HomeMy Public PortalAboutLPSSDR Final Red Lined for public comment June 2023
June 2023 1
DRAFT FOR PUBLIC COMMENT - JUNE 2023
MSD Low Pressure Sewer
System Design Regulations
June 2023
June 2023 2
Table of Content
SECTION 1-INTRODUCTION ................................................................................................................................. 3
1.01 General ............................................................................................................................................................ 3
1.02 LPSS Definitions ............................................................................................................................................ 3
1.03 Responsibilities ............................................................................................................................................... 4
1.04 Design Scenarios ........................................................................................................................................... 4
SECTION 2 - PLAN REVIEW SUBMITTAL REQUIREMENTS ........................................................................ 6
2.1 LOW PRESSURE SEWER SYSTEM DESIGN REPORT .................................................................. 6
2.2 DESIGN DRAWINGS ...................................................................................................................................... 7
SECTION 3 - PUMP STATION AND FORCE MAIN DESIGN CRITERIA ....................................................... 8
3.1 METHODOLOGY FOR DETERMINING DESIGN FLOWS ....................................................................... 9
3.2 HYDRAULIC DESIGN .............................................................................................................................. 9
3.3 STORAGE REQUIREMENTS ............................................................................................................... 11
3.4 FORCE MAIN DESIGN .......................................................................................................................... 12
3.5 GRINDER PUMP SYSTEM RECOMMENDED DESIGN .................................................................. 12
SECTION 4 - PIPING AND VALVES .................................................................................................................... 13
4.1 PIPE MATERIAL AND CONNECTIONS .............................................................................................. 13
4.2 FORCE MAIN REQUIREMENTS & APPURTENANCES ................................................................. 15
4.3 TRANSITION PIPING .................................................................................................................................... 19
4.4 SHUT-OFF AND CHECK VALVES ............................................................................................................. 19
4.5 DETENTION PIPE .................................................................................................................................. 22
4.6 VALVE JUNCTION BOX, ARV, AND EMERGENCY TRUCK CONNECTION STRUCTURE
REQUIREMENTS ................................................................................................................................................. 23
SECTION 5 – SUBMITTALS, INSPECTION AND ACCEPTANCE REQUIREMENTS ................................ 24
5.1 PRE-CONSTRUCTION SUBMITTALS .................................................................................................. 24
5.2 FINAL CONSTRUCTION INSPECTION ................................................................................................ 24
5.3 REINSPECTION OF WORK .................................................................................................................... 25
5.4 CONSTRUCTION ACCEPTANCE ................................................................................................................. 26
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SECTION 1-INTRODUCTION
1.01 General
A. To provide efficient, cost effective and reliable service to the customers of the
Metropolitan St. Louis Sewer District (MSD), a sanitary low pressure sewer system
(LPSS) will only be considered where a thorough study of all alternatives clearly indicate
a gravity collection and disposal system with (or without) a central sewage pump station
is not practical or feasible. The minimum size of a central pump station dedicated to
MSD shall have an average daily influent flow rate of 6 gallons per minute (gpm) or
greater.
B. Prior to the project design, it is the responsibility of the design engineer to contact MSD’s
Engineering (Plan Review) Department to determine the following:
1. Will the District allow the construction of a LPSS?
2. Are there additional requirements due to the project’s location or force main size?
3. Does the designer have the latest version of the LPSS design requirements?
C. The following are general guidelines and standard specifications for regional sanitary low
pressure sewer systems (LPSS) to be installed within the jurisdiction of The Metropolitan
St. Louis Sewer District. These requirements are both a design guide and a
supplement to the MSD Standard Construction Specifications.
1.02 LPSS Definitions
The following describes a low pressure sewer system. Unless all the items listed are satisfied, a
system will not be considered a LPSS and will not be governed by these design requirements.
Refer to the current version of the Standard Pump Station Design and Construction
A. Requirements for those pressurized sewers systems not meeting the LPSS criterion.
1. All pump stations are privately owned.
2. All pumps shall be grinder type only.
3. Any force main crossing property lines shall be public and located in proper
easements. Isolation structures are required at any public/private crossing.
4. All force mains from the private pump stations shall be private up to the valve
junction box (see section 3 under RESPONSIBILITIES).
5. The maximum pipe diameter of a LPSS force main shall be 10”.
6. All private connections to a public force main are to be made through valve junction
boxes (VJB). These assemblies provide the following:
A check valve at the discharge end of the customer’s private line for the
prevention of public sewage escaping onto their property should a break
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occur on their private force main. For isolation, a shut-off valve is also
required in the private line between the check valve and public force main.
Two shut-off valves on the public force main for the purpose of isolating
customers in the event of a force main failure. Customers upstream from the
failure can then direct their flow towards an emergency truck connection
structure (see definition 7) while the customers downstream can continue to
use the unaffected remainder of the force main in a normal manner. Refer to
Section 3.6 and example details (Figures 1-5).
New Valve Junction boxes used to accomplish new connections on existing
(public) LPSS’s are public and shall be noted as such on the plans.
7. An emergency truck connection structure is a 2-inch shut-off valve and a quick
coupling. These structures are to be located at the upstream end of each force main
branch and used as a convenient point to connect a tank truck during force main
emergencies. The truck can keep isolated customers in service until the force main
is repaired along with allowing for cleaning of the forcemain. See Section 3.6 and
example detail Figure 6.
1.03 Responsibilities
The Metropolitan St. Louis Sewer District (Pump Station Division of Operations) shall be
responsible for each public portion of the low pressure sewer system (LPSS), including all
repairs and operations of the public force main, valve boxes and valve box piping.
