HomeMy WebLinkAbout0184.094,
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Ma.rch 3, 1994
THE HONORABLE CITY CmmCIL
Palo Alto~ California
Stom Rrain SYgtem Infrastructure Review
Members of the council:
Report in Srief
This report is background information for the March 7~ 1994 Council
etudy session regarding the storm drain system infrastructure. The
report discusses the recently completed Storm Drain Conditio!'.
Assessment and Storm Drain Master Plan studies. Executive
summaries for both of these studies are included as attachments to
this report (Attachments 1 and 2). Complete copies of the studies
are available for reference in the Public works Engineering office.
The report also discusses a proposed capital improvement. prog1'am,
based on the studies l and bond financing and storm drainage fee
increases for funding the program. The recommended capital
improvement program. includes a lO-year, $4 ~ 7 million pipeline
rehabilitation element and a 30-year. $55 million capacity
augmentation element.
Background
In 19'5~ the City contracted with an engineering consultant to
prepare a master pla~ for future storm drain system improvements.
The master plan report identified a series of projects designed to
bring the system up to an acceptable level of service. Although
several of the highest priority projects were constructed, the
majority of the recommended work still has not been completed.
primarily due to a lack of sufficient f~din9.
As part of the 1987-88 budget review process. Council directed
staff to place the storm drain system on an enterprise fund basis,
in order to provide a stable funding base for needed storm drain
infrastructure improvements. In November ~989, Council adopted a
formation ordinance. which established the Storm Drainage
Enterprise Fund and approved a rate setting resolution w.t-.ich
established a..'"l initial monthly storm drainage fee of $3.25 per
month for single-family residential property (CMR:510:9~
CMR:SS3:9) _ The rate schedule approved for the Storm Drainag'S!
Utility was purposely set ~t a minimal level which would support
only an initial [f'.inor capital improvement program. Limited funding
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was included tc address the highest priority capit~l i~provements,
but no funding was included for rehabilitation of the: existing
storm drain n~twork. Prior to reque6ti~g funding for a full-scale
capital improvement program, staff proposed to prepare an updated
storm cIr-ain master plan and conduct a condition assessment of
existing infrastructure in order to delermine f 1.lture capital needs.
Council approved the rate sch.edule with the underst-!lncing that
ra.tes would not be increased for a. pe"riod. of at least three year&~
pending completion of the master plan and condition alis~ssment
studies.
Since collection of the storm drainage fee began in February 19?O,
several high priori ty storm drain capital improvement projects have
~en undertaken, in addit.ion to the master plan and condition
asaessment studies. The Everett Avenue/Hallithorne Avenue Storm
Drain Improvemen~s were completed in 1993. This project included
the installation of 7600 linear feet of pipeline, providing
improved drainage for the Downtown North neighborhood. Staff has
alEJo implemented an annual curb and gutter repair program to
correct local drainage problems throughout the City. Consultants
are currently designing major improvements. to the Airport Pump
Station. as well as upgrading the equipment at five existing pump
stations which discharge atormwat.er from low-lying storm drains
into local creeks. A project to replace a limited number of
existing deteriorated storm drains is also 'in the design stage at
this time_
The focus of the master plan and cot'~dition assessment studies is to
examine the adequacy of the City~s underground storm dra..i!1 system.
The studies do not address eitb~r the l~rge-scale flood potential
from local creeks or localized ponding problems caused by damaged
curb and gutter. ~egional flood protection provided by San
Francisquito.. Matadero, :earron~ and Adobe Creeks is under the
jurisdiction of the S~~ta Clara Valley Water District. That agency
has the respor.sibility for tnaking t;.he cro€"-ek improvements necessary
to eliminate the special flood hazard areas outlined on the Federal
Emergency Management Agency's flood. ins1.O.r~j.ce maps. At ~he
opposite end of the spectrum, the City is responsible for localized
ponding of water along th~ edge of the street. which occurs when
sections of curb and gutter gettle unevenly or are uplifted by tree
roots. In areas like Barron Park. where streets were not
constructed with concrete curb and gutter. local ponding is caused
by uneven roadway shoulders that contain multiple depressions and
ridges. Replacement of damaged :curb and gutter is performed on an
annual basis in conjunction with the street resurfacing and
sidewalk repair capital improvement projects. In accordance with
the Barron Park Drainage and Street __ Design Guidelines adopted by
Council in February 1993 (CMR; 151: 93) . some local drainage features
will be constructed in Barron Park "'·hen new underground pipelines
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are installed, but che pro70sed program does not include funding to
install curbs and gutters throughout the neigr.b-orhood.
Piscussion of Methodology
1_ Storm Drain Condition Assessment
On May 27 I 1.991~ Council approved an agreement with CH2M Hill
california. Inc.~ in the amount of $820,000; to perform a condition
assessment of the existing storm drain system and develop
recommendations fer rehabilitation/replacement of deteriorated
pipelines (CMR:269:91). The consultant's scope of work included
three pri~~ry casks:
• condition Assessment
Evaluation of the condition of the existing storm drain system
through video inspection of undergro~~d pipelines and visual
inspection of manho~e8 and catch basins. Identification and
analysis of system defects and recommendations for
cost-effective methods of rehabilitation or replacement,.
including appropriate materials I methode and cost estimates.
• Storm Drain Map and Inventory Database Update
Compilation of accurate inventory data for each pipeline,.
manhole~ and ca.tch basin in the system. including size.
material,. and system configuration, in order to enable the
City to update its storm drain maps and inventory database_
• Undocumented COnnection Identification
Identification of undocumented connections to the storm drain
system and investigation of their source, in order to enable
t.h'.!--City to eliminate illicit connections (such as sanitary
sewer lines and industrial discharges) as required by its
National pollut,;nt Discharge Elimination System stormwater
permit .
.It" technical summary of the pipeline analysis performed by the
consultant during the Storm Drain Condition Assessment study is
attach~d as an appendix to this report (Attachment 3). ~ter the
s~o~ drain pipelines were inspected ~~d evaluated. they were rated
and pleced into one of five condition categories, Grade A through
P. The categories follow the grading system used in schools. with
category A pipelines judged to be in the best cor.dition and
category F pipelines the worst. Pipelines within Categories C, D
and F require replacement or rehabilitat.ion in the near future.
while those in Categories A and B are in good to f.air condition and
do not require repairs at this time. A similar scoring system was
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developed to prioritize the catch basin and manh~le repairs.
