing.
(a) Manholes shall
be tested for leakage using a vacuum test in accordance with the ASTM C1244 standard
in effect when the testing is performed, available as noted in Appendix D. A manhole may be backfilled prior to
performing a vacuum test, but if the manhole fails the vacuum test, backfill
shall be removed so repairs to the manhole can be made from the outside of the
manhole prior to retesting.
(b) The manhole vacuum test shall conform to the following:
(1) The initial
vacuum gauge test pressure shall be 10 inches Hg; and
(2) The minimum
acceptable test hold time for a 1-inch Hg pressure drop to 9 inches Hg shall
be:
a. Not less
than 2 minutes for manholes less than 10 feet deep in depth;
b. Not less
than 2.5 minutes for manholes 10 to 15 feet deep; and
c. Not less
than 3 minutes for manholes more than 15 feet deep;
(c) The
manhole shall be repaired and retested if the test hold times fail to achieve
the acceptance limits specified in (b), above.
(d) Inverts and shelves shall not be installed until after
successful testing is completed.
(e) Immediately following completion of the leakage test, the frame
and cover shall be placed on the top of the manhole or some other means used to
prevent accidental entry by unauthorized persons, children, or animals, until
the contractor is ready to make final adjustment to grade.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.18
Inverted Siphons.
(a) Inverted siphons
shall have not less than 2 barrels with a minimum pipe size of 6 inches.
(b) Maintenance
manholes and appurtenances shall be provided at both ends of the siphon to
facilitate convenient flushing and maintenance of the siphons.
(c) Pipe sizes and a
hydraulic head shall be selected to secure velocities of at least 3.0 feet per
second for average design flows in each siphon.
(d) The inlet and
outlet details shall be arranged so that flow can be diverted to one barrel, so
that either barrel may be taken out of service.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.19 Protection
of Water Supplies.
(a) There shall be
no physical connection between a public or private potable water supply system
and any sewerage such that sewage or polluted water could pass into the potable
supply. No water pipe shall pass through
or come in contact with any part of any sewer or sewer manhole.
(b) No sewer shall
be located within the applicable well protective radii established in Env-Dw
300 for any public water supply well or within 75 feet of any private water
supply well.
(c) Sewers shall be
located at least 10 feet horizontally from any existing or proposed water main.
(d) A deviation from
the separation requirements of (b) or (c), above, shall be allowed where
necessary to avoid conflict with subsurface structures, utility chambers, and
building foundations, provided that the sewer is constructed with force main
construction materials that meet the requirements in Env-Wq 704.08.
(e) Whenever sewers must cross water mains, the
sewer shall be constructed as follows:
(1) Vertical separation of the sewer and water
main shall be not less than 18 inches, with water above sewer; and
(2) Sewer pipe joints shall be located at least 6
feet horizontally from the water main.
Source. (See Revision Note at chapter heading for Env-Wq
700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 704.20 Service
Connections.
(a) Service
connections shall use sanitary tee or wye fittings for all new sewer
construction.
(b) The centerline of
all building connections shall enter the top half of the sewer.
(c) Any service
connection with a vertical rise up to 4 feet may have the sewer fitting set
vertically.
(d) Any service
connection with a vertical rise up to 12 feet shall employ non-encased risers
that protect against pipe penetration or failure at the fitting by the use of
bell-on-bell connections.
(e) For existing
sewers where fittings cannot be installed, saddle connections shall be used.
(f) Pressure
sewerage shall have an isolation valve or curb stop valve installed at the
property line. If a check valve is used at the property line, the valve shall
be installed within a vault to facilitate maintenance.
(g) Roof downspouts,
exterior or interior foundation drains, sump pumps, or other sources of surface
water run-off or groundwater shall not be directly or indirectly connected to a
public sewer.
Source. (See Revision Note at chapter heading for Env-Wq
700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
PART Env-Wq 705 SEWAGE PUMPING STATIONS
Env-Wq 705.01 Sewage
Pumping Station Design Requirements:
Flooding and Weather Protection.
(a) Sewage pumping
stations shall be designed for uninterrupted operation during a 25-year flood, and
shall be protected against damage from a 100-year flood. The sewage pumping station shall be readily
accessible.
(b) Flood elevations
shall be determined using flood maps or in accordance with Env-Wq 1503.09
(f)(1) and (f)(2).
(c) Each sewage
pumping station shall be protected against extreme weather conditions, such as
excessive heat or humidity or excessively cold temperatures, that could cause
the pump station components to stop functioning.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 705.02 Sewage Pumping
Station Design Requirements: Wet Well
and Dry Well Construction.
(a) The wet well and
the discharge manifold shall be configured to prevent grit from settling back
into pump discharge lines of pumps that are not operating.
(b) Wet and dry
wells including their superstructure shall be completely separated and sealed.
(c) Wet well design
shall avoid vortexing and air entrainment near the pump suction intakes.
(d) A separate sump
pump shall be provided in the dry well to remove leakage or drainage, with the
discharge above the alarm level of the wet well.
(e) Wet wells for
sewage pumping stations of greater than 200 gpm capacity shall have either:
(1) Division walls so that the station can be
kept in operation when work is required in the wet well; or
(2) A bypass connection to allow for connection
of a pump around the wet well for maintenance, repairs and construction.
(f) The effective
capacity of the wet well shall be based on the cycle time of the pumps for
constant speed operation so as to prevent short cycling of the pumps.
(g) The wet well
floor shall have a minimum slope of 1 to 1 to the hopper bottom.
(h) The horizontal
area of the hopper bottom shall be limited to that area required for proper
installation and function of the inlet.
(i) Wet wells shall
be tested prior to operation using exfiltration testing method ACI 350.1 Method
HST-NML in effect at the time the wet well is installed, available as noted in
Appendix D. Any visible signs of leakage
shall be repaired and retested prior to placing the wet well in service.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 705.03 Sewage Pumping Station Design
Requirements: Allowable Pump Types, Pump
Controls and Pump Size.
(a) The following
types of sewage pumping stations shall be allowed:
(1) Dry well/wet well type design with pumps and
drives located in a separate dry chamber with flooded suctions;
(2) Suction
lift type with pumps and drives in a separate dry chamber; and
(3) Submersible
type with pumps submerged.
(b) A minimum of 2 pumps, each designed to handle
peak hourly flows, shall be provided.
(c) Where 3 or more
pumps are provided, they shall be designed such that, with any one unit out of
service, the remaining units shall have the capacity to handle peak hourly
sewage flows.
(d) The use of
jockey pumps shall be evaluated to optimize the efficiency of the pumping
station operation.
(e) All
pumps shall be protected from damage due to large solid objects.
(f) Pumps shall be
capable of passing 3-inch solids, or 2.5-inch solids if preceded by a grinder
unit.
(g) Submersible
pumps shall be capable of removal without disconnecting pipes or dewatering and
reseating using non-corroding guide rails or cables.
(h) Self-priming
suction lift pump systems shall be designed such that:
(1) The system’s reprime capacity is greater than
the static suction head; and
(2) The system’s available net positive suction
head is at least 6 feet greater than the required net positive suction head.
(i) Pumps shall be
protected by check valves from being driven in the reverse direction.
(j) Pump controls
shall provide autostart of lag pump should lead pump fail to start.
(k) Flooded suction
pumping systems shall be designed such that:
(1) Shut-off
valves are provided in the suction piping;
(2) Shut-off
valves and check valves are provided in the discharge piping; and
(3) Discharge
shut-off valves are located downstream of the check valve.
(l)
Shut-off and check valves for submersible pumps shall be placed in a
separate chamber for ease of maintenance.
Source. (See Revision Note at chapter heading for Env-Wq
700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 705.04 Sewage Pumping Station Design
Requirements: Pump Station Access. Sewage pumping stations shall meet the
following requirements:
(a) Dry wells shall provide
accessibility for the repair and removal of pumps, motors, and other items of
equipment that are essential to the sewage pumping process;
(b) Separate
exterior entrances shall be provided to both wet wells and dry wells of sewage
pumping stations;
(c) For
built-in-place sewage pumping stations, access to lower levels shall be by
stairways with handrails;
(d) Prefabricated
stations may have ladders with less than or equal to a 75 degree slope or
spiral stairs;
(e) Vertical
distances between floors or rest landings shall not exceed 12 feet;
(f) Safety barriers
to prevent falling shall be provided at landings;
(g) Power elevators proposed for all deep
stations shall have a capacity limit of not less than 600 pounds;
(h) Lifting equipment
shall be provided for submersible pump removal; and
(i) Lifting chains
shall be stainless steel or other corrosion resistant material.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
705.05 Sewage Pumping Station Design Requirements: Flow and Pump Usage
Measurement.
(a) Sewage pumping
stations with capacities of more than 250 gpm or equipped with variable speed pumps
shall have continuous flow recording and totalizer capability.
(b) Sewage pumping
stations equipped with constant speed pumps with capacities of 250 gpm or less
shall have:
(1) A running meter that indicates the cumulative
running time of each pump; or
(2) The continuous flow recording and totalizer
capability as per (a), above.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
705.06 Sewage Pumping Station Design Requirements: Potable Water Restrictions
and Protection.
(a) Where potable
water is used for pump sealing purposes, the potable water supply shall be
protected by a break tank or reduced pressure zone back flow preventer.
(b) Water ejectors
connected to a potable water supply shall be prohibited.
(c) All floor and
walkway surfaces shall slope to a point of discharge.
(d) Connections between
raw, partially treated, or fully treated sewage and potable water shall be
prohibited unless adequate backflow prevention equipment is installed.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 705.07
Sewage Pumping Station Electrical Requirements.