Responsibility for the private portion of the LPSS shall be as follows:
1. All permits, inspections and acceptances of each individual branch system shall be the
sole responsibility of the St. Louis County Plumbing Department or appropriate city
agency.
2. The individual property owners shall be liable for the maintenance and operation of their
own individual branch systems. They are also responsible for obtaining MSD approval
for all future pump station upgrades that include pump replacements or pump station
replacements. The owner shall be responsible for choosing the proper pump based on
ultimate build-out flow. If post construction a new planned ultimate build out is added,
the developer of that new system will be responsible for modifying all effected systems.
3. The property owners’ branch system is considered to be:
a. The branch pressure piping running from the pump station discharge to the
check valve inside of the valve junction box. This includes the check valve.
b. The individual pump station and all related appurtenances.
c. The branch gravity system running from the private building to the pump station.
1.04 Design Scenarios
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The design engineer is reminded that an adequately designed LPSS has pumps that regularly
and often provide sufficient force main flushing velocities to minimize problems with odors and
clogging.
This specification will describe two design situations. The first is the construction of a new
LPSS and the second is for the requirements of an additional private pump station or stations
connecting into an existing LPSS.
1. New LPSS:
a. For this scenario, the developer’s engineer is responsible to design the low
pressure sewer system to operate smoothly with the expected number of private
pump stations and with the public sewer system it connects to.
b. The design shall allow for any potential future growth on the system.
c. Pay close attention to the velocity in the public force main. Calculations must
show the selected pumps will regularly produce a minimum of two (2) feet per
second (f.p.s.) velocity during normal operating conditions at all points of the
force main.
d. The engineer shall calculate the pump discharge flows in the full range of
operating conditions.
e. All assumptions made and all steps of the calculations shall be clearly
documented.
f. The range of head at the connection point to the existing public sewer system
must be considered in the hydraulic calculations, if applicable.
g. The engineer shall provide the expected average daily flow (ADF), and peak
daily flow (PDF) for each customer.
h. Pump size and pump type must be submitted for all customers on the LPSS.
2. Existing LPSS:
a. This situation applies where a customer or customers propose to connect into an
existing LPSS. “Customer” includes single family residences.
b. The developer’s engineer is required to provide MSD with pump discharge
calculations. Engineers shall fully research and document the existing system to
determine the number or type of pumps presently connected. Where necessary,
MSD may assistance in this task by providing available information on the
existing system.
c. Velocity calculations must show the selected pumps will regularly produce a
minimum of two (2) feet per second (f.p.s.) during normal operating conditions in
the new public force main.
d. The range of head at the connection point to the existing public sewer system
must be considered in the hydraulic calculations, if applicable.
e. The engineer shall provide the expected ADF and PDF for each customer.
f. Pump size and pump type must be submitted for all customers of the LPSS.
3. Existing Public Forcemain
a. Connections into forcemains attached to public pump stations shall be avoided.
No connections shall be approved without MSD operations consent.
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SECTION 2 - PLAN REVIEW SUBMITTAL REQUIREMENTS
In addition to the normal submittals, the following material must be submitted to the
Engineering Department for review of any proposed low pressure sewer system. Plans
submitted to the District that do not have the required number of drawings and/or low pressure
sewer system design report data shall be returned to the designing engineer with a "request for
missing material." No attempt will be made to review incomplete submittals.
Upon completion of the review, the Engineering Department will forward all comments to
the designing engineer. After the design engineer has had an opportunity to review these
comments, a meeting may be arranged with the Plan Review Engineer to clarify any questions
that may arise.
2.1 LOW PRESSURE SEWER SYSTEM DESIGN REPORT
Two (2) copies of the low pressure sewer system design report shall be provided. In the case of
a single family residence, only sections A, B.1, B.2, C, and F immediately below need be
included. The report shall be typed and bound in 8-1/2 inch x 11 inch booklet form in the
following format:
A. Title Page
1. Project name and MSD Project (P) number
2. Date
3. The developer/owner
4. Engineering firm preparing plans
5. Seal of a Professional Engineer registered in the state of Missouri
B. Sewer System Information
1. Introduction
Type, location and size of development.
Number of and range in size of lots or buildings to be serviced.
2. Existing Sewer System
Location and type of sewer system the force main will discharge to. It is
strongly preferred that LPSS systems discharge to gravity sewers. Common
force mains or pump stations placed in series shall be avoided and would
require a meeting with MSD to approve.
3. Future of Sanitary Sewer Service
State whether the entire development will be serviced by the proposed phase
or if several phases will be involved.
State the number of lots this phase will encompass initially and finally (if
future phases are to be constructed)
State whether other areas outside of the development may be tributary to the
pump station.
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C. Pump Station and Force Main Design Calculations (see Section 2).
D. Downstream Pump Station Detention Pipe Design Calculations
Structural calculations shall be submitted verifying the minimum pipe materials specified
in Sections 2.3 and 3.5 are adequate.
E. Design Summary
1. Force Main Size, Material, Type or Class and Length
2. Force Main Test Pressure - This test pressure value is derived from the selected
pump manufacturer’s performance curve. It is the maximum pump head or shut-off
head in psig, plus 50 psig. The pressure value shall be clearly indicated on each
force main profile sheet as "FORCE MAIN TEST PRESSURE".
F. Manufacturer’s Pump Specifications and Catalog Sheets
1. The manufacturer's specifications and catalog sheets for the pumps shall be
included in the appendix of the Low Pressure Sewer System Design Report booklet.