Prior to establishing a capital improvement progra~, staff ~orked
with the consultant to develop the program guidelines and time
schedule. The timing of the improvements is constrained by two
competing factors. From one viewpoint; it would be desirable to
complete the work as soon as po9sible~ in orde::-to avoid any
potential pipeline failures or further deterioration of the storm
drain system. On tn~ other h~~d, the improvements must be phased
to fit within available funding levels and staff; a ability to
administer the work. In particular. since the deteriorated
pipelines are scattered throughout the City, the number of repair
locations on an individual project must be limited in order to keep
the project manageable and cost-effective.
Staff proposes to implement the pipeline rehabilitation projects in
two distinct phases. In the first phase, all of the Category D and
F pipelines will be replaced or rehabilitated. regardless of
location. This phase of construction will address the most
severely deteriorated pipelines in a timely manner~ All defective
manholes or catch basins adjacent to these pipelines will be
repaired at the same time as the pipeline. In the second phase,
repairs on the Category C pipelines and catch basins and manholes
will be grouped into separate construction projects, based upon
geographical location~ The City is divided into 13 drainage basins
as shown on Figure ES-l of the attached Storro Drain Condition
Assessment. executive s;,umnary 'Attachment 1) . Phase 2
rehabilitation projects within one or mere basins will be performed
&equentially throughout the City. The basins containing the
largest number of defective pipelines will receive t.he highest
priority in the construction sequencing. In order to prolong the
life of City streets r trencb.less construction techniques (e.9 ~
sliplininq, inversion lining. etc.) will be used whenever feasible.
In addition, storm drain rehabilication projects will be
coordinated with other utility infr-astructure and screet
resurfar::ing project.s to I11inimize the disruption to local
neighborhoods ~ The timing and cost of the proposed pipeline
rehabilitation program is outlined in the -Discussion of Results·
section of this report.
2. Storm Drain Master Plan
On Septe~r 3; 1991, Council approved an agreement with CH2M Hill
California, Inc .• iII. the amount of $400,CeO to prepare a storm
drain master plan. design storm drain improvements for the Everett
Avenue area, design a pilot-scale stormwater diversion project~ and
develop Barron Park Drainage/Street Design. !3uidelines 'CMR:4 07: 91) .
Approximately $200,000 of the fUl,ds ilte:ce applied t.oward the master
planning component of the agreement. The crynsultant~B scope of
work for the storm drain maeter plan included the following tasks:
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e Computer model
Development of a computer model to simulate the operation of
the City's existing storm drain system.
• Evaluation of Existing St.orm Drain System
Evaluation of the exis=ing storm
transport stormwater runoff
Identification of portions of
insufficient capacity.
• Recommended Improvements
Recommendaticns for cost-effective
eXisting storm drain system to
projected st~rmwater runoff.
drain system's ability tc
during storm events.
the system that have
methods of augmenting the
enabla lt to carry the
A te-chnical summary of the computer model used to develop the Storm
Dra.in Mast~r Plan is attached as an appendix t.o this report
(Att.achment 4). The initia.l step in the modeling process was
establiehing design criteria. ~hese criteria define the level of
drainage service the storm drain network is expected to prcvide.
The first factor to be considered is the design storm return
period. Drainage facilities ~re designed to various storm return
periods dependent on the area served and level of service desired.
For example, the .$anta Clara Valley Water District designs its
flood control facilities, which typically serve areas many square
miles in si~e~ for the 1 percent flood event. The 1 percent f~ood
is the flow of water that r~s a 1 percent chance of occurring in
any given year. It is sometimes referred to as the IOO-year flood~
because it is t;'..e flow that would be equa.led or exceeded an average
of one time every hundred years. measured over a long time period.
Municipal storm drain syBtems~ which serve a much smaller area and~
t.hus. have less capacity to cause damage if they overflow" are
commonly designed for return periods ranging from 3 yea:z.'s to 25
years. The capacity of Palo Alto~s existing storm drain system,
which was designed in many phases over the last 75 years, varies
from a 3-year to approximately a lO-year return period. It is not
clear what return period was used to develop the drainage
improvements recommended in the 1965 master plan. The report
discusses a 10 -year return period for new facilities, but aleo
refers to a -reasonable level of performance-for modifications to
the existing drainage system. After researching the drainage
standards for neighboring cities and considering current
engineering standards/ staff has used a lO-year storm return period
in developing its new storm drain master plan. A drainage system
designed to this standard will be able t.o handle a storm which
produces about 1.6 inches of rain in a period of six hours.
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~o additional factors that affect storm dLain design are tailwater
conditions and pipeline surchargi:lg. Tailwater refel"S to the water
level of a creek or other water body into which a pipeline drains.
Tailwater conditions have a markec effect on a pipeline's capacity.
For example~ a pipelin€ discharging into an empty creek has more
capacity than a pipeline whos~ outfall is submerged beneath a
flowing creek. Due to the relative flatness of t.he urbani2::ed
po.rtion of Palo Alto. most of the storm drains empty into the
creeks well below the top of bank and will back up whe~ the creeks
are flowing at their ~o·year water level. As a resuJt, the.storm
drain model factors in this condition when assessing the adequacy
of the City's drainage system.
Ideally I a storm drain systeTr, .. auld be desig-ned se that t.he
pred.icted stormwater runoff could f10\lo' by gra'\dty within the
underground pipelines, The design capacity of a pipeline is
typically calculated based upon this scenario, However, a pipeline
can actually carry additional water beyond its "gravity flow"
capacity without causing water to back up into the streets. This
phenQalena. by which IJipelines actually become pressuriz-ed and carY7'
additional water is called -BuI'charging lll . Under surcharged
conditions, water rises above the top of the pipeliy:!'!! within
manholes ~~d catch baeins as it passes through these structures.
Staff baa elected to allow surcharging of pipes in the storu drain
system as long as the water stays below street level. This
decision allows the use of smaller diameter pipelines l resulting in
substantial savings without c~~romising flood protection.
Identification of specific pipeline improvements required to
eliminate street ponding was an iterative process. Tr~ consultant
evaluated various solutions in order to identify the least-cost
alternative. Proposed capital improvements include replacement of
existing pipelines, installation of parallel pipelines, creation of
additional out falls into creeks, and diversions of stormwater from
one drainage system to another. once the individual drainage
systems were modeled, staff worked wit~ ~he co~sultant to
prioritize the systems for improvements. Factors such as the
n\~r of ponding locations, duration of ponding. land use, 1965
master plan improvement priorities! and historical dra~nage
problems were used to set the system priorities. The timing and
cos~ of the proposed master plan pipeline improvements is outlined
in the -Discussion of Results W section of this report 4
DiscussioD of ReBults
1. Storm Draip condit jon ABBe9ement
The Storm Drain Condition Assessment report concl udes that the
majority of the City's existing storm drain sy&tern is: in good
condition. Eighty percent of the televised pipel~nes received a
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grade of "A" cr ~B·. indicating they are in good to fair condition
and do not require repair in the near future. The l.-eport
recommends that 25 percent of these pipelines be retelevieed in
approximately ~6 years (half of the average remaining life of the:
"A-and ·B· pipes. bas~d upon an estimated total life of 1S years) •
to obtain a. representa.tive sample of the pipeline8~ condition.