(a) Submersible
pumps for sewage pumping stations shall conform to the NEC requirements adopted
by reference in the state building code pursuant to RSA 155-A:1, IV, for
installation in areas classified by the NEC as class I, division 1.
(b) Electrical
systems and components, including motors, lights, cable, conduits, switch
boxes, and control circuits shall be protected from flooding in accordance with
Env-Wq 705.01.
(c) Electrical
systems and components including motors, lights, cable, conduits, switch boxes
and control circuits in enclosed or partially enclosed spaces where flammable
mixtures occasionally may be present, including raw sewage wet wells, shall be
certified by their manufacturer as:
(1) Complying with the NEC requirements adopted
by reference in the state building code pursuant to RSA 155-A:1, IV, for class
I, division 1 locations; or
(2) Being rated for class I division 2
requirements where mechanical ventilation is provided in accordance with the
NFPA as adopted by reference in the state fire code in Saf-C 6000.
(d) All electrical equipment
and work shall comply with the requirements of NEC as adopted by reference in
the state building code pursuant to RSA 155-A:1, IV, and NFPA as adopted by
reference in the state fire code in Saf-C 6000 in effect at the time of
installation.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
705.08 Sewage Pumping Station
Ventilation Requirements.
(a) Mechanical ventilation for personnel and
equipment shall be provided for all occupied spaces within sewage pumping
stations in accordance with the NFPA as incorporated by reference in the state
fire code in Saf-C 6000.
(b) Mechanical ventilation for below-grade dry
wells shall be provided, so arranged as to independently ventilate the dry well
and the wet well.
(c) There shall be no interconnection between the
wet well and dry well ventilation systems.
(d)
Switches for operation of ventilation equipment shall be marked and located
conveniently.
(e) Dehumidification
shall be provided in below-ground dry wells.
(f) Ventilation of
wet wells shall provide at least 30 air changes per hour if the ventilation
system is operated intermittently, or at least 12 air changes per hour if the
ventilation system is operated continuously.
(g) Fans installed
within the wet well structure shall be suitable for a class I, division 1,
group C and D environment.
(h) Ventilation of submersible
pump chambers or suction lift wet wells where there is no occupancy for regular
maintenance purposes may be by gravity ventilation.
(i) Ventilation
exhaust from wet wells shall not cause an odor nuisance to the public or
surrounding occupied buildings.
(j) Access doors to
wet wells shall have warning signs on the underside which read, “Warning -
Hazardous Area, enter only with proper equipment” or “Confined Space, Entry by
Permit Only”, as appropriate.
(k) The ventilation
system of the dry well shall be capable of continuously providing at least 6
air changes per hour when the facility is occupied, and at least 3 air changes
per hour when not occupied.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 705.09 Sewage Pumping Station Alarm Systems.
(a) Alarm systems
meeting the requirements of (b) through (j), below, shall be provided for all
sewage pumping stations.
(b) The alarm signal shall be activated in any
one of the following circumstances and in any combination of the following
circumstances:
(1) High water in the wet well;
(2) Low water in wet well;
(3) Loss of one or more phases of power supply or
severe voltage drop;
(4) High water level in the pump room sump;
(5) Loss of the alarm transmission capability;
(6) Standby generator application, if applicable;
(7) Pump malfunction, including shaft seal
failure;
(8) Loss of air pressure in a bubbler tube
system;
(9) Level sensing malfunction or failure;
(10) Loss of ventilation in areas classified as
class 1 division 2 and using mechanical ventilation per the NFPA as
incorporated by reference in the state fire code in Saf-C 6000;
(11) Intrusion; or
(12) Temperature outside normal operating ranges.
(c) The high water
and low water alarm triggers shall be separate devices, independent of the pump
wet well level control system and set at elevations above and below the lag
pump on and off elevations, respectively.
(d) Operation of the
alarm system shall be indicated on a panel with a light which lights up upon
activation of the alarm system.
(e) The power source
for the alarm system shall be:
(1) An independent battery with continuous
charge; or
(2)
(f) The
alarm signal shall be transmitted through a 24 hour per day, 7 day per week notification
system to the appropriate utility operator.
(g) The alarm shall
include a local audible enunciator and a light.
(h) Provision shall
be made to permit silencing of the audible enunciator manually, after the alarm
has been sounded, but the light shall continue until the alarm condition has
been rectified.
(i) Alarm signals
for privately-operated sewage pumping stations shall be transmitted to the
responsible maintenance person directly or via an answering service.
(j) If a central
supervisory control and data acquisition (SCADA) system exists at the WWTP, the
pumping station alarms shall be connected to the SCADA system using
programmable logic controller (PLC) technology.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 705.10 Sewage Pumping Station Operation and Maintenance Manual.
(a) The owner shall submit an operation and maintenance manual that provides
information and guidance for day-to-day operation of each sewage pumping
station to the department within 60 days following substantial completion of
construction of the pump station.
(b) The operation and maintenance manual required
by (a), above, shall include all information that is necessary to operate and
maintain the specific equipment at the pumping station, including but not
limited to the following:
(1) Information
on process design assumptions;
(2) Unit
process information that includes detailed process descriptions, control
measures and monitoring procedures for processes, if applicable;
(3) Start-up
procedures for each unit operation as applicable and each piece of equipment;
(4) Maintenance
management systems;
(5) Laboratory
test procedures;
(6) Safety
procedures;
(7)
Organizational structure and administrative procedures;
(8)
Troubleshooting procedures;
(9) Emergency
operation plan;
(10) Staffing
requirements;
(11) Process and
instrumentation diagrams;
(12) Checklists
for systems and components for the operator’s use in developing a maintenance
program for pump stations;
(13) Utility
emergency contact information;
(14) Staff
training and licenses necessary for the chief operators and assistant
operators;
(15) A list of
each chemical used at the pump station and what the chemical is used for,
together with the applicable material safety data sheet (MSDS); and
(16) Equipment
supplier manuals.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 705.11 Sewage Pumping Station Emergency Operation.
(a) The engineer shall
recommend emergency operation procedures to prevent the back-up, overflow, or
other unpermitted discharge of wastewater from the sewage pumping station.
(b) An independent engine-generator type source
of electric power shall be provided for electrically-driven pumps. This source shall be automatically activated
by failure of any phase of power supply or upon any fluctuation in voltage, the
amount or duration of which would cause damage to the motors. Installations shall comply with all
applicable requirements of the NEC and
the state fire code in Saf-C 6000.
(c) The emergency power generator shall be
permanently secured in place, with provisions for removal to facilitate
generator repair or replacement.
(d) Provisions shall be made for automatic and
manual start-up and cut-in. The controls
shall be such that upon automatic start-up under emergency conditions,
shut-down shall be accomplished automatically on restoration of utility power
with controlled shut-down of unit.
Manual shut down shall also be provided.
Provision shall be made to allow pumps to run down before re-energizing
on transfer of power.
(e) The emergency power generator shall be sized
to sequentially start and operate all pumps needed to handle design maximum waste flows, plus lighting,
ventilation, controls, screening, and, if applicable, grinding.
(f) The emergency
power generator shall be located above grade with ventilation of exhaust gases.
(g) All emergency
power generation equipment shall be provided with instructions for routine
exercising, load testing, and maintenance.
(h) The generator
engine controls shall be equipped with an automatic exerciser which can be set
on any selected schedule to start the generator, run the generator under
no-load or load conditions by selection, and shut the generator off without
actuating the alarm system.
(i) Subject to (j),
below, the owner shall provide each emergency generator with enough fuel
for the generator to run under full load
or peak station flow for at least 48 hours or under normal operating conditions
for at least 96 hours, whichever requires the greater amount of fuel.
(j)
Alternatives to a generation set may be provided in the following
circumstances:
(1) Sewage pumping stations with capacities of 100
gpm or less may use wet well storage over and above normal operating system
storage provided that:
a. The additional wet well storage volume below
all entering and exiting piping shall provide at least 6 hours of flow
detention at average daily flow; and
b. A suitable receptacle shall be included in
the electrical supply panel for connection to a portable generator with manual
transfer; and
(2) For sewage pumping stations with duplex pumps,
a standby engine drive system which automatically starts on power loss to drive
one pump may be furnished as an alternative to a permanent generator.
(k) Sewage pumping
station by-passes shall not discharge raw sewage either overland or to any water
course.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
PART Env-Wq
706 SITING OF WWTPs
Env-Wq 706.01 WWTP
Location.
(a) WWTPs shall be
located and designed such that the impact of possible odor problems and safety
and health problems to the adjacent properties are minimized to the extent
practicable.
(b) Factors to
consider when siting a WWTP shall include, but not be limited to, the
following:
(1) The type of WWTP to be constructed and the
level of odors that typically are generated by that type of WWTP;
(2) The current and projected land use
surrounding the proposed site;
(3) The current and projected population surrounding
the proposed site;
(4) The direction of prevailing winds in relation
to populated areas;
(5) The proposed location’s susceptibility to
flooding;
(6) Regionalization options of WWTPs for sewage
and septage receiving;
(7) Impacts to surface waters, wetlands, habitat,
and wildlife, including any threatened or endangered species;
(8) Traffic impacts on surrounding areas;
(9) Potential for effluent reuse; and
(10) Such additional information as is collected
for the environmental review required by Env-Wq 500, if applicable.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 706.02 Buffer
Distances. Buffer distances shall be
as follows:
(a) Wastewater
treatment ponds shall be located not closer than 600 feet from any residence;
and
(b) Processing units
in a conventional WWTP shall be located not closer than 300 feet from any
residence.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 706.03 Flooding.
(a) WWTPs shall be:
(1) Designed to provide for uninterrupted
operation of all process units during a 25-year flood; and
(2) Be placed above or otherwise protected
against damage from a 100-year flood.