2. The manufacturer's catalog sheets shall be marked to identify the applicable items
selected.
3. Specifications and performance curves shall be included for each pump proposed by
the design engineer.
2.2 DESIGN DRAWINGS
Three (3) copies of the design drawings shall be provided. The design drawings shall be
individual 24 inch x 36 inch design plan sheets. Each sheet must indicate the MSD P or Project
Number in the lower right corner and must be sealed by a professional engineer registered in
the State of Missouri.
A. Cover Sheet
1. General Site Plan (1 inch = 50 ft scale)
2. All buildings and/or residences with top of foundation (TF) and basement floor
(BF) elevations noted.
3. All sanitary sewers and storm sewers with their manholes identified.
4. All streets.
5. All low pressure sewer system force mains and the locations of all valve junction
boxes, emergency truck connection structures, air/vacuum release valves and
clean-outs.
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B. Force Main Plan and Profile (1 inch = 50’ ft scale horizontal and 1 inch = 10 ft vertical)
1. Identify the force main size, pipe material and over all length.
2. Locate force main appurtenances, such as, clean-outs, combination air/vacuum
release valves, valve junction boxes, emergency truck connections and isolation
valves. The distance between each appurtenance shall be indicated.
3. Locate mechanically restrained joints at angle points, tees, and valves when
required by the pipe joint design. Indicate the number of restraining joints
required both upstream and downstream from an angle point, tee, or valve.
Thrust blocks are not allowed.
4. Show the force main test pressure on each profile sheet.
5. Show two typical Tuned Locator Marker locations on both the plan and profile
and refer those locations to the locator marker note in Sections 3.2.G and H.
C. Miscellaneous Details
1. Provide a sheet that will contain details on items such as:
2. Force main clean-outs
3. Combination air/vacuum release valve chamber
4. Valve junction boxes
5. Force mains taps with their associated valve junction boxes
6. Grinder pumps with pump curves, wetwells, and associated piping
7. Include actual “pump off” elevation in grinder pump detail.
Refer to example details Figures 1-9.
SECTION 3 - PUMP STATION AND FORCE MAIN DESIGN CRITERIA
The design engineer shall submit calculations and rationale supporting the system
design including non-residential wastewater loading and system flow calculations. Section 3.1A
describes the wastewater loading requirement. This specification will have only general
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guidelines for the statistical approach to LPSS design. The calculations and rationale for that
approach must be submitted for review.
Specifications for the worse case hydraulic design are outlined in this section beginning with
3.2.
3.1 METHODOLOGY FOR DETERMINING DESIGN FLOWS
A. Non-Residential Development Area
The average daily flow (excluding infiltration) for non-residential development areas shall
be based on one of the following:
1. Actual Water Use Records of like facilities
2. The current Rules of the Department of Natural Resources Division 20, Clean
Water Commission, Chapter 8. Design Guides (10CSR 20-8.021, 1.E.1).
3. Industry Standards
B. Residential Development Area
The average daily flow (excluding infiltration) shall be based upon the methods outlined
in the latest edition of the MSD Rules and Regulations and Engineering Design
Requirements for Sanitary Sewer and Stormwater Drainage Facilities.
C. Future Development
In designing all components of the force main, consideration must be given to the
potential need to expand or modify the facility to accommodate the future development
of areas tributary to the system. As a minimum the following items should be
considered:
1. The ultimate flow should be considered in selection of the pumps if the development
is staggered. Odor control may be required as part of the project to eliminate odor
complaints. Maintenance of the odor system will be the responsibility of the
eventual property owner.
2. The ultimate flow should also be considered in sizing the force main.
3.2 HYDRAULIC DESIGN
The design engineer shall perform the analyses shown in the table immediately below for the
hydraulic design of an LPSS with multiple pumps. In LPSS’s with just one pump, analyze both
old and new pipe roughness.
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Hydraulic Design Cases
Design Case No. of pumps on
simultaneously
Hazen-Williams
pipe roughness
Notes
Maximum Flow
Case
See Method for estimation
table below
Old (see next
pg)
Include pumps farthest from
system discharge
Average Flow
Cases
See paragraph at the
bottom of this page
Old (see next
pg)
Include pumps farthest from
system discharge
Minimum TDH
Case
One New (see next
pg)
Include the pump under the
least head
The goals of the hydraulic design are to check that each grinder pump station can easily handle
the peak daily inflow in all cases, while maintaining force main velocities between 2 and 8 feet
per second in the Maximum and Average Flow cases. Further guidance for the estimation of the
Maximum Flow Case is indicated in the table below.
Method for estimation of system flow in Maximum Flow Case
Type of pump Method
Centrifugal Formula Q=0.5N+20, in Ch. 2 of USEPA Pub. 625/1-91/029
Pos. displacement (PD) Statistical maximum number of pumps on simultaneously
In the absence of other guidance, for PD pumps assume that the Average Flow Case results
from one less pump on simultaneously than in the Maximum Flow Case. For centrifugal pumps,
assume “N-1” instead of “N” in the USEPA formula shown above. Pump run out will be checked
in the Minimum TDH Case. (“N” is the number of homes served and “Q” is design flow in gallons
per minute.)
At the discretion of MSD, the Maximum Flow Case may be modified.
In those systems with three or less grinder pumps, the minimum 2 feet per second velocity shall
be achieved with only one pump in operation. The hydraulic calculations are to be based on the
following procedure:
Total Dynamic Head (TDH)
TDH (feet) = Static head plus friction losses in new or existing force main and
station piping = Hs + Lf + Ls
Estimate the TDH for each private pump station in the LPSS in accordance with the Hydraulic
Design Cases above.