After these initial inspections are made, staff can determine
whether any further evaluation is justified. Twenty percent of the
pipeli:J.es fell into the ·C", liD". or "Fn condition categories.
Approximately one-half of these (-40~OOO linear feet, including all
of the "F~ and ·on pipelines and a portion of the ·C" pipelines/
scattered throughout the City at 130 locations) have defects which
warrant corrective work. and are scheduled for replacement or
rehabilitation in the proposed c&pital improvement program_ Based
upon further evaluation by the coneultant r it is recommended that
repair of some of the Cat~go~J C pipelines be deferred, and that
these pipelines {-40,DOO linear feet} be retelevisea and evaluated
in approximately ten yearB~ In addition to the pipelines, 14
percent (564 of 3,698) of the catch basins and manholes need to be
repaired or replaced as part of the program. Tabular summaries of
the results of the Storm Drain Condition Assessment are contained
in the attached eXec:Jtive summary (Attach.'lIent 11.
The Storm Drain Condition Assessment report recommends a $4-.7
million (1993 dollarsj capital improvement pr~am to correct the
exiating defects in the City's storm drain system. The estimated
project coste are budget-level figures which include allowanceB for
engineering design, construction administration~ inspection,
materials testing. and contingency. Consio:!sring the urgency of the
repairs, availability of funding and staff resources, it is
recommended t.hat this initial storm drain rehabilitation program be
implemented over a ten-year period. This scheduling approach will
enable the City tc eliminate known defects in the storm drain
system before the 40,000 linear feet of pipeline, currently in
marginal condition l has deteriorated enough to require
rehabil.itation. As described earlier. staff proposes to schedule
the rehabilitation projects in t\lltO distinct phases. During the
first phase, all of the Categor~ liD-and -Fa pipelines would be
replaced or rehabilitated over a t~o-year period. During the next
seven years, 31,500 linear feet of category ·C· pipelines would be
addressed cn a basin b)~ basin basis, starting with the basins
containing the most defective pipelines. In year tE!n~ the
remaining Category ·e" pipelines currently in marginal condition
would be retele"~ised am! reevaluated ~ A cost. breakdown for the
proposed ten year storm drain rehabilitation capital improvement
program is presented ir. Attachment 5.
2. 5~orm Drain Master elan
The Storm Drain Kaster Plan report contains the results of the
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ca.pacit.y analysis of the City's storm drain system. Using the
designated design crit~ria, a large portion of the systero la~ks
sufficient capacity to carry the predicted stormwater runoff from
the ten-year storm. various manholes and catch basinG throughout
t:.he City are projected to overflow into streets fOI' durations
ranging from 15 minutes to over five hours. This overflow would
result in extremely high gutter flows, with ponded water
accumulating along streets in the affected areas. ~though this
amount of excess water would not result in loss of life or create
widespread flooding of pTopeTty~ it would have the potential ~o
make streets impassable and cause damage to low-lying property.
The Storm Orain Mast.er Plan report present.s recommendations for
pipeline improvements required to eliminate most overflo~in9 of
major pipelines during the ~O-year storm event~ In general,
improvements are not recommended for less critical drainage systems
subject to flooding for lesa: than 15 minutes~ In additio:l,
improvements ar~ not recommended for smaller pipeli~es providing
local drainage, since they do not pose the same threat of flooding
as the larger trunk lines.
Staff worked with the consultant to develop a prioritized list of
storm drain improvement projects. The projects were divided into
three priority groups for implementation~ Priority group 1
includes projects that augment drainage systems with the greatest
potential for flooding, based upon the results of the cOOlputer
mode~ing analy~is, historical maintenance records. and
recommendations contained in the 1965 master plan. A high priority
was also placed on projects that relieve capacity deficiencies by
diverting water via a ne ... pipeline alignment int.o a creek or
anot.her drainage system. This type of solution provides local
drainage to etreets that presently do not have underground storm
drains. in addition to removing excess water from undersized storm
drains. Projects within priority group 2 address existing drainage
systems in areas with less 3evere capacity problems. These
projects invol-.re t.he replacement of undersized pipelines or the
const::ru.cticn of parallel pipelines to supplement the existing
drainage SYBteII'.S~ Upon completion of the projects in priority
groups 1 and 2. all of the deficient drainage systems will have
been improved, b'.lt there stilJ will be S':Itne reT'Cairdng pipelines
subject to overflowing into the street. Priority group 3 projects
include installation of replacement or parallel pipelines to
eliminate remaining flooding problems on systems that have been
upgraded th~ough earlier projects.
The Storm Drain Maeter Plan repo~t recommends a $55 million {1993
dollars) capital improvement program to augment the capacity of the
City's existing storm drain system. The estimated project costs
are budget-level fi~~res, which include allowances for engin€ering
design, construction administration, inspection, materials testing.
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and conl:ingency. Based upon the expected availability of funding
and staff resources I it is reco~~nd~d tha~ the storm drain master
plan improvements be constructed over a period of approximately 30
years. ?he actual project scheduling and sequencing may vary from
the proposed program as staff gains more experience in project
implementation. The Priority Group 1 irtprovements, which are
estimated to cost $23 million, are scheduled for completion over a
period of 12-l4 years. Priority Group 2 projects, estimated at $7
million~ will be completed in 3 -5 years; and priority Group .3
projects will take an additional 13-15 ye.e:.rs at a cost of $25
million. A cost breakdown for the proposed storm drain ~a6ter plan
improvement projects is presented in Attachment 6.
