HomeMy WebLinkAboutCC AG PKT 2003-12-08 #K AGENDA REPORT �� 3
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DATE: December 8, 2003 2 .
l
TO: Honorable Mayor and City Council
THRU: John B. Bahorski, City Manager
FROM: Douglas A. Dancs, P.E. Director of Public Works /City Engineer
SUBJECT: COUNCIL APPROVAL: PUBLIC WORKS — DESIGN
CRITERIA FOR SEWER FACILITIES
SUMMARY OF REQUEST:
The proposed City Council action will adopt Council Resolution approving
design criteria for sewer facilities and authorize the Director of Public Works /City
Engineer to make changes as required by new regulations, for improvements to the sewer
infrastructure and for the protection of public health and safety.
BACKGROUND:
The City has prepared design criteria for sewer facilities which will be used as a design
manual with minimum standards for the City's use in constructing and upgrading all
sewer facilities in the City. In addition, the criteria manual will be used by developers
who may need to upgrade sewer facilities.
The attached design criteria outlines the basic principles involving sewer design, pump
station design, private systems, and references standard drawings. The City's water and
sewer consultant, AKM Consulting Engineers, prepared the manual and the Engineering
Division has also reviewed different cities criteria and materials to develop the attached
sewer design criteria. The criteria are consistent with current regulations including the
City's Waste Discharge Requirements from the April 2002 California Regional Water
Quality Control Board Order No. R8- 2002 -0014 which requires "(A) Develop design and
construction standard and specifications for the installation of new sewer systems, pump
stations and other appurtenances; and for the rehabilitation and repair of existing sewer
systems; and (B) Develop procedures and standards for inspecting and testing the
installation of new sewers, pumps, and other appurtenances and for rehabilitation and
repair projects.
The Director of Public Works /City Engineer will also be authorized to make any changes .
to the manual as required by a new regulation such as the Orange County Sanitation
District or the State Water Quality Regional Board, for improvements to the sewer
infrastructure, and to make any changes as required to protect public health and safety.
Agenda Item A
FISCAL IMPACT:
There is no fiscal impact associated with this action.
RECOMMENDATION:
It is recommended that the City Council adopt Council Resolution approving
design criteria for sewer facilities and authorizing the Director of Public Works /City
Engineer to make changes as required by new regulations, for improvements to the sewer
infrastructure, and for the protection of public health and safety.
Prepared By:
OOP
01 . j......d_ 11P Alli tillie _/
M K. Vukojevic, P.E. Douglas • . • an '
Deputy City Engineer Director Pub ' - ∎ orks /City Engineer
• TE I► "APR() e ii.
Jo • r, . Bahorski, City Manager
/i
Enclosure: Design Criteria for Sewer Facilities
Resolution No.
Agenda Item
CITY OF SEAL BEACH
Design Criteria
for
Sewer Facilities
•
Prepared for
CITY OF SEAL BEACH
Seal Beach, California
Prepared by
AKM CONSULTING ENGINEERS
101 Pacifica, Suite 150
Irvine, California 92618
July 2003
TABLE OF CONTENTS
Section Page
1 Standard Requirements 1
2 Calculations Required 1
3 Size 1
4 Minimum and Maximum Slope 1
5 Design Flow Criteria 2
6 Standard Location and Alignment 3
7 Easements 3
' 8 Horizontal Curves 4
9 Stationing Procedure 4
10 Minimum Depth 4
- 11 Sewer Pipe Material 4
12 Manholes 4
12.1 Manhole Requirements 4
12.2 Manhole Type and Size 5
12.3 Manhole Covers 5
12.4 PVC Lined Manholes 5
13 Clean -Outs 6
14 Separation Between Sewer and Water and Recycled Water Lines 6
15 House Laterals 6
16 Private Sewer System 7
17 Sewer Pump Station 8
17.1 General 8
17.2 Standards and Codes 8
17.3 Design Flows and Heads 9
17.4 Drivers 9
17.5 Wet Well 9
17.6 Emergency Storage 10
17.7 Dry Well 11
17.8 Standby Equipment 11
17.9 Pumps 12
17.10 Valves and Gates 15
17.11 Magnetic Flow Meters 19
17.12 Piping and Support System 20
17.13 Ancillary Equipment 22
1 CITY OF SEAL BEACH
rtrpts•%Seal BeachtDesign Cnteria Sewer Facilities (Jul b3) DESIGN CRITERIA FOR SEWER FACILITIES
TABLE OF CONTENTS
(Continued)
17.14 Electrical Equipment 29
17.15 Instrumentation and Controls 29
17.16 Supervisory Control and Data Acquisition (SCADA) System 33
17.17 Pressure Gauges 33
17.18 Pump Station Facility 34
17.19 Force Mains 35
17.20 Access Roads 35
17.21 Flood Control 35
17.22 Grading and Area Drainage 35
17.23 Soils Report 35
17.24 Surveying 36
17.25 Security 36
17.26 Water Supply System 36
17.27 Landscaping and Irrigation System 36
17.28 Construction 36
18 Standard Sewer Notes 37
LIST OF STANDARD DRAWINGS
S -1 Manhole Details
S -2 Concrete Base and Joint Details
S -3 Manhole Shaft Location Details
S-4 Traffic Manhole Frame and Cover
S -5 PVC Pipe Bedding & Special Details
S -6 VCP or PVC Typical Lateral
S -7 Cut In Wye Connection
• S -8 VCP Pipe Bedding Details
S -9 Terminal or Main Cleanout Detail
S -10 Concrete Encasement Type A, B & C
S -11 Concrete Slope Anchors
S -12 Steel Casing Pipe
S -13 Drop Manhole Details
S -14 PVC -Lined Manhole for Sewers
S -15 PVC Liner Details
S -16 Gas Flap Installation
S -17 Flat Top Manhole
S -18 Separation Criteria
2 CITY OF SEAL BEACH
rlrpts:ISeal BeachlDesign Cnteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
1. STANDARD REQUIREMENTS
The design and construction of all sanitary sewer system facilities to be operated and
maintained by the City of Seal Beach shall be in accordance with these Design Criteria, the
City of Seal Beach's Standard Drawings, City of Seal Beach Specifications for the
Construction and Inspection of Sanitary Sewers, Standard Specifications.for Public Works
Construction, as well as the water quality guidelines and requirements of the State of
California and County of Orange.
2. CALCULATIONS REQUIRED
Substantiating engineering calculations for design flows; pipe size; pump, motor, generator,
wet well size and appurtenant equipment selection; structural design, and bedding /backfill
designs shall accompany plan submittals to the City. All calculations shall be sealed and
signed by a California registered professional engineer.
Where flow from anew development or redevelopment is added to an existing sewer, the
existing sewer will be flow monitored for a minimum period of two weeks to verify the
existing minimum, average, and peak dry weather flows.
3. SIZE
Gravity Sewers
The minimum size gravity sewer shall be 8- inches in diameter. The City of Seal Beach may
accept 6 -inch diameter sewer lines if they must be used to provide adequate velocity.
Sewer pipes shall not be constructed in a common trench with another utility._ Adequate
horizontal and vertical clearance shall be maintained in accordance with the State of
California Department of Health Services "Criteria for the Separation of Water Mains and
Sanitary Sewers ", summarized on Standard Drawing S -14.
Force Mains
The size of sewer force mains shall be determined during the design phase of the project
based upon a comparative study of the construction cost and pumping costs for several
alternative sizes. In no case shall a force main be less than 4 inches in diameter. The
capacity of the force main shall be the design peak flow from the pump station. The
minimum design velocity for a force main shall be 3.0 fps, and maximum allowed 5.0 fps.
The discharge shall be into a manhole with a smooth flow transition to a gravity sewer. The
force main terminal manhole shall be PVC lined.
All force mains shall have a tape attached to the pipe, identifying it as a sewer pipe.
4. MINIMUM AND MAXIMUM SLOPE
All sewers shall be designed and constructed to provide a mean velocity of not less than two
(2) feet per second (fps) when flowing at the estimated average dry weather flow as
calculated using Manning's formula with an "n" value of 0.013. Subject to the velocity
limitations contained in this subsection, the slope shall be maximum possible. Drop
manholes shall not be used to reduce slopes to the minimum allowed.
1 CITY OF SEAL BEACH
rrpts:lSeal BeachlDesign Cnteria Sewer Facilities (Jul 173) DESIGN CRITERIA FOR SEWER FACILITIES
The maximum allowable slope shall be the slope which generates a maximum flow velocity
of 6 fps at the peak dry weather flow rate in vitrified clay pipe (VCP), and 5 fps in polyvinyl
chloride pipe (PVC) as calculated using Manning's equation with an °n" value of 0.013.
The minimum slope on 6 -inch sewer shall be 1% where the tributary area consists of less
than 20 dwelling units (d.u.) or its flow equivalent.
Sewer pipes shall have a constant slope between the upstream and downstream manhole
of each reach. Any reach of sewer containing sags of any amount shall be removed and
reconstructed at the design slope at no cost to the City of Seal Beach. The total cost of
inspection, administration, and retesting of improperly installed sewers shall be bome by the
contractor. The City of Seal Beach shall not accept any sewer that does not meet these
requirements. There shall be no exception to the proper slope requirement.
5. DESIGN FLOW CRITERIA
The average dry weather flow (Qadwf) rates for sewers shall be calculated using the unit flow
factors contained in Table 1 and the tributary land uses. Where appropriate, and when
required by the City of Seal Beach, the unit flow factors shall be evaluated by the design
engineer based upon the specific land uses and densities proposed for new development or
redevelopment.
Table 1
Unit Flow Factors
Land Use Category Unit Flow Factor
Land Use Designation Description Gallons /Acre /Day
RHD Residential High Density 2,200
RMD Residential Medium Density 2,000
RLD Residential Low Density 1,850
C Commercial 2,100
R -G Recreational /Grass 130
PLU /R Public Land Use /Recreation 130
O -E Oil Extraction 0
MSSP Main Street Specific Plan 2,100
M -1 Light Manufacturing 3,167
The peak dry weather flow (Q in cubic feet per second (cfs) shall be determined from
Qadwr in cfs based upon the following equation:
Qpdwf = a Q adwf b
Coefficients a and b shall be based upon a minimum of two weeks of flow monitoring where
the tributary flow from a new development or redevelopment is added to an existing sewer.
Where such information is not available, the following equation shall be used to determine
the peak dry weather flow:
Qpdwf=2.1 Qadwf 0.92
The determination of the peak dry weather flow shall also consider other factors such as
pumped flows and large sewer flow generators.
2 - CITY OF SEAL BEACH
rlrpts:ISea► BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
•
The peak wet weather flow shall be based upon recorded historical information where
available and applicable. Otherwise, the peak wet weather flow shall be calculated as the
larger of:
Q=3.1 Qadwf
Q =1.35 Qpd,f
The peak dry weather flow rate in pipes 15- inches and smaller will be limited by the
calculated depth to pipe diameter ratio of d/D = 0.5; and 18- inches and larger d/D = 0.64.
The pipe shall flow at a calculated depth to pipe diameter ratio of no more than 0.8 with the
peak wet weather flow.