1. Static Head (Hs) for each private pump station
Eh = Maximum elevation in new and existing force main
E1 = Wet well low water elevation (Pump Off)
Static head Hs (feet) = Eh - E1
2. Head loss (Lf) from friction in each section of new and existing force main to the
gravity sewer discharge point
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Length = Total length of force main pipe, plus equivalent length of valves and
fittings (feet)
Lf (feet) = Length x Friction Factor/100
Where: Friction Factor = Friction head loss (feet) per 100' pipe = 0.2083 x (100/C)^1.85
x Q^1.85/d^4.8655 (Hazen and Williams formula)
Where: d = Inside diameter of pipe (inches), C = C-Factor (see 4. below) and Q = FLOW
(GPM) through that section
Note: Losses can also be calculated by adding Hazen-Williams pipe loss to separately
calculated valve and fitting losses. The valve and fitting losses may be calculated by use
of the formula head loss = KV^2/2g, with V equal to velocity in feet per second and g
equal to the acceleration of gravity, which is 32.2 ft per second^2. Use reasonable K
values accepted by the industry.
3. Head loss (Ls) from friction in each private station piping
Length = Total length of the station piping, plus equivalent length of valves and
fittings (feet)
Ls (feet) = Length x Friction Factor/100
4. The following Hazen and Williams C-Factors shall be used for computation of
friction losses:
Unlined iron or steel pipe-old, new C=100, 140
All other pipe (incl. Plastic and lined DIP)-old, new C=120, 150
5. TDH (feet) = Hs + Lf + Ls
Adjust the flows from each pump station until the TDH of each station matches
the discharge head on its manufacturer’s pump performance curve.
A computer model such as EPANET or PIPE-FLO can be used in the hydraulic
design. When using a computer model, pumps can be iteratively sized in order to
achieve the hydraulic goals of the design (see the previous page). A clearly
labeled computer model node diagram shall be included in the hydraulic report
along with system head and pump curves, estimated velocities, and estimated
maximum system pressures.
3.3 STORAGE REQUIREMENTS
If the low pressure sewer system discharges to an existing MSD sewer system that terminates
at a public pump station with detention reservoirs instead of a back up generator, that station’s
24 hour detention capacity must be increased to match the new incoming flow. It is the LPSS
developer’s responsibility to make that upgrade.
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Twenty-Four Hour Storage Volume Requirements:
Vs = ADF (GPD) x 1 Day = Cylindrical Volume of detention reservoir pipe used.
The volume of the incoming gravity lines or wet well shall not be considered in sizing of
the twenty-four hour storage. Only the volume of the detention reservoir shall be used.
NOTE: The lowest development elevation must be above the elevation of the highest
point of the detention chamber plus two (2) feet.
It is the responsibility of the developer’s engineer to check the capacity of the existing sewer
system and to coordinate with MSD in the expansion of the existing sewer system, if required.
3.4 FORCE MAIN DESIGN
During normal operations, a minimum cleansing velocity of two feet per second shall be attained
on a regular basis. Maximum velocity in the system should not exceed eight feet per second.
The minimum permissible inside diameter of a public force main is 2 inches. Exceptions to this
rule are at the discretion of MSD.
High points on the force main shall be avoided wherever possible by varying force main depth.
Pressures greater than or equal to 0 psig must be maintained throughout all force mains at all
times.
3.5 GRINDER PUMP SYSTEM RECOMMENDED DESIGN
A minimum of 50 gallons of storage shall be included in the grinder pump station wetwell
between the invert of the incoming lateral and the “pump off” elevation. Include protection from
uplift as required.
A quick disconnect with a suitable isolation valve and connecting piping to the pump station
discharge shall be included for the purpose of emergency pumping and to serve as a cleanout.
A runtime meter and a visual and audible high water alarm should be provided and installed.
The minimum permissible inside diameter of a private residential force main is 1.25 inches.
Grinder pump motors shall be non-overloading throughout the pump curve.
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SECTION 4 - PIPING AND VALVES
The following specifications shall be used for installation of piping and valves. Flanged or
grooved end piping shall be acceptable means of connecting valves and piping.
All pipes within structure walls shall have six-inch minimum clearance from the inside face of the
structure to the first fitting to allow for proper maintenance access.
4.1 PIPE MATERIAL AND CONNECTIONS
A. Internal piping includes a maximum of four feet (4’) outside a structural wall. The
following materials shall be used for internal piping:
1. Four Inch (4”) Diameter and larger:
A. Ductile iron pipe specified in this section shall be cement lined mortar in
accordance with ANSI A21.4/AWWA C104 and buried portions must be
polyethylene encased per ANSI A21.4/AWWA C105.
B. Ductile iron fittings shall be cement lined and have an alkyd-phenolic primer
coating or equal.
Flange Joints
Ductile iron pipe Class 53 ANSI A-21.51 (AWWA C -151). All bolts and nuts
for flange connections must be 316 stainless steel (minimum). All flange
gaskets must be full faced1/8 inch thick red rubber.
Grooved End Joints
Ductile iron pipe Class 53 ANSI A-21.51 (AWWA C-151) with rigid radius
grooves for end preparation in accordance with AWWA C606. Mechanical
couplings shall be of ductile iron conforming to ASTM A-536, Grade S nitrile
gasket compounded to conform to ductile iron pipe surfaces with 316
stainless steel nuts and bolts.