(b) Flood elevations
shall be determined using flood maps or in accordance with Env-Wq 1503.09
(f)(1) and (f)(2).
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 706.04 Effluent
Quality. The degree of treatment provided
at a WWTP shall be designed to meet the effluent discharge limitations and
water quality standards established by applicable provisions of:
(a) The state
surface or ground water discharge permit;
(b) Env-Wq 1700,
relative to surface water quality standards;
(c) The federal
surface water discharge permit; or
(d) The Clean Water
Act.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
PART Env-Wq 707 BASIS OF DESIGN REPORTS FOR WWTPs
Env-Wq 707.01 Basis
of WWTP Design.
(a) The WWTP design
shall provide flexibility for operating within the expected range of wastewater
characteristics and volumes.
(b) A pilot test
that complies with Env-Wq 717.04 shall be conducted for a proposed treatment
technology if:
(1) Effluent permit limits are at or near the
limits of the proposed treatment technology;
(2) Anticipated wastewater characteristics:
a. Are not typical of those commonly received by
a WWTP due to low- or high-strength effluent, high strength sidestreams, or
industrial waste contributions; and
b. Have a recognized potential to adversely
affect the performance of the proposed treatment process; or
(3) Extreme weather or population fluctuations
have a recognized potential to adversely affect the technology’s performance.
(c) The owner shall
submit a basis of design report as described in Env-Wq 707.02 through
Env-707.07 to the department for review and approval prior to final design.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 707.02 Basis
of Design Report: Project Planning.
Relative to general WWTP information and project planning, the basis of
design report shall include a description or analysis of:
(a) Character and
use of the receiving waters;
(b) Location and
topography of the WWTP site, including:
(1) Scale maps and topographical maps depicting
natural boundaries in the project area and any existing service areas; and
(2) Photographs of the project area and any
existing service areas;
(c) Population
trends and anticipated future growth, by including with the basis of design
report population projections based on historical population data from the
United States Census Bureau for no less than 20 years prior to submission of
the basis of design report, if available;
(d) Environmental
resources present using maps, photographs and narrative description as
available; and
(e) A public
participation and education plan; including:
(1) Education relative to need for the project;
(2) Utility operational service levels required;
and
(3) Funding and revenue strategies to be used.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 707.03 Basis
of Design Report: Existing Facilities. For existing facilities, the basis of design
report shall include a description or analysis of:
(a) Existing
facilities, including:
(1) Condition of existing facilities, including:
a. Adequacy of current facilities;
b. Suitability for continued use;
c. Conveyance, treatment, storage and disposal
capabilities;
d. Existing capacity of each component;
e. Analysis of overall current energy
consumption; and
f. Reference an asset management program, if
applicable;
(2) Location maps of existing facilities;
(3) Schematic process layout of all existing
facilities;
(4) Summary of recurring compliance issues; and
(5) History of major system components,
including:
a. Operational history;
b. Renovations; and
c. Expansions;
(b) Current
financial status of existing facilities, including:
(1) Current rate schedules;
(2) Annual operation and maintenance costs with a
breakout of current energy costs;
(3) Other capital improvement programs;
(4) Tabulation of users by monthly usage
categories for the most recent fiscal year; and
(5) Status of existing debts and required reserve
accounts;
(c) Water, energy,
or waste audits and outcomes thereof, if applicable;
(d) Existing and
projected flow;
(e) Flow
composition, waste strength and peaking factors based on historical records, if
records exist;
(f) If no records
exist, domestic waste strength and peaking factors based on:
(1) An average daily per capita contribution of
0.20 pounds of TSS and 0.17 pounds of BOD5, if garbage grinders are not prevalent in the
area;
(2) An average daily per capita contribution of
0.25 pounds of TSS and 0.22 pounds of BOD5, if garbage grinders are
prevalent in the area;
(3) An average daily per capita contribution of
0.04 pounds of total nitrogen;
(4) An average daily per capita contribution of
0.006 pounds of total phosphorous; and
(5) Not less than 70 gallons of flow per capita
per day nor more than 100 gallons of flow per capita per day;
(g) For process-related upgrades to existing
WWTPs, or where sampling of the future influent wastewater stream is possible,
the sampling results for the following influent wastewater parameters from
plant records for the previous 2 years or, if such data is not available, from
sampling designed by the engineer to produce representative results:
(1) Biochemical Oxygen Demand (BOD5);
(2) Total Suspended Solids (TSS);
(3) pH;
(4) Temperature;
(5)
Total Kjeldahl Nitrogen (TKN);
(6) Alkalinity;
(7) Chemical Oxygen Demand (COD), as applicable; and
(8) Total Phosphorous, as applicable;
(h) Industrial
wastes, if present, quantified and characterized as follows:
(1) Use an industry-by-industry chemical analysis
from existing pretreatment programs including conventional pollutants (BOD5
and TSS), nutrients, pH, and non-conventional parameters potentially present in
the waste stream; or
(2) In the absence of
existing pretreatment programs, full waste characterization shall be performed;
and
(i) Septage
receiving and treatment capacity, based on:
(1) The septage volume and characterization
expected to be received during the planning period of the WWTP;
(2) Septage strength of 6,500 mg/L BOD5,
12,900 mg/L TSS, 590 mg/L total Kjeldahl nitrogen (TKN), and 210 mg/L total
phosphorous, if specific data is not available; and
(3) Appropriate peaking factors to account for
seasonal variations in septage quantities from the specific service area.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 707.04 Basis
of Design Report: Project Need. For existing and proposed projects, the basis
of design report shall address the need for the project based on a description
or analysis of the following:
(a) Conditions
requiring improvements;
(b) The design
period for the WWTP, which shall be not less than 20 years unless a
shorter design period is shown to be more cost effective when taking into
consideration construction of additional facilities needed to meet the peak
demand of the 20-year design period.
(c) The design period evaluation shall include:
(1) An evaluation of future expansion requirements
in excess of the planning period, when laying out and designing major treatment
units and WWTP hydraulics;
(2) Design flows for domestic, commercial,
industrial and infiltration/inflow (I/I) flows, as applicable;
(3) Stormwater flows, for WWTPs with combined
sewers within the service area;
(4) Design flow values, including the following:
a. Annual average flows;
b. Peak hourly flow;
c. Maximum daily flow;
d. Maximum monthly flow;
e. Minimum monthly flow; and
f. Minimum daily flow;
(5) Total influent TSS and BOD5
loading, calculated as the sum of domestic, commercial, industrial, and septage
loads throughout the design period of the WWTP; and
(6) A mass balance, performed as follows:
a. The mass balance shall be prepared for
average conditions and appropriate peaking factors used for peak design
conditions;
b. The mass balance shall include BOD5
and TSS loadings for each appropriate process and for all side streams;
c. The mass balance shall include nutrient
loadings when the WWTP is designed for nutrient removal; and
d. Sidestream flows returned to the liquid
treatment process as the result of sludge, scum, or other floatable matter processing
shall be characterized as to solids and organic content, with the
characterization being included in the design loadings for both liquid and
solids treatment processes;
(d) Relative to WWTP
hydraulics, the basis of design report shall address the following:
(1) Hydraulic profiles of each treatment process
on the design drawings indicating water surface elevations for peak hourly and
annual average design flows against 25-year flood and average levels of the
receiving waters;
(2) Hydraulic design under peak hourly flow
conditions, including associated sidestream flows, to be passed through the
WWTP with the largest or longest flow path of each unit process removed from
service;
(3) Design allowance for maximum flows to pass
through the WWTP when and if the largest pump or other piece of mechanical
equipment is out of service; and
(4) A minimum velocity of 2.0 feet per second at
design annual average flow and 1.5 feet per second at minimum flow in channels
carrying unsettled wastewater unless wastewater is managed to prevent
sedimentation of solids;
(e) Present and
proposed future discharge permit limits, if any; and
(f) The effect on
the wastewater treatment process of industrial wastes likely to be encountered
in the influent waste stream.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 707.05 Basis of Design Report: Treatment Technology Options Considered. For each treatment technology option
considered, the basis of design report shall include a description or analysis
of:
(a) The facilities associated with each proposed
treatment technology option;
(b) Design
calculations and parameters used for sizing the unit processes and components
for evaluation purposes to demonstrate compliance with all applicable federal
and state design requirements;
(c) Environmental
impacts, including:
(1) Direct and indirect impacts on floodplains,
wetlands, land resources, endangered species, and properties of historical and
archeological significance;
(2) Generation and management of residuals and
wastes; and
(3) Sprawl-related impacts;
(d) Sustainable
utility management practice considerations, including:
(1) Water and energy efficiency, including:
a. Water reuse and conservation;
b. Energy efficient design to reduce electrical
demand and minimize carbon footprint, including:
1. Blower and pump sizing to provide
energy-efficient operation at a full range of flow rates;
2. Use of premium efficiency motors;
3. Installation of heat recovery systems; and
4. Use of biogas capture and reuse if digesters
are proposed;
c. Renewable energy generation, if applicable to
the treatment technology option; and
d. Water and energy usage of each option as
compared to other treatment technology options;
(2) Aspects of project that preserve or mimic
natural processes to manage onsite stormwater, if applicable to the treatment
technology option; and
(3) Site management of stormwater runoff volume
and peak flows through infiltration, evapotranspiration, harvest and use, if
applicable.