3. Future Funding Needs
In April 1992, S4.7S million in utility revenue bonds were issued
to finance the storm drain capital il1'.provement program through FY
!99J-94~ In accoTdance with the recommendations contained in the
Storm Drain.Condition Assessment and Master Plan reports discussed
above .. staff is proposing $9.4: million in capital ~.mprovements for
FY 1.9.94-~5# :19.95-96, and 1996-97. The proposed program includes
$6.75 million for master plan projects, $1 million for condition
asse~ament projects. $0.3 million for the nonpoint source pollutioli
control program, ~~d $1.35 million for ongoing programs (program
administration, curb and gutter replacement~ erosion control
projects) ~ In order to fund this program, staff has determined
that it will be necessary to issue additional revenue bonds in the
fall of 1994. In addition, it will be necessary to increase the
storm drai~age fee by approximately 31 percent to finance the bond
debt service for these capital improvements~
The storm drainage fee has not been increased since it was
originally implemented in February 1990. The fee: is currently
$3.25 per equivalent residential unit (ERO) per month. By
definition, single-family and duplex residential units are billed
one ERU; and other land uses are billed one ERUj per 2500 square
feet of impervious area on the property. The pr~sed increase
from $3.25 to $4.25 per ERU represents an increase of 31 percent.
The etorm drain fee is currently 2.2 percent of the average
residentia.l ut.ility bill. An addit.ional charg'e of $1 per month
increases the average residential bill ~f O~7 percent. ~Jerall,
the cumulative proposed FY 1994-95 utility rate adjustments for all
City utilities would increase the typical bill by 5.8 percent (s€e
Attachment 7).
In order to implement a comprehensive storm drain capital
improvement p:::-ogram as outlined in the Storm Drain Condition
Assessment and Master Plan reports, addition.al revenue bonds will
need to be issued peri-::>dically; and the: storm drainage fee will
need to be correspondingly increased. A projection of futu:::-e
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capital expenditures and resultant rate increases is shown in
Attachroent 8. The progr~m proje~tion is based on assumptions of a
3 percent average annual inflation zate. the eale of revenue bonds
every three years to financ~ capital expenditures, and completion
of all projects within a period of approximately 30 years. In
order to support this pzogram, the storm drain fee would need to be
increased by 30-35 percent every 3 years for a period of 15 years
and approximately 20 percent every 3 years for ~~ addi~ional lS
years.
Summary
Staff has completed Storm Drain Concit ion Assessment and Storm
Drain Master Plan stud~es to dete~ine future capital improvements
needs for the storm drair~ system infrastl:ucture. The studies
recommend both a ten-year, $S million replacement/rehabilitation
program for existing deteriorated pipelines and a thirty-year, $55
million program for system capacity augmentation. Staff recommends
that capital improvement costs be financed through the sale of
revenue bonds backed by the StOr1Il Drain Enterprise Fund. Staff
further recommenda a rate increase of 31 percent. to fund $9.4
million of capital improvements proposed for FY 1994-95 through
1996-~7.
Future Act ions
Staff will return to Council with recommendations to:
1. Approve and adopt the Storm Drain Condition Assessment report
dated June 19.93 with respect t.o the scope of the physical
improvements.
2. Approve and adopt the Storm Drain Master Plan report dated
Decembar 1993 with respect to the scope of the physical
improvements.
3. Direct staff to proceed with the implementation of the capital
improvements outlined in the Storm Drain Condition Assessment
and Storm Drain Master plan, as part of the FY 1994-95 bQdget
process, including a storm drainage fee increase and issuance
of utility revenue honds to finance the improvements for the
next t~-ee years. Staff would return to Council periodically
for approval of incremental funding to complete the remainder
of the program.
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Respectfully submitted,
JOE TERESI
Se..-,ior Engineer Assistant Director of Public Works
H-JlPL!--~~ GLENN S. ROBERTS
Director of Public Works City Ma..."lager
Attachments; 1
2 -
3 -
4
5
6 -
7 -
8 -
Storm Drain Condition Assessment executive
summary
Storm Drain Master Plan executive summary
Storm Drain COndition Assessment technical
summary
Storm Dr~in Master Plan technical summary
Storm Drain Condition Assessment cost breakdown
Storm Drain Master Plan cost breakdown
T~ical residential bill comparison
Forecast of storm drainage expenditures and.
rate increases
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Attachment 1
Storm Drain Condition Assessment
Final Report
Prepared for
City of PaIo Alto
Prepared by
ClUMHILL
Oakland, California
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June 1993
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ES, Executive Summary
ES,l Introduction
In !991, the City of Palo Alto embarked 00. Storm Drain CoDditioD AssessmCDl project
to inspect, inventory, and assess the condition of components of !be City's storm drain
sy.....,. The program's cbjec'Jves wen: to field verify the City's existing storm drain
maps, identifj potential illicit connections, provide an evalIl2tlon of the system's current
condition, and recommend projects to correct observed defects in the storm drain syston.
The proposed improvements, which iDclDde replacement and rehabilitation of storm drain
jripeIines and structures, were in::orporated into • n:commend'" rehabilitation program.
AdditioDally, collected information can be used to n:fine the City', S<orm Drain
Eutorprise Fund fee structure to man: accurately reflect actual conditions found in Palo
Alto.
ES.2 Field Activities and Data CoDectiOD
VISUal inspection< of pipelines ,ad S!IUCtW:es were performed by field crews from July
1991 through September 1992, in the drainage basins shown in Figure £S-l. Docu
mentarion consisted of data Jryg sheets '00 phOlOg:-aphs for stru;:run:s, aDd vi"eo
recordings for closed -circuit television (CCTV) inspection of the interior of pipelines.
!nspectio1lS were coOOucted OD 396,005 lineal feet storm drain pipelines, 8 to 96 in::bes in
cIiametm-. Pipeline inspection was used to de"'rmine the structural coOOition of the
pipeliDe. Noted defects aDd coDditions inclDded cracks, offset 0' openjoints, lead line or
Ia!eraI connection defects, root intrusion, sources of flow, sources of infiltration, aDd
pipeline sags.
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FIGURE E5-1
STORM DRAIN BASINS
PALO ALTO STORM DRAIN CONDITION ASSESSMENT
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StructUre inspections were performed On 4,4&8 structures, of which 3,898 are City-owned
and S90 fan UI¥!er the responsibility of pri .... at-e ov,fJ}l!:rs or agenc~ such as the California
DepartmeDl of Transportation (Caltrans), Sam. Clara County, and Stanford Univer<ity.
ES.3 Field Inspection Findings
During the field inspections, pipeline and srru<:lUre inventories from the STORMS data
b= and the City's storm drain maps we,., compared 10 actua1 field conditions.
Differences between the storm drain maps and field conditions were noLed and the maps
were corrected. When new stnJC:rures were encountered. CH2M HllL's field
,.",cseutative assigned stn/CIlIIe 0IlIllbers according to the City's numbering convention.
Field iDspection dam delivered 10 !be City include<l ccrv vide<J tapes and data log
sheets. sttucture inspection sheets. network fault '"1"',.. ... pottDlial illicit connection
reports. and revised storm drain maps.