2. Three inch (3") Diameter and smaller:
Solvent-Weld Joints
ASTM 1785 Schedule 80 PVC, ASTM D2855 Practice for making Solvent
Cemented Joints, and ASTM F402 Practice for safe handling of Solvent
Cements, Primers, and Cleaners
June 2023 14
Grooved Joints
ASTM 1785 Schedule 80 PVC roll grooved pipe in accordance with C-
606. Mechanical couplings shall be of ductile iron conforming to ASTM A-
536, Grade T or S nitrile compound gaskets conforming to ASTM D-2000
designation 5BG615A14B24 with 316 stainless steel nuts and bolts.
3. With a high density polyethylene (HDPE) force main there is no transition required to
enter a structure regardless if the internal installation is grooved or flanged.
4. Fasteners
All installed fasteners shall be 316 stainless steel
The threaded portion of the stainless steel fasteners shall be coated with a
stainless steel anti seize compound.
B. The following materials shall be used for the force main piping:
1. Four inch (4") Diameter and larger:
AWWA C-900 PVC Class 150 (DR-18)
HDPE Pipe. See specifications in Section B.2.
AWWA C-909 PVCO
2. Three inch (3") Diameter and smaller:
PVC pipe meeting ASTM D2241 (SDR 21) with integral bell and gasket joint
design meeting the requirements of ASTM D3139 and F477. Solvent weld
pipe joints meeting ASTM D2672 and Solvent cements meeting ASTM
D2564. Minimum pressure class shall be PC 150.
HDPE Pipe. Pipe shall be manufactured from a PE 3408 resin listed with the
Plastic Pipe Institute (PPI) as TR-4. The resin material will meet the
specifications of ASTM D3350-99 with a cell classification of PE: 345464C.
Pipe shall have a manufacturing standard of ASTM F714. Pipe shall be IPS
DR 11 unless otherwise specified on the plans.
HDPE fittings and accessories material specification as follows:
Butt Fusion Fittings - Fittings shall be PE3408 HDPE, Cell Classification of
345464C as determined by ASTM D3350-99. Butt Fusion Fittings shall have a
manufacturing standard of ASTM D3261. Fabricated or molded fittings shall have
the same pressure rating as the pipe unless otherwise specified on the plans.
Fabricated fittings are to be factory manufactured.
June 2023 15
Electrofusion Couplings and Restraints - Couplings shall be PE3408 HDPE, Cell
Classification of 345464C as determined by ASTM D3350-99. Electrofusion
Couplings shall have a manufacturing standard of ASTM F-1055. Couplings shall
have the same pressure rating as the pipe unless otherwise specified on the
plans. Electrofusion Restraints shall be made of the same specified material and
to the same standards as the Electrofusion Couplings.
Contractors must have their HDPE butt fusion installers qualified with training
from the pipe distributor or a manufacturers’ representative.
Connections to non-HDPE Material –
HDPE Flanged, Grooved and Mechanical Joint Adapters – Flanged and Mechanical
Joint Adapters shall be PE 3408 HDPE, Cell Classification of 345464C as
determined by ASTM D-3350. Flanged, Grooved and Mechanical Joint Adapters
shall have a manufacturing standard of ASTM D-3261. Flanged and Mechanical joint
adapters shall use a ductile iron back up ring or gland, grooved adapters shall use a
stainless steel IPS roll groove transition. Fittings shall have the same pressure rating
as the pipe unless otherwise specified on the plans.
Mechanical Type Couplings – Mechanical couplings used to connect HDPE pipe or
fittings to non-HDPE material or used for repair shall create a restrained joint with a
pressure rating equal to that of the HDPE pipe or fittings.
4.2 FORCE MAIN REQUIREMENTS & APPURTENANCES
The following elements shall be included in the force main system design:
A. Air Relief / Vacuum Valves (ARV)
Automatic combination vacuum air relief valves shall be placed at high points in
the force main as required.
1. The valve shall be equipped with all backwash accessories.
2. ARVs that will regularly operate at pressures less than 5 psig shall be
designed for proper operation at these pressures.
3. The 60 inch diameter ARV pre-cast set-over structure shall be identical to
the 60 inch structures described for the valve junction boxes. The
structure shall be vented where required by MSD. See Section 3.6 and
Figure 7.
4. Odor control devices may be required as determined by MSD.
June 2023 16
Acceptable Manufacturer: ARI D-Series (Wastewater use only)
B. Connection to Gravity System
Force mains shall discharge to the gravity sewer system at a manhole. The point of
connection
shall be no more than one foot above the flow line of the receiving manhole. Inside drops
will not be permitted. Odor control devices may be required as determined by MSD.
C. Connection to Forcemain Systems
1. Existing LPSS
i. Connections into existing LPSS’s system shall be coordinated with MSD
and the owner(s) of the pump stations.
2. Existing Public Forcemain
i. Connections into existing forcemain tied to public pump station shall be
coordinated with MSD. Thickness testing may be required depending on
the type of pipe being connected to.
D. Gravity Manhole Rehabilitation
The sides and bottom of the force main discharge manhole and a minimum of
five (5) manholes downstream of the point of connection shall be lined. The
lining shall be a solventless, 100% solids corrosion resistant epoxy coating or
multiple layers of structural fiberglass molded to the existing structure with a non-
porous diaphragm bonded between the fiberglass layers.
Acceptable Manufacturer: Raven Lining Systems AquataPoxy A-6, Terre Hill
Composites Multiplex Liner THC-610-SL-68, or approved equal.
