Appendix D
Technical Memorandum
on Pump Station
Condition Assessment
City of San Carlos Sewer Collection System Master Plan
Technical Memorandum
San Carlos Sewer Collection System Master Plan
Subject:
Sewer Pump Station Condition Assessment
Prepared for:
City of San Carlos
Prepared by:
Aaron Hope, P.E.
Reviewed by:
Tony Valdivia, P.E., Gisa Ju, P.E.
Date:
Reference:
March 21, 2012
RMC Project No. 0464-001
This Technical Memorandum (TM) presents the observations and recommendations resulting from staff
interviews and a visual inspection of the City of San Carlos’ wastewater pump stations. This work has
been performed as part of the Condition Assessment and Rehabilitation/Replacement Program (Task 6) of
the Sewer Collection System Master Plan project.
This TM is organized as follows:
1. Introduction
2. Pump Station Reliability and Emergency Operations
3. Scope of Condition Assessment
4. Condition Assessment Findings
5. Useful Life and Summary of Recommendations
1 Introduction
The City of San Carlos owns and operates a total of seven wastewater pump stations as a component of its
wastewater collection system. Four of these pump stations are considered major facilities (they collect and
pump sewage from a number of residential and/or commercial customers), two pump stations are minor
(they serve only one customer), and one pump station is a wet-weather “booster” facility.
The major pump stations are as follows:
 Upper Crestview
 Lower Crestview
 Tierra Linda
 Associated Pump Station (commonly referred to as “The Associate”)
The two minor pump stations serve a single commercial user, the Kelly Moore manufacturing and
commercial facility, on Old County Road near Commercial Street. Only one of these pump stations
(referred to as the Kelly Moore I Pump Station) was visited as part of this project; the other minor station
(Kelly Moore II) serves a single commercial bathroom and was not accessible at the time of the visit.
The major and minor pump stations function to lift wastewater from low points in the collection system.
Depending on the station, these flows are lifted to a higher elevation so that sewage can be conveyed via
gravity or, as in the case of the Associated Pump Station, to the South Bayside System Authority (SBSA)
San Carlos Pump Station.
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Pump Station Condition Assessment
The wet weather pump station, called the “Industrial Booster Pump Station,” is located adjacent to the
Pulgas Creek stormwater pump station on Industrial Road. The intended purpose of this pump station is to
reduce the risk of sewer overflows during large rain events by lowering the hydraulic grade line in the
sewers at the southern end of Industrial Road.
A site visit to the four major pump stations, the wet-weather pump station, and the Kelly Moore I pump
station was conducted by Aaron Hope and Tony Valdivia of RMC Water and Environment (RMC) on
February 9, 2012. RMC staff were accompanied by Frank Amoroso, Public Works Supervisor for the City.
The purpose of this site visit was to document existing conditions at each of the pump stations based upon
visual inspection and interviews with the accompanying City staff. RMC also reviewed available pump
station plans for comparison to field conditions.
2
Pump Station Reliability and Emergency Operations
Overall, the City does not experience any critical, ongoing issues with its pump stations, and pump station
failure has not historically been a cause of sanitary sewer overflows. The City’s emergency response plan
for pump station operation includes both internal City resources and a contract agreement with Rain4Rent
to provide support in the event of a major issue.
Typically, emergency planning scenarios include power failure (usually short term but not uncommon in
this region) and sudden equipment failure. In the event of power failure, the City may mobilize a Cityowned “Vactor” vacuum truck to remove sewage from pump station wet wells. In addition, the City
maintains a 4-inch trash pump, which can be used for bypassing a failed pump station.
In the event that City resources are not available or are insufficient to handle a significant or prolonged
emergency, the City can request emergency standby power and pumping equipment from Rain4Rent.
Rain4Rent has specifications for each of the City’s pump stations and maintains up-to-date documentation
so that it can deliver the correct equipment to the site. Rain4Rent staff is trained to install and operate
equipment, as required. The City reports that this arrangement with Rain4Rent has worked well and that it
will continue this arrangement in the future.
Several other aspects of the City’s approach to pump station management help provide operational
reliability:




There is redundancy in the alarm/controls systems. Each of the major pump stations has a highlevel float alarm in addition to ultrasonic level monitoring for SCADA.
The City contracts with Peninsula Pump to exercise all of the pump station valves twice per year.
Operators cannot clear critical alarms from SCADA central – crews must visit pumps and verify,
in person, that the pump station is in working condition. All other types of alarms can be cleared
from SCADA central.
SCADA panels and control systems are new and identical at all pump stations; this consistency
reduces system complexity and ultimately makes the pump stations easier to manage and maintain.
3 Scope of Condition Assessment
Field inspection was limited to those conditions that could be directly observed from the ground surface,
including a visual inspection and observation of noise, odor and vibration. The scope of this evaluation
did not include in-depth structural, electrical, mechanical or civil evaluations, calculations or
investigations. However, capacity analyses were conducted for two of the major pump stations (Tierra
Linda and The Associate) and for the Industrial Booster station as part of the trunk system capacity
evaluation conducted for the larger Master Plan effort.
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Pump Station Condition Assessment
The sections below provide a general overview of the types of issues that have been identified at each
station. Specific issues observed at each station, as well as recommended actions to correct observed
deficiencies, are summarized in Section 4.
3.1
Pumping Equipment
With the exception of the Industrial Booster Pump Station, all of the City’s wastewater pump stations
utilize submersible pumps in a concrete wet well. Submersible pumps (including close-coupled motors) are
installed at the bottom of the wet wells, which vary in depth, while electrical equipment is housed in an
enclosure adjacent to the wet well. When correctly designed and installed, submersible pumps often
operate without significant issues, and this appears to be the case with all of the City’s pump stations.
Where problems do occur, they are most often associated with noise and vibration during pump operation,
pump “ragging,” capacity degradation due to pump wear, or inadequate pump access. The City has
reported no such problems with their existing pumps, and none were observed during field visits.
Noise
Submersible pumps are rarely subject to noise complaints during normal operation because the motors are
relatively small (all of the City’s wastewater pump motors are 10 Hp or less) and are often submerged and
situated below grade. Abnormal noise or vibration is often a symptom of an operational problem that
should be investigated further.
Pump “Ragging”
“Ragging” is a general term for pump clogging due to stringy or fibrous materials in the wastewater flow.
Wastewater pump impellers are designed to accommodate solids in wastewater and pass these without
issue. However, not all pumps are designed to combat ragging as effectively as do others. Ragging is
typically a problem associated with larger stations, as smaller residential stations do not regularly
encounter these types of materials. Pump impellers can sometimes be retrofit for improved ragging
performance, but screening or grinding of influent flow may be required for ongoing problems. Persistent
pump ragging may also be an indication of inadequate pumping energy at the eye of the impeller, which
could suggest oversized pump or operation at too slow a speed.
Pump Wear
Over time, pump performance may diminish due to normal wear. Degradation in pump performance may
be exacerbated if the wastewater contains unusually high levels of grit or solids, which will wear down the
pump impeller and interior surfaces more quickly. As pump components wear, hydraulic efficiency will
degrade, and the pump performance will drift away from its design performance curve. Eventually, pump
performance may be inadequate to handle incoming flows, and pump inefficiencies will result in a higher
pump operating cost. Pump wear can be assessed directly, through inspection, or indirectly, through
monitoring and trending of pump performance (discharge flow and head). The most common solution for
diminishing performance due to wear is replacement of the pump impeller, though electrical and other
mechanical issues should be ruled out as the root cause, as well.