6. STANDARD LOCATION AND ALIGNMENT
In local residential and industrial streets, sewer pipes shall be located six (6) feet from the
centerline of the street in the center of the driving lane. In major, primary, and secondary
highways, the sewer pipes shall be located in the center of the driving lane nearest to the
center of the street, but will not be located in the median strip or parking lanes.
All- weather access roads capable of accommodating all required construction and
maintenance equipment shall be provided for all sewers not located within a paved street.
In curved streets, gravity sewer mains shall be constructed in straight reaches between
manholes. In no case shall the outside of the sewer main be closer than four feet to the
closest curb face.
A maximum horizontal separation between sewer and domestic water mains shall be
achieved by aligning the sewer on the opposite side of the centerline from the domestic
water main.
7. EASEMENTS
Permanent easements, where absolutely necessary, shall be a minimum of 30 feet in width
and shall be shown on the plans. Temporary easements for construction only shall be
shown on the plans including date of termination.
Where applicable, permanent easements shall be recorded on the tract map, and granted to
the City of Seal Beach. When applicable, separate easement documents for both
permanent and temporary easements shall be prepared (on standard title company forms)
and presented to the City of Seal Beach for acceptance and recording.
The City will accept sewers on private streets upon granting of an easement to the City.
The City will not accept any easement for sewers if said easement cannot be accessed with
a flush truck through its entire length.
Sewer easement shall be located entirely on one lot. Building set backs shall be minimum
20 feet from easement edges.
3 CITY OF SEAL BEACH
r rpts :ISeal BeachtDesign Critena Sewer Facilities (Jul V3) DESIGN CRITERIA FOR SEWER FACILITIES
8. HORIZONTAL CURVES
Gravity sewer mains shall not be designed with horizontal curves.
9. STATIONING PROCEDURE
Centerline stations for sewers shall be shown on the plans. Sewer centerline stations shall
be independent of street stationing. All manholes shall be numbered and the numbers
noted on the plans (example: MH #1). Sewer stations shall start at 1 +00.00 at the
downstream point of connection and increase upstream to the last manhole on a sewer line.
Intersecting sewer lines will be independently stationed from their downstream point of
connection and increase upstream to the last manhole. Each line shall be independently
labeled for identification as "Sewer Line A ", "Sewer Line B", etc.
10. MINIMUM DEPTH
Minimum depth of cover from finish street grade to the top of sewer main pipe shall be
seven (7) feet unless otherwise approved by the Director of Public Works /City Engineer.
Sewer house connections shall be installed so that there is a minimum of six (6) feet of
cover from the top of the curb to the top of the pipe at the curb line. At the time of
construction, stakes shall be provided for location and grade of each house connection.
11. SEWER PIPE MATERIAL
All gravity sewers shall be either extra strength VCP or SDR -26 PVC. Imperfections shall
not be allowed in either type of pipe. Sewer service laterals shall be of the same material as
the main line sewer - either extra strength VCP or SDR -26 PVC pipe.
All sewer force mains operating at pressures of less than 40 psi shall be PVC pipe meeting
AWWA C -900 Class 200 pipe standards. All other force mains shall be either glass or
polyurethane lined ductile iron pipe.
All gravity sewers in industrially zoned areas or major commercial areas shall be extra
strength VCP.
12. MANHOLES
12.1 Manhole Requirements
A manhole will be required at:
A. The upstream end of each line, change in grade or size, change in alignment, or
intersection of two (2) or more sewers
B. At a lateral when it is the same size as the main line sewer
C. Along the sewer main at maximum distances of 300 feet for 6 -inch sewers, 400 feet
for 8 -inch and larger sewers.
4 CITY OF SEAL BEACH
rlrpts:ISeal BeachtDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
12.2 Manhole Type and Size
Manholes shall be precast reinforced concrete with eccentric cone in accordance with City
of Seal Beach Standard Drawings S -1 through S-4. Minimum diameter shall be 48 inches
and larger sizes shall be required as shown in the following table:
Manhole Sizes
Sewer Main Maximum Branch Size Manhole Size Frame and Cover
(inches) (inches) (inches) (inches)
8 -15 10 48 30
18 -21 12 60 30
24 -36 15 72 36
Extra Depth Requirements
Depth of Cover Manhole Size -
(feet) (inches)
• 6 or less 60
6.5 -12 48
12.5 -16 60 _
16.5 and greater 72
All manholes shall be provided with at least all- weather vehicular access.
12.3 Manhole Covers
Manhole covers shall be cast iron in accordance with City of Seal Beach Standard Drawing
S-4. The size shall be determined from the table in Section 12.2. Manhole covers shall
have one (1) vent hole and one (1) pick hole.
Temporary covers may be necessary in new streets. In these cases, the manhole shaft shall
be left six (6) inches, minimum, below subgrade. A heavy metal plate acceptable to the City
of Seal Beach inspector shall be provided to cover the manhole opening. Cleats shall be
provided in at least four (4) points for the underside of the temporary cover to prevent the
temporary cover from moving. These cleats shall extend a minimum of 3 inches from the
cover plate and shall be welded to the plate.
Plywood shall be cut to the shape and size of the manhole base and placed in the base
before the temporary cover is placed on the shaft. At the completion of final paving, each
manhole shall be raised to final grade by the installation of grade rings, as necessary, and
the installation of the permanent frame and cover assembly.
12.4 PVC Lined Manholes
The following manholes will be lined with PVC:
A. If the sewer has a slope of 5% or greater, all the manholes on the sewer
B. Where there is a change in slope, from steep to flat, of 3% or greater, the manhole
at the grade change and the next manhole upstream
C. All drop manholes as shown on City of Seal Beach Standard S -13
5 CITY OF SEAL BEACH
rrpts:ISeal BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
D. All force main terminal manholes
E. As required by the Director of Public Works /City Engineer
The approved PVC liners are Ameron T -Lock liner and Koroseal Lok -Rib by B. F. Goodrich.
Refer to Orange County Sanitation District Standard Drawing S -065 for PVC liner details.
13. CLEAN -OUTS
Use of clean -outs as shown in the City of Seal Beach Drawing S -9 shall be limited to the
following instances unless approved otherwise by the Director of Public Works /City
Engineer.
A. At the upstream end of short sections of sewer, Tess than 250 feet which will be
extended within three months.
•
B. All sewer laterals at the property owner's side of the property line.
C. Special instances such as on a sewer lateral to a single family residential lot where
the dwelling unit is set back more than 100 feet from the property line, where there is
a large slope up to the building pad from the property line and a grade change in the
lateral is necessary, or where the sewer lateral enters the rear of the lot from a
public right -of -way.
D. On a lateral where the overflow level of the lowest wastewater fixture in the building
is below the rim elevation of the uphill sewer manhole on the main line. In this
situation the rim elevation of the clean -out installed at the property line shall be at
least 6- inches below the overflow elevation of the lowest waste water fixture on the
lateral. A backflow prevention device is required on the lateral.
14. SEPARATION BETWEEN SEWER AND WATER AND RECYCLED WATER LINES
Horizontal and vertical separation between sewer mains and water and reclaimed water
lines will be provided in accordance with the State of California Department of Heath
Services "Criteria for Separation of Water mains and Sanitary Sewers" and Standard
Drawing No. S -18.
' 15. HOUSE LATERALS
Sewer laterals shall be constructed to the property line from the main line and there shall be
a separate lateral for each individually owned building.
Sewer laterals shall have a minimum 4 -inch diameter. Apartment and condominium
developments shall have at least one (1) 6 -inch, or one (1) 8 -inch lateral to serve each
building in the development which contains more than one dwelling unit.
Laterals shall have a minimum slope of 2 %.
6 CITY OF SEAL BEACH
rlrpts (Seal BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
Laterals shall be located at the center of each lot and shall be constructed perpendicular or
radial to the property line. If the developer must install a sewer lateral at a location other
than in the center of a lot due to unavoidable interference, the improvement plans shall
indicate the centerline station of the lateral on the sewer and show the distance from a
property corner. In no case shall a sewer lateral be located within 12 feet of a property
corner. Refer to Section 13 and Standard Drawing S -9 for cleanouts on laterals.
Permanent visible monuments shall be set to indicate the locations of all sewer laterals. A
1 high "S" shall be chiseled in face of curb where the lateral crosses under the curb or
on the edge of alleys in Old Town. The method used shall be indicated on the plans. A
licensed Civil Engineer or Land Surveyor shall verify locations of set monuments.
The sewer laterals from the main to the building, and inside the buildings are governed by ,
the Uniform Plumbing Code and enforced by the City of Seal Beach Building Official.
The sewer house laterals between the main sewer line and the property line are owned by
the property owner, and NOT by the City of Seal Beach.
16. PRIVATE SEWER SYSTEMS
All plans submitted for review and approval for commercial /industrial developments and
residential developments with private sewer systems shall show the plans, profiles, and
details of private onsite sewer systems. The private sewer systems shall be planned,
designed, and constructed to the same standards as the City of Seal Beach's public sewer
system. Sewer pump stations on private property shall be. designed, administered, and
inspected by the City of Seal Beach or its designated representative. The private property
owner shall be responsible for all costs associated with such design, administration, and
inspection.
Each site shall be reviewed on an individual basis at the time plans are submitted. As a
condition of service, the City of Seal Beach shall require the property owner to enter into an
agreement with the City acknowledging that the onsite facilities are private and shall be
properly maintained according to industry standards and the Santa Ana Region of the
Regional Water Quality Control Board's Waste Discharge Requirements covered under
Order No. R8- 2002 -0014. The property owner shall further agree to hold the City harmless
from any claims on the design, maintenance and operation of the private onsite systems.
All onsite sewer collection systems for commercial /industrial developments shall be private
and shall be owned, operated and maintained by the property owner up to the City's sewer
line in a public street. A cleanout or manhole shall be installed at the owner's side of the
property line in accordance with City Standard Drawing S -6. Each building onsite shall
have an individual sewer lateral with a monitoring manhole. Monitoring manholes shall be
installed in accordance with City criteria. All laterals from a building shall be connected to
the main lateral upstream of the monitoring manhole for that building. No lateral
connections are to be made downstream of the monitoring manhole. The City's authority to
enter on the property for industrial waste discharge is provided in the ordinance for this item
and easements for separate ingress and egress will not be required.
7 CITY OF SEAL BEACH
rIrpts:ISeal BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
17. SEWER PUMP STATIONS
17.1 General
All sewer pump stations conveying wastewater flows to the City of Seal Beach's collection
system, including those from private systems, shall be designed, administered, and
inspected by the City of Seal Beach, or its authorized representative.
The general criteria outlined herein shall apply to all sewer pump stations. The detailed
design criteria for each sewer pump station will be established based upon the specific
conditions of each installation on a case -by -case basis. Sewer pump stations shall be
designed according to the following design criteria:
• • Small sewer pump stations shall be the stainless steel slide -rail submersible type with a
minimum of two recessed impeller centrifugal pumps, permanent standby
generator /automatic transfer switch, and peak flow storage. Large sewer pump stations
shall be wet well and dry well type with permanent standby generator /automatic transfer
switch, and peak flow storage. Pumps shall be either the recessed impeller, or non -clog
type, as determined by the Director of Public Works/City Engineer.