E. New Manhole Construction
When a new manhole is to be constructed at the point of connection to the
gravity system, the manhole shall be manufactured with a flexible sheet liner with
locking extensions. The bottom of the new manhole shall be treated with the
epoxy coating specified above.
Acceptable Manufacturer: Ameron Protective Lining Division, Amer-Plate T-Lock, or
approved equal.
F. Mechanically Restrained Joints
Force mains that are not of solvent weld joint or fusion weld joint design shall be
fitted at all angle points, tees and valves with mechanically restrained joints
designed to withstand the thrust developed under the test pressure plus 50 psi.
The required number of mechanically restrained joints from the angle point, tee,
or valve shall be determined by the design engineer and shown in plan and
profile (see Section One)
G. Clean-Outs
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At least one clean-out is required on any public force main. They shall be placed
at major changes in direction and where one public force main connects to
another. The maximum clean-out spacing shall be 400 feet. Refer to Figures 8
and 9 for clean-out configuration examples. The emergency truck connection
shown in Figure 6 is counted as a clean-out.
H. Tuned Locator Markers
Tuned locator markers shall be installed directly above the forcemain and no
deeper than five feet (5’). A minimum six-inch (6") separation shall be
maintained between the top of the force main and the locator marker.
Acceptable Manufacturer: "Green Sanitary marker" model 1424-XR/iD locator ball,
manufactured by the 3M Dynatel Company
I. Tuned Locator Tape
Tuned Locator Tape shall be installed in addition to the locator balls. This tape shall be
installed directly above the forcemain and no deeper than four feet (4’). A minimum of
1’ separation between the locator ball and locator tape is required.
Acceptable Manufacturers: 3M model 7900 XT Locator tape, manufactured by the 3M
Dynatel Company.
J. Tracer Wire
Tracer Wire can be used as an alternative per MSD discretion.
Acceptable Manufacturers: Copperhead Soloshot Extra-High Strength Tracer Wire, or
Engineer approved equal.
K. Location of Tuned Locator Markers
Tuned Locator Markers shall be installed:
Every 100 feet along force main runs.
Five (5) feet back from the pavement edge on both sides of a road crossing
Fifteen (15) and five (5) feet back from each side of an angle point.
Or as otherwise directed by MSD.
L. Provide a minimum cover of three feet (3’) over all public force mains.
M. Pipe installation:
2-1/2 inch and smaller PVC or HDPE pipe with solvent cement, fuse-welded, and/or
restrained joints shall be “snaked” in the trench to allow for expansion and
contraction.
June 2023 18
3 inch and larger pipe solvent cement, fuse-welded, and/or restrained joints shall be
analyzed by the designer to determine if there is a need for expansion fittings.
Single elbows greater than 45 degrees shall not be used on force mains to
accomplish horizontal and vertical turns, except on pump station discharge piping.
Assemble solvent weld joint pipe in accordance with manufacturer’s
recommendations
N. Force Main Taps:
The minimum tap size shall be 2 inch.
Use brass or stainless steel tapping saddles or sleeves specific for the tapped force
main type. The tap connection shall be flanged or with a type CC female thread that
only accepts a CC male thread on a corporation stop tapping valve.
The corporation stop shall have a CC type inlet and a female threaded outlet. From
the threaded outlet use a threaded brass nipple and a brass full faced flange to
mate with a PVC or HDPE flange on the force main.
Use a flanged cast iron resilient wedge valve for 4 inch taps.
Acceptable Manufacturer: American Flow Control Series 2500
The tap valves may be buried after the tap is made.
Install a valve junction box containing a shut-off valve and a check valve in close
proximity to the tap. The junction box shall be a 48 inch or 60 inch pre-cast
concrete set-over structure identical to the structures described for the valve
junction boxes. See Section 3.6 and Figure 1-5.
2. Where a public force main terminates into an existing force main that is a low
pressure sewer system, make the connection with a valve junction box. See
Section 3.6 and Figures 1-5.
3. Where two branches of a low pressure sewer system meet install a valve
junction box but with no check valve. See Section 3.6 and Figures 1-5.
O. Bored Road Crossings:
A HDPE force main may be directionally bored without the use of a liner pipe or
casing. SDR 11 pipe must be used, and the owner of the road must give
permission.
All PVC pipe at a bored road crossing must be installed inside a liner pipe. Refer
to and follow the Metropolitan St. Louis Sewer District Construction
Specifications Section M but do not use grout to fill the space between the liner
and the carrier pipe. Use casing spacers as directed by their manufacturer.
Bored Road Crossing shall include public/private driveway.
Acceptable Manufacturer: Raci by Public Works Marketing, Inc.
P. Hatch access lids and frames for 60 inch diameter precast concrete structures
Inside of right of way
June 2023 19
1. Gray iron construction with stainless steel spring, fasteners, and gray iron
hinges. Suitable for high density traffic (H-20) loading.
1. Spring assist opening, spring to be attached to lid, with hold open arm.
Spring shall move out of the clear opening of the frame when the lid is
open.
2. Provide 30”x30” opening and lid with non-skid surface
3. Provide positive means of holding lid down
Acceptable Manufacturer: Neenah R-6662-PS or approved equal
Outside of right of way
1. Aluminum construction with stainless steel spring, fasteners, and hinges.
2. Spring assist opening with-hold open arm
3. Provide 30”x30” opening and lid with non-skid surface
4. Provide positive means of holding lid down
Acceptable Manufacturer: Halliday H1R3030 or approved equal
4.3 TRANSITION PIPING
When PVC pipe (See Section 3.1) is used for force main a transition pipe must be used to make
the transition between the internal structure piping and the force main outside the structure.