The majority of def<cU fOUDd in !be televised pipelines were light and tn<ldium debris.
light roots at !be joim, ligbI corrosion in the pipe. and light vertical sags Overall, the
.,onn drain system is in good coadition. However, !ben: wen: cases of more serious
defects, which were i<kmitied and J'I1lked aa:ordine 10 tho <OIldition scoring syst=.
The majority of the inspected = were in good coodition. However. some
S!I1ICIUreS showed signs of deterioration of !be covers, grau:s, or Ih< SlIUCtwe itse!f.
These structures were identified and ranked IIXOIdini 10 !be coadruon scoring system,
and included in the teCOIIl11HlDded rdlabiliWioD program.
A rotal of eigbty-ooe netwon: faul. r<p01IS were $\IbmitIcd 10 !be City duriDg !be cour>e
of field inspections. These reports ~ o!>setveO rom ....... of defects or other
conditions which could cau .. SUUCIW2l f&ilure ,or sysIem i>k><:UF. Such observations
included collapsed pipe and severe debris. M of mid,Decomber ) 992. ~ of !he neIWan:
~II~ ES,5
~ -.:;---------------
~ • )
" .
~;' _'" ' "L '''''.".,;
,,/
.. -
faults bad been {:.O!'teC:tCd. After review by City staff. it was decjded tc correct several of
tho _ faults tbroIIgb the recommended rehabilitation program.
Undnormrrud COlIUCCtions to the storm drain system were recorded .and illicit connection
IepotU MrC forwuded to the City. The f'.eld crew perwnnel identified
490 ,""""'"........, cooooctions during the course of the proj~l.
The CCTV pipeline iDspcctioos also identified utility pipeline. or conduits that crossed
dmlugb storm drain pipeliDco. The inspc<:tion =" ... found 62 of these utility line
crossiIIa>.
IDf"", .. lion .... also oo:qaired 011 die physical c:bara<:\eri$ti of those ~ located in
tho CiIy bile ~ by otbots lOCh as CaltraDs, SaD!a Clan ComIty, and SWlford
Univonity. Allboagb _ ~ .", not oWDOd by the City. !bey do provide
drainage wiIbin die City and in many cues die oon-City draiDage sy= eventuaIly
=meet willi tho CRy's SIOI1D dn.iD notwmI.:. As part of !his project. the field =ws
localod and performed abbreviated inspections on S90 structures oWDOd by 0Ihe ..... The
pIlIJlOSC of _ inspections was to supplemem the City's invenlOly of SUUCIIUl:s which
CODtribuIc 10 die Sloan drain system.
ES.4 System Condition Assessment
ResuIts from the field inspections were used 10 assess the condition of the Palo Alto
storm draio system and develop rebabilitalion projects. Cost estimates for each
rebabiJiwion project were developed, and tbe rehabilitation pro~ were then pri<>ritized
based upon severity of defocts and location within the City.
Pipeline conditions were quantified by • scoring system that assigned. pain! score to
each defect found i:I. pipe during ccrv inspection. The sum of paints for each pipe's
--
•
-,-
...•.
defect .... is the pipe condirion score. All pipelines were placed in one of five condition
categorics ranging fJom "A" (gaed) 10 "F" (replace or rchabilil3l< immedialely), based
upon pipe: scores. Pipeline condition :a5sessmen! findings 2Ie summarized ii'l Tab!! ES·I.
Approximately 80 pcrceru of tile inspected pipelines faIl into condition categories • A" and
"8", indicating the system is in gaed condition.
Table ES-l
Summary of Pipeline Conditions
PipelIne Segments
Category Nmuwaf l.eniths of
Condition Segments Segments (feet) Percent of Total-
A 1.288 25<),247 63.3
B 289 54,832 16.4
C 219 70,132 17_7
D 25 9,423 2.4
F 3 871 0.2
Total 1,824 369,005 100
·Percentage based I!pOD length of pipelint segmcms.
Each structure·s condition was rated as ·8000:." -fair,· or "'poor." The structure was
also given a co!>:lidon score to accoun! for structural defect> such as cracks, fractures,
breaks:--and ho1es. The crack severity .score ranges from 0 for a stnJctlm: that has
"caved-in." 10 10 for a structure in perfect condition. The number of structures requiring
Iehabilitadon is summariz<d in Table ES-2. Over 85 perce", of the impe<;ted Sl!Ucturcs
were in good or fair condition,and dc noc require rehabilitation OJ' other corrective ~ark:.
ES-7
-_._--------...
Table ES-2
Summary of Structure Conditio.
ToW "'umber of Cily-Owned
Srrucrures Inspec1ed
Rcl!abiliWion
Number of CaIch Basins
Nwn~ of Mmbol",
Total Number of StrucIUres
3,898
490
~
564
ES.5 Rehabilitation Techniques
PeJUnl of l1Ispe<:ted
Structures
100
12.6
....L2
14.5
Six pipeline rel!.tbiliwion a1!efnatives wm: chosen for use in Palo Alto from the
DIIDIOroUS meIbods availllble. The pipeline rel!.tbilitation methods assessed in this study
irItIwk IiIlnre CCIV inspection, point repai.T>, Welw seal, sliplining, inversion lining,
and nplacement.
Stmcmre rehabililation is <kpendent upon the <ypc of defects obsenIed dnr'.ng field
inspection. Rehabiliution techniques for this program consist of installing bicyclc-proof
graIOS, replacing covers or grates, realigniDg or replacing structure frames, and
conductIog complete sttucture replllcemcnt. The rc.:oIIllDtDded strucnm: rehabilitation
program also inclu<les converting all Type B catcb b.1Sins to Type A by installing the
bood structun:.
The recommended rehabiliwion teclmique WlS based upon the conditioD a.ssessmeol
analysis. For pipelines, • preSCDl-worth analysis thaI """"ned the rehabilitation melbods
,.ith respect 10 condition scores and observed defects and then compared the cstimalf.d
costs of various rehabilitation me!bods was conducted 10 selecl the least-cost and most
appropriate rehabilitation alternative. The analysis was performed on a pipe-by-pipe
ES-8
. '-
--------.-----.~~.,. ---
basis; however, as projects are identified for fmal design, t.fJese recolIIDl~ndations can
change according 10 decailed projecl information"
ES.6 Recommended Rehabilitation Program
The purpose of the rehabilitation program is to develop a ",bedule of potential
expeDdirures based upon a prioritized list of projects. Because future conditions (e.g.,
regulations, avail.ble tochnologyJ may chll'lge, this recommended program can and
should change as more detaiied information is developed and rehabilitation technology
improves.