17.2 Standards and Codes
Sewer pump station designs shall be based upon current codes and standards, including
but not limited to:
• Waste Discharge Requirements covered under Order No. R8- 2002 -0014 issued by
the Regional Water Quality Control Board, Santa Ana Region
• Hydraulic Institute Standards
• California Administrative Code, Title 8, Article 59- Electrical Safety Orders
• National Electrical Code
• NFPA 820 Fire Protection in Wastewater Treatment Plant and Collection System
Facilities
• Uniform Building Code
• Uniform Plumbing Code
•
• Uniform Mechanical Code
• Standard Specifications for Public Works Construction
• Standard Plans for Public Works Construction
• OSHA Construction Safety Orders
• American Water Works Association
• American Society for Testing Materials
8 CITY OF SEAL BEACH
rlrpts:tSeal BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
17.3 Design Flows and Heads
The pump stations shall be designed with a firm pumping capacity equaling the greater of:
• . Tributary peak wet weather flow
• Flow that will provide a minimum velocity of 3 fps in the force main.
The standby pump will have the same capacity as the largest pump in the pump station.
In selecting the number, capacity, and operating characteristics of the pumps, the minimum,
average, peak dry weather and peak wet weather flows, as well as wet well size and
operating band shall be considered. The selected design shall minimize pump cycling and
odors.
The total dynamic head (the sum of static lift, velocity head, and frictional losses in the
station piping/ valving and force main) shall be determined for all operating conditions, wet
well and discharge point water surface elevations, and a range of frictional coefficients
(Hazen Williams C factor of 100 to 150).
Calculations documenting the determination of flows and head calculations shall be
submitted along with the recommended pumps. Prior to final acceptance, the design
engineer shall obtain written verification from the recommended pump manufacturers that
the selected pumps shall perform throughout their operating range as designed at the
published efficiencies free from cavitation, vibration, and premature failure.
17.4 Drivers
The pumps shall be driven by submersible or vertical dry pit immersible motors. All motors
shall be explosion proof. Motors operated by variable frequency drives shall be inverter duty
motors. Nameplate horsepower shall be at least 20 percent greater than the maximum
brake horsepower needed within the operating range of the pump.
Variable frequency drives shall be provided with bypass contactors to operate the pumps at
full speed.
Small pump stations may be designed with constant speed pumps. Larger pump stations
may require the use of variable speed drives. The decision of the Director of Public
Works /City Engineer shall be final as to the type of driver to be used.
17.5 Wet Well
The wet well shall be sized to
• Provide adequate submergence
• Provide adequate net positive suction head available (NPSHA)
• Prevent frequent pump cycling
• Provide emergency storage
9 CITY OF SEAL BEACH
rirpts:ISeal BeachlDesrgn Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
Submergence provided shall prevent formation of vortices and air being drawn into the
pump. It shall also prevent cavitation. The minimum submergence shall be at least one foot
greater than that required by the pump manufacturer.
The net positive suction head available shall be calculated as:
NPSHA =2.24 (P
Where
P Atmospheric pressure (psia)
P,= Vapor Pressure of liquid at the maximum expected temperature (use 0.59 psia)
H,= Friction and minor losses between the wet well and the pump suction flange in feet of
liquid
Z= Difference in elevation between the minimum wet well water level and pump datum, in
feet. Use — when the pump datum is higher than the minimum wet well water level.
The minimum NPSHA shall be at least eight feet greater than the net positive suction head
required (NPSHR) by the selected pump for the maximum expected flow through the pump.
The wet well shall be sized to provide the storage capacity which will preclude exceeding
the following number of pump starts per hour:
Motor Maximum Starts Minimum Cycling Time
Horsepower per Hour (Minutes)
Up to 20 6 10
25 to 50 4 15
60 to 75 3 20
100 and larger 2 30
Wet well bottom corners shall be sloped at 1:1 and slope to the suction pipe inlet to prevent
the accumulation of debris on the wet well floor.
Influent pipe(s) shall not enter the wet well in a position which may cause pre- rotation of the
flow into the pump suction, and turbulence in the wet well. The influent velocity into the wet
well shall be no greater than three (3) feet per second.
For large pump stations, a partition wall(s) with sluice gates may be required to isolate a
portion of the wet well for cleaning.
17.6 Emergency Storage
Emergency storage volume needed shall be evaluated for each pump station based upon
the tributary area and expected ultimate wastewater flows. The minimum volume of
emergency storage shall be 30 minutes of ultimate peak wet weather flow without
surcharging the tributary collection system. The emergency storage volume may be
provided in the wet well or in a separate adjacent PVC lined overflow structure.
10 CITY OF SEAL BEACH
rlrpts:lSeal BeachlDesign Critena Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
Where possible, the invert of the overflow structure shall be higher than the low water
elevation of the pump station wet well to allow gravity drainage of the stored sewage to the
wet well. There shall be a minimum of two connecting pipes between the overflow structure
and the wet well. The connecting pipes shall be equipped with flap gates on the wet well
side. The floor of the overflow structure shall slope to the connecting pipes.
All overflow structures shall be equipped with an access hatch, and three 30 -inch diameter
maintenance access holes. A 2 -1/2 inch hydrant water connection shall be provided near
the overflow structure for use in periodic cleaning. The water supply to the hydrant water
connection shall have a reduced pressure backflow preventer.
The higher of the maximum storage level and overflow level shall be set at least one foot (1-
ft) lower than the top of the lowest manhole in the system, basement or p -trap of the
plumbing fixture connected to the system.
. 17.7 Dry Well
The dry well shall meet the following criteria:
A. Pumps shall be placed to provide minimum clear space of 3' -6"
B. The lowest level of the pump station dry well shall have a sump pit with duplex
explosion proof submersible pumps controlled by float switches. The sump pumps
shall discharge to the wet well above the maximum water level.
C. Discharge piping and the force main shall be placed in the dry well along the
common wall with the wet well. The flow meter shall be placed inside the dry well
sufficiently downstream of the last pump discharge pipe. If there is not sufficient
room, the flow meter shall be placed in a below grade vault adjacent to the pump
station structure.
D. Catwalks or mezzanine levels shall be provided to access the flow meters, valves,
and other portions of the equipment
17.8 Standby Equipment
All pump stations shall have standby equipment capable of handling the ultimate peak wet
weather flow during a commercial power outage and /or with the largest unit out of service.
This criteria shall apply to all essential electrical and mechanical equipment including
pumps /motors, fans, air compressors and sump pumps.
There shall be a minimum of one standby main sewage pump equal in size to the largest
duty main sewage pump in the station.
All pump stations shall have a permanent standby generator and an automatic transfer
switch sized to start and operate all the sewage pumps needed for ultimate peak wet
weather flow, sump pump, ventilation fans, lighting, instrumentation, controls, and telemetry
with voltage dip not to exceed 16% when starting any motor.
11 CITY OF SEAL BEACH
rlrpts:ISeal BeachlDesgn Criteria Sewer Facilities (Jul 103) DESIGN CRITERIA FOR SEWER FACILITIES
Generators shall be skid mounted, permanently anchored to the foundation, and housed in
an acoustically insulated enclosure. Exhaust mufflers shall be super critical grade designed
for noise level not to exceed the noise level allowed within each particular area.
Load banks sized for 80% of the generator capacity shall be provided. Load -banks shall be
mounted in the vicinity of the generator and protected with adequate enclosure suitable for
- the location as required by NEMA Standards.
Portable trailer mounted generators are acceptable only for locations where installation of a
permanent skid - mounted generator is not feasible. When a portable trailer mounted
generator is furnished, a power receptacle shall be permanently installed for quick
connection.
- Standby generators shall be furnished with battery chargers and block heaters.
. The standby generator shall be a diesel or natural gas powered generator. The diesel fuel
- - powered generators shall be equipped with a sub -base fuel tank sized for a minimum of 12
hours of continuous full load operation. Standby generators shall be units pre- approved by
the South Coast Air Quality Management District.
• 17.9 Pumps
Submersible pumps shall be the recessed impeller type. Wet well -dry well pumps shall be
either non -clog or recessed impeller type suitable for operation when the dry well is flooded.
Pumping capacity and head shall be considered in the selection of the type of pump for the
wet well -dry well pump stations.
SUBMERSIBLE RECESSED IMPELLER CENTRIFUGAL PUMPS
Recessed impeller centrifugal pumps are designed to handle stringy materials and up to 25
times the amount of solids of conventional non -clog pumps. Some recessed impellers are
labeled by pump manufacturers as torque -flow, bladeless and sphere flow. However, all of
these pump models follow the general design of placing the impeller away from the fluid
stream in order to pass stringy material without clogging the hydraulic passages.
The recommended minimum design criteria in the selection of recessed impeller centrifugal
pumps are as follows:
12 CITY OF SEAL BEACH
r ipts:ISea! BeachMDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
a. Pump impeller efficiency shall be selected with the best possible efficiency at design point or at the
operating range of the pump.
b. Maximum Speed 1750 rpm or shall not exceed the limitation as recommended by the Hydraulic
Institute Standards for Centrifugal Pump application -
c. Materials of • NiHard (minimum of 550 Brinnell hardness) or stainless steel Type 316
Construction impeller with a removable wear plate of the same material as the impeller
• NiHard (minimum of 550 Brinnell hardness) or cast iron casing, as
determined by the Director of Public Works /City Engineer.
• Stainless steel Type 316 shaft.
• Tandem mechanical shaft seal system for the motor with two totally
independent seal assemblies and Tungsten - Carbide seal faces
d. Upper and Lower Radial and thrust bearings, grease lubricated with minimum B -10 bearing life
Bearings of 60,000 hours.
e. Slide Away Foot mounted discharge elbow and adaptor, base plate, upper and lower rail
Coupling supports, lifting yoke, and cable. All metal to metal interfaces where
movement may occur shall be non - sparking.
f. Electric Motor • For wet well installation, motors shall be designed for Class I, Group D,
Division 1 explosion proof.
• NEMA Design B, heavy duty, high efficiency, non - overloading, with a
nameplate horsepower at least 20% greater than the maximum
horsepower required over the entire operating range.
• Thermal overload protectors imbedded in the motor windings.
• Motors shall be inverter duty if operated by variable frequency drives.
g. Painting and Coating All wetted surfaces in contact with wastewater shall be coated with coal tar
epoxy enamel. Surface preparation shall be in accordance with SSPC -SP5,
white metal blast cleaning. Prime coat to DFT =I.5 mils, Amercoat 71, Engard
422 or equal. Two or more coats, DFT =16 mils, Amercoat 78HB, Engard 464
or equal. Total system DFT =17.5 mils.
Extemal surface exposed to corrosive environment shall be coated and
painted by amine -cured epoxy. Surface preparation shall be in accordance
with alkaline cleaned, SSPC -SP1. Prime coat and finish coat shall be three
or more, DFT =16 mils. Amercoat 395, Engard 480 or equal.