The following methods shall be used:
A. Four Inch (4") Diameter
The D.I.P. internal structure piping shall pass through the set-overs of the structure wall
and attach to the PVC force main by a long pattern sleeve mechanical joint with Mega-
Lug retainer glands.
B. Three Inch (3”) Diameter and Smaller
Transition the Schedule 80 PVC internal structure piping to the SDR-21 PVC force main
with a PVC coupling outside of the structure wall.
4.4 SHUT-OFF AND CHECK VALVES
June 2023 20
Approved shut-off and check valves shall be placed in each valve junction box. The check
valves shall be located on the customer side of the private shut-off valve. Refer to Figures 3
and 4 for proper valve location within the valve junction box.
All valves shall be rated so as to withstand normal working pressure plus allowances for water
hammer and all field installed fasteners shall be 316 stainless steel.
A. Shut-off Valves 3 inch and 4 inch
Shut-off valves shall be plug type and shall be of cast iron body, ASTM A126 Class B, or
ductile iron ASTM A536. Valve plugs shall be cast iron ASTM A126 Class B, or ductile
iron meeting ASTM A536, Grade 65-45-12, covered with a Buna-N Rubber compound.
The seats are to be a corrosion resistant alloy either 304 stainless steel or nickel.
1. Flange Valves
Flange valves shall be in accordance with ANSI B16.1 Class 125 standards.
2. Grooved End Valves
Grooved end valves shall have end-to-end dimensions in conformance with
AWWA C-509 with the grooved ends conforming to AWWA C-606 rigid grooving
dimensions.
3. Sleeve type bearings shall be utilized in both the upper and lower trunions.
Bearings shall be corrosion resistant and have a low coefficient of friction.
4. Valves shall be able to pass a sphere not less than 80% of the diameter of the
valve size.
5. Valve Operators
Valves shall be provided with a two-inch (2”) square operating nut and wrench
head.
6. Valves shall be rated at 175 pounds.
7. Valves larger than 4 inch shall be submitted for approval. The Pump Station
design guildlines (PSDR) can be used as a reference for larger valves.
Acceptable Manufacturer: Valves are to be Milliken, fig. #601-N, Victaulic Series 365,
or approved equal.
B. Shut-off Valves 3 inch for use on cleanouts
June 2023 21
Shut-off valves shall be ball type and shall be of ductile iron body and endcap, ASTM
A395, with grooved ends. Valve stem and ball shall be chrome plated carbon steel.
Seats shall be PTFE. Provide lever handle.
Acceptable Manufacturer: Ball valves shall be Victaulic Series 726 or approved equal.
Note: Install lever handle so that the valve opens upwards.
C. Check Valves 3 inch and 4 inch
Check valves shall be of the swing check type with iron body and bronze trim. Check
valves shall be flanged end type or grooved end type with outside spring and lever or
weighted arms. Valves larger than 4 inch shall be submitted for approval. The Pump
Station design guildlines (PSDR) can be used as a reference for larger valves.
Acceptable Manufacturer: Check Valves shall be Clow Fig. F5340,Victaulic Series 317
or approved equal.
D. Shut-off Valves 2-1/2 inch and Smaller (also see section E. below)
Shut-off shall be threaded bronze Milwaukee BA-100 ball valves or Victaulic Series 721
standard port ball valve with ductile iron body, ASTM A-536, Grade 65-45-12, and Type
316 stainless steel ball and stem, TFE seats, 600 psi (4130 kPa). Shut-off for air release
valves shall be 2-inch diameter Milwaukee BA260 ball valve with stainless steel body,
ball and stem, threaded ends, lever handle, TFE seats, minimum 600 psi (4130 kPa), or
approved equal.
E. Check Valves 2-1/2 inch and Smaller
Check valves shall be Hammond IB904 threaded bronze or equal or Victaulic Series 712
check valve with working pressure to 300 psi, ductile iron body, ASTM A-536, Grade 65-
45-12, and Type 316 stainless steel clapper with Nitrile Bumper and Bonnet seals. The
Victaulic check valve shall have rigid grooves to specification ANSI/AWWA C606.
Note: Use brass pipe nipples when installing brass and bronze valves.
June 2023 22
4.5 DETENTION PIPE
Detention pipe(s) required by Section 2.3 shall be a minimum of ASTM C76 Class III, B wall
minimum, O-ring type reinforced concrete pipe. No lift holes shall be allowed unless otherwise
permitted by the District. Designer shall submit calculations for uplift and anchor detention
pipes as required.
The detention pipe ends shall be sealed using pre-cast bulkheads with O-ring gaskets. Also, an
"A-lok" gasket shall be installed for the 12 inch outfall pipe.
June 2023 23
4.6 VALVE JUNCTION BOX, ARV, AND EMERGENCY TRUCK CONNECTION
STRUCTURE REQUIREMENTS
All private pump stations must be connected into the LPSS force main through a valve junction
box as specified below. In addition to the valves located in the valve junction box, it is
recommended each private pump station should have its own check valve and shut-off valve.
Emergency truck connection structures shall be located at the upstream end of all public force
branches unless otherwise directed by MSD.
1. Valve junction boxes on 2-inch diameter force mains and emergency truck
connection boxes shall be a minimum of 48 inch diameter pre-cast concrete riser
sections with pipe opening slots or an aluminum hatch. A MSD approved
manufacturer must produce these pre-cast structures. A standard size 26 inch
cast iron frame and cover shall be centered over a reinforced pre-cast concrete
top section. See Figure 1. A design must be submitted for all structure tops
subject to vehicular loading.