ES.6.1 hoject Priorities
--. In order 10 develop. rehabiliUtion program, eacb projecl was assigned. prinrity based
upon locaion and pipeline condition score; those proje.."tS with the higbesI priority wen:
then scboduled with the earliest SUirt da2s. The top prinrity of the rehabilitation program
is 10 repair or replace those pipes with the most severe Slrl"'-!uroil defects because of the
threat to publlc bealth and safety. In addition, 5trUCtUr3l repairs should be condUCll:d in
one area at a time, as much as possible, to minjmize disruption of uaffic and
neighborhoods.
ES.6.1.1 Pipeline Rehabilitation
The pipeline rehabilitation progr.un was divided into two pilase.,. The flJ>! pbas< will
correct !hose pipes in die "F" and "D" ,",odition ClI~ories. The seeood pbas< will
address rehabilitnion of all pipes in the 'C" condition category. Wben rehabilitation was
J'CCOmmeoded (Oi a pipe segment, manhole and caleb basin rebabilitation were com::lated
,.ilh the pipeline projects.
ES-9
<.:
..-J'"
ES.6.1.i.! Phase 1. Pipes in the "F" and 'D' condition category (score, above
2,500 points) were designated for the iJljtiaJ phase of rehabilitation work. Projects in this
. category were assign«! for implementation wilhilLthe fIlS! 2 years of the City's storm
dtain rehabilitation program. This approach addresses all "F" condition pipe, in the flm
yep! and mjnimizes the amount of revisiting areas in the second year.
The ba.'ins were prioritized according to the IlUlllber of 'P' and "D" pipelines. and the
boslns with the most severe projects were assigned for impleme~tation fIlS!. The basins
',e listed in order of priority for :be first phase of rehabilitation in
Table ES-3.
ES.6.1.1.2 !'base 2. Pipes with • 'C' condition score (scores between 900 and
2.500 points) were slated for repair. replaoemen!. and in some cases CCTV inspection; in
!be IIOCODd phase of:be rehabilitation program. Phase 2 of:be program will be
implemeDlcd jmny<fi.tcly after Phase I. Phase 2 projects were prioritized based upon
tbcir basin location and :ben :be pipe segment condition score. The basins are listed in
order of priority for the IIOCODd phase of rehabilitation in Table ES-3. Por this project.
PIwe 2 is programmed 10 be performed over an 8-year period. bowever. the length of
time may vary .s projects are imp!=emed
ES.6.1.2 Structure Rehabilitation
Structure rehabilitation was coordinated wilh the pipeline ropair projects, Repair:; to
SINCIUI'eS on !he pipelines included in Phases 1 and 2 of the pipeline rehabilitation
program were assigned the same priority as !hose pipelines. S= DOt cOO!dinated
with. specific pipeline project were included in Phase 2 according to drainage basin
location and prioritized based upon the foDowing scheme;
ES-IO
, . )
Table ES-3
Prioritized Basins for Pha.« 1 and Phase 2 Rebabilitation
Numb« of Number of J Number of
·'F" liD" Ire"
Condition Conditio.a I Condition
BasU! Rank Basin Pipes Pipes Pipes
Phase 1 Rehabilitation, Year 1 of Program
1 NWB 1 4 .. r-.---2· NWA 0 5
3 NWC 0 4 I
4 SEA 1 0 -
5 SEB 1 1
6 SEC 0 I
Phase I Rehabilitation, Year 2 of Program
I SWjj 0 5
2-NEA 0 1
3 NEe 0 I -
4 BL 0 I -
5 NEB 0 1 .-
Phase 2 Rehabilitation. Years 3 through lO-
t SWB --45
2 NWB -42
3 NWC --35
4 NEB --22
S Nl:A -.. 19
6 NbC -15
1 SEC -9
8 NWA -9
9 SEA -9
10 SEB .. -~
11 SWC -I 3
12 BL --I 2
13 SWA --I 1
"l'eriod can valJ as projects are implemented_
lOOI14B6.SFO
~-------,
!D2rill:
I
2
3
4
s
6
Type bf Rehabilitation
Catch basin and manhole repl=ment
Replacement of structure cover
IoslalJation of calI:h baslD bicycle-proof ga"
Replacement of stnICture frame
Stnu:tcre fnme realignment
Conversion of Type B calI:b basins to Type A
ES.6.2 Recommended Program
The =ommended rd!abilitation program was developed based upon !be criteria discussed
above and includes p'..habiliwion of catch basins. IIl3Dbolos. and pipelines throughout !be
City, The ProgIllJD is SIlIIDIlZrized in Table ES-4.
The lecommended program SI3ItS wilh Phase 1 won over • 2-year period that flIIgeIS
severe pipeliDc cIefecI5, This portion of !be progzam will cost approximately
S1.23 million and will include rehabilitation of 10.294 tineal feet of pipeliDc and three
5tructureo. The remainder of !be IeC01IlmeJIded rehabilitation program is scheduled for
!be foUowing years. For this ~ it is assumed that Phase 2 projOC!5 will be
compteed in 8 years. resulting in an average cost of approximately $0.43 !!tillion per
year. This lOtallO-year program is expected to cost approximately $4,7 milll!!lhnd
includes rehabmtation of 490 calI:b basins, 14 "",llheles, and rehabilitation or periodic
CCVT inspection of 247 pipeline segments :OIllIing approxlma",ly 80,420 lineaI feel of
pipe. OveraiJ, tbe =ommended program provides for tbe following:
""-
• The pipelines with the highest coodition scores, includmg aU "F" and "D"
pipes, will be rehabilitau:d in !be fun 2 year.;.
ES-12
,
"
'J
Table ES-4
Rehabilitation Proara", Summary
E.'IIlnloted Capllol Cast"
Proj""'" ($1,000)
Number of [ .. ngth of Nu",be. of
Phase l'lpelln .. Pipelines Stnlcturrs Pipeline, Structures Total
I-First Year Rehabilitation 18 5,665 0 760.2 0.0 760.2
I-Second Year Rehabill,"tion 10 4,629 3 461.8 6.1 467.9
,},-Rehabilil8tion-Following
7 Years· 103 31.574 561 2,144.2 1,233.8 3,378.0
Periodic eerY-Year 10" 116 38,558 0 69.S 0 69.S
Totn' 247 80,426 564 3,435.7 1.239.9 4.675.6
-Capital co~ts based upon a 1993 ENR Index of 6293 fOT the San Ff.!lncisco area.
hperiod may Vllry as projects arc implemented.
, I
I
]001 rofD4.sr:o
'.
,
I
I
I
!. ,
i·,
-." ,
;'l>::-;~i~:,
.'