13 - CITY OF SEAL BEACH
rlrpts•ISeal BeachlDesrgn Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
DRY WELL NON -CLOG CENTRIFUGAL PUMPS
The recommended minimum design criteria in the selection of the non -clog dry well pumps
are as follows:
a. Pump impeller efficiency shall be selected with the best possible efficiency at design point or at the
operating range of the pump.
b. Maximum Speed • 1750 rpm for pumps with discharge nozzle diameter up to 12 -inch,
• 1175 rpm for pumps with discharge nozzle diameter from 14 to 16 -inch,
• Shall not exceed the speed limitation recommended by the Hydraulic
Institute Standards for Centrifugal Pumps.
c. Materials of • Cast iron or NiHard (as directed by the Director of Public Works /City
Construction Engineer) casing with stainless steel Type 316 impellers and wear rings
(0.5" minimum thickness).
• Stainless steel Type 316 shaft.
• Dual Tungsten - carbide seals.
• Combination radial and thrust bearings for upper and lower bearings,
grease lubricated with minimum B -10 life of 60,000 hours when operating
at design point. .
d. Electric Motor Motors shall be NEMA Design B, heavy -duty, high efficiency with Class B or F
insulation. Motors shall be non - overloading over the entire operating range,
with a nameplate horsepower rating a minimum of 20 percent greater than the
maximum horsepower required over the operating range.
Motors located in a damp environment and in a dry pit shall have 2 cycles of
solid baked epoxy vacuum impregnation.
Motors shall be inverter duty if operated by variable frequency drives.
• Motors shall be immersible, capable of operating continuously in air without
the use of sewage pumped for cooling.
e. Painting and Coating All wetted surfaces in contact with wastewater shall be coated with coal tar
epoxy enamel. Surface preparation shall be in accordance with SSPC -SP5, -
white metal blast cleaning. Prime coat to DFT =1.5 mils, Amercoat 71, Engard
422 or equal. Two or more coats, DFT =16 rails, Amercoat 78HB, Engard 464
or equal. Total system DFT =17.5 mils. .
Extemal surface exposed to corrosive environment shall be coated and
painted by amine cured epoxy. Surface preparation shall be in accordance
with alkaline cleaned, SSPC -SP1. Prime coat and finish coat shall be three or
more, DFT =16 mils. Amercoat 395, Engard 480 or equal.
14 CITY OF SEAL BEACH
rtrpts:ISeal BeachlDessgn Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
DRY WELL RECESSED IMPELLER CENTRIFUGAL PUMPS
The recommended minimum design criteria in the selection of recessed impeller centrifugal
pumps installed in dry wells are as follows:
a. Pump impeller efficiency shall be selected with the best possible efficiency at design point or at the
operating range of the pump.
b. Maximum Speed 1750 rpm or shall not exceed the limitation as recommended by the Hydraulic
Institute Standards for Centrifugal Pump application
c. Materials of • NiHard (minimum of 550 Brinnell hardness) or stainless steel Type 316
Construction impeller with a removable wear plate of the same material as the impeller
. , _ • NiHard (minimum of 550 Brinnell hardness) or cast iron_ casing, as
determined by the Director of Public Works /City Engineer.
• Stainless steel Type 316 shaft.
• Tandem mechanical shaft seal system for the motor with two totally
independent seal assemblies and Tungsten - Carbide seal faces
d. Upper and Lower Radial and thrust bearings, grease lubricated with minimum B -10 bearing life
Bearings of 60,000 hours when operating at design point.
e. Electric Motor NEMA Design B or F insulation, heavy duty, high efficiency, non-
overloading .
• Thermal overload protectors imbedded in the motor windings
• Two cycles of solid baked epoxy vacuum impregnation of the windings.
• Motors shall be inverter duty if operated by variable frequency drives.
• Motors shall be immersible, capable of operating in air continuously
without the use of the sewage pumped for cooling.
g. Painting and Coating All wetted surfaces in contact with wastewater shall be coated with coal tar
epoxy enamel. Surface preparation shall be in accordance with SSPC -SP5,
white metal blast cleaning. Prime coat to DFT =I.5 mils, Amercoat 71, Engard
422 or equal. Two or more coats, DFT =16 mils, Amercoat 78HB, Engard 464 .
or equal. Total system DFT =17.5 mils.
Extemal surface exposed to corrosive environment shall be coated and
painted by amine -cured epoxy. Surface preparation shall be in accordance -
with alkaline cleaned, SSPC -SP1. Prime coat and finish coat shall be three or
more, DFT =16 mils. Amercoat 395, Engard 480 or equal.
17.10 Valves and Gates
Pump stations are equipped with various types of valves to prevent backflow, to isolate the
equipment from the system, to control hydraulic surges and to drain the piping system
during scheduled repair and maintenance. Each valve type differs in construction,
materials, .and operation depending on the service and application. All valves shall be
suitable for wastewater service.
15 CITY OF SEAL BEACH
Npts :ISeal BeachtDesign Criteria Sewer Facilities (Jul 103) DESIGN CRITERIA FOR SEWER FACILITIES
All interior surfaces of valves in contact with wastewater shall be epoxy coated. All valves
10 -inch diameter and larger shall be provided with motor operators. Manually operated
valves located more than six feet above the operating floor shall be equipped with chain
wheel operators, with the chain extended 36 inches above finish floor. Motor operated
valves' shall be provided with a manual hand wheel and manual push button station
conveniently located below the valve, 5 feet above finished floor.
SLUICE GATES
Sluice gates shall be fumished with stainless steel frames and slides with embedded bronze
seats, Type 316 stainless steel stem, and adjustable bronze bushed stem guides. Sluice
gate manual operator shall have AWWA square nut; manual crank operator with floor stand
and 2 -speed gear reducer designed for opening time of not to exceed six minutes. Motor
operator shall be provided when required by the Director of Public Works /City Engineer.
• Motor operated gates shall be designed for opening and closing times of one foot per
minute.
Sluice gates shall be specified to be furnished with pattern wall thimbles to match the
concrete thickness where the gate is to be installed.
Sluice gates shall be Rodney Hunt or equal.
ECCENTRIC PLUG VALVES
Non - lubricated eccentric plug valves shall be used as isolation valves. Valves shall have
hard rubber (suitable for sewage service) resilient faced plugs and flanged ends. Valve
seats and discs shall be stainless steel, Type 316. Bodies shall be semi -steel with raised
seats. Valves shall be of the bolted bonnet design. Valve design shall allow repacking
without removing the bonnet, and the packing shall be adjustable. All exposed nuts, bolts,
springs, and washers shall be stainless steel, Type 316. Valves shall have permanently
lubricated stainless steel bearings in the upper and lower plugstem journals.
Manual valves shall have a 2 -inch square nut and lever actuator. Levers shall be field cut
as required to be operable in their installed locations.
Eccentric plug valves may be used as pump control valve to alleviate hydraulic surges
. - during normal starting and stopping of the pumps and as surge anticipators when required.
These valves shall have hydraulic cylinder type operators with adjustable opening and
closing times. Where the valve is used as a surge relief valve, emergency (upon failure of
power supply) opening and closing times shall be specified.
Where space permits, all eccentric plug valves shall be installed with the shaft in the
horizontal position. The orientation of the plug with respect to the fluid flow direction shall be
as recommended by the manufacturer. The valve manufacturer's recommended installation
instructions to prevent clogging of the valves during extended shutdown periods shall be
• strictly followed.
Valves shall have unobstructed port area of not less than 80- percent of total pipe area.
16 CITY OF SEAL BEACH
rtrpts•lSeal BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
Eccentric plug valves shall be as manufactured by DeZurik Corporation, Keystone, Drum -
Owens (Homestead), Milliken, or equal.
BALL VALVES
When required by the Director of Public Works /City Engineer, ball valves shall be used as
pump control valves or for surge relief where flow characteristics requires the valve trim that
would match that of the ball valves.
Small diameter ball valves (3/4 inch to 2 -1/2 inch diameter) shall be used as isolation shut
off valves for potable or pump station water system.
All ball valves shall be in accordance with ANSI /AWWA C 507, with cast iron, ductile iron,
cast steel, or stainless steel bodies, support legs or pads, flange ends, suitable for velocities
up to 35 fps, temperatures up to 125 degrees F, and design pressures to 150, or 250 psi
depending on the pressure range required by the system. The balls shall be cast iron,
ductile iron, cast steel or stainless steel, shaft or trunion- mounted, with tight shut -off, single
or double seat, and full bore. The valves shall be rubber, with stainless steel or monel
shafts, and at least one thrust bearing. Except for stainless steel, ferrous surfaces of valves
in contact with wastewater shall be minimum 16 mil epoxy - coated.
Ball valves shall be as manufactured by Jamesbury Corporation, Wm. Powell Company, or
equal.
CHECK VALVES
Check valves shall be installed at each pump discharge piping to prevent backflow of
wastewater which can cause severe damage to the pump impeller and shaft, and
recirculation of flows back to the wet well in stations with multiple pumps. Valves shall
comply with the requirements of AWWA C508.
Check valves shall be the outside lever and spring type swing check valves. They shall be
installed in the horizontal position to prevent accumulation of solids downstream of the valve
which can cause clogging of the valves.
Swing check valves shall have a flanged cover piece to provide access to the disc. The
valve body, cover, and disk shall be cast iron conforming to ASTM A 126 Grade B. Disc
facing shall be rubber conforming to ASTM D2000 2BG715. Seat ring and clapper arm shall
be cast bronze conforming to ASTM B584 Alloy C 84400. Clapper arm shall be clamped to
the hinge pin with stainless steel screws and jam nuts.
Ferrous surfaces of valves in contact with wastewater shall be minimum 16 mil epoxy
coated.
Swing check valves shall be as manufactured by APCO (Valve and Primer Corp.), Kennedy,
Crane Company, or approved equal.
17 CITY OF SEAL BEACH
rlrpts.lSeal BeachlDesign Critena Sewer Facilities (Jul V3) DESIGN CRITERIA FOR SEWER FACILITIES
SEWAGE SURGE RELIEF VALVES
The necessity for surge control devices shall be determined through a complete surge
analysis of the pumping system. Although surge tanks are the most reliable means to
alleviate damaging surges in the force mains, sewage surge relief valves may be required
by the system. Where surge relief valves are required, the valve shall be installed in the
discharge piping manifold and connected to the wet well. The valve shall be designed to
open immediately when the system pressure exceeds the Toad setting of the counterweights
and shall close slowly at an adjustable speed upon return of system pressure to normal.
The surge relief valve body shall be constructed of a heavy cast -iron or cast steel disc
having rubber seating face; and corrosion resistant shaft and cushion chamber.
Sewage surge relief valves shall be as manufactured by APCO (Valve and Primer
Corporation), Empire Specialty Co., Inc, or approved equal.
SEWAGE AIR RELEASE VALVES
Sewage air release valves shall not be used unless absolutely necessary. The design
engineer shall endeavor to provide a system which rises continuously from the pump station
to the discharge point. Where absolutely necessary, sewage air release valves shall be
provided to vent accumulating air or gas during pumping operation or entrapped during
initial operation. Air release valves shall be installed at high points of the piping systems.