2. All ARV (air/vacuum release valve – see Figure 7) structures, and all valve
junction boxes on 3-inch and 4-inch diameter force mains, shall be a minimum of
60-inch diameter precast concrete riser sections with pipe opening slots. A MSD
approved manufacturer must produce these pre-cast structures. A standard size
square hatch access lid and frame with a 30-inch x 30-inch opening shall be
centered over a reinforced precast concrete top section. All ARV must be
properly braced and supported, as well as the emergency truck connections. See
Figures 4, 5 and 7 and LPSSDR section 3.2.N. A design must be submitted for
all structure tops subject to vehicular loading.
3. The interior piping and valves shall be installed so there is a 12 inch clear space
between the piping and the rock filled base. Valves and piping shall be securely
supported from below with concrete blocks.
4. The valve junction box and emergency truck connection structures shall be set on
standard pre-cast bases, to be firmly rested on a 2 ft deep base of 3/4-1 inch
clean rock. The concrete bases shall have the same diameter as the precast
concrete structures and have 24 inch diameter holes in their centers. Filter fabric
shall be used to line the excavation and placed over each pipe opening slot
before placement of the rock base. See Figures 1, 2 and 6.
5. The 2 inch ball valve of the emergency truck connection station shall be
supported to the wall of the structure by two 1-1/2 inch x 1-1/2 inch x 3/8 inch
stainless steel angle brackets. See Figure 6.
June 2023 24
SECTION 5 – SUBMITTALS, INSPECTION AND ACCEPTANCE REQUIREMENTS
In addition to the normal construction inspection by MSD Inspectors, Operations personnel shall
make a final inspection of the low pressure sewer system (LPSS) construction. The contractor
responsible for constructing the LPSS shall give forty-eight (48) hour notice to the Development
Inspection Department of MSD when the facility is ready for this inspection. Failure to have the
inspection performed at the proper time during the construction process could result in the
District requiring the removal and reconstruction of the completed work.
5.1 PRE-CONSTRUCTION SUBMITTALS
Before the beginning of construction of the LPSS, the contractor shall submit the
following to MSD for approval :
1. Shop drawings of valve vaults (before manufacture).
2. Manufacturer catalog sheets and information on pipe, fittings, valves and pipe joint
restraint.
3. Proof of training for HDPE pipe butt fusion installers, if applicable.
4. Grinder pump curves.
5.2 FINAL CONSTRUCTION INSPECTION
This inspection shall be performed after one hundred percent (100%) of the LPSS has been
completed, and all submittals have been reviewed and approved.
A. Inspection Purpose
1. Verify valve junction box(es) are(were) installed correctly.
2. Verify the valves turn and work correctly and were installed correctly
3. Verify emergency truck connection(s) are(were) installed correctly.
4. Verify air release valve(s) are(were) installed correctly.
5. Verify cleanout(s) are (were) installed correctly.
6. Verify locator tools (ball,rope, tracer wire) can be found and mark the
locations for as-builts.
7. MSD Construction Development Inspection will provide the contact for the
Pump Station Division Engineer for purpose of scheduling the final 100%
inspection. This final inspection will be done by Pump Station personnel
and will not constitute the final dedication inspection of the project and will
only comprise the LPSS components of the project.
8. If deficiencies are found during the inspection the Pump Station Division
Engineer will provide a list to development inspection for further follow up.
June 2023 25
9. As part of the As-Builts and inspection process, the surveyor for the
designer must include x,y coordinates for the locator markers installed on
the forcemain. MSD Operation will locate and mark the forcemain for the
surveyors.
B. Submittal Requirements
While requesting this inspection the following items shall be submitted to MSD for
distribution to the appropriate MSD personnel:
As-Built mylars and three sets of as-built prints of the LPSS site prepared by a
professional engineer or land surveyor registered in the state of Missouri, certifying
that all structures and sewers were built in accordance with the approved plans and
located within existing easements
A complete set of the as-built drawing computer files in AutoCADD Lt format and
PDF files (Accela attachment)
C. Odor Control
The Owner shall make provisions for odor control (such as adding fresh water to
grinder pump station wetwells, minimizing wetwell detention time, chemical
addition, etc) in those LPSS systems that are in the early construction stages
before ultimate development.
5.3 REINSPECTION OF WORK
The District will perform one final inspection and one re-inspection of the construction at no
charge to the Owner. The Owner shall be responsible for all costs associated with the
additional re-inspections due to the failure of the Contractor to satisfactorily correct the identified
deficiencies.
Once the Pump Station Division/Operations Department final 100% inspection, or re-
inspection(s), are complete, all defective items corrected, and all required documentation is in
the possession of the District, MSD Operations will issue a notification to MSD Engineering
Department accepting the asset(s), strictly for the purposes of Operations and Maintenance,
and identifying the effective date of that acceptance. MSD Operations Department will begin
operating and maintaining the public portions of the LPSS system effective this date.
June 2023 26
5.4 CONSTRUCTION ACCEPTANCE
Construction Acceptance of the Low Pressure Sewer System shall be subject to the completion
of all items stated above as well as the satisfactory completion of all site restoration. The District
will begin maintenance of the public force main at final construction acceptance which shall
come from the Pump Station Division Engineer as noted in the aforementioned section. MSD
Development Inspection is responsible for the final dedication inspection of the project as a
whole.