Pump Access
Submersible pumps are typically brought to the surface for maintenance and inspection. This is easiest for
operators and also eliminates the need for confined space entry to the wet well. Guide rails and chains
(usually stainless steel) are designed to raise the pumps through hatches as the top of the wet well. If these
systems are designed and installed correctly, submersible pump access is rarely an issue. Issues do
develop when larger pumps are retrofit into existing wet wells, and access can be compromised in these
cases. At smaller stations (e.g., Kelly Moore I), the City has elected to forgo hatch access and instead
utilizes manhole covers for access to these very small pumps.
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Pump Station Condition Assessment
3.2
Discharge Piping
The term “discharge piping” is used to define piping between the pump discharge connection (in the wet
well, in the case of a submersible pump station) and a point downstream of the discharge valves. Piping
downstream of this point is considered to be the force main, and is beyond the scope of this assessment.
Discharge piping is often ductile iron, but depending on age and pressure capacity may be cast iron,
polyvinyl chloride (PVC), fiberglass or stainless steel. Ductile and cast iron are typically specified to be
coated for external corrosion protection. All ferrous metal in the wet well, including pipe supports and
bolts, is subject to corrosion over time, and new pump stations very often require high grade stainless steel
for these accessories (galvanized steel may be acceptable in some circumstances).
Surface corrosion does not always signal a significant problem so long as the pipe wall thickness is
sufficient for the operating pressure, however the presence of pitting in the pipe wall or significant
degradation of flange bolts may be a concern. This assessment did not investigate corrosion beyond a
visual inspection.
3.3
Valves
In most cases, the City’s pump discharge valves are located in a valve vault adjacent to the wet well. Some
stations have valves in the vertical discharge piping within the wet well, but this is less desirable due to
access issues. Valves typically consist of an isolation valve and a check valve, one for each pump
discharge. Exposed valves are ideal for access; however, the City has buried valves at The Associated
Pump Station.
Common issues with valves include valve freezing (the valve becomes stuck in one position), failure to
seal (usually due to internal wear or obstructions), and leaks within the valve body (usually at the valve
stem bushing). Regularly operating the valve (as the City does) can prevent freezing and maintain valve
operation. Most valves can be “rebuilt” when required, as opposed to replacement, and valves can operate
for decades if maintained regularly.
3.4
Electrical Equipment
Electrical equipment at the City’s submersible pump stations is housed within an electrical panel adjacent
to the wet well. Thorough evaluation of the electrical gear is beyond the scope of this assessment,
however the City may wish to investigate these items in the future. Electrical codes change over time,
particularly with respect to operator safety, and it is common for older stations to not meet current codes
for new construction.
Only one of the City’s pump stations, Tierra Linda, has a standby diesel generator. The other stations have
electrical connections for a portable generator. The City exercises the Tierra Linda generator monthly to
confirm proper operation, which is the recommended practice for such equipment.
3.5
Controls and Communication
The City has standardized supervisory controls and data acquisition (SCADA) across all of its pump
stations. Instrumentation required for operation of submersible pump stations is minimal, and the City
utilizes ultrasonic level sensors with float backups for redundant monitoring and alarming of wet well
levels. The City has the ability to monitor station and alarm status remotely, and has implemented a policy
that requires operator visits to clear critical alarms such as pump failure. Radio communication is used to
transmit control and status signals to and from the remote pump station sites, and City staff indicates that
communication is reliable.
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3.6
Wet Well
All of the City’s submersible pump station wet wells are cylindrical concrete structures. Condition and
operational issues at submersible wet wells vary depending on the design of the wet well and the
characteristics of the incoming flow. Properly designed, many wet wells serving residential areas will
operate with very minimal maintenance. Issues that may develop at submersible pump stations include
buildup of grease, grit and sludge, odor, and corrosion of the wet well structure.
Grease, Grit and Sludge
Grease in a wet well may originate from either domestic or commercial sources. Generally, a pump station
serving primarily residential areas will exhibit only minor grease build-up. Pump stations serving
commercial land uses, and in particular restaurants or food processing facilities, may exhibit more
significant grease build up, particularly if grease traps are not installed or maintained upstream of the
collection system. Because grease is less dense than water, it tends to accumulate at the water surface and
coat the walls and surfaces of a submersible pump station, making it difficult to remove using just the
pumps. High pressure spraying or scraping is often required to remove grease, and enzyme-based solutions
may be added upstream of the pump station to control significant grease issues. The City utilizes an
enzyme-based system at its Tierra Linda Pump Station.
Grit and sludge issues may occur in a submersible wet well if the design of the wet well does not allow for
scouring velocities to develop during pump operation. Areas within the wet well where velocities are not
sufficient to stir up accumulated solids are sometimes referred to as “dead zones,” and may require extra
maintenance in order to maintain proper pump station operation. To combat this issue, wet wells are
typically designed to slope toward the submersible pump intake, and existing wet wells may be retrofit in
some cases to improve wet well hydraulics. Alternatively, submersible pump manufacturers may offer
mechanical solutions to promote scouring of the wet well. Many Flygt pumps, for example, can be fitted
with mixing valves (wet well space permitting) that automatically divert an initial amount of pump flow
back into the wet well each time the pump actuates.
Odor
Odor issues typically develop as wastewater ages, but may be less of an issue in the absence of sensitive
receptors like homes and public spaces. Typically, wastewater residence time in a small submersible
pump station will not be sufficient to generate odors unless the station is relatively far downstream in the
collection system (and further from the source of the oldest wastewater). Odor issues can be combated
operationally by limiting residence time in a station wet well (adjusting level controls or changing
pumping equipment), through chemical addition in the upstream system, or by scrubbing vented air. Most
submersible stations have passive air venting through a small vent pipe, but some of the City’s older
stations do not.
Wet Well Corrosion
Unlined concrete wet wells may be subject to degradation through reaction with hydrogen sulfide
produced during anaerobic digestion of raw wastewater. Hydrogen sulfide is always present in wastewater
facilities, but the amount that is present depends of the age and nature of the wastewater, wet well
hydraulics and other site-specific considerations. Symptoms of minor, often not structurally significant,
corrosion may include concrete discoloration and exposed aggregate. Advanced, structurally significant,
symptoms include exposed or disintegrated rebar, and softening of concrete to significant depth. Testing
and structural evaluation of existing concrete are beyond the scope of this assessment, but the City should
continue to monitor for signs of corrosion at all unprotected concrete structures – RMC did observe signs
of minor hydrogen sulfide corrosion at the City’s oldest stations, which also lack air venting. Protective
coating above the low water level may be required in the future if signs of corrosion increase or structural
inspection reveals a more serious issue.
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3.7
Site Access, Drainage and Security
Site access by maintenance vehicles appears to be adequate at all stations. Generally, station access and
roadway turning radii should allow the largest anticipated maintenance vehicle to enter and exit the site
without complex maneuvering and with minimal impacts to traffic of adjacent roadways. For small
submersible stations, a standard flatbed truck with a small crane is often sufficient to pull the pumps from
the wet well, and larger crane vehicles may not be required.
Site drainage should generally convey runoff away from electrical and mechanical equipment and towards
stormwater infrastructure (e.g. catch basin). Areas of the facility that may be subject to incidental
wastewater spills during routine maintenance should generally be drained back to the wet well or to the
sewer system.
Basic site security is recommended to prevent unauthorized persons from accessing electrical or
mechanical equipment or gaining access to dangerous areas like the wet wells. Not all of the City’s pump
station facilities are fenced, but all electrical cabinets, hatches and covered protecting vital equipment
should be locked at all times. The City reports no problems with vandalism at its pump station sites.
4 Condition Assessment Findings
The condition assessment findings for each pump station are summarized in the sections that follow.
Findings are based on visual inspections of these pump station facilities and interviews with City staff.