Entrapped air or gases can reduce pumping capacity of the pumping system or cause
corrosion of the piping system with gases containing hydrogen sulfide. The air or gas vent
located at the pump station plant shall be discharged to the wet well.
The valves shall have long float stems and bodies to minimize clogging. Each valve shall be
furnished with backwashing accessories to remove solids accumuled inside the valve.
Water supply and connection shall be provided with appropriate reduced pressure backflow
preventer near the valve for backwashing.
Sewage air release valves shall be as, manufactured by APCO (Valve and Primer
Corporation), Val -Matic (Valve Manufacturing Corporation), or approved equal.
REDUCED PRESSURE BACKFLOW PREVENTERS
Backflow preventers shall be installed where utility water or plant water is connected to the
potable water supply to prevent contamination of the potable water system. The valves shall
be designed to operate on the reduced pressure principle. The valve assembly shall consist
of two spring loaded check valves, automatic differential pressure relief valve, drain valves
and shut -off valves. The body materials shall be bronze for working pressure of not less
than 150 psi, with bronze and stainless steel trim. Drain lines and air gaps shall be
provided. All backflow preventers shall be registered with County Health Department and
must be approved for use in the City of Seal Beach.
Backflow prevention valves shall be as manufactured by Cla -Val Company or Febco.
18 CITY OF SEAL BEACH
r rpts (Seal BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
PUMP CONTROL VALVES
The pump control valves shall be installed in the pump discharge pipe to minimize hydraulic
surges during normal starting, stopping and emergency stopping of the pump during power
failure or emergency stopping caused by system failures.
The pump control valve shall be operated by hydraulic (oil) or pneumatic operator with a
reserve accumulator system as back -up energy source to operate the valve during power
failure. The pump control system shall be designed to start the pump against a closed valve.
Once the pump has developed pressure, the pump control valve shall start to open until it
reaches the maximum open position. Stopping sequence shall cause the pump control
valve to close. Complete closure of the valve shall signal the pump to stop. Emergency
power failure shall cause the pump control valve to close.
The normal opening, closing, and emergency closing times of the pump control valve shall
be independently adjustable. Range of adjustment shall be determined based upon the
results of surge analysis. Final settings of closing and opening times shall be verified during
pump station start-up. Settings shall be included in the Operation and Maintenance Manual.
17.11 Magnetic Flow Meters
Each pump station shall be equipped with metering equipment to measure outlet flow and
provide flow signal for recording, totalizing or control of other equipment. In addition, the
flow meter shall be used for pump field performance test to measure capacity and efficiency.
The meter shall be magnetic type suitable for wastewater service.
Magnetic flow meters shall be provided at the pump station discharge manifold capable of
metering the full range of flow with an accuracy of ±1 percent of flow rate from 10 to 100
percent of scale. At a velocity below 1 foot per second, the accuracy shall be ±0.1 percent
of the full scale. The meter shall be installed in the piping manifold with minimum straight
approach of 4 and 2 diameters upstream and downstream respectively.
The size of the flow meter shall be selected to cover the entire velocity range expected.
The magnetic flow meter shall utilize characterized electromagnetic induction to produce a
voltage linearly proportional to the average flow rate. The metering system shall consist of a
sensor with field coils, transmitter and interconnecting cables to make a complete operating
flow metering system. The meter shall be bipolar pulsed dc type with continuous automatic
zeroing.
The sensor shall be flange tube with non - conductive liner. The tube shall be constructed of
Type 316 stainless steel with carbon steel flanges AVWVA Class D if the coils are external to
the tube. The sensor rating shall be NEMA 4, and capable of withstanding accidental
submergence in water to a depth of 30 feet for 48 hours. The meter shall include a positive
zero feature for periods when the metering portion of the process pipe is not full.
Liner material shall be neoprene, except for liquids which may deposit non - conductive
coatings, which shall have Teflon linings. The specific conductivity of the liquid shall not
preclude meter operation.
19 CITY OF SEAL BEACH
rlrpts:ISeaI BeacMDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
Grounding electrodes shall be of the same material as the sensing electrodes and shall be
furnished mounted on each end of all flanges.
Transmitters shall be provided for either local or remote indication as required for each
particular project. Remote transmitters shall be NEMA -4X enclosures suitable for wall ,
mounting. Transmitters shall produce a 4 -20 ma -dc output signal into a minimum Toad of 800
ohms linear flow, and a scaled pulse for totalization. All electrical equipment furnished with
the magnetic flow meter shall carry a UL label.
Magnetic flow meters shall be Tigermag manufactured by Sperling Instrument Co., Inc. or
approved equal.
17.12 Piping and Support System
The pump station piping and supports system consists of the gravity sewer, pump suction
• and discharge piping, station water or utility water piping, potable water piping, air piping,
sanitary drainage piping, fire protection, and sprinkler piping systems. Most of these piping
r systems are adequately specified by the applicable sections of the Uniform Plumbing Code,
Fire Codes and the Standard Specifications for Public Works Construction. .
This Section includes special requirements and recommended practices involving the
design of piping and the support system.
A. Piping
1. Materials
Ductile iron pipe shall be used in pump station main piping, consisting of
suction and discharge piping, discharge manifolds, force mains as specified
in Section 11, and water piping 2 -1/2 inch and larger. Ductile iron pipe shall
be in accordance with SSPWC, and ANSI A21.5I (AWWA C151). All internal
surfaces of ductile iron pipe and fittings for water service shall be cement
mortar Tined and sealed with bituminous coating in conformance with AWWA
C104. Internal surfaces of ductile iron pipe for sewer service shall be lined
with polyurethane or glass.
Unless otherwise specified, all joints of ductile iron pipe shall be 125-lb flange
in conformance with ANSI B16.1, B16.2 and A21.10 (AWWA C110). Sleeve
or mechanical grooved type couplings shall be provided at the suction and
discharge piping of the pump, and between the magnetic flow meter and the
isolation valves to allow removal of the equipment for maintenance.
All bolts shall be of Type 316 stainless steel with bronze nuts or cap screws
of copper— copper silicon alloy, conforming to ASTM B 98, Alloy C 65100,
designation H04, or alloy C 65500, designation H04. Where anaerobic
Conditions are anticipated, Type 304 stainless steel shall be used.
Mechanical -type couplings (grooved) shall be used between the valves,
pumps, meters and the piping system for the above ground installation.
' Groove type couplings shall not be used for underground installation.
20 CITY OF SEAL BEACH
rIrpts:ISeal BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
Mechanical -type couplings shall be cast as manufactured by Victaulic, Gustin
Bacon or equal.
Sleeve -type couplings shall be of fabricated steel with steel bolts and with
sizes to fit outside diameter of the ductile iron pipe. The middle ring shall not
be less than 1/4 -inch in thickness and minimum of 5 to 7- inches long. The
follower shall be single piece contoured mill section welded and cold -
expanded as required for the middle rings. The coupling shall be equipped
with a gasket to make the joint water - tight. The coupling shall be factory
epoxy coated suitable for sewer service.
Sleeve couplings shall be installed in the piping systems subject to differential
settlement as in the force main that connects the piping inside the pump
station building to the yard piping. Two sets of sleeve couplings shall be
installed with spacing as recommended by the coupling manufacturer.
Where sleeve couplings are installed in the piping system subject to thrust
loads, the coupling shall be provided with restraining bolts. The bolts shall be
designed in conformance with AWWA Design Manual M -11.
Sleeve -type couplings shall be as manufactured by Rockwell (Smith - Blair),
and Dresser.
2. Suction Pipe
The suction pipe shall meet the following requirements:
a. The suction pipe shall be sized to provide a minimum velocity of 3 feet
per second, and a maximum velocity of 6 feet per second throughout
the operational range of the pump.
b. The inlet velocity to the eye of the impeller shall meet the pump
manufacturer's requirements. The largest suction inlet available shall
be selected.
c. The suction pipe shall be flat, or slope up to the pump to eliminate the
formation of air pockets. Reducers shall be the eccentric type, with
flat top, matching the crown of the suction pipe.
d. There shall be a straight length of pipe of minimum 5 diameters before
the suction elbow to provide uniform flow to the pump.
e. The inlet of the suction pipe shall be a long radius elbow with a flared
bell. The inlet location shall be in accordance with the hydraulic
institute standards. The velocity at the inlet to the suction bell shall be
• less than 2.5 feet per second.
f. The suction line isolation valve shall be full port eccentric plug valve
located close to the wet well wall, allowing sufficient room for removal
of the bolts and servicing of the valve.
21 CITY OF SEAL BEACH
rlrpts.lSeal BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
g. A pressure gauge capable of measuring the entire range of pressures
expected at the entrance to the pump shall be provided as close to
the pump as possible. The gauge shall be installed on a 1/2 inch NPT
pipe tap with a ball isolation valve and chem seal with snubber.
3. Discharge Pipe
The discharge pipe shall meet the following requirements:
a. Discharge pipes shall be sized for a minimum velocity of 3 feet per
second and a maximum velocity of 6 feet per second.
b. The discharge nozzle for dry well installed pumps shall be directed
towards the wet well and rotated 45 degrees from the suction line.
c. The discharge pipe shall be connected to the discharge header at an ,
angle of 45 degrees.
d. A pressure gauge shall be installed on the discharge nozzle or as
close to the pump as possible. The gauge shall be installed on a 1/2
inch NPT diameter pipe tap with a ball isolation valve and chem seal
with snubber.
e. A 1 -1/2 inch diameter pipe with a ball isolation valve shall be installed
between the top of the pump casing and the wet well.
B. Pipe Support Systems
All piping systems, including connections to equipment, shall be designed with
proper support to prevent undue deflection, vibration, and stresses on piping,
equipment, and structures resulting from normal operation and seismic events. All
supports and parts thereof shall conform to the requirements of ANSI /ASME B 31.1
except as specified herein.
Ductile iron pipe of any size shall have a minimum of 2 supports per straight length
not to exceed 10 feet of unsupported span. One of the supports shall be located at
the joint.
Where the piping system is subject to thrust as a result of hydraulic surge or
actuation of a surge relief valve, a thrust support or a hydraulic shock suppressor
shall be provided.
All pipe supports shall be galvanized after fabrication.
17.13 Ancillary Equipment
Each pump station shall be designed to provide the, necessary ancillary equipment to
support the operation and maintenance of the facility. This equipment is essential to the
22 CITY OF SEAL BEACH
rlrpts.ISeal BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
operation and maintenance of the system. Ancillary equipment or systems that are
discussed herein are commonly required equipment or systems in a wet well -dry well pump
station.
A. Hoisting Equipment
Most pump stations are located underground to provide adequate submergence for
the pumps. Therefore, the substructure and superstructure need to be designed to
allow for installation and removal of equipment. The provisions for access hatches,
lifting hooks, hoisting systems, roll -up doors and other means to provide ease of
maintenance shall be carefully investigated and designed as required.
For wet well -dry well type pump stations equipped with either vertical non -clog dry
well pumps or submersible pumps mounted in the dry well, a traveling bridge crane
shall be provided. The bridge crane shall be designed to have a travel and span
capable of reaching the pumps, meters and valves. Where the valves are located in
areas which are inaccessible to the crane, lifting eyes attached to the ceiling shall be
provided directly above the valve or equipment. A floor access hatch shall be
• provided when required.