(e) Ultimate sludge
disposal plans, including contingency plan as required by Env-Wq 716 for sludge
stabilization, sludge thickening, and sludge dewatering; and
(f) Estimates of
capital and operating costs for each treatment technology option, including:
(1) Construction costs;
(2) Total project costs;
(3) Average annual operation and maintenance
costs over the life of the project; and
(4) Energy costs.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 707.06 Basis
of Design Report: Life Cycle Comparison
of Treatment Technology Options. For
life cycle comparison of treatment technology options, the basis of design
report shall include a description or analysis of:
(a) Capital,
operation and maintenance costs, including energy costs;
(b) Life cycle
comparison over a 20-year planning period unless an alternative length planning
period is justified;
(c) Discount rates, based
on the discount rate set forth in Appendix C of OMB circular A-94 available at www.whitehouse.gov/omb/circulars/a094/a94_appx-c.html;
(d) Present worth analysis
using total project cost including construction and non-construction costs;
(e) Average annual
operation and maintenance costs over the life of the project, converted to
present day dollars using a uniform series present worth calculation;
(f) Deductions of
the present worth of the salvage value;
(g) Net present
value calculations for each evaluated treatment technology option; and
(h) Non-economic
factors such as social and environmental aspects; including, but not limited
to:
(1) Reliability;
(2) Operational complexity;
(3) Expandability; and
(4) Sustainability.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 707.07 Basis
of Design Report: Proposed Project –
Recommended Treatment Technology.
The basis of design report shall include a recommended treatment
technology and a description or analysis of:
(a) The selected
treatment technology, explaining justification for making the selection over
other available treatment technology options;
(b) Design criteria
summary;
(c) Site layout and
hydraulics profile;
(d) Treatment
process schematics;
(e) Cost summary;
(f) For a proposed
modification or addition to an existing WWTP, a construction sequence for
maintaining WWTP operations and permit compliance during construction and
testing; and
(g) An overall
project schedule from design through completion of construction that also
includes the meetings between the owner, design engineer, and department review
staff required by Env-Wq 707.08 and any additional meetings considered
necessary by the owner and design engineer.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 707.08 Meetings
Required.
(a) The owner and
design engineer shall meet with department review staff:
(1) At or prior to project initiation for the purpose
of outlining project scope and goals; and
(2) Upon completion of the basis of design report
for the purpose of reviewing report recommendations, department comments on the
report, and project progression plans.
(b) If one or more
meetings with the department in addition to those included in the project
schedule are considered necessary for the project progression by the owner and
design engineer, the design engineer shall contact department review staff to
schedule such meeting(s).
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
PART Env-Wq 708 ADDITIONAL WWTP REQUIREMENTS
Env-Wq 708.01
Installation and Initial Operation. For items of equipment that are essential to
the treatment process, the owner shall have a
representative of the manufacturer:
(a)
Inspect
the installation; and
(b) Supervise the
initial operation.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.02 Required
Redundancy.
(a) Standby units
shall be provided for all critical components.
(b) For pumps and other
critical hydraulic components, the WWTP shall have one standby unit for every 3
units, or fraction thereof, required to handle peak design flow or load.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.03 Planning
for Unit Process Maintenance and Dewatering Required.
(a) The WWTP shall
be designed to facilitate unit process maintenance such that:
(1) Each unit of the WWTP can be removed from
service independently;
(2) The design facilitates WWTP operation during
unit maintenance and emergency repair so as to minimize deterioration of
effluent quality;
(3) Solids retention, sludge handling, and
disinfection are addressed as specified in this chapter; and
(4) WWTP by-passes that allow raw or
insufficiently treated sewage to be discharged directly to a water course are
prevented.
(b) For WWTP upgrade
or expansion, the technical specifications prepared per Env-Wq 703.02 shall
include a detailed description of how to maintain existing WWTP operations,
delineating the suggested construction sequence and number of units to be
removed from treatment operation.
(c) A means of unit
isolation and dewatering shall be provided for each process unit.
(d) Each tank shall
be protected against flotation.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.04 Piping
and Flow Distribution Devices.
(a) Piping and
channels throughout the WWTP shall be designed to carry the maximum design
flows as follows:
(1) Gravity influent sewers shall not be
surcharged during normal operating conditions;
(2) Bottom channel corners shall be filleted,
with the elimination of pockets and corners where solids can accumulate;
(3) Suitable gates, stop logs, or plates shall be
placed in channels to seal off unused sections that might accumulate solids;
(4) Non-corrodible materials shall be used for
gates; and
(5) Channels that may not be used for
considerable periods of time shall have valved drains.
(b) Flow distribution
devices shall be designed to:
(1) Control organic, solids, and hydraulic
loading to WWTP process units;
(2) Provide distribution to individual treatment
units to ensure equal distribution among all units;
(3) Provide visible status indication for
influent flow to each unit via weirs, sluice gates, slide gates, control
valves, or other means;
(4) Provide positive scum and foam removal in all
channels and distribution structures that have a trapped-free surface; and
(5) Not rely on effluent weirs and flow route
symmetry for flow control.
(c) Underflow shear
gates for balancing flows shall not be permitted.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.05 WWTP
Design and Layout. In addition to
complying with applicable federal, state, and local building requirements, the
design and layout of WWTPs, including building interiors and mechanical layouts,
shall include provisions for future expansion and upgrades as follows:
(a) Locations of
foreseeable future facilities shall be indicated on the construction drawings;
(b) WWTP hydraulics,
sizing of conduits connecting unit processes, and flow distribution shall
provide for future expansion; and
(c) Plugs, blind
flanges, sluice gates, and valving shall be designed to facilitate expansion
with minimal disruption to operating facilities.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.06 Design
and Layout of Chemical Feed Equipment: Storage Requirements. General equipment design shall meet the
following criteria so as to allow for the continuous supply of accurate amounts
and rates of chemicals throughout the range of feed requirements:
(a) Materials and
surfaces that will come in contact with chemicals or solutions thereof shall be
resistant to the chemicals and their solutions, with corrosive chemicals being
introduced in a way that minimizes the potential for corrosion;
(b) Chemicals that
are incompatible shall not be stored or handled together;
(c) Liquid chemical
storage tanks in excess of 55 gallons shall have a liquid level indicator and:
(1) An overflow and a contained receiving basin;
or
(2) A drain capable of receiving and containing
accidental spills or overflows equal in volume to 110 percent of the storage
tank capacity;
(d) All liquid chemical
storage tanks shall be properly labeled;
(e) The day tank or
solution tank, if provided, shall provide a means to maintain a uniform
solution strength;
(f) Overflow pipes
shall:
(1) Have a submerged discharge to a containment
vessel;
(2) Be visible to the operator under normal
operating conditions; and
(3) Be marked to designate the pipe’s origin tank
and the chemical being conveyed;
(g) Acid storage
tanks shall be vented to the outside atmosphere, with each tank having a
separate vent and a valved drain to protect against backflow;
(h) Carts,
elevators, hoists, and other appropriate means for lifting chemical containers
shall be provided;
(i) Provision shall
be made for the proper transfer of dry chemicals from shipping containers to
storage bins or hoppers, in a way that minimizes dust entering the room where
the equipment is installed;
(j) Ventilation or
personal protection, or both, shall be provided to prevent operator exposure to
dust and chemicals, whether in the storage, transfer or application areas;
(k) Vents from
feeders, storage facilities, and equipment exhaust shall discharge to the
outside atmosphere above grade and away from air intakes; and
(l) Interior floor drains
in chemical storage areas shall discharge to a holding tank.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.07 Design
and Layout of Chemical Feed Equipment: Feed Requirements.
(a) A separate
feeder shall be used for each chemical applied.
(b) Chemical feeders
shall be manually and automatically controlled with the automatic controls
designed to allow override by the manual controls.
(c) Chemical feed
rates shall be adjustable based on appropriate control parameters.
(d) Dry chemical
feeders shall measure chemicals volumetrically or gravimetrically and provide
adequate solution water and agitation of the chemical in the solution tank.
(e) Water supply for
chemical feed applications, when needed, shall be sufficient in quantity and
pressure for the intended application.
(f) A means of
measuring supply water shall be provided when preparing specific solution concentrations
by dilution.
(g) The water supply
shall be treated as necessary to ensure compatibility with its intended use.
(h) Chemical feed
equipment shall be located in a dedicated room or area to reduce hazards and
dust problems.
(i) The length of
feed lines shall be minimized by locating the equipment as close to the
application point(s) as practical.
(j) The chemical
feed equipment shall be accessible for servicing, repair, and observation of
operation.
(k) Feed lines shall
be:
(1) As short as possible;
(2) Easily accessible along the line’s entire
length;
(3) Protected from freezing;
(4) Readily cleanable; and
(5) Color coded and labeled.
(l) Color coding of
WWTP piping and chemical feed lines shall:
(1) For upgrades to existing plants, comply with
either the existing WWTP color coding system or section 4.4.5 of TR-16, 2011
Edition, available as noted in Appendix B; and
(2) For all new WWTPs, comply with color codes
specified in section 4.4.5 of TR-16, 2011 Edition, available as noted in
Appendix B.
(m) When conveying
gases, the feed lines shall slope upward from the chemical source to the
feeder.
(n) Provision shall
be made for measuring quantities of chemicals used to prepare feed solutions.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.08 Operation
and Maintenance Manuals.
(a) Operation and maintenance manuals providing
information and guidance for day-to-day operation of the WWTP shall be
submitted to the department within 60 days following substantial completion of
construction of the WWTP.