In this section, the terms “Good”, “Fair”, and “Poor” are sometimes used to describe asset conditions. The
table below describes the intended meaning of these terms:
Good
Asset has had no
operational problems,
requires only typical
preventive maintenance,
and/or shows no signs of
deterioration
March 2012
Fair
Asset has had only minor
problems, has had minor
repairs in addition to typical
preventive maintenance,
and/or shows little sign of
deterioration
Poor
Asset has had major operational
problems, has had major repairs
or has been repaired several
times, and/or shows visible signs
of deterioration.
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4.1
Lower Crestview Pump Station
The Lower Crestview Pump Station consists of a concrete wet well and valve box, as well as an above
grade electrical/SCADA panel. Lower and Upper Crestview Pump Stations operate in conjunction with
one another, with Lower Crestview pumping to Upper Crestview. The lower pump station will stop
pumping if the upper pump station fails. Operators report that these pump stations cycle about every 40
minutes during normal, dry-weather conditions. Two pumps are installed in the wet well, and operators
report that only one is required for wet weather operation.
The table, below, summarizes general pump station information:
Lower Crestview Pump Station Information
City Designation Code
PS07
Year Constructed/Improved
10/1/1975
Last Serviced
3/31/2011
Pump Type
Submersible
Number of Pumps
2 (1 duty, 1 standby)
Pump Manufacturer &Model
Flygt 3126
Motor Horsepower
9.4 HP
Discharge Size
4-inch
Drive type
Constant Speed
Valve Location
Valve box
Overall, this pump station is in good condition, despite being one of the City’s oldest. More detail and
specific observations are noted in the table that follows. The primary concern is corrosion of valves and
enclosures, potentially due to site drainage conditions.
Lower Crestview Pump Station
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Pump Station Condition Assessment
Lower Crestview Pump Station Condition Assessment
Aspect
Comments
Lower Crestview Pump Station
Concerns/
Recommendations
Photo Documentation
Electrical
Enclosure
Overall, the electrical
enclosure looks to be in fair
condition. The bottom of the
enclosure is at-grade.
Corrosion (rust) is evident at the bottom of the
enclosure. This may be indicative of water entering
the enclosure and/or poor site drainage conditions.
There appears to be evidence of standing water
around the site and at the bottom of the enclosure.
Recommend evaluation of water-tight enclosure to
determine if infiltration is occurring. If so, take
measures to prevent water from entering the
enclosure or replace the enclosure..
Evidence of corrosion and moisture
intrusion in the electrical cabinet
Standby Power
Pump station has an
electrical connection for a
standby generator.
No immediate concerns; City’s contractor maintains
compatible standby power generation equipment.
Portable emergency generator connection
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Aspect
Comments
Lower Crestview Pump Station
Concerns/
Recommendations
Photo Documentation
Controls and Communication (SCADA)
SCADA
Panel/Screen
Primary Level
Instrumentation
Secondary Level
Control/Level Alarm
Communications
Flow monitoring
Panel is new and in good
condition
Ultrasonic sensor
High level float as a backup
to SCADA
Radio telemetry
Flow monitoring is not
performed at this site.
No immediate concerns
No immediate concerns
No immediate concerns
No immediate concerns; line of sight communication
is reported to be acceptable for reliable
communication.
Flow monitoring can be useful in tracking impeller
wear and troubleshooting other pump station issues.
The City may wish to consider adding a flow meter
(typically, electromagnetic-type) as part of future
pump station upgrades.
The SCADA Panel/Screen
The controls and communication
equipment is relatively new and includes
battery backup
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Aspect
Comments
Lower Crestview Pump Station
Concerns/
Recommendations
Photo Documentation
Wet Well
Grease
This pump station
experiences minor grease
buildup
No immediate concerns; the residential service area
does not contribute significant grease to the
collection system. City staff report that minor grease
build-up is easily combated with quarterly cleaning at
this station.
Odor
No odor issues reported
No immediate concerns; the relatively short
wastewater residence time in the wet well and
upstream system result in no significant issues.
Structural Condition
Wet well is unlined concrete
but appears to be in good
condition.
Protective coating above the low water level may be
required in the future if signs of corrosion increase.
The wet well cover exhibits
signs of ongoing corrosion.
Venting
March 2012
This pump station does not
have an air vent.
Renewal of protective coatings will prolong the life of
metallic components by insulating the metal from the
elements. Corrosion is not structurally significant at
this time and protective coating can prevent further
deterioration. If the hatch is replaced in the future,
aluminum, galvanized steel or stainless steel hatches
may be used to eliminate the need to provide
protective coating.
The pump station hatch exhibits signs
of corrosion (inside of cover)
Wet well cover (top side)
Venting of air helps prevent the accumulation of
hazardous gases. The City’s newer station (Tierra
Linda) has a simple 4” air-vent. Venting is
recommended to be installed at this location
(minimum of 4” to 6”).
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San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Comments
Lower Crestview Pump Station
Concerns/
Recommendations
Photo Documentation
Valves
Valve vault
Valves are partially buried
Recommend improving drainage of this box. If
possible, valves should be fully exposed, with a layer
of drain rock below to minimize standing water.
Alternatively, the existing utility box can be replaced
with a concrete box with bottom that is drained back
to the wet well.
Valves
Valves show indications of
corrosion
The valves are operated regularly and City reports
that valve operation is acceptable. Surface corrosion
appears cosmetic; however, a renewed protective
coating is recommended to prevent continued
degradation in this moist environment.
Valve Vault Cover
Corrosion of the existing, half-buried
valves is apparent
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Pump Station Condition Assessment
Aspect
Comments
Lower Crestview Pump Station
Concerns/
Recommendations
Photo Documentation
Discharge Piping
Piping
Discharge piping is ductile or
cast iron (material has not
been confirmed).
RMC recommends renewing the protective coating on
the discharge piping and replacing corroded bolts with
stainless steel bolts. Non-stainless piping in wet wells
is typically provided with an epoxy coating.
No protective coating is
evident; pipe surface shows
corrosion but no significant
pitting.
Bolts appear to be corroding
to a greater extent than the
piping.
Existing pump discharge piping
Pumping Equipment
Pumps
Pump Operation
Pump Access
Two submersible 9.4 HP
Flygt pumps, Model No.
3126.
No issues reported by staff.
No vibration or excessive
noise was observed or
reported.
Pumps are accessed via new
steel chains and rails
Pump performance was not confirmed.
No immediate concerns; pumps appear to be operating
well (flow performance was not confirmed).
No immediate concerns
New chains and guide rails
Site Conditions
Site Access
March 2012
Site is easily accessible
No immediate concerns
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Pump Station Condition Assessment
Aspect
Drainage
Comments
The site gently slopes toward
a catch basin at the north end
of the site. However, there
are depressions in the
asphalt which contribute to
ponding near the valve box
and electrical enclosure
Security
This pump station does not
have a fence, but security has
not been an issue.
The electrical panel is locked
to prevent tempering, and
pump station access is padlocked to prevent
unauthorized entry.
Lower Crestview Pump Station
Concerns/
Recommendations
Site drainage may contribute to corrosion of the control
panel and sediment buildup in the valve box.
Regrading and paving to direct water away toward the
catch basin more efficiently is advisable, but not urgent
if the impacts of ponding can be mitigated through
other improvements listed above.
Photo Documentation
The valve box is lid is not secured, and the City may
wish to secure this to prevent unauthorized operation
of the discharge valves (which may render the pump
station inoperable and damage the pumping
equipment).
The existing valve vault (foreground)
is not secured, and there is evidence
of water ponding on the site.
No signs of vandalism or
graffiti.
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4.2
Upper Crestview Pump Station
The Upper Crestview Pump Station is nearly identical to the Lower Crestview Station in configuration;
they were installed at the same time. The station consists of a concrete wet well and valve box, as well as
an at-grade electrical/SCADA panel. This station receives pumped flow from Lower Crestview Pump
Station, and the station controls between the two stations are coordinated as described in the previous
section for the Lower Crestview Pump Station.