Bridge cranes shall have a manually or electrically operated hoist, trolley and end
trucks, all designed to conform to all applicable codes, and OSHA safety
requirements. Where possible, monorail hoists may be used in lieu of the traveling
bridge cranes.
Where space permits, a hoisting system shall be designed to allow direct transfer of
equipment from the dry well to a flat bed truck. Traffic into the pump station building
shall be given special consideration and necessary turning radius shall be provided.
B. HVAC and Odor Control Systems
A typical pump station consists of the wet well, dry well or the pump room, motor
room, electrical and control room, and ancillary equipment rooms. Each of these
rooms requires different methods and degrees of heating, air conditioning and
ventilation to provide the following conditions:
1. A safe and comfortable working environment for personnel;
2. To facilitate proper operation of equipment;
3. To minimize corrosion of equipment and building materials; and
4. To prevent accumulation of explosive and hazardous gases.
The heating, ventilating and air conditioning (HVAC) system and odor control
systems shall be designed and controlled as one integrated system. Air distribution,
building enclosures, wall penetrations, wind directions, building occupancies, and
area classifications shall be carefully investigated. HVAC systems shall be designed
in accordance with the American Society of Refrigeration and Air Conditioning
23 CITY OF SEAL BEACH
rlrpts:ISeal BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
Engineers (ASHRAE), State of California Energy Conservation Standards Title 24
and the NFPA 820 Fire Protection in Wastewater Treatment Plants.
Equipment conveying corrosives shall be of material that is corrosion resistant, such
as fiberglass reinforced plastic (FRP) or stainless steel. If FRP ductwork is used, it
shall have flame spread of less than 25, and a smoke propagation of less than 400,
and be of fire resistant rating. Air containing flammable and explosive vapors or toxic
gases shall not be recirculated.
Air conditioning may be required for pump stations with VFD's.
Depending upon classification, motors for supply and exhaust fans shall be explosion
proof, totally enclosed fan cooled (TEFC) units.
C. Wet Well Ventilation "
The pump station wet well receives and stores wastewater before it is pumped to the
force main. Corrosive and hazardous gases are normally present in the wet well.
These gases can become a safety hazard to operating personnel or can cause
corrosion of building materials and equipment in the wet well. In order to minimize
accumulation of gases inside the wet well, the wet well shall be flushed with fresh air
by an adequately sized ventilation system.
Ventilation rates shall be in accordance with:
1. NFPA 820 Fire Protection in Wastewater Treatment Plants
2. Occupational Health and Safety Act (OSHA)
Pump station wet wells are classified into two types depending on their use;
1. Accessible Wet Well.
2. Sealed Wet Well.
ACCESSIBLE WET WELLS
Wet wells which require routine access for maintenance shall be provided with
adequate fresh air ventilation in order to provide a safe environment for maintenance
personnel, to prevent accumulation of explosive gases, and to minimize corrosion of
equipment installed in the wet well. The internal surfaces of the wet well shall be
Tined with PVC for corrosion protection.
The following minimum ventilation criteria shall be used:
1. All accessible wet wells shall be provided with continuous ventilation of a
minimum of 15 air changes per hour.
2. Where intermittent ventilation is required, the ventilation rate shall be at least
30 air changes per hour.
•
24 ' CITY OF SEAL BEACH
rlrpts:lSeal BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
All electrical equipment and fans inside the accessible wet well shall be explosion -
proof designed and manufactured for Class I, Division I, Group D. All other design
criteria shall be in accordance with NFPA 820 Fire Protection in Wastewater
Treatment Plants.
SEALED WET WELLS .
Sealed wet wells shall be designed to be low maintenance. The internal surfaces of
the wet well shall be lined with PVC for corrosion protection.
Sealed wet wells shall be provided with static vents to accommodate air
displacement due to the rise and fall of the water level in the wet well. The vent shall
• - have a minimum diameter of one -half the diameter of the incoming sewer. The vent
pipe shall be connected to the nearest sewer maintenance hole where possible.
Where the pump station is located away from any sensitive area, vent pipe could be
extended above the roof line with a minimum of 15 feet from any window or fresh air
inlet.
All electrical equipment inside the sealed wet well shall be classified in accordance
with NFPA 820, Fire Protection in Wastewater Treatment and Collection System
Facilities.
C. Odor Control
The need for odor control systems shall be evaluated for each project. Such
evaluation shall be based on a life cycle cost of 20 years with major consideration of
the power and chemical consumption, first cost, maintenance cost, reliability and
efficiency of the system.
Odor control systems may consist of activated carbon scrubbers, chemical scrubbers
utilizing a chemical absorption process for removal of odors, or chemical or air
injection systems.
For the chemical scrubbing systems, foul air from the plant process facility is
introduced into the scrubber vessel with an atomized mist chemical solution
containing sodium hypochlorite. Oxidation of odorous compounds occurs upon
contact with the scrubbing mist, and is removed in the condensate. The scrubber
should be designed to remove a minimum of 99 percent of hydrogen sulfide in the
foul stream. Acceptable chemical scrubber manufacturers are Calvert Environmental
Co., San Diego, CA, and Quad Environmental Technologies, Corp., Highland Park,
IL.
All odor control and ventilation equipment shall be suitable for continuous exposure
to saturated hydrogen sulfide gas, sodium hypochlorite mist, sodium hydroxide mist
and sulfuric acid. Electrical equipment shall have explosion proof enclosure designed
for hazardous condition for Class 1, Division 1, locations. J
For air pollution permits, consult South Coast Air Quality Management District.
25 CITY OF SEAL BEACH
rtipts:ISeat BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
D. Dry Well Ventilation
The pump station dry well is normally located adjacent to the wet well to house the
pumps, valves, meters and other ancillary equipment.
The dry well and equipment rooms shall be designed for a ventilation rate of at least
15 air changes per hour or ventilation rate equivalent to cool internal heat load from
the equipment whichever is greater or not greater than 60 air changes per hour. The
sensible cooling ventilation rate shall be calculated as follows: -
H= cfm x1.09xt -
where: -
H - Internal heat gain from equipment, Btu per hour
cfm - Air flow, cu ft per minute
t - Change in internal temperature, degree F. Use 10 degrees F for
change in internal temperature as adequate for sensible cooling.
Where a pump station is equipped with variable frequency drives (VFD), the VFD
shall be installed in an air conditioned room with 90 percent efficient outside air
filters. VFD units are inherently sensitive to temperature, dust, moisture and other
corrosive elements in the air. For constant speed pump stations, the motor control
center (MCC) and control rooms shall be equipped with a ventilation fan and 90
percent efficient outside air filters. Pump and equipment room air inlets shall be
provided with 30 percent efficient outside air filters. All air filters shall be provided
with differential pressure gages to indicate when the filters are clogged, and flow
detection devices connected to alarm signaling systems to indicate ventilation •
system failure. '
E. Fire Protection System
Where required by NFPA or by the Fire Department, necessary fire protection
systems shall be provided in required areas. For areas housing electrical equipment
such as the motor control centers, computer rooms and control rooms, an approved
type fire protection systems shall be provided.
F. Gas Detection System
Combustible gas detection equipment shall be provided in the wet well and dry well,
and other areas where hazardous gas may be present, to record, activate alarms
and /or to operate the ventilation system. The stationary gas detection system shall
be capable of measuring concentrations of hydrogen sulfide, methane gas and /or
petroleum vapor in the air.
The combustible gas sensor shall be DET TRONICS Point Watch Infrared
Hydrocarbon Gas Detector Model PIR9400 or equal. The sensor shall be mounted
in the wet well such that it can be removable externally for maintenance and
calibration. It shall be connected to the programmable logic controller (PLC). The
PLC shall monitor the combustible gas sensor through the 4 -20 mA signal which
26 CITY OF SEAL BEACH
rrpts.tSeal BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
1
shall be proportional to combustible gas concentrations of zero to 100 %. Two (2)
PLC adjustable alarms shall be provided. 6% lower explosion level (LEL) shall
indicate a warning, and 10% LEL shall indicate an alarm. Alarm beacons shall be
installed in the dry well and the electrical room.
An entry control station shall be provided in a NEMA 4X stainless steel enclosure
with vandal resistant hardware, and amber and green NEMA 4 vandal resistant pilot
lights at or near each entry. They shall indicate a potentially dangerous condition in
the pump station based on the loss of the ventilation system, combustible gas, loss
of positive pressure in the electrical room, or loss of negative pressure in the dry
well. Both lights shall be dark if there is a component or power failure. A lamp test
switch shall be provided, which will activate all entry control system lights for ten
seconds for testing.
G. Compressed Air System
For pump stations using surge tanks, air operated valves; pneumatic tools for `
maintenance purposes, and instrument air, a compressed air system shall be
provided. The air system for pneumatic tools shall consist of a lubricated type air
compressor, receivers, air dryers and necessary piping system. For an instrument
air system, a dedicated non - lubricated type air compressor, receiver, dryer and
necessary piping system shall be provided. Where the valve operators are designed
as pump control valves with the option to have controlled closing during power
failure, the air receivers shall be sized to store compressed air capable of stroking
the air cylinders three (3) complete cycles between the specified operating pressures
during power outages.
H. Hydraulic System
Pump stations equipped with hydraulic operated valves shall be provided with
hydraulic systems. The hydraulic system shall be either a package system supplied
with each valve, or one complete package to operate multiple valves. The system
shall consist of an oil reservoir, hydraulic pumps, control valves, hydraulic cylinders,
limit switches and nitrogen gas - filled accumulators where the valves are required to
operate during power outages. The valve opening and closing ranges shall be
specified. Final field adjustments shall be made during pump station start -up.
I. Noise Control
The pump station shall be designed to meet the minimum noise level requirement of
the City of Seal Beach Municipal Code (The Code) and the Occupational Safety and
Health Administration (CAUOSHA). All mechanical equipment and enclosures shall
be acoustically treated to bring the noise level down to an acceptable limit. These
' attenuation devices may consist of exhaust mufflers, sound isolators or acoustical
panels.
The pump stations shall be designed with noise levels not more than 5 dBA above
the ambient noise level as measured at the property line of the nearest recipient
(neighbor). A 24 hour noise level reading shall be measured at the pump station site
as basis of the design.
' 27 • CITY OF SEAL BEACH
rirpts•ISeal BeachlDes gn Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
•
In the absence of actual field measurements, the presumed ambient noise level shall
be deemed to be the minimum ambient noise level for each zone as follows:
Sound Level "A" Decibels
(In this chart, daytime levels are to be used from 7:00 A.M. to 10:00 P.M. and
nighttime levels from 10:00 P.M. to 7:00 A.M.)
Presumed Ambient Noise Level (dBA)
Zone Day Night
Residential 50 40
Public Facility, Commercial, Recreational 60 55
Industrial 65 65
At the boundary line between two zones, the presumed ambient noise level of the
quieter zone shall be used.