(b) The operation and maintenance manuals
required by (a), above, shall include all information that is necessary to
operate and maintain the specific equipment at the WWTP, including but not
limited to the following:
(1) Information
on process design assumptions;
(2) Unit
process information that includes detailed process descriptions and accepted
parameters, control measures and monitoring procedures for the various
processes;
(3) Start-up
procedures for each unit operation and piece of equipment;
(4) Maintenance
management systems;
(5) Laboratory test
procedures;
(6) Safety
procedures;
(7)
Organizational structure and administrative procedures;
(8)
Troubleshooting procedures;
(9) Emergency
operation plan;
(10) Staffing
requirements;
(11) Process
and instrumentation diagrams;
(12) Checklists
for systems and components for the operator’s use in developing a maintenance
program for WWTPs;
(13) Utility
emergency contact information;
(14) Staff
training and licenses necessary for chief operator and assistant operator;
(15) A list of
each chemical used in process and what the chemical is used for, together with
the applicable MSDS ; and
(16) Equipment
supplier manuals.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.09 Site
Access.
(a) WWTP access
roads shall provide access to all delivery and loading points.
(b) Roadway design and
construction details shall be as required for the types of vehicles that will
access the site and in accordance with local and state requirements.
(c) Access to the
site shall be controlled with a perimeter fence and lockable gate(s).
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.10 Site
Grading.
(a) Grading or
drainage systems for the WWTP site shall be designed to handle surface runoff.
(b) All-weather
walkways shall be provided for access to all units.
(c) Surface water
shall not be permitted to drain into any process unit.
(d) Drains and
runoff in areas contaminated by sludge or wastewater shall discharge to the
treatment facilities for processing.
(e) Drainage from
chemical storage and handling areas shall discharge to the WWTF for processing.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.11 Outside
Lighting. Outside units, tanks,
equipment, and work areas shall be lit using energy efficient lighting so as to
allow safe inspection of the facility in all ambient conditions.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.12 Floor
Slope. Floor surfaces shall be
sloped to allow drainage to a point of collection such as a sump or drain.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.13 Access
to Equipment.
(a) Suitable openings,
hatches, or other means shall be provided for removal of machinery and
equipment.
(b) Openings shall
be large enough to allow for removal of the largest piece of equipment or
largest component if equipment is disassembled.
(c) Lifting devices, properly sized for the
required loads, shall be provided for removal of equipment.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.14
Essential Power Requirements for WWTPs.
(a) Subject to (b),
below, power shall be provided at all times to operate essential equipment
including, but not limited to:
(1) Preliminary treatment;
(2) Influent pumping;
(3) Primary treatment;
(4) Critical secondary treatment;
(5) Intermediate pumping;
(6) Other critical treatment processes;
(7) Disinfection;
(8) Effluent pumping;
(9) Lighting and ventilation that is essential to
the safe operation of the WWTP; and
(10) Alarm systems and essential controls.
(b) An owner shall
not be required to provide power to operate all essential components at all
times if the owner develops and obtains department approval for an alternate
load management plan pursuant to (c) and (d), below.
(c) The alternate
load management plan shall contain the following:
(1) A demonstration that the discharge limits set
forth in the WWTP’s discharge permit will continue to be met during the
emergency generator operation;
(2) A description of the electrical load imposed
by various pieces of equipment, ranked by importance and ability to by cycled;
(3) A description of the maximum and minimum
amount of time process equipment can be operated without adversely effecting
wastewater operations; and
(4) A list of equipment that the WWTP cannot run
without operating and demonstrate the available emergency power available for
that minimum load.
(d) The department shall
approve the alternate load management plan if it determines that the plan will
allow the WWTP to operate as needed to not violate its discharge permit.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.15 Instrumentation
and Control Requirements. Any
supervisory control and data acquisition (SCADA) system included in the design
shall have the following minimum capabilities:
(a) Air flow rate
and flow pacing of blowers;
(b) Alarm generation
and history;
(c) Influent flow
history and trending;
(d) Dissolved oxygen
history and trending;
(e) Power monitoring
for main process pumps and motors and blowers and motors, including at a
minimum the ability to monitor:
(1) Power factor data at equipment startup;
(2) Total harmonic distortion; and
(3) Total energy usage;
(f) Return activated
sludge pump flow rate and pacing;
(g) Real time
monitoring and recording of energy use; and
(h) Automated
equipment system monitoring and control for the following, as applicable:
(1) Pumps;
(2) Chemical feed systems;
(3) Disinfection;
(4) Aeration system;
(5) Digester; and
(6) Dewatering.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.16 Essential
Water Supply Requirements for WWTPs.
(a) A pressurized
potable water supply shall be provided for firefighting and use in the WWTP.
(b) No piping or
other connections shall exist in any part of the WWTP or collection system that
might cause the contamination of a potable water supply.
(c) The chemical
quality of the water supply shall be checked for suitability for its intended
uses such as heat exchangers and chlorinators.
(d) Potable water from a municipal or separate supply may
be used directly at points above grade for the following hot and cold supplies with no additional backflow protection:
(1) Lavatory sinks;
(2) Toilets;
(3) Showers;
(4) Drinking fountains;
(5) Laboratory sinks, if protected against back
siphoning; and
(6) Slop sinks, if protected against back
siphoning.
(e) All potable
water supply mains shall be protected against contamination with a
reduced-pressure-zone backflow preventer that meets the requirements of Env-Dw
505, including local approval if required.
(f) Hot water for
any unit cited in (d), above, shall not
be taken directly from a boiler used for supplying hot water to a sludge heat
exchanger, digester heating coils, or
similar process.
(g) Where a public
water supply is not available, a separate drilled well shall be provided as a
potable water supply.
(h) Where a potable
water supply will be used for any purpose other than those listed in (d),
above, a backflow protection device that meets the requirements of Env-Dw 505,
including local approval if required, shall be installed.
(i) Vacuum breakers
shall be installed on the water supply to the laboratory.
(j) The number of
backflow devices required shall be minimized by providing a separate,
non-potable, in-plant water system using a single backflow protection device.
(k) A sign shall be
permanently posted at each hose bib, sill cock, or other fixture on the
non-potable water system indicating that the water is not safe for drinking.
(l) Where break
tanks are used for backflow prevention, water shall discharge to the break tank
through an air-gap at least 6 inches above the maximum flood line or the spill
line of the tank, whichever is higher.
(m) Where a separate
non-potable water supply will be provided, a backflow prevention device shall
not be required.
(n) Hydrants for
fire protection and hydrants for yard use shall:
(1) Be clearly distinguished from one another
with different paint colors; and
(2) Have different-sized nozzles for hose
connections.
(o) Locations of
fire protection hydrants shall be approved by the appropriate local official.
(p) Hydrants fed by
the potable water supply system shall be protected from cross-contamination as
required by the owner of the water system.
(q) Toilets and
showers shall be provided for the projected number of operators with separate
toilets and showers for men and women.
(r) Slop sinks for
general cleaning shall be provided.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.17 Wastewater
Flow Measurement.
(a) Means for measuring,
recording, and totaling both raw influent flow prior to sidestreams and
effluent wastewater flow after WWTP water withdrawal shall be provided.
(b) Provisions for
measuring, recording, and totaling the flow of return activated sludge, primary
sludge, waste secondary sludge, and other major sludge streams shall be
provided.
(c) All flow
measurement equipment shall be:
(1) Sized to perform effectively over the full
range of expected flows; and
(2) Protected against freezing.
(d) Installation of
flow measuring equipment shall be such that the required hydraulic conditions
necessary for accurate measurement are provided.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.18 Sampling.
(a) Sampling sites
shall:
(1) Be readily accessible by WWTP personnel;
(2) Not be located in confined space areas;
(3) Be free of tripping, slipping, and falling
hazards;
(4) Have a supply of electrical power with a
ground fault interrupt; and
(5) Be supplied with batteries or connected to
the emergency power source.
(b) To prevent
freezing, samplers shall be housed in enclosed and, if needed, heated
structures or equipment enclosures designed for outdoor use.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.19 WWTP
Outfalls.
(a) Provision shall
be made for effective dispersion of the effluent into the receiving water body
so as to meet the water quality criteria as specified in Env-Wq 1700.
(b) The outfall pipe
outlet(s) shall be submerged at all times.
(c) The outfall pipe
shall be so constructed and protected against the effects of flood water,
tides, ice, or other hazards as to reasonably ensure its structural stability
and freedom from stoppage.
(d) Outfall pipes
shall not impede or otherwise interfere with navigation.
(e) A manhole shall
be provided at the shore end of all gravity outfall sewers extending into the
receiving stream.
(f) Outfall pipe and
fittings shall be constructed of ductile iron, HDPE, or PVC material.
(g) All ductile iron
pipe shall be corrosion protected if installed in a corrosive environment that
could reduce the typical life expectancy of the pipe.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.20 Safety. The following features shall be incorporated
into the design and construction of WWTPs for the protection of visitors and
facility operations staff:
(a) Hand rails,
guards, safety netting, and barricades around tanks, trenches, pits,
stairwells, floor openings, maintenance access areas, and other hazardous
structures;
(b) Gratings over
areas of treatment units where access for maintenance is required;
(c) First
aid equipment;
(d) Appropriately
placed warning signs and labels as per the NFPA as incorporated by reference in
the state fire code in Saf-C 6000, and
(1) Slippery areas;
(2) Non-potable water fixtures;
(3) Low head clearance areas;
(4) Open service manholes;
(5) Hazardous chemical storage areas
(6) Flammable fuel storage areas; and
(7) Confined spaces;
(e) Personal protective clothing and equipment as per
(1) Eye, ear, and face protection;
(2) Respiratory protection; and
(3) Head, hand, and foot protection.