,
" . \..f
"
'.', f..
"1,:;','
",-..
. """
• R.!habilil:2tioiJ for the pipeiines witll "C· (:ondition scores (berween 900 and
2,500 points) will be performed in the following 7 years, nowever. this
period may be adjusie<l as projects are implemocted.
• Periodic CCTV inspection of condition .. C ~ pipelines not requiJing
rebabililation will be performed in year 10.
• Preventive CCTV impect.ion of 25 peTCl!nt of the system"s cundition ·A~
and "B" pipelines, will be performed in approximalely 16 yean;, This
progrun includes CCTV inspection of 1,538 pipe segmerus ., an _red
capital cost of 5137,()(J(),
ES.6.3 Implementation Plan
The l'eCOmlIlCIIded rdlabilitalion plllll developed in thi.I ICpOI1 provides t:Je City with
budget level estimates for capital costs and rehabilitation recommend.1tions based on daIlI
obtained in this project, A5 the City procuds with its plans to implement projects
identified here, information must be collecu:d during preliminary cogincering studies 10
evaluate rehabilllation rwmuneyylations against detailed site information. In addition. the
number of available rehabilitation methods will increa.<e in the futwe with ad.""",," in
reI!a~ilitation technology. thus providing the City with other options for rehabilitation.
The next ,tep' in implementing the =ommended rdlabilitation plan would includ:::
1. Coordinate recommended rdlabilitation with pipe sizing requirements dial
wm be developed in the City's Storm Drain Master Plan.
2. Review Cc:rv inspection tape and log sheets and structu..., inspectiou logs
and pholographs. Verify !be extent and Iocetion of poim repair<.
ES-14
3. Colle..:t site specific dalJ., including the follo ...... ing:
• Above ground interferences to rehabilitation methods, inciudmg
commerce, ilIld exjstin~ strucrur.:s
• Impacts rehabili:tatioD might ha \.'c OIl traffic
• Adjacent land uses
• SOU ooodidons
• Pipeline alignment
• Distance berween lcecSS points
• Pipeline shape
• Need far bypass pWllping
• Existing and ""I1IiIed hydrauUc capacity
• Load ""I1Iirements. wrucb would be bome by the rehabilitation
method, due to groundwaltr and doItrroration of !be original pipe
4. Review recommended rehabilitation methods considering the detailed site
information collected.
5. Perform a search for other alternative rehabilitation methods. Many
communities and agODcies in !be Bay Area and C'.alifarnia have ongoing
rehabililation programs for saniwy as well as "ann drain systems, thus
providing additional information sources for new ide;iS and products.
6. Develap deraiIed cost estimates for selected altemative(s).
Additionally. the City can coordinate rna; ntenanr:e and capital improvements by taking
advantage of its STORMS software package. The recommended rehabilitatian projects
could be incotporated into the STORMS database as future projeru. The fu= projects
option in STORMS coula !ben be used to assL<t in developing !be City's 5 ·year capital
improyemenlS program. By including tbe proj.:crs in STORMS, the .ma base would be
easily accessible allowing the City to update the .. babilita"a. pragram as specific
projects are completed.
ES-JS
,,'---------,--_.-
---
Storm Drain Master Plan
Prepared for
City of Palo Alto
Public Works Department
Prepared by
CHZMH1LL
Ile<tmber 1993
,
! .
Executiye Summary
Background
In 1965, !be City of Palo Alto adapted a Storm Drainage Master Plan (Brown & Caldweil,
196.5) that presented a long term program fm improving: ;he storm drainage system. Th~
City has been using this plan for O""....uly 30 years as a guide for identifying SIOITll drain
capital imIr.OvemetltS. The highest prioriI)' prop:ts in the 1965 nuster plan have been
implemented; bowcver~ many of tlle recommended projects still have not been compl~red
~ to funding shortageS. In 1990, !be Cily established a Stann Drain Enterprise FUDd to
provide a consistent: source of funding for stann drair. infrastrucrure improvements. A
cood!tioo assessment: program and a masler plan t.rpdate were authorized to evaluate the
.. !sting coDdition of !be storm drainage system aDd ideatify ~ssary capacity
improvements hased on current analytical tedmiques. Tru:se studies "'ill establish !be
framework for the storm drainage caplw improvement program for the next 20 to 30
years. TIle condition assessment results were presented in the Storm Drain Condition As
sessment Report (CH2M HILL. 1993), This report presents the Stonn Drain Master Plan.
Methodology
This master plan was develope<iusing • dynamic C<lmptlter-based model interfaced with •
geographic information system (GIS). This approach provides the City with an on-line
master pl&nning tool that = be reused, modified and expanded as system improvements
..... CODStrUcled. This >Iso aIJows the City to modify the plan as coDditions change without
requiring a COIDI'Iete revision of the Master Plan Repon.
Modeling to develop this master plan was performed on approximately 30 percent of !be
City's storm drain system (159,000 linezI feet), which includes !be maio< drainage lines,
generally those ever 18 inches in diameter. Hydrologic: and hydraulic design criteria were
esrablishM as a part of me master plan effort. 'The de~ign criteria requires chat pipelines
have the capacity 10 convey the lO·year frequency> 6-hour duration storm when !be 10-year
frequency tailwater eJevation is applied lit the receiving waters (creeksj. Surcharging of the
pipes is a1Jowed; however, the hydrat!lic grnde line (HGL) must remain below !be street
level.
Model dara were collected from a variety of souroes aDd input into the GIS. The City's
200-sca1e storm drain maps provided !be b .. is for the storm d. ... in inventory including
drainage subbasins. pipeljIX: configuration and pipeline sizes. f'ipelrne rim and inven
elevation data were obtained from surveying and through inlJ:rpolatioD between known
points. The City was divided into 29 drainage rubbasins (designated AA through ZZ, BA,
ZA, and ZB). The modeled pipelines and !be subbasin boUDdaries are shown in Figure
ES-l. Subbasin characteristics such as area, slope, width, drainage input locatiOns, 'inftltra
tion rate~ depression storage and Manning's roughness were obtained from the stonn drain
SFOlOOl28Af.~ ES-I
.-._----
>~.lt, ..
. --i
--~:~:.: -.;
\ -.' -",
• I
. .