J. Sump Pumps
A sump pit shall be provided in all underground structures such as dry wells, valve
and electrical vaults. The sump pit shall be equipped with an adequately sized plus a
standby unit, each having a minimum capacity of 50 gpm. Submersible sump pumps
shall be used and controlled by a duplex type control, an automatic alternator and a
float switch level control. The control system shall be designed to start the standby
pump when the lead pump fails to start or when the water level continues to rise
while the lead pump is operating. Both pumps are to stop at low water level.
Sump pump discharge pipe, fittings and valves shall be Schedule 80 PVC pipe, with
minimum diameter of 2- inches. Each sump pump discharge pipe shall be provided
with a swing check valve and isolation gate valve mounted above, both in the vertical
position. A common discharge manifold shall terminate inside the wet well with the
wall penetration above the highest surcharge elevation of the wet well.
K. Spare Parts
Pump station electro- mechanical equipment shall be provided with spare parts
necessary to ensure continuous operation. The recommended spare parts shall be
determined by the project design engineer with assistance from the Director of Public
' Works /City Engineer. The following shall be the minimum list of spare parts:
1.. One set of pump and motor bearings for each size and model of pump unit.
2. One set of pump seals for each size and model of pump unit.
3. One set of pump and casing wear rings for each size and model of pump unit.
4. One set of pump and motor for each size and model of pumping unit.
5. One dozen fuses for each size of fuse.
6. A printed circuit board for each size and model of the variable frequency
drives.
28 CITY OF SEAL BEACH
rlrpts :ISeal BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
The spare parts shall be delivered to the project site no later than two (2) months
prior to pump station start up. Spare parts required during testing and start-up shall
be provided by the contractor.
17.14 Electrical Equipment
Electrical systems in the pump station consist of the power supply, power transformers,
motor control centers, electric motors, electric variable speed drives, electrical wires and
conduits, lighting fixtures, and other associated interface with the instrumentation and
control systems.
A. Power Supply
The standard power supply to the pump station shall be 480 volts.
B. Motor Control Centers (MCC)
All motor starters and disconnect switches shall be installed in Motor Control Centers -
(MCC). MCC rooms shall be located away from hazardous gas or other corrosive
environments. Mechanical ventilation equipment shall be provided to maintain air
circulation. All fresh air inlets to the MCC rooms shall be provided with 90 percent
efficient inlet filters.
Where environmental problems exist in the pump station location, such as the
presence of dust, moisture from sea water, or corrosive gas, the MCC room shall be
designed to have adequate ventilation and provided with air cleaning equipment
such as de- humidifiers, filters or carbon absorbers.
The MCC circuit breaker handles must be provided with safety interlocks.
C. Electrical Cables and Conduits
All electrical cables and conduits shall be designed in accordance with the NEMA
Area Classification as required by the service area. All electrical conduits shall be
PVC coated galvanized rigid metallic conduits or Schedule 80 PVC. All conduits
shall be sized for 100 year service. Spare conduits may be required. The minimum
size conduit shall be 1 -inch.
17.15 Instrumentation and Controls
The instrumentation and control system shall be designed to operate the pump station to
match the flow characteristics of the service area. The control system - shall consist of the
wet well level control, flow metering equipment, pressure gages and switches, fire alarms
and gas detection instruments.
29 CITY OF SEAL BEACH
Arpts.ISeal Beach1Design Criteria Sewer Facilities (Jul b3) DESIGN CRITERIA FOR SEWER FACILITIES
A. Pump Control System
' 1. General
The pumps shall be controlled by the level in the wet well. The primary and
secondary level sensors shall be an ultrasonic level type. The wet well shall
be provided with a redundant float switch type low -low level cut -off switch and
a high -high level alarm switch. Each pump shall be provided with a high
discharge pressure switch to activate failure alarm during accidental closure
of the discharge valve, failure of the pump control valve to open, or failure of
the check valve to open. All failure alarm switches shall be provided with
alarm lights located in the Local Control Panel (LCP) and the Main Control
Board (NCB). LCPs shall be located near the pumps, while the MCB may be
located in another building or in a remote location.
The pump control system shall consist of both "hard wired" controls and a
Programmable Logic Controller (PLC). During normal operation, the PLC will
be controlled by the ultrasonic level control. Upon Toss of ultrasonic level
signal or failure of the PLC, the control system will automatically switch from
the PLC to the "hard wired" system. The "hard wired" system will then be
controlled by the float switch for which the pump station will operate in a "fill -
and -draw" mode.
2. Constant Speed Pump Control System
•
The operating sequence is applicable for multiple pump units installed in a
smaller wet well. The pump station will start in sequence, pumps start and
stop in the reverse order.
This sequence is recommended for the following reasons:
a. To maintain uniform flow into the receiving system
b. To provide smaller wet well storage volume and less number of motor
starts per hour;
c. To reduce sewer gas emission to the atmosphere by•maintaining a
constant water level in the wet well.
3. Variable Speed Drives.
Variable speed (matched -flow) pumps shall be used for the following
conditions;
a. Where more uniform discharge to the receiving system is required;
b. Where there is not enough space in the pump station to
accommodate installation of multiple smaller unit constant speed
pumps;
30 CITY OF SEAL BEACH
rlrpts:ISeaI BeachlDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
c. Where the wet well volume is limited to satisfy maximum starts per
hour;
d. Where sewer gas emissions to the atmosphere should be limited;
The variable speed drive pumps shall be controlled as follows:
a. When the wet well level reaches the first set level, the lead pump
start and ramp to a minimum preset speed. As the flow increases, the
pump speed will increase in proportion to the increase in flow in order
to maintain the level in the wet well until the pump has reached its
maximum speed.
b. When the inflow to the wet well exceeds the maximum capacity of the
lead pump, the control system will then start the lag pump. The lag
pump will increase its speed while the lead pump will decrease its
speed up to the point where the two pumps share the flow, both at the
same speed. As the inflow increases, the two pumps will increase
• their speeds in proportion to the inflow until the pumps have reached
the maximum pump design flow, in the case of two pump
combination.
c. A drop in wet well level equivalent to a decrease in pump station
inflow will signal the pumps to slow down until a preset speed is
reached. Then the lag pump will stop, and the lead pump will increase
its speed in proportion to the inflow.
d. Further drop in wet well level will signal the lead pump to slow down
until the minimum level is reached, at which level, the lead pump will
stop.
e. In the event that either the lead pump or the lag pump fails, the wet
well level will rise and the standby pump will be started at the same
time the failure alarm is activated. The standby pump will be provided
with a variable speed drive.
For pump stations equipped with more than two variable speed pumps, the
same operating sequence will be followed.
4. Combination Constant Speed And Variable Speed Drive Pumps .
Where a combination of constant speed and variable speed drives are
required by the pumping system, the variable speed pump shall be used as a
jockey pump. This design, however, is often discouraged due to the
complexity of the control system. The jockey pump with variable speed drive
shall be sized to serve as a lead pump and to trim the flow, in excess of what
the constant speed pump can not deliver. The sequence of operation shall be
as follows:
31 CITY OF SEAL BEACH
r rpts:ISeal BeachtDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
a. At a preset level in the wet well, the lead pump with variable speed
drive shall start and increase its speed to a minimum preset speed. As
the inflow into the wet well increases, the pump speed shall increase
to match the incoming flow.
b. When the pump speed has reached the maximum speed and the
inflow is increasing, the constant speed pump shall start.
c. Due to the increase in capacity of the constant speed pump, the wet
well level will drop and this shall cause the variable speed pump to
slow down and maintain the level in the wet well.
d. Further increase in the incoming inflow will increase the speed of the
variable speed pump until the maximum capacity of the pump station
is reached. Decease in wet well inflow shall reverse the sequence
until the lead pump has reached its minimum speed. When the inflow
is less than the capacity of the pump at its minimum speed, the lead
pump shall stop after a preset time delay.
The cost of transfer switch gear and the reliability of the whole system
shall be taken into consideration when evaluating the different types
of drives.
- The variable speed drives shall be provided with bypass contactors to
operate the pump at full speed when the VFD is not available.
5. Float Level Switch
The float level switches shall be used to detect the low -low level cut -off and
the high -high water level alarm, and as an auxiliary system in the event of
failure of the primary and secondary ultrasonic level control systems. When
the water level in the wet well reaches the high -high level, the control system
(US Filter CBIT B300 single stage controller or approved equal) shall initiate
a timed pump down using all pumps. The pump station shall be capable of
operating indefinitely in this mode. The float switch shall be direct acting with
a single pole mercury switch which activates when the longitudinal axis of the
float is horizontal and de- actuates when the liquid level falls 1 -inch below the
actuation level. The switch shall be encapsulated in a chemical resistant
polypropylene casing with a firmly bonded electrical cable protruding. The
entire assembly shall be watertight and impact resistant designed and
manufactured for Class 1 Division 1, Hazardous Conditions. Float switches
shall be Roto -Float as manufactured by Anchor Scientific or approved equal.
Submersible dewatering sump pumps located in dry wells and valve
structures shall be controlled by float switches. Float switches shall be
designed and manufactured suitable for the area classification of the sump
pit.
32 CITY OF SEAL BEACH
rirpts:lSeal BeachMDesign Criteria Sewer Facilities (Jul 103) DESIGN CRITERIA FOR SEWER FACILITIES
6. Ultrasonic Level Control
The pump station's primary level control and the secondary level control shall
be the ultrasonic level sensors. Accordingly, two ultrasonic level sensors shall
be provided. The transducers shall be hermetically sealed, self cleaning with
built -in temperature compensation 6 beam angle, suitable for installation in a
sewage pump station wet well.
Ultrasonic measuring systems shall be the Hydroranger with XPS -15
transducer as manufactured by Milltronics, or approved equal.
17.16 Supervisory Control and Data Acquisition (SCADA) System
Where the pump station operation is required to be monitored or controlled remotely at a
central station, SCADA system equipment shall be provided. The system shall consist of the
Remote Terminal Unit (RTU) located in the pump station connected to a computer at a
designated central station. The signal to the central station shall be transmitted over the
telephone lines, or radio.
The pump operation is normally initiated by a motor starter mounted in the Motor Control
Center (MCC) Room. The starter is controlled by a local switch or push buttons or by local
control automation, such as the PLC, RTU or the Process Control Module (PCM). The PCM
is an intelligent RTU.
The local control panel normally houses the Programmable Logic Controller (PLC) which is
designed to perform the pump station control commands, and receive and send commands
between the RTU and the Central Station. Other signals, such as wet well levels, flow,
pressure, etc., may send signals directly to the RTU.
The RTU's are classified as "smart" (intelligent) or "dummy" RTU's. The smart RTUs are
capable of providing local control and data gathering, while the dummy RTUs take
information and monitor data and execute commands from the Central Station.
The Central Computer System function consists of display information such as graphics and
tables. It also gathers historical data such as trends of pumping cycles, measurement of
flows and pressures, equipment running time, number of pump starts per hour, and many
more features if designed with these features.
17.17 Pressure Gauges
In a wet well -dry well type pump station, pressure gauges shall be installed at the suction
and discharge sides of each pump to measure the pump total dynamic head. The pressure
gauges shall be at least 4 -1/2 inches in diameter. Where seal flushing water is required, a
pressure gauge and low pressure switch shall be provided to activate an alarm in case of
loss of flushing water. A low flow alarm switch may be used in lieu of the pressure switch.