General pump station information is summarized in the table below.
Upper Crestview Pump Station Information
Pump Designation Code
PS06
Year Constructed/Improved
10/1/1975
Last Serviced
3/31/2011
Pump Type
Submersible
Number of Pumps
2 (1 duty, 1 standby)
Pump Manufacturer &Model
Flygt 3126
Motor Horsepower
9.4 HP
Discharge Size
4-inch
Drive type
Constant Speed
Valve Location
Valve box
More detail and specific observations are noted in the table that follows. Overall, this pump station is in
good condition; the primary concern is corrosion of valves and enclosures. Many of the issues observed at
this station are similar to those observed at Lower Crestview.
UpperCrestview
Crestview Pump
Upper
Pump Station
Station
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Upper Crestview Pump Station Condition Assessment
Aspect
Comments
Upper Crestview Pump Station
Concerns/
Recommendations
Photo Documentation
Electrical
Enclosure
The bottom of the enclosure
is at-grade.
Enclosure shows signs of age, but is in no immediate
need of replacement.
Enclosure is showing minor
signs of corrosion on the side,
but corrosion appears stable.
Rust at the bottom may be indicative of a nonwaterproof enclosure or a failed seal.
Corrosion noted on metal
bracing and enclosure welds.
Recommend renewing protective coating on rusted
areas of enclosure and verifying that water infiltration
into cabinet is not an ongoing concern.
Exterior protective coating
appears to be in good
condition.
Minor corrosion in the electrical
enclosure
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Aspect
Standby Power
Comments
Pump station has an
electrical connection for
standby generator.
Upper Crestview Pump Station
Concerns/
Recommendations
No immediate concerns; City’s contractor maintains
compatible standby power generation equipment.
Photo Documentation
Portable emergency generator
connection
Controls and Communication (SCADA)
SCADA Panel/Screen
Primary Level
Instrumentation
Panel is new and in good
condition
Ultrasonic sensor
No immediate concerns
No immediate concerns
Secondary Level
Control/Level Alarm
High level float as a backup
to SCADA
No immediate concerns
Communications
Radio tower appears to have
somewhat obstructed line of
sight. Staff noted that
communication is interrupted
occasionally
Recommend trimming of trees as necessary to ensure
consistent communications integrity.
There is no flow monitoring
This is not a concern, but flow monitoring can be
useful in tracking impeller wear and troubleshooting
other pump station issues
Flow monitoring
The controls and communication
equipment is relatively new and
includes battery backup
Trees must be kept trimmed to
ensure reliable communication
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Aspect
Comments
Upper Crestview Pump Station
Concerns/
Recommendations
Photo Documentation
Wet Well
Grease
Odor
Structural Condition
No issue
No issue
Some concrete aggregate
visible at higher wet well
levels.
No immediate concerns
No immediate concerns
Protective coating above the low water level may be
required in the future if signs of corrosion increase.
Venting
This pump station does not
have an air vent.
Venting of air helps prevent the accumulation of
hazardous gases. The City’s newer station (Tierra
Linda) has a simple 4” air-vent. Venting is
recommended to be installed at this location
(minimum of 4” to 6”).
View inside of the wet-well
Valves
Valve Box
Valves
The lip of the vault appears to
have little clearance above
the surrounding grade.
Recommend improving drainage of this box. Raising
the lip of the vault relative the ground surface would
likely reduce water entering the vault.
Valves are partially submerge
in standing water.
If possible, valves should be fully exposed, with a
layer of drain rock below to minimize standing water.
Alternatively, the existing utility box can be replaced
with a concrete box with bottom that is drained back to
the wet well.
Uniform rust noted on valves
Protective coating should be applied as necessary to
prevent further corrosion. Reducing sediment buildup will also reduce corrosion.
Valve box drainage is poor and
corrosion is evident
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Pump Station Condition Assessment
Aspect
Comments
Upper Crestview Pump Station
Concerns/
Recommendations
Photo Documentation
Discharge Piping
Piping
Discharge piping is ductile or
cast iron (material has not
been confirmed).
RMC recommends renewing the protective coating on
the discharge piping and replacing corroded bolts with
stainless steel bolts. Non-stainless piping in wet wells
is typically provided with an epoxy coating.
No protective coating is
evident; pipe surface shows
corrosion but no significant
pitting.
Bolts appear to be corroding
to a greater extent than the
piping.
Discharge piping shows signs of
corrosion, including flange bolts.
Pumping Equipment
Pumps
Two submersible 9.4 HP
Flygt pumps, Model No.
3126.
Pump performance was not confirmed.
No issues reported by staff.
Pump Operation
No vibration or excessive
noise was observed or
reported.
No immediate concerns; pumps appear to be
operating well (flow performance was not confirmed).
Pump Access
Pumps are accessed via new
steel chains and rails
No immediate concerns
March 2012
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San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Comments
Upper Crestview Pump Station
Concerns/
Recommendations
Photo Documentation
Site Conditions
Site Access
Site is easily accessible
No immediate concerns
Drainage
The site appears to have
good drainage
No immediate concerns
Security
This pump station does not
have a fence, but security has
not been an issue.
The valve box is lid is not secured, and the City may
wish to secure this to prevent unauthorized operation
of the discharge valves (which may render the pump
station inoperable and damage the pumping
equipment).
The Electrical panel is locked
to prevent tempering, and
pump station access is padlocked to prevent
unauthorized entry.
Paved access at the Upper
Crestview Pump Station
No signs of vandalism or
graffiti.
March 2012
19
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
4.3
Tierra Linda Pump Station
The Tierra Linda Pump Station is the City’s highest volume pump station, and its newest. The area
tributary to this pump station used to flow into the Belmont sewer system until about 2002. The station
was designed with two submersible pumps, each sized to handle a peak wet weather flow of 250 gallons
per minute. A passive overflow diversion to the Belmont system still exists if flows exceed the capacity of
the station. This is the only pump station with permanently installed standby power.
This pump station is well-maintained and, overall, in good condition. Specific observations are given in the
table, below.
General pump station information is summarized below.
Tierra Linda Pump Station Information
City Designation Code
PS05
Year Constructed/Improved
9/1/2002
Last Serviced
3/15/2011
Pump Type
Submersible
Number of Pumps
2 (1 duty, 1 standby)
Pump Manufacturer & Model
Flygt 3127
Motor Horsepower
10 HP
Discharge Size
6-inch
Drive type
Constant Speed
Valve Location
Valve box
Emergency Generator
28 kW Olympian Diesel Generator Set
Tierra Linda Pump Station
March 2012
20
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Tierra Linda Pump Station Condition Assessment
Aspect
Comments
Tierra Linda Pump Station
Concerns/
Recommendations
Photo Documentation
Electrical
Enclosure
Enclosure is in good condition
No immediate concerns
Standby Power
28 KW Diesel Standby
Generator with testing panel.
Anchorage bolts may be undersized relative to current
seismic standards (no evaluation has been performed
to confirm) and corrosion of these bolts is apparent.
Generator is tested monthly
Recommend replacing bolts with stainless steel bolts
sized in accordance with current seismic code. A
seismic evaluation would be required.
Existing generator bolts
may be undersized and
show signs of corrosion.
March 2012
21
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Comments
Tierra Linda Pump Station
Concerns/
Recommendations
Photo Documentation
SCADA
SCADA Panel/Screen
Panel is new and in good
condition
No immediate concerns
Primary Level
Instrumentation
Ultrasonic sensor
No immediate concerns
Secondary Level
Control/Level Alarm
High level float as a backup
to SCADA
No immediate concerns
Communications
No issues noted.
No immediate concerns
Flow monitoring
There is no flow monitoring
This is not a concern, but flow monitoring can be
useful in tracking impeller wear and troubleshooting
other pump station issues.