.~'" .
maps, USGS topographic maps, and estimates based on t.."'le soil and vege{2;dv~
chan:c.teristks of the area, The percent i.mpervio:ls data fer the subbasins were de[emtinec!
from aerial photographs. discllssicns with Cily Puolic Works and Planning Department
mff, past CH].M HIll. ex.periencC'., and cvrnparisons of modeled flows to flows estimated
wing other methods. Model results were compared with flows generated using other
~Jtods, such as regional regTes:!: Lon equation'S and 'he Rational method, as a check on the
flows being generated by me model. De!:aHed calibration of the model was 00{ performed;
bowever. a calibration effort will be: concru\:Led in the near furure to compare the model
flows with actual field-measured rainfall and flow data. Existing land-use data weIe
obtained from me City's 200-5<ale Zoning Maps. Because of the City's bv.ilt-OU1 naMe,
furure changes w. land use patterD.S were consjdered 10 have an iruignific.aru effect on the
drainage system and were not :nod,led.
The Environmental Protection Agency', (EPA) Storm Water Managemont Model (SWMM)
was used 1<l perform the hydrologic and hydrauliC analysis of the storm drain syS'.eIIl. The
c'Xisting system ,,'as mitia.lly modeled to determine the severity of capacity deficiencies.
Improvement altemati ves were developed and analyzed using the system model.
Alternatives inclu<led providing paral1<1 pipes where feasible, repacing existing pipes with
Illrger pipes, and di~ flow ar<MInd ponions of the system with inadequate capacity.
AI_ves previously identified in the 1965 Master Plan were evaluated and incorporated
in the L"!1provemem recomrneodarions where possible. For example, alternatives to avoid:
construction on busy streets or to use streets that have been "reserved" for storm drain
pipelines were develope<l based on :ecomn:endations contained in the 1965 Master Plan. In
gooeral. alternative solutions were developed for 'y= that exhibited IDng-duratio.
flooding. The recommended imprcvtmerus were divided into projects that include
construction of new diversion pipelines and outfalls, expansion of existing ;rump stations,
and construction of replacem<:nr and pazallel pipel;" ....
C'.apital Improvement Plan
The recommended improvemenrs for Uldividual drainage systems (Syst..'"ID AA througb ZZ,
AB~ ZA. and ZB) were prioritized based on tl-..e duration of flooding. extent of floodm,g.
type of land use flooded, 1965 Master Plan report priorities, and historical flooding
pattem.5. The system priorities are shown in Table ES-l. Using the sys<.em priorities, a
logical construction sequence, and cost-effectiveness considerations, individual projects
were prioritized. New pipelines and/or system (xpansions were given a higher priariry
than panIlel or replacement pipelines because they will provide the most substantial and
cost-effective system improvements. A capital improvement program (CIP) was developed
Uliing the prioritized list of projects and • projected annual budget of $2,000,000. Projects
were separated into an initial 5-year CIP and • secoodary ClP. The full CIP consilts of
36 projects ID be implemented over the next 30 y""''"S at an estimated coS! of $55,000,000.
Table ES-2 includes a list of recommended projects and their estimated costs for the cilUre
CIP.
ES-3
'~,-------
:
Table [S-I
System Priorities
Category I: Seve,.. Flooding in High Priority A,....
System CC
BB
IT
GO
MM
ww
EE
NN
DD
Category U: Moderate Flooding in Moderately Critical AT ...
System JJ
ZZ
QQ
xx
ZB
Category ID: Moderate FloodiDg in Less Critieal Areas
Systom
El Cmtro
Whitsen
KK
ZA
AA
Catego!")' IV: MiDlmal FloodiDg
System uu
BA
00
SF01OOI2IBI.~ ES-4
,
Tablt ES--2
Prioritind Liq or Improytmmt Prajft'lS
s ....... Improvement Typ.!:
PRlORITV GROUP 1
TTlWWflO( Ormt St."'eC1 Pipeline
lA Donna Street Pipeline
cc Newd1 Road. Pipelim. .and Outfall
cc H ...... A= Pipeline
BB Ur..col!l A"eDUoe Pipelme
CCIBB Dana .",-VCll.J:: Pipeiine
s_
00 Plu, D!> Divcnioo
GG LoW! Road Outfall
GG w...my S<=t 0utf>lI
MM Mid<Il_d Road Pipdill<
GG Mid&field Road Outfali
MM PanIld Pip<s
EE PanIIcI Pip<s
NN PMalI,l Pip<s
DD 01 Basln
CC Pitman Avc:oue Pipeline
BB Kellogg AY<CUe Pipeline
lJ Cahfornia Avenue PIperine
s.wtolal
Subtrotal Priority Group 1
PRIORITY GROUP 2
QQ
xx
Sf()IOOllC24. ~ ES-5
Impro"em~1 Cost
($ mDUons)
1~3 Dollars
2.04
2.03
l.!!9
1.33
$9.32
0.01
0.45
%.19
0.54
2.J1
1.20
1.96
0.16
l.!2
1.43
095
S13.86
$23.18
LIS
.75
Coruinued
-------_._----------
t·.hle ES·2
Prioritiud list or lmpro'o'ement Proj~""1s
Improtlement Cost
($ mllUons) 5,...... ImprotietntDl T~ 1993 DolJan
ZB P>nJ1<J Pipes U9
I.aa=o RepI.....,." Pipe> 0.3:"i
EI c.onu !!<pI........., PIpes 0.18
KK PinIIel P\pel 0.49
ZA p...noJ PIpes 0.02
loA Rep"""""'" Pipes 0.95
SA Replacemeru Plpe5 0.15
()() ParalIol Pipe> 0.16
UU Replo<ealott, Pipes 0.13
_ PrIori<y G ... p 2 56.47
PRIORlIT GROUP 3
CC RepIa=teDl Pipes 058
BB PlIBlkI PiposIRep1atomem PIpes 0.96
Tr Pan.~.1 Pip<slRepl><ement PIpes 1.30
GG MaU<!= Pump Swio. Up~ 3.07
GG Ptnilel PiposIRepIaa:ml:n! PIpes 12.90
WW PmJ)el PipalRepI ........ PIpes 2.53
DD Pua[ld Pipes 2.00
IJ P.,..1e1 Pipes 1.65
_ Priority Group 3 S24.!19
T-' $54.64
SFOLOOJJOC. WP5 ES-6
A.ttact-..ment 3
Storm Drain Condition Assessment Tecr~icdl Summary
Between July 1991 and September 199~, the consultant televised and
evaluated nearly 400;000 linear feet of storm drain pipeline.
Th~ir a~alysis included the entire storm drain network except fot
IIlead lines" or "laterals" {short lengths of pipeline connecting
catch has ins to manholes) and pipelines owned and maintained by
other agencies, such as Cal trans and Santa Clara County. 7hey also
inspected and evaluated nearly 4500 manholes and catch basins
throughout the City. Any differences between the City;s records
~~d actual field conditions were noted