A pressure switch shall be provided between the pump and the check valve or pump control
valve to activate an alarm in the event of failure of the valve to open or accidental closure of
any isolation valve located at the pump discharge piping. A micro - switch attached to the
valve shaft may be provided in lieu of the pressure switch.
33 CITY OF SEAL BEACH
rlrpts:ISealBeacMDesign Critena Sewer Facilities (Jul 03) DESIGN CRITERIA FOR SEWER FACILITIES
All, pressure gauges and switches installed in a piping system carrying solids bearing fluids
such as wastewater, sump pump discharge or chemical lines shall be provided with
diaphragm seals and snubbers where pulsating flow is expected. The assembly shall be
provided with an isolation ball valve for maintenance. Diaphragm seal material shall be
compatible with the pressure and fluid being handled.
In a submersible pump station, a pressure gauge /switch shall be installed in the discharge
pipe of each pump in the valve vault upstream of the check valve. The discharge pressures ,
shall be indicated in the pump control panel.
•
17.18 Pump Station Facility
The pump station facility includes the pump station structure, buildings, electrical substation
or transformer, access roads and other appurtenant equipment inside the property. The
facility design shall incorporate access road and security. The architectural treatment shall
blend with the surrounding area.
A. Building Design and Materials of Construction
The pump station usually consists of an underground concrete structure to house the
wet well and the dry well. Where the pump station requires an above ground
structure to house the electrical room, generator room, office area and maintenance
shop, the above ground building shall be designed in accordance with the
requirements of the Uniform Building Code. In general, all buildings shall be cast -in-
place concrete or masonry block wall construction.
Wet Well and Dry Well. The wet well and dry well shall be reinforced cast -in -place
concrete with wall thickness to withstand the earth loads, and shall be heavy enough
to resist floatation without earth skin friction resisting the outside surfaces when the
wet well is empty.
The size and configuration of the wet well shall be designed in accordance with
Section 17.5. The bottom of the wet well shall be sloped to at least 15 degrees and
corners grouted to prevent accumulation of solids during operation.
The dry well shall be designed to provide the following:
1. Minimum of 42 -inch clear working clearance between pumps and piping;
2. Access doors, stairways and landing;
3. Access opening for equipment installation, maintenance and removal;
4. Hoisting equipment or lifting hooks;
5. Adequate ventilation -
6 Fire protection equipment where required.
34 CITY OF SEAL BEACH
rlrpts•ISeal Beach%Design Cnteria Sewer Facilities (Jul V3) DESIGN CRITERIA FOR SEWER FACILITIES
17.19 Force Mains
The minimum diameter for a force main shall be 4 inches. The capacity of the force main
shall be the design peak flow from the pump station. The minimum design velocity for a
force main shall be 3.0 fps, and maximum allowed 5.0 fps for PVC and 6.0 fps for DIP. .
Force mains shall continuously rise from the pump station to the terminal manhole to
eliminate the need for air and vacuum release valves.
For new pump stations with phased development of the tributary area, dual force mains may
be required. The Director of Public Works /City Engineer shall select the number of force
mains that will be installed at each pump station.
17.20 Access Roads
Pump stations shall be designed with access roads for construction, operation and
maintenance of the equipment. The roads shall have turning radii suitable for the size of
vehicle, or heavy hoisting equipment necessary for installation, removal or delivery of
equipment or supplies into the station. Pavement sections shall be able to support the load
of the heaviest anticipated equipment to be used in the station. Where monorail hoists or
, traveling cranes are required, adequate headroom clearance shall be provided or loading
docks can be used to limit the height of the building. .
17.21 Flood Control
The pump stations shall be designed with with ground level floor one foot above the
expected value100 -year flood elevation. Where available and current, information contained
in the Orange County Public Facilities and Resources Department documents can be used
to determine the expected value 100 -year flood elevation.
All hydrologic and hydraulic calculations and design shall be in accordance with the
standards of the jurisdictional flood control agency standards.
17.22 Grading and Area Drainage
The site drainage shall be designed to prevent standing water or the erosive effects of storm
runoff. Pavement areas shall have a positive drain of up to 3 %. Flow lines shall have a
minimum of 1% slope. Underground structures shall not be constructed in partially cut and
partially fill. Where this condition exists, the site shall be over - excavated and re- stabilized.
The pump station shall be designed not to float where high groundwater exists.
17.23 Soils Report
A geotechnical investigation shall be conducted to determine the underground soils
conditions. The Soils Report shall show the foundation design criteria, corrosiveness of soils
and ground water, groundwater elevations if it exists,, and possible hazardous materials
underground. Cleaning of such materials shall be addressed in the construction contract, or
can be awarded to a separate hazardous materials contractor as determined by the Director
of Public Works /City Engineer.
35 CITY OF SEAL BEACH
rirpts.ISeal BeachMDesign Criteria Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
17.24 Surveying
The control bench marks shall be referenced from the County of Orange records. Where
existing survey is available, field check existing data with the new datum and the existing •
building or structure. The location of the pump station should be tied to a nearby street and
to an existing property line. Basis of survey bearings and control shall be given if the local
coordinate are established.
17.25 Security
The pump station site shall be provided with chain Zink fence or masonry block wall fence, as
directed by the Director of Public Works /City Engineer. The fence or wall shall be designed
in accordance with applicable American Public Works Association Standards. The entrance
gate shall be secured with a padlock. Where the pump station has a superstructure housing
the motor control center and the generator, the building shall be equipped with intrusion
alarms. Where there is no superstructure, the NEMA 3R enclosure housing the motor
control center shall be equipped with an intrusion alarm. The alarms shall be connected to a
horn mounted in the building, a red beacon light mounted outside the building or above the
NEMA 3R enclosure, and remoted via telemetry to the main control system.
17.26 Water Supply System
The pump station water supply system shall be provided for pump seal water system,
irrigation system, rest rooms and housekeeping hose downs. A backflow preventer shall be
installed in the pipeline connecting the hose bibs, seal water and irrigation system. Seal
water systems shall utilize air gap tanks, and not be directly connected to the water supply
system. All piping shall be designed in conformance with the Uniform Plumbing Code.
17.27 Landscaping and Irrigation System
Plants selected should be drought resistant and irrigation system equipment should utilize
water saving kits controlled by automatic timers.
17.28 Construction
The pump station shall be constructed in conformance with the specifications and drawings.
The pump station construction shall be administered and inspected by the City of Seal
Beach, or its designated representative.
A. Shop Drawing Submittal and Shop Drawing Review
The Technical Specifications shall specify the requirements for shop drawing
submittal and review process.
Once the project is awarded, shop drawing submittals need to be reviewed and
accepted. The shop drawing review is one way to check compliance with the
specifications. It also serves as a mechanism to get from the contractor the -
equipment as specified. Where a substitution to specified equipment is proposed to
the construction project Design Engineer for review, the design project engineer
should be consulted.
36 C/TY OF SEAL BEACH
Arpts:lSeal BeachMDesign Criteria Sewer Facilities (Jul U3) DESIGN CRITERIA FOR SEWER FACILITIES
B. Equipment Installation and Testing
The equipment installation and testing shall be specified in each equipment
specification. Normally, the equipment shall be specified to be installed by the
Contractor. under the supervision of a certified factory representative. After
installation, the Contractor shall conduct trial operation of the equipment, and make
the necessary adjustments as required. When the equipment becomes operational,
the Contractor shall test the equipment in the presence of the City's representative.
The test shall include a performance test, simulating the manual and automatic
operation, and checking of other components in compliance with the specifications.
A continuous test using the actual process material shall be conducted without any
breakdown prior to final acceptance.
• C. Operation and Maintenance Manuals
The Operation and Maintenance Manual shall be prepared by the construction
contractor based upon the plans and specifications, and assistance from equipment
• manufacturers, to clearly describe how the pump station shall operate under normal
and emergency conditions, and how it should be maintained.
Final payment shall not be made to the Contractor until the Operation and
Maintenance Manual is approved by the Director of Public Works /City Engineer..
- D. Operator Training
Each pump station has unique operational requirements and some have equipment
that requires familiarization by the station operators. The Contractor shall provide
training, through respective authorized equipment representatives, to the station
operators as specified in the Contract Documents.
18. STANDARD SEWER NOTES
The following notes must appear on the plans under Standard Sewer Notes.
A. The sewer Contractor shall have a copy of the Project Plans and Specifications, as
well as the City of Seal Beach Design Criteria for Sewer Facilities on the job site.
B. The Contractor shall obtain a City and /or County permit for work done on public
right -of -way.
C. The Director of Public Works /City Engineer's Office shall be called for inspection five
(5) working days before start of work at (562) 431 -2527.
D. A pre- construction conference shall be held 48 hours before starting construction
work.
E. The Contractor shall expose all join points to the existing sewer system for
verification of location and elevation before construction.
37 CITY OF SEAL BEACH
rlrpts :ISeal BeachlDesign Critena Sewer Facilities (Jul '03) DESIGN CRITERIA FOR SEWER FACILITIES
F. Stations shown as 1 +00.00 are sewer stations and are independent of all other
stations.
G. All laterals shall be staked by a surveyor before trenching and a complete set of cut
sheets shall be supplied to the City Inspector.
H. The City will inspect and test the sewer collection system and lateral sewers to the
property clean -out. Privately owned sewer laterals from the property line clean -out
will be inspected and tested by ---
J. All sewer lines shall be balled in the presence of the City Inspector before
completion of all leakage tests.
. K. Pipeline leakage tests shall be made in the presence of the City Inspector, only after
backfill has been completed, compaction tests on backfill have been made, and the
' backfill has been accepted by the City Inspector.
L. All sewer main lines shall be inspected using a closed circuit television system. Two
' recordings shall be made of the inspection on a DVD disk in accordance with the
City of Seal Beach Specifications for Video Inspection of Sewer Lines, and provided
to the City. One recording shall inspect the system constructed with no flow, and
one shall conduct the inspection with flowing water.
M. The Contractor shall provide the City with an as -built set of job prints with tie -down
measurements for all laterals and manholes.
N. Before final acceptance, the developer's engineer signing the plans shall furnish the
City with a set of as -built mylars of the sewer plan.
O. Curbs, or pavement surfaces in Old Town alleys, shall be inscribed with an, °S"
indicating locations of all sewer laterals.
P. Curbs shall be inscribed with ties for all manhole locations.
Add the following notes to plans having on -site work which will be dedicated to the
City:
Q. Trench backfill, on all sewer and water to be dedicated to the City, shall be
compacted to 90% relative density as determined by the five -layer test method
(California 216G). Tests will be required every 300 -feet of trench or as determined
by the City Inspector. The developer shall submit written results of compaction
testing to the City before acceptance. If in dedicated street or future street,
compaction will be as required by governmental agency having jurisdiction, but no
Tess than 90 percent relative compaction.
38 CITY OF SEAL BEACH
r1rpts :ISeal BeachtDesign Cnteria Sewer Facilities (Jul V3) DESIGN CRITERIA FOR SEWER FACILITIES