The existing SCADA and
controls are new and
function well for the City
Fuses on the Electrical
Panel
March 2012
22
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Comments
Tierra Linda Pump Station
Concerns/
Recommendations
Photo Documentation
Wet Well
Grease is an issue at this
pump station. Grease buildup
is mitigated with an
automated enzyme injection
system consisting of a
peristaltic pump and a 7
gallon enzyme tank. This
system is located in a
manhole directly upstream of
the pump station.
No immediate concerns
Odor
There are odor issues, but no
complaints because of the
station’s somewhat isolated
location
No immediate concerns
Structural Condition
Wet well has been epoxy
lined and appears to be in
good condition.
A wet well overflow
connection is present, which
is unique to this station
No immediate concerns
Venting
The pump station wet well is
vented which is
recommended.
No immediate concerns
Grease
An enzyme-based grease
control system is used at
this station.
The wet well is vented,
which is recommended for
all submersible stations.
March 2012
23
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Comments
Tierra Linda Pump Station
Concerns/
Recommendations
Photo Documentation
Valves
Valve vault
Vault is new and in good
condition.
A hatch would allow for easier access to the valve
vault and could be locked for additional security.
Access to the valve vault
requires moving two large
pieces of metal plating; there
is no hatch.
Valves
Valves are accessible and in
good condition.
No immediate concerns. City reports that ball checks
have performed reliably.
The station uses ball checks,
which is unique to the City’s
stations.
The existing valve vault is
in good conditions and is
well drained. Ball check
valves (on left) are used at
this station.
March 2012
24
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Comments
Tierra Linda Pump Station
Concerns/
Recommendations
Photo Documentation
Discharge Piping
Piping
Discharge piping has a
protective coating.
No immediate concerns
Bolts appear to be stainless
steel.
6” Force Main
Pumping Equipment
Pumps
Two submersible 10 HP Flygt
pumps, Model No.3127
Staff noted that it is
undesirable to run both
pumps at the same time
because downstream PVC
components may break if
subjected to high flow and
pressure.
Pump Operation
March 2012
No vibration or excessive
noise was observed or
reported.
Although running both pumps at the same time is not
typically necessary, City reports that this capability
must be maintained. In light of this, RMC recommends
replacing the downstream components with adequate
pressure capacity to eliminate this concern.
Pump access rails and
chains
No immediate concerns; pumps appear to be
operating well (flow performance was not confirmed).
25
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Pump Access
Comments
Pumps are accessed via new
steel chains and rails
Tierra Linda Pump Station
Concerns/
Recommendations
No immediate concerns
Photo Documentation
Site Conditions
Site Access
Site is easily accessible
No immediate concerns
Drainage
The site appears to have
good drainage
Pump Station is surrounded
by screened fence and locked
gate.
No immediate concerns
Security
Valve vault is not lockable.
No immediate concerns. The existing level of
protection is appropriate given that there are no
reported security issues. The City may wish to
consider a lockable valve vault cover (also see
comments under “Valves”, above)
Security fence around the
Tierra Linda Pump Station
March 2012
26
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
4.4
Associated Pump Station
The Associated Pump Station (often referred to as simply “The Associate”) is the City’s oldest pump
station. This pump station receives flow from local industry on the east side of Highway 101, including a
solid waste collection operation. Sewage consists mostly of industrial wash down water. The station pumps
directly to the SBSA San Carlos Pump Station via a force main that crosses Holly Street to the south.
This pump station recently underwent improvements including a new driveway, new buried valves, and
fencing. Additional planned improvements include modification of the existing bypass pumping discharge
connection to allow for easy connection of the City’s existing trash pump and removal of the large crane
arm at this site, which is not used.
Overall, this pump station is in good condition, with the exception of corrosion on the discharge piping
flange bolts. More detail and other specific observations are noted in the table, below.
General pump station information is summarized below.
Associated Pump Station Information
City Designation Code
PS02
Year Constructed/Improved
10/1/1970
Last Serviced
3/31/2011
Pump Type
Submersible
Number of Pumps
2 (1 duty, 1 standby)
Pump Manufacturer &Model
Flygt 3127
Motor Horsepower
9.4 HP
Discharge Size
4-inch
Drive type
Constant Speed
Valve Location
Valve box
TheAssociated
Associated Pump
The
PumpStation
Station
(“The Associate”)
March 2012
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San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
The Associated Pump Station Condition Assessment
Aspect
Comments
Associated Pump Station
Concerns/
Recommendations
Photo Documentation
Electrical
Enclosure
Enclosure recently received a
protective coating and the
outside appears to be in fair
condition. However, there is
minor corrosion inside the
enclosure. This enclosure is
elevated above the concrete
slab and, because of this, it is
protected from stormwater
ponding.
Enclosure shows signs of age, but is in no immediate
need of replacement. Rust at the bottom of the
enclosure may be indicative of a non-waterproof
enclosure or a failed seal.
RMC recommends the City continue to refresh the
protective coating at regular intervals. This pump
station is closer to the Bay than other stations;
because of this, moisture intrusion is a concern.
Evidence of corrosion and
moisture intrusion in the
electrical cabinet
Standby Power
Pump station has an
electrical connection for
standby generator.
No immediate concerns; City’s contractor maintains
compatible standby power generation equipment.
Portable emergency generator
connection
March 2012
28
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Comments
Associated Pump Station
Concerns/
Recommendations
Photo Documentation
SCADA
SCADA Panel/Screen
Panel is new and in good
condition
No immediate concerns
Primary Level
Instrumentation
Secondary Level
Control/Level Alarm
Communications
Ultrasonic sensor
No immediate concerns
High level float as a backup
to SCADA
Radio telemetry
No immediate concerns
Flow monitoring
Flow monitoring is not
performed at this site.
No immediate concerns; line of sight communication
is reported to be acceptable for reliable
communication.
Flow monitoring can be useful in tracking impeller
wear and troubleshooting other pump station issues.
The City may wish to consider additional of a flow
meter (typically, electromagnetic-type) as part of
future pump station upgrades.
The controls and communication
equipment is relatively new and
includes battery backup
SCADA Interface mounted on
the outside of the control panel
March 2012
29
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Comments
Associated Pump Station
Concerns/
Recommendations
Photo Documentation
Wet Well
Grease
No grease issues were
reported
Odor
Industrial sewage present at
this station can have foul
odor, but there are no
complaints due to the isolated
location.
Structural Condition
Wet well appears to be in
good condition. Interior is
protected by a bituminous
coating that is aging but intact
No immediate concerns
This pump station does not
have an air vent.
Venting of air helps prevent the accumulation of
hazardous gases. The City’s newer station (Tierra
Linda) has a simple 4” air-vent. Venting is
recommended to be installed at this location
(minimum of 4” to 6”).
Venting
March 2012
No immediate concerns; the industrial service area
that drains to this pump station does not contain much
grease and so this is not likely to be a problem in the
future.
No immediate concerns
Bituminous coating on the
inside of the Wet Well
30
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Comments
Associated Pump Station
Concerns/
Recommendations
Photo Documentation
Valves
Valve vault
Valves
There is no single valve vault
at this pump station (as is the
case with the other major
pump station). Instead, the
isolation valves are buried
while the check valves are
located in the wet well.
Buried valves may be a concern because they cannot
be easily replaced if, for example, the valves become
stuck in the closed position.
Isolation valves are buried
and their condition could not
be determined.
RMC recommends renewing the protective coating on
the check valves to maximize their useful life.
The underground valving may be bypassed with the
force main bypass connection (which is unique to this
pump station). This configuration provides redundancy
to the buried valves. However, this bypass connection
is not accessible because of the direction the pipe
faces (north, toward the creek). The City has plans to
reorient the piping so that the connection faces south
(toward Holly). RMC encourages the City to
implement this improvement.