(f) Gas detectors
for use in occupied areas rated under the NEC, as adopted by reference in the
state building code pursuant to RSA 155-A:1, IV, as Class 1, Division 1, Group A, B, C, and D
locations or areas classified as Class 1 Division 2 through the use of
mechanical ventilation per the NFPA as incorporated by reference in the state
fire code in Saf-C 6000;
(g) Provisions and
equipment for permit-required confined space entry in accordance with
(h) Ventilation of
enclosures in accordance with the NFPA as incorporated by reference in the
state fire code in Saf-C 6000;
(i) Fire protection
systems and equipment; and
(j) Machinery guards
around belts or other moving parts.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.21 Hazardous
Chemical Handling.
(a) The materials
used for storage, piping, valves, pumping, metering, and splash guards shall be
specially selected so as to be compatible with the physical and chemical
characteristics of each hazardous or corrosive chemical that will be used at
the WWTP.
(b) Chemical storage
areas shall be enclosed in dikes or curbs that will contain the stored volume
until the spilled chemical can be safely transferred to alternative storage or
released to the wastewater at controlled rates that will not damage facilities,
inhibit the treatment processes, or contribute to stream pollution.
(c) Eye wash
fountains and deluge showers using potable water shall be:
(1) Provided in the laboratory and on each floor
or work location involving hazardous or corrosive chemical storage, mixing or
slaking, pumping, metering, or transportation loading;
(2) As close as practicable to possible chemical
exposure sites; and
(3) Fully usable during all weather conditions.
(d) Eye wash fountains,
including self-contained eye wash fountains and eye wash stations, and deluge showers shall be designed in
compliance with the ANSI/ISEA Z358.1 standard in effect at the time of the
eye-wash fountain or deluge shower specification and available as noted in
Appendix D. If the water heater system for the eye wash fountains and deluge
showers is not separate from the WWTP hot water supply, mixing valves with
scald protection shall be provided to maintain the required water temperature.
(e) All piping
containing or transporting corrosive or hazardous chemicals shall be identified
with labels every 10 feet and with at least 2 labels in each room, closet, or
pipe chase. Pipes containing hazardous
or corrosive chemicals shall not be located above shoulder level except where
continuous drip collection trays and coupling guards will eliminate chemical
spray or dripping onto personnel.
(f) All pumps,
feeders, connections, and couplings for hazardous or corrosive chemicals shall
have guards that will effectively prevent spray of chemicals into space
occupied by personnel. The splash guards
shall be in addition to guards intended to prevent injury from moving or
rotating machinery parts.
(g) All hazardous
waste generated shall be managed in accordance with RSA 147-A and Env-Hw
100-1100.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.22 Laboratory
Equipment.
(a) Subject to (b),
below, all WWTPs shall include a laboratory and the equipment needed for
wastewater analysis, process control tests, discharge permit tests, and quality
control analysis checks.
(b) If the owner chooses
to not include a laboratory in the WWTP, the owner shall contract with an
outside laboratory for all testing services specified in (a), above.
(c) Laboratories
shall be ventilated in accordance with the NFPA as incorporated by reference in
the state fire code in Saf-C 6000.
(d) Laboratory floor
surfaces shall be slip-resistant and fire-resistant, as well as highly
resistant to acids, alkalis, solvents, and salts.
(e) The laboratory
shall have at least 2 exit doors, with glass windows for easy visibility, to
allow for straight egress. Panic
hardware shall be installed on all doors.
(f) Vacuum break
type faucets shall be supplied for laboratory sinks. Plumbing shall be based on the types of
substances that may be discarded in the drain lines, with acid- or chemical-
resistant waste drain lines being installed as needed.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.23 WWTP
Alarms.
(a)
Alarm systems shall be included to notify WWTP operators of any
circumstance or condition that threatens public health or safety or the ability
of the WWTP to provide adequate treatment of the wastewater in accordance with
the effluent limitations set forth in the discharge permit.
(b) A 24 hour per
day, 7 day per week notification system shall be installed at the WWTP control
room. Where a WWTP is not manned on a 24
hour per day basis, an additional notification system shall be installed at the
police station, fire station, or any other locale having 24 hour per day
manning, including a commercial dispatch service or SCADA enunciation system.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 708.24 Testing. All liquid containing vessels and structures
shall be leak tested prior to operation in accordance with manufacturer’s
recommendations and any applicable industry standards and regulatory
requirements. Any visible signs of
leakage shall be repaired and retested prior to placing the unit in service.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
708.25 Septage Receiving Stations. Any septage receiving station shall have:
(a) Drainage tied into the WWTP process to
prevent run off of spilled septage; and
(b) For gravity off-loading systems, grading such
that septage trucks can be completely off-loaded by gravity.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
PART Env-Wq 709
INFLUENT HEADWORKS
Env-Wq
709.01 Screening Devices:
Location, Operation, and Maintenance.
(a) Each WWTP shall have mechanized screening for
influent sewage that operates continuously or using automated controls.
(b) Any screening device installed in a building
where other equipment or offices are located shall be separated from the rest
of the building and provided with separate outside entrances and mechanical
ventilation.
(c) Each mechanical screening unit shall have
controls that:
(1) Cause the
cleaning mechanism to operate at a predetermined high water level; and
(2) Allow the
mechanism to operate on a timing device.
(d) Facilities for removal, handling, storage,
and disposal of screenings in a sanitary manner shall:
(1) Include an
accessible platform from which the operator can rake screenings easily and
safely if cleaned manually; and
(2) Have drains
for the platform area and all storage areas.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq 709.02 Screening
Devices: Design and Capacity.
(a) Each by-pass screen device shall have clear openings
between bars from 1.0 to 1.75 inches wide.
(b) Clearance between bars on coarse racks or
screens preceding mechanically-cleaned screens may be greater than 1.75 inches.
(c) Manually-cleaned screens shall be:
(1) Designed and
installed to accommodate being cleaned;
(2) Be placed
on a screen slope of 30 to 45 degrees with the horizontal if for non-emergency
use; and
(3) Used only
in by-pass channels.
(d) Clear openings for mechanical screens other
than by-pass screens and preliminary screens or racks shall be ½-inch or less
to maximize removal of inert
material.
(e) For manually-cleaned bar screens, the screen
chamber shall be designed to provide a velocity through the screen of one foot
per second at an average rate of flow calculated from design average daily
flow.
(f) For mechanically cleaned screens, maximum
velocities during wet weather periods shall not exceed 2.5 feet per
second, calculated based on the vertical open cross-sectional area below
the flow line.
(g)
The screen channel invert shall be 3 to 6 inches below the invert of the
incoming sewers. To prevent jetting
action, the length and construction of the screen channel shall provide for a
reestablished hydraulic flow pattern following the drop in elevation.
(h) The capacity of all screening equipment shall
be as follows:
(1) If one unit
is installed, the unit shall be sized to handle peak hourly design flow;
(2) If multiple
units are installed for flexibility of maintenance, the peak hourly design flow
shall be handled by the remaining units with the largest unit out of service;
and
(3) To avoid
excessive head loss and potential damage to very fine screens when very fine
screens are installed, multiple stages of screens with progressively smaller
openings shall be used.
(i)
Influent channels shall be equipped with gates to isolate each screening
device. The channel preceding and
following the screen shall be shaped to eliminate settling of solids.
(j)
Where a single mechanically-operated screening device is used, auxiliary
manually-cleaned screens shall be provided.
The design shall include provisions for automatic diversion of the
entire sewage flow through the by-pass screen if the mechanical unit fails.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
709.03 Grit Removal Facilities.
(a) Grit removal facilities shall be provided for
all WWTPs for protection of downstream processes and equipment.
(b) If grit is removed by a means that causes the
grit to contain excess organics or water, or both, for the method of final grit
disposal to be used, the WWTP shall include grit washing and dewatering
facilities as necessary. Impervious
surfaces with drains shall be provided for grit handling areas. Grit conveying equipment shall be designed to
avoid loss of material and shall be protected from freezing. A pressurized water supply shall be provided
for cleanup.
(c) Where a single mechanically-operated grit
removal device is used, auxiliary manually-operated grit removal equipment
shall be provided. Design shall include
provisions for automatic diversion of the entire sewage flow through the
by-pass grit removal device should the mechanical unit fail.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
709.04 Grinding Facilities. Grinding devices may be used in addition to
screening devices if the following requirements are satisfied:
(a) Grinding devices installed in addition to mechanical
screening devices in a building where other equipment or offices are located
shall be separated from the rest of the building, provided with separate
outside entrances, and provided with mechanical ventilation; and
(b) Grinding devices that are installed in
addition to mechanical screening devices shall have slots no more than ¼-inch
wide and be designed to cut or shred material below the surface of the sewage.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
PART Env-Wq 710
FLOW AND WASTE STRENGTH EQUALIZATION
Env-Wq
710.01 Flow and Waste Strength
Variations. If the WWTP is expected
to experience significant variations in organic or hydraulic loadings, the WWTP
shall incorporate methods and equipment to address the variations by either:
(a) Flow or waste strength equalization; or
(b) Alternate means that will ensure that the
WWTP operates effectively under the varying conditions.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
710.02 Equalization Tank: Location and Size.
(a) Equalization basins shall be located
downstream of pretreatment facilities such as mechanical screens, grinders, and
grit chambers.
(b) Equalization capacity shall be sufficient to
dampen expected flow and strength variations to the extent that is economically
advantageous or justified through a life cycle cost analysis.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
710.03 Equalization Tank: Aeration and Mixing.
(a) Aeration or mechanical mixing equipment shall
be provided to maintain adequate mixing, using corner fillets and hopper
bottoms with draw-offs to alleviate the accumulation of sludge and grit.
(b) Aeration equipment shall be provided to
maintain a minimum of 0.5 mg/L of dissolved oxygen in the mixed basin contents
at all times, with an air supply that is isolated from other WWTP aeration
requirements to facilitate process aeration control.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
710.04 Equalization Tank: Controls and Drainage.
(a) Inlets and outlets for all basin compartments
shall be suitably equipped with accessible external valves, stop plates, weirs,
or other devices to permit flow control and the removal of an individual unit
from service.
(b)
Equalization tanks shall allow the entire tank contents to be drained at a
controlled rate and introduced to the remainder of the treatment process.
(c) Facilities shall be provided to measure and
indicate liquid levels and flow rates.
Source. (See Revision Note at chapter heading for Env-Wq
700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
PART Env-Wq 711
SETTLING
Env-Wq
711.01 Primary Settling Tanks.
(a) Inlets to primary settling tanks shall be
designed to:
(1) Dissipate the
inlet velocity in each tank to prevent short circuiting; and
(2) Distribute
the flow equally to multiple tanks.
(b) Channels in settling tanks shall be designed
to prevent sedimentation. Corner pockets
and dead ends are not permitted and shall be eliminated if they occur.
(c) Provisions shall be made for elimination or
removal of floating materials in inlet structures having submerged ports.
(d) The minimum length of flow from inlet to
outlet in rectangular settling tanks shall be 20 feet.
(e) Primary settling tanks shall have a minimum
side water depth of 12 feet.
(f) Effective scum collection and removal
facilities shall be provided ahead of the outlet weirs on all settling tanks.
(g) Overflow weirs shall be adjustable for leveling.
(h) The tops of troughs, beams, and similar
construction features that are submerged shall have a minimum slope of 1.4
vertical to one horizontal.
(i) If primary settling tanks are part of the
WWTP design, a minimum of 2 primary settling tanks shall be provided.
(j) All primary settling tanks shall provide safe
and easy access for maintenance and protection of operators. Access stairways and elevated walkways shall
be equipped with handrails. Walls of
primary settling tanks shall extend a minimum
of 6 inches above the surrounding ground surface, be provided with safety
railings, and have not less than 12 inches freeboard.
(k) For sludge removal from primary settling
tanks, provision shall be made for:
(1) Sampling
and measuring flow of the sludge; and
(2) For sludge
hoppers in rectangular settling tanks, a 1.7 horizontal to one vertical minimum
slope of the side walls.
(l) Settling tanks designed for use without
mechanical equipment for sludge collection and removal shall be prohibited.
(m) Air lift type of sludge removal shall be
prohibited. Primary sludge shall be
removed from the sludge hoppers by positive displacement pumps with timers for
control of pumping periods.
(n) Average surface overflow rates for primary
settling tanks shall not exceed 600 gpd per square foot (gpd/sf) for WWTPs
having an average design flow of 1 million gallons per day (MGD) or less.
(o) Average surface overflow rates for primary
settling tanks shall not exceed 1,200 gpd/sf for WWTPs having an average design
flow greater than 1 mgd, unless reduced primary removal rates are provided in
the design loadings for subsequent secondary treatment units.
(p) Surface overflow rates for peak hourly flow
shall not exceed 3,000 gpd/sf.
(q) If activated sludge is wasted to the primary
tanks, average overflow rates shall not exceed 800 gpd/sf and peak hourly
overflow rate shall not exceed 1,200 gpd/sf.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
711.02 Secondary Settling Tanks:
Number and Types of Units.
(a) Multiple secondary settling tank units
capable of independent operation shall be provided.
(b) A minimum of 3 independent secondary settling
tanks shall be provided when the average daily
design flow is equal to or greater than 5.0 MGD.
(c) Secondary settling tanks for activated sludge
may be rectangular or circular, and shall be designed to separate and concentrate
mixed liquor, remove settled sludge, and skim, collect, and remove scum and
other floatables.
(d) Secondary settling tank walls shall:
(1) Extend at
least 6 inches above the surrounding ground; and
(2) Provide not
less than 12 inches of freeboard.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
711.03 Secondary Settling Tanks:
Design Criteria for Solids Loading.
(a) Secondary settling tanks shall be designed
integrally with the design of the aeration basins and sludge return
facilities. Secondary settling tank
sizing shall be based on solids loadings, sludge settleability, settled sludge
concentration, and return sludge rates.
(b) Solids loading shall be calculated as
follows:
(1) Peak solids
loading rate shall be computed based on the design mixed liquor suspended
solids (MLSS) under aeration and the design maximum daily flow rate plus the
corresponding recycle rate required to maintain the design MLSS;
(2) Allowable
solids loading rates shall be determined using solids flux analysis, expected
sludge characteristics, and a settling tank factor of safety of 1.3 to 1.5
times the maximum daily flow; and
(3) Settling
tank area shall be determined based on a solids flux analysis as specified in section 6.3.5.4 of TR-16, 2011
Edition, available as noted in Appendix B.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
711.04 Secondary Settling Tanks:
Design Criteria for Overflow Rates.
(a) Subject to (b), below, the design overflow rates
shall be determined from solids flux analysis and solids loadings.
(b) In lieu of (a), above, activated sludge
settling tanks treating domestic wastes may be sized according to Table 711-1
below, wherein overflow rates are based on solids flux with a factor of safety
of 1.3 against settling tank failure, overflow rates for systems with a
selector are based on settling characteristics typical of mixed liquor with a
sludge volume index (SVI) of 150 mL/g, and overflow rates for systems without
selectors are based on settling characteristics typical of a mixed liquor with
a SVI of 200 mL/g:
Table 711-1: Secondary Settling
|
MLSS, mg/L |
Surface Overflow Rates at Critical Loading with SVI
= 150 mL/g, gpd/sf |
Surface Overflow Rates at Critical Loading with SVI
= 250 mL/g, gpd/sf |
|
1,500 |
2,100 |
1,850 |
|
2,000 |
1,710 |
1,450 |
|
2,500 |
1,400 |
1,140 |
|
3,000 |
1,140 |
900 |
|
3,500 |
930 |
690 |
|
4,000 |
760 |
550 |
|
4,500 |
610 |
440 |
|
5,000 |
510 |
340 |
(c) Side water depth for secondary settling tanks
shall be as follows:
(1) For
rectangular units , 12 to 13 feet;
(2) For
circular units up to 40 feet in diameter, 12 feet;
(3) For
circular units 40 feet to 75 feet in diameter, 14 feet;
(4) For
circular units 75 feet to 125 feet in diameter, 16 feet; and
(5) For
circular units greater than 125 feet in diameter, 18 feet.
(d) Circular settling tanks shall have a minimum
bottom slope of 0.25 inches per foot.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
711.05 Secondary Settling Tanks:
Design Criteria for Inlets and Outlets.
(a) Inlets shall be designed to minimize
short-circuiting and to distribute flow across the entire settling tank.
(b) Scum gathering in the inlet area shall be
minimized.
(c) V-notch weirs shall be provided for all
outlets. Head over the base of the
V-notch shall be less than the depth of the notch. Weirs shall be adjustable to correct for any
differential settlement of the tanks.
(d)
Effluent launders shall be designed to convey the maximum instantaneous flow
without surcharging.
(e) Launder inverts shall be sloped a minimum of
0.5 percent.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
711.06 Secondary Settling Tanks: Design
Criteria for Sludge and Scum Removal.
(a) Sludge collection and withdrawal facilities
shall be designed to accommodate the withdrawal of sludge solids.
(b) Circular units shall be designed to allow
alternate sludge wasting and tank drainage from the center of the units.
(c) Rapid sludge removal systems in circular
settling tanks shall be designed so that return rates can be directly varied by
changes in return sludge pumping rates.
Sludge collection tubes on rapid sludge removal systems shall have a
submerged discharge to the center well.
(d) Chain and flight sludge collectors in
rectangular settling tanks shall be designed with a minimum horizontal velocity
of 2 to 3 feet per minute with flights at least 10 feet on center.
(e) Effective baffling to prevent velocity and
density currents within the tank and scum removal equipment shall be provided
in each secondary settling tank. Scum
removal equipment shall facilitate the positive movement of scum to the scum
hoppers.
(f) Scum hoppers shall have provisions to
facilitate the flushing of scum from the hopper.
(g) Scum piping shall be sized for proper
movement of viscous foams.
Source. (See Revision Note at chapter heading for Env-Wq
700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
711.07 Secondary Settling Tanks:
Design Criteria for Return Sludge.
(a) Return sludge rate capabilities shall be designed
to be the greater of 100 percent of maximum month design flow or 150 percent of
annual average day design flow.
(b) At least one return sludge pumping unit shall
be provided for each settling tank. The
maximum required return sludge capacity shall be available with the largest
pumping unit out of service. Pumps may
be placed on suction headers, but the arrangement and valving shall be such
that any one settling tank can be isolated with a single pump.
(c) A positive suction head shall be provided for
all return sludge pumps.
(d) Return sludge pumps shall have at least
3-inch suction and discharge openings.
(e) Rate of sludge return shall be varied by
means of variable speed motors, drives, or timers.
(f) Return sludge suction and discharge piping
shall be at least 4 inches in diameter and designed to maintain a velocity of
not less than 2 feet per second when operating at average sludge return rates.
(g) Suitable devices shall be provided for
sampling and measuring return sludge flow rates. Measuring devices shall totalize and record,
as well as indicate flows.
(h) Capability shall be provided to return and
waste sludge concurrently.
(i) Provisions shall be made for the draining and
flushing of discharge lines.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
711.08 Secondary Settling Tanks:
Design Criteria for Waste Sludge.
(a) Means for measuring, sampling, and
controlling the rate of waste activated sludge flow shall be provided. Measuring devices shall totalize and record,
as well as indicate flows.
(b) Waste sludge shall be discharged to primary
settling tanks, units for concentrating the waste sludge, storage tanks,
digesters, dewatering devices, or to other means of direct removal from the
plant.