Buried valves in front of the
pump station
Bypass pumping discharge
connection
The protective coating of the
check valves in the wet well
appear to be in poor
condition.
March 2012
31
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Comments
Associated Pump Station
Concerns/
Recommendations
Photo Documentation
Discharge Piping
Piping
The discharge piping is
ductile or cast iron (material
has not been confirmed).
Part of the discharge piping
appears to have a protective
coating, while other parts do
not.
Where there is no protective coating, the discharge
piping shows uniform corrosion. RMC recommends
renewing the protective coating on the discharge
piping and valves to maximize their useful life. Nonstainless piping in wet wells is typically provided with
an epoxy coating.
Some of the bolts appear to have been replaced with
stainless steel while others show advanced stages of
corrosion. RMC recommends replacing all corroded
bolts with stainless steel.
Existing pump discharge
piping
Mechanical
Pumps
Two submersible 9.4 HP
Flygt pumps, Model No.
3127.
Pump performance was not confirmed.
No issues reported by staff.
Pump Operation
No vibration or excessive
noise was observed or
reported.
No concerns; pumps appear to be operating well (flow
performance was not confirmed).
Pump Access
Pumps are accessed via new
steel chains and rails
No immediate concerns
March 2012
32
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Comments
Associated Pump Station
Concerns/
Recommendations
Photo Documentation
Site Conditions
Site Access
Drainage
Security
March 2012
Site is easily accessible from
Holly Street.
The site appears to have
good drainage. No evidence
of ponding was observed.
The site has recently been
repaved and the asphalt is in
good condition.
Pump Station is surrounded
by screened fence and locked
gate. Level of protection is
appropriate given that there
are no ongoing security
issues.
No immediate concerns
No immediate concerns
No immediate concerns
Security Fence at the
Associated Pump Station
33
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
4.5
Kelly Moore I Pump Station
Kelly Moore I is one of the City’s two minor pump stations. The pump station serves a single commercial
customer, the Kelly Moore manufacturing and commercial facility. The facility originally discharged by
gravity to the sewer system, but in 2000, the City constructed sewer improvements in the area that
prevented gravity discharge from the Kelly Moore facility; hence, the City constructed the two small
stations to correct this situation.
General pump station information is summarized below.
Kelly Moore I Pump Station Information
City Designation Code
PS03
Year Constructed/Improved
8/1/2000
Last Serviced
4/1/2011
Pump Type
Submersible
Number of Pumps
2 (1 duty, 1 standby)
Pump Manufacturer &Model
Barnes SE411
Motor Horsepower
0.4 HP
Discharge Size
2-inch
Drive type
Constant Speed
Valve Location
Valve box
Kelly Moore I Pump Station
March 2012
34
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Kelly Moore I Pump Station Condition Assessment
Aspect
Comments
Kelly Moore I Pump Station
Concerns/
Recommendations
Photo Documentation
Electrical
Enclosure
Enclosure is in good condition
No immediate concerns
Standby Power
Pump station does not have
standby power generation or
a standby power electrical
hookup.
The lack of standby power capabilities is likely not an
issue due to the small size of flows into this pump
station. In the event of a power loss, a vactor truck
would be capable of transporting flows and the City
could coordinate with Kelly Moore to reduce
wastewater until the situation was resolved.
Electrical and SCADA
Enclosure
SCADA
SCADA Panel/Screen
Panel is new and in good
condition. The pump station
has an alarm indicator (red
light) which is visible from the
street
No immediate concerns
Primary Level
Instrumentation
Ultrasonic level sensor
No immediate concerns
Secondary Level
Control/Level Alarm
There is a high level float as a
backup to SCADA.
No immediate concerns
Communications
Radio telemetry
No immediate concerns; line of sight communication
is reported to be acceptable for reliable
communication.
March 2012
Control and SCADA Enclosure
with Alarm Indicator
35
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Flow monitoring
Comments
Flow monitoring is not
performed at this site.
Kelly Moore I Pump Station
Concerns/
Recommendations
Flow monitoring can be useful in tracking impeller
wear and troubleshooting other pump station issues.
However, the small size of this pump station does not
warrant flow monitoring. The cost of the meter and
installation may not be justified given the relatively
inexpensive replacement cost of the pumps.
Photo Documentation
Wet Well
Grease
Grease did not appear to be
an issue at this pump station
nor did the operator report
grease problems.
No immediate concerns
Odor
No odor issues reported
No immediate concerns; the relatively short
wastewater residence time in the wet well and
upstream system result in no significant issues.
Structural Condition
Wet well appears to be in
very good condition.
No immediate concerns
Venting
The wet well is semi-vented
through small perforations in
the manhole cover.
No immediate concerns
No valve vault – valves are
located within the wet well.
Valves are small, 3” PVC,
and appear to be in good
condition.
No immediate concerns
Kelly Moore I Wet Well
Valves
Valve vault
Valves
March 2012
No immediate concerns
36
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Comments
Kelly Moore I Pump Station
Concerns/
Recommendations
Photo Documentation
Force Main
Piping
Discharge piping is PVC and
appears to be in good
condition..
No immediate concerns
PVC discharge piping is in
good condition
Mechanical
Pumps
Vibration
Pump Access
March 2012
Two submersible pumps, 9.4
HP, Flygt 3127
No issues reported by staff
No vibration or excessive
noise was reported
Steel chains and rails are not
present at this pump station
as they are at the other pump
stations.
Pump performance was not confirmed
No concerns; pumps appear to be operating well (flow
performance was not confirmed)
Although no chains are present, the pumps and the
discharge manifold are lightweight and may be lifted
directly from the wet well by a small transportable
crane or winch. Overall, because of their small size,
this is not expected to be an issue. However, the City
would have to lower an operator into the wet well to
undo the union in order to decouple the discharge
piping assembly.
37
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Comments
Kelly Moore I Pump Station
Concerns/
Recommendations
Photo Documentation
Site Conditions
Site Access
Site is easily accessible
No immediate concerns
Drainage
The site appears to have
good drainage
Pump station is not fenced.
There have been no reports
of vandalism or theft.
No immediate concerns
Security
March 2012
No immediate concerns
38
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
4.6
Industrial Wet Weather Pump Station
The Industrial Wet Weather Pump Station (often referred to as the “Industrial Booster Pump Station” or
the “Pulgas Booster Pump Station”) only operates during wet weather. The intended purpose of the booster
pump station is to prevent overflows in the trunk sewers in Industrial Road upstream of Brittan Avenue by
“boosting” flow to the downstream sewers. The pump station is controlled by water level in an upstream,
shallow manhole. When the water level reaches a predetermined “pump on” level, the pump begins to
draw flow directly from the surcharged pipeline. Flow is returned to the same pipeline 60 feet
downstream.
The effectiveness of this station in reducing upstream surcharging has not been confirmed. RMC notes that
the close proximity of the suction and discharge connections and apparent lack of backflow prevention
toward the upstream connection may limit the effectiveness of operation. It should be noted that based on
the results of the capacity assessment, RMC has recommended that this pump station be replaced and a
new force main be installed which extends all the way to the San Carlos Pump Station. These upgrades
will significantly reduce the hydraulic grade line in the trunk sewers along Industrial Road during wet
weather flows.
Currently, the Industrial Wet Weather Pump Station consists of a single horizontal pump in a dry-pit
configuration. Because the station is not considered a critical component of the collection system, there is
no redundancy. The pump station is new (completed in 2009) and all pump components that could be
visually inspected are in good condition.
General pump station information is summarized below.
Industrial Wet Weather Pump Station Information
City Designation Code
PS08
Year Constructed/Improved
8/14/09
Last Serviced
3/31/2011
Pump Type
Submersible, Dry Pit, Horizontally Mounted
Number of Pumps
1 duty
Pump Manufacturer &Model
Flygt 3127
Motor Horsepower
7.4 HP
Discharge Size
6-inch
Drive type
Constant Speed
Valve Location
Dry-Pit Vault
Industrial Booster Pump Station
March 2012
39
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Industrial Wet Weather Pump Station Condition Assessment
Aspect
Comments
Concerns/
Recommendations
Documentation
Electrical
Enclosure
Electrical equipment is
housed in the Pulgas Creek
Wet Weather Pump Station
building.
The existing building appears to be in sound
condition, but is older construction that is likely not
designed to current seismic codes. The City may
wish to perform a full seismic analysis of this structure
to determine if it is subject to failure during a large
earthquake.
Pulgas Creek Pump Station
Building
Standby Power
There is no standby power for
this pump station (and no
electrical hookup)
This is a non-critical pump station, for wet-weather
only. If a power failure were to occur during a
significant storm event, the City could call on help
from Rain4Rent to provide emergency power.
SCADA Panel
Panel is new and in good
condition
No immediate concerns
Level Instrumentation
An ultrasonic level transducer
monitors level of the
upstream sewer and controls
the pump on/off. No
instrumentation issues were
reported for this pump station.
No immediate concerns
SCADA
The existing SCADA panel is
new and in good condition.
March 2012
40
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Communications
Flow monitoring
Comments
Radio tower. There are no
reported communication
issues.
There is no flow monitoring
Concerns/
Recommendations
No immediate concerns
Documentation
Dedicated flow monitoring would not be necessary for
this pump station because of its infrequent use.
Dry-Pit Vault
Structural Condition
A single concrete dry pit
houses the pump and valves.
Pit is in good condition. The
pit is in good condition.
No immediate concerns
The pump dry pit is new and in
good condition.
Suction and Discharge Piping
Piping
Discharge piping is coated,
ductile iron with stainless
steel bolts.
No immediate concerns
The piping system is in very
good condition.
Pumping Equipment
Pumps
Pump Station consists of a
single submersible, dry pit,
horizontally mounted pump,
7.4 HP, Flygt 3127
No immediate concerns; operation was not witnessed
during field visit (station can only operate in wet
weather)
Pump Operation
No vibration or excessive
noise was or reported.
Stainless steel guide rail
system is new
No concerns. Performance could not be confirmed.
Pump Access
No concerns
Horizontally mounted Flygt
Pump
March 2012
41
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Aspect
Comments
Concerns/
Recommendations
Documentation
Site Conditions
Site Access
Drainage
Security
Site is easily accessible
Site appears to have no
drainage issues
All pipe, pump, electrical
components are secured in
the dry pit or in the electrical
building.
Both the dry-pit access and
building enclosure are locked
and secure.
March 2012
No immediate concerns
No immediate concerns
No immediate concerns
Access the Pump Dry-Pit via
steel cover
42
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
5 Useful Life and Summary of Recommendations
This section summarizes the important recommendations identified in Section 4. It also lists the typical
useful life of major wastewater pump station components in comparison to the current age of the City’s
pump station assets. The expected life of an asset is the typical duration that equipment is predicted to
operate when properly maintained. Expected life is a general value that is used to trigger a condition
assessment of equipment to determine if the asset should be replaced or if extended service is possible.
This condition assessment found that many of the City’s pump station assets are beyond or nearing their
typical useful life. However, this does not necessarily mean that replacement is the immediate course of
action. In fact, with diligent maintenance, wastewater equipment often exceeds typical useful life values.
Where RMC has identified that an asset is at or beyond its useful life and where our inspection revealed
that an asset is indeed deteriorating, we have recommended actions which will inhibit further deterioration
so that the useful life may be extended. However, as older equipment continues to operate beyond its
typical useful life, even if properly maintained, the City should conduct condition assessments more
frequently so as not to compromise reliability.
The tables presented in this section provide a summary of recommendations and useful life information.
More detailed about specific recommendations along with supporting documentation is given in Section 4.
Note that because all of the SCADA systems at the City’s pump stations are new, recommendations related
to electrical equipment do not apply to the SCADA system (e.g. new panel, new screen, new wiring, new
level transducers, etc.).
Source of Useful Life Data
The expected useful life values given in this section are based on RMC’s experience with wastewater
assets, equipment life expectancy provided by equipment suppliers, and on published values by the
Environmental Protection Agency (EPA). The EPA publication “Asset Management: A Handbook for
Small Water Systems” provides expected life data for assets typically found at wastewater facilities. This
document is referenced by presentations and publications related to asset management for a wide range of
equipment including pump station equipment. RMC’s wastewater life expectancy data and the EPA
published data were compared in determining the range of useful life values for this project.
Capital Improvement Costs based on Recommendations
Overall, the City’s pump stations are in acceptable condition and this condition assessment evaluation has
found that no major capital improvements are necessary. The recommendations presented in this section
are considered operational and maintenance related and so cost estimates are not provided. In general,
these recommendations are not expected to cost more than $20K each.
Industrial Booster Pump Station
The Industrial Booster pump station is currently in good condition and there are no immediate
improvement needs. However, based on the results of the capacity assessment, RMC has recommended
that the Industrial Booster Pump Station be replaced and a new force main be installed to reduce wet
weather surcharging in the trunk sewer along Industrial Road. Therefore, an individual table showing
recommendations for this pump station is not shown in this section.
March 2012
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San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Table 1: Lower Crestview – Useful Life and Recommendations Summary
Current
Age
Typical
Useful
Life
Electric
Conduit,
Wiring, and
Fixtures
(Does not
include
SCADA
system)
37
20-25
Electrical
Enclosure
37
Major
Components
Recommendations Based on Visual Inspection
The original equipment is beyond typical useful life for similar
equipment in wastewater facilities. A detailed inspection of the conduit
and wiring was not conducted as part of this work and so the actual
condition could not be assessed; however, the City operators did not
indicate any equipment problems.
Because of the age of this pump station, the City should have an
electrical engineer conduct a thorough condition assessment of the
electrical components.
15-25
The original equipment is beyond typical useful life for similar
equipment in wastewater facilities.
RMC recommends an evaluation of the enclosure to determine if
infiltration is occurring. If so, the City should take measures to prevent
water from entering or replace the enclosure.
Valves
37
25-40
The valves are nearing the end of their typical useful life for wastewater
valves; however, the City operators did not indicate any equipment
problems.
RMC recommends renewing the protective coating to prevent further
surface corrosion.
Discharge
Piping (DIP,
or similar)
37
30-40
The discharge piping is nearing the end of typical useful life for
wastewater valves; however, the City operators did not indicate any
issues with the piping.
RMC recommends renewing the protective (epoxy) coating on the
discharge piping and replacing corroded bolts with stainless steel bolts.
The pump station would need to be shutdown for as long as two days to
complete this work. Another option is to replace the discharge piping
with new epoxy coated DIP. Although the material cost for replacement
would be more expensive, the pump station could be brought back into
service faster (with 4 to 8 hours) and the useful life would be reset.
Concrete
Wet Well
Wastewater
Pump
Other
March 2012
37
30-50
The wet well appears to be in good condition.
RMC recommends installing a 4-inch or 6-inch vent on the wet well to
vent hazardous gasses.
The useful life of submersible wastewater pumps are extremely variable and depend on
wastewater constituents, environmental conditions, and maintenance. The City staff did not
report any excessive vibration or operational issues that would be indicative of a shortened
useful life. Therefore, RMC recommends that the City continue routine maintenance and
monitor any changes in performance.

Lock valve box
44
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Table 2: Upper Crestview – Useful Life and Recommendations Summary
Current
Age
Typical
Useful
Life
Electric
Conduit,
Wiring, and
Fixtures
(Does not
include
SCADA
system)
37
20-25
Electrical
Enclosure
37
Major
Components
Recommendations Based on Visual Inspection
The original equipment is beyond typical useful life for similar
equipment in wastewater facilities. A detailed inspection of the conduit
and wiring was not conducted as part of this work and so the actual
condition could not be assessed; however, the City operators did not
indicate any equipment problems.
Because of the age of this pump station, the City should have an
electrical engineer conduct a thorough condition assessment of the
electrical components.
15-25
The original equipment is beyond typical useful life for similar
equipment in wastewater facilities.
RMC recommends an evaluation of the enclosure to determine if
infiltration is occurring. If so, the City should take measures to prevent
water from entering or replace the enclosure.
Valves
37
25-40
The valves are nearing the end of typical useful life for wastewater
valves; however, the City operators did not indicate any equipment
problems.
RMC recommends a renewed protective coating to prevent further
surface corrosion. In addition, the valves should be fully exposed, with
a layer of drain rock below to minimize standing water. Alternatively,
the existing utility box can be replaced with a concrete box with
bottom that is drained back to the wet well.
Discharge
Piping (DIP,
or similar)
37
30-40
The discharge piping is nearing the end of typical useful life for
wastewater valves; however, the City operators did not indicate any
issues with the piping.
RMC recommends renewing the protective (epoxy) coating on the
discharge piping and replacing corroded bolts with stainless steel
bolts. The pump station would need to be shutdown for as long as two
days to complete this work. Another option is to replace the discharge
piping with new epoxy coated DIP. Although the material cost for
replacement would be more expensive, the pump station could be
brought back into service faster (with 4 to 8 hours) and the useful life
would be reset.
Concrete
Wet Well
Wastewater
Pump
Other
March 2012
37
30-50
The wet well appears to be in good condition.
RMC recommends installing a 4-inch or 6-inch vent on the wet well to
vent hazardous gasses. This action will help maximize the useful life
of the wet well.
The useful life of submersible wastewater pumps are extremely variable and depend on
wastewater constituents, environmental conditions, and maintenance. The City staff did not
report any excessive vibration or operational issues that would be indicative of a shortened
useful life. Therefore, RMC recommends that the City continue routine maintenance and
monitor any changes in performance.


Lock valve Box
Frequent tree-trimming to ensure consistent communications integrity
45
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Table 3: Tierra Linda – Useful Life and Recommendations Summary
Current Age
Typical
Useful
Life
Electric
Conduit,
Wiring, and
Fixtures
(Does not
include
SCADA
system)
10
20-25
Electrical
Enclosure
10
Major
Components
Recommendations Based on Visual Inspection
The original equipment is within typical useful life for similar
equipment in wastewater facilities and City staff did not
report any electrical issues.
No recommendations
15-25
The original enclosure is within typical useful life for similar
equipment in wastewater facilities and City staff did not
report any issues.
No recommendations
10
Valves
25-40
The original valves are within typical useful life for similar
equipment in wastewater facilities and City staff did not
report any issues.
No recommendations
10
Discharge
Piping (DIP,
or similar)
30-40
The original discharge piping is within typical useful life for
similar equipment in wastewater facilities and City staff did
not report any issues.
No recommendations
10
Concrete
Wet Well
30-50
The wet well is within typical useful life for similar
equipment in wastewater facilities and appeared to be in
good condition.
No recommendations
Wastewater
Pump
Other
The useful life of submersible wastewater pumps are extremely variable and depend on
wastewater constituents, environmental conditions, and maintenance. The City staff did
not report any excessive vibration or operational issues that would be indicative of a
shortened useful life. Therefore, RMC recommends that the City continue routine
maintenance and monitor any changes in performance.



March 2012
A valve vault hatch would allow for easier access to the valves and could be
locked for additional security.
Recommend replacing standby generator anchorage bolts with stainless steel
bolts sized in accordance with current seismic code
Staff noted that it is undesirable to run both pumps at the same time because
downstream PVC valves may break if subjected to high flow and pressure. RMC
recommends replacing the components downstream of the pump station with
adequate pressure capacity to eliminate this concern.
46
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Table 4: Associated Pump Station – Useful Life and Recommendations Summary
Current
Age
Typical
Useful
Life
Electric
Conduit,
Wiring, and
Fixtures
(Does not
include
SCADA
system)
42
20-25
Electrical
Enclosure
42
Major
Components
Recommendations Based on Visual Inspection
The original equipment is beyond typical useful life for similar
equipment in wastewater facilities. A detailed inspection of the conduit
and wiring was not conducted as part of this work and so the actual
condition could not be assessed; however, the City operators did not
indicate any equipment problems.
Because of the age of this pump station, the City should have an
electrical engineer conduct a thorough condition assessment of the
electrical components.
15-25
The original equipment is beyond typical useful life for similar
equipment in wastewater facilities.
RMC recommends the City continue to refresh the protective coating
at regular intervals. This pump station is closer to the Bay than other
stations; because of this, moisture intrusion is a concern.
Valves
Force Main
(DIP, or
similar)
42
(check
valves)
42
25-40
30-40
The check valves are beyond their end of typical useful life for
wastewater valves; however, the City operators did not indicate any
equipment problems. Because the isolation valves are buried, RMC
could not confirm their condition.
RMC recommends renewing the protective coating on the check
valves to maximize their useful life.
The original discharge piping is beyond typical useful life for similar
equipment at wastewater facilities; however, the City operators did not
indicate any issues with the piping.
RMC recommends renewing the protective (epoxy) coating on the
discharge piping and replacing corroded bolts with stainless steel
bolts. The pump station would need to be shutdown for as long as two
days to complete this work. Another option is to replace the discharge
piping with new epoxy coated DIP. Although the material cost for
replacement would be more expensive, the pump station could be
brought back into service faster (with 4 to 8 hours) and the useful life
would be reset.
Concrete
Wet Well
Wastewater
Pump
Other
March 2012
42
30-50
The wet well appears to be in good condition.
RMC recommends installing a 4-inch or 6-inch vent on the wet well to
vent hazardous gasses. This action will help maximize the useful life
of the wet well.
The useful life of submersible wastewater pumps are extremely variable and depend on
wastewater constituents, environmental conditions, and maintenance. The City staff did not
report any excessive vibration or operational issues that would be indicative of a shortened
useful life. Therefore, RMC recommends that the City continue routine maintenance and
monitor any changes in performance.

No other recommendations
47
San Carlos Sewer Collection System Master Plan
Pump Station Condition Assessment
Table 5: Kelly Moore I Pump Station – Useful Life and Recommendations Summary
(years)
Typical
Useful
Life
(years)
Electric
Conduit,
Wiring, and
Fixtures
(Does not
include
SCADA
system)
11
20-25
Electrical
Enclosure
11
Major
Components
Current
Age
Recommendations Based on Visual Inspection
The original equipment is within typical useful life for
similar equipment in wastewater facilities and City staff
did not report any electrical issues.
No recommendations
15-25
The original enclosure is within typical useful life for
similar equipment in wastewater facilities and City staff
did not report any issues.
No recommendations
Valves (PVC)
11
25-40
The original valves are within typical useful life for
similar equipment in wastewater facilities and City staff
did not report any issues.
No recommendations
Force Main
(PVC)
11
15-30
The original discharge piping is within typical useful life
for similar equipment in wastewater facilities and City
staff did not report any issues.
No recommendations
Concrete Wet
Well
11
30-50
The wet well is within typical useful life for similar
equipment in wastewater facilities and appeared to be
in good condition.
No recommendations
Wastewater
Pump
Other
March 2012
The useful life of submersible wastewater pumps are extremely variable and
depend on wastewater constituents, environmental conditions, and
maintenance. The City staff did not report any excessive vibration or
operational issues that would be indicative of a shortened useful life.
Therefore, RMC recommends that the City continue routine maintenance and
monitor any changes in performance.

No other recommendations
48