(c) Waste sludge facilities shall be designed to
pump the expected minimum and maximum rates of wasting.
(d) Provisions shall be made for the draining and
flushing of discharge lines.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
PART Env-Wq 712
CHEMICAL COAGULATION FOR PRIMARY AND SECONDARY SETTLING TANKS
Env-Wq
712.01 Chemical Coagulation:
Application and Mixing.
(a) Chemical coagulants shall be applied at a
rate proportional to the wastewater flow.
(b) Rapid and thorough mixing of the wastewater and
coagulant(s) shall be provided in small tanks or pipes using:
(1) Inline
blenders;
(2) Air mixers;
(3) Mechanical
mixers; or
(4) Baffles.
Source. (See Revision Note at chapter heading for Env-Wq
700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
712.02 Chemical Coagulation: Flocculation Tanks..
(a) Flocculation following chemical coagulant
mixing shall be completed in channels or tanks that meet the following
requirements:
(1) At least 2
flocculation tanks or channels having a combined detention period of between 20
and 30 minutes shall be provided;
(2) Mixing
shall be balanced to avoid under-mixing or over mixing such that:
a. Chemicals
are completely dispersed;
b. Flocculated
particles do not settle; and
c. Flocculated
particles are not sheared; and
(3) Independent
controls for each tank shall be provided.
(b) Settling tank design shall conform to Env-Wq
711.
(c) A means of dewatering all tanks shall be provided.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
712.03 Chemical Coagulation: Process Impacts. Chemical coagulation shall not be used unless
the owner first evaluates the following potential impacts due to chemical
addition:
(a) Increased sludge production;
(b) Change in sludge thickening and dewatering
characteristics;
(c) Biological phosphorous removal and denitrification
capability;
(d) Sludge settling characteristics in subsequent
treatment processes; and
(e) Increased operation and maintenance costs of
the chemical feed system.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
PART Env-Wq 713
SUSPENDED GROWTH BIOLOGICAL TREATMENT
Env-Wq
713.01 Activated Sludge: General
Design Requirements.
(a) The activated sludge process and its various
modifications shall be used only where sewage is amenable to biological
treatment.
(b) WWTP design shall provide for multiple
aeration tanks capable of passing peak hourly flow with one unit out of service
and of meeting process requirements with all units on line.
(c) Where the WWTP design provides for all return
sludge to be mixed with the raw sewage or primary effluent at one location,
then the mixed liquor flow rate to each aeration unit shall be equal by means
of a controlled distribution structure.
(d) All activated sludge designs shall include
provisions for the control of bulking sludge and filamentous micro-organisms.
(e) Return sludge equipment shall comply with the
following:
(1) The return sludge
rate shall be varied by means of variable speed motors, drives, or timers. All designs shall provide for flexibility in
operation. The return sludge rate shall
be at least 100 percent of average annual influent design flow and sufficient
to maintain design MLSS at maximum day flow rates;
(2) The maximum
return sludge capacity shall be obtained with the largest pump out of service;
and
(3) A method
for observing, sampling, and controlling return activated sludge flow from each
settling tank shall be provided.
(f) Waste sludge facilities shall comply with the
following:
(1) In addition
to capacity required for return sludge pumping, waste sludge pumping facilities
shall be provided with a minimum capacity not less than 25 percent of design average
rate of wastewater flow, or a minimum of 10 gpm, whichever is larger. Waste sludge pumps shall function
satisfactorily at 0.5 percent of design annual average wastewater flow;
(2) Waste
activated sludge may be discharged to the primary settling tanks, sludge
digestion tanks, sludge thickening or dewatering processes, storage tank or any
practical combination of these units; and
(3) A method
for observing, sampling and controlling waste activated sludge flow shall be
provided.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
713.02 Activated Sludge: Aeration
System Requirements.
(a) An aeration system shall be designed to:
(1) Meet
maximum oxygen demand and mixing requirements and maintain process performance
with the largest unit out of service;
(2) Provide for
varying the amount of oxygen transferred in proportion to the load demand on
the WWTP; and
(3) Have motors,
gear housing, bearings, grease fittings, and other parts requiring maintenance
in a location that is:
a. Accessible
under routine operating conditions; and
b. Protected
from submergence and spray as necessary for proper functioning.
(b) The mechanism and drive unit for oxygen
transfer shall be:
(1) Designed
for the expected conditions in the aeration tank in terms of power performance;
and
(2) Tested and
certified by the aerator manufacturer.
(c) Each aeration drop leg shall be equipped
with:
(1) Control
valves that have indicator markings for throttling and complete shut off; and
(2) Air flow
measurement capability.
(d) Air filters shall be:
(1) Provided in
numbers, arrangement, and capacities to furnish at all times an air supply
sufficiently free from dust to prevent damage to blowers and clogging of the
diffuser system used; and
(2) Equipped
with a means to measure pressure drop across the air filters.
(e) Blowers shall be located in a room that:
(1) Is
separated from the office, laboratory, or control room by insulated walls to
minimize blower noise, such that the noise level does not exceed 90 decibels in
the blower room and does not exceed 50 decibels in the office, laboratory, or
control room;
(2) Has
mechanical ventilation; and
(3) Is equipped
with heat recovery units if economically justified based on life cycle cost
analysis.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
713.03 Activated Sludge: Aeration
System Performance Requirements.
(a) To allow for increased energy efficiency in WWTF
operation through the expected life of a WWTF, the owner shall:
(1) Provide
multiple blowers for diffused air systems that are sized to:
a. Meet the
current facility peak aeration demand;
b. Meet
turndown requirements as described in (b), below; and
c. Avoid
over-aerating at current daily minimum flows;
(2) Conduct an
energy evaluation to determine the optimum blower sizing, turndown, and
staging;
(3) If current
peak aeration demands are below peak design aeration demands, provide sufficient
blower capacity to meet current peak aeration demands while ensuring that
blower rooms are large enough to accommodate the blower configuration necessary
to meet peak design demands;
(4) Demonstrate
financial capacity or set up a reserve account to set aside the estimated money
required to install additional blowers when needed to meet increased peak
aeration demands; and
(5) Arrange
blowers in such configuration and capacities as to meet the current peak
aeration demands with the single largest unit out of service.
(b) The aeration system shall be designed to:
(1) Have
sufficient turndown capability that does not extend beyond the efficient
operational range of the blowers, when using multiple same-sized blowers or
staging with multiple varied-sized blowers;
(2) Not
over-aerate or require blowing off excess air at initial year minimum flows;
and
(3) Operate
most efficiently at average organic loading conditions.
(c) Air requirements for a diffused air system
shall be determined incorporating the following factors to be included in the
design specifications or supporting documentation submitted to the department:
(1) Tank depth;
(2) Alpha
factor of waste;
(3) Beta factor
of waste;
(4) Certified
aeration device transfer efficiency;
(5) Minimum
aeration tank dissolved oxygen concentration;
(6) Mixing
requirements needed to maintain solids suspension;
(7) Critical
wastewater temperature; and
(8) Altitude of
WWTP.
(d) Aeration requirements for carbonaceous BOD5 removal shall be based upon
the maximum monthly BOD5
loading.
(e) All aeration equipment shall be capable of
maintaining a minimum of 1.0 mg/L of dissolved oxygen in the mixed liquor
unless a lower minimum dissolved oxygen can be justified based on process
modeling.
(f) Diffused air system design shall use data
derived from pilot testing or an empirical approach.
(g) When pilot facility or experimental data is
not available, the design oxygen requirements shall:
(1) Be 0.8 to
1.2 pounds of oxygen per pound BOD5 removed;
(2) Be 4.57
pounds oxygen per pound design maximum day total Kjeldahl nitrogen (TKN)
available for nitrification, where TKN available for nitrification is
calculated as influent TKN less nitrogen required for carbonaceous growth less
non-biodegradable nitrogen; and
(3) Include
oxygen demands due to high BOD5 and TKN concentrations in recycle
flows such as heat treatment and digester supernatants, vacuum filtrate, belt
filter pressate, waste sludge recycled to primary clarifiers, and elutriates.
(h) The aeration system shall be designed to
match the diurnal organic load variation while economizing on power input.
(i) The capacity of the blowers or air
compressors shall be based on the site altitude and site specific minimum and
maximum summer and winter temperatures.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
713.04 Activated Sludge: Protection
of Aeration Systems.
(a) Electrical controls for all aeration
equipment shall be protected from the elements.
(b) Where extended cold weather conditions occur,
the aerator mechanism and associated structure shall be protected from freezing
due to ice formation from splashing.
Source. (See Revision Note at chapter heading for
Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14
Env-Wq
713.05 Activated Sludge: Aeration
Tank Design.
(a) The aeration tank size for any particular
adaptation of the activated sludge process shall be determined by:
(1) Pilot
studies; or
(2) Rational
calculations based primarily on solids retention time (SRT) and MLSS levels
while also considering other factors, including but not limited to capacity,
wastewater characterization relevant to the proposed process, diurnal load
variations, degree of treatment required, pH, temperature, alkalinity, and
dissolved oxygen.
(b) The engineer shall furnish aeration tank
sizing calculations to the department with the engineering design documents.
(c) Aeration tank volume requirements for
nitrification shall be based on maximum monthly loading.
(d) The dimensions of each independent mixed
liquor aeration tank or return sludge re-aeration tank shall be such as to
maintain effective mixing and use of air, provided that liquid depths shall be
not less than 12 feet nor more than 25 feet.
(e) Inlets and outlets for each aeration tank
unit shall be equipped with valves, gates, stop plates, weirs, or other devices
to permit flow control to any unit and to maintain a constant liquid level
while preventing short-circuiting through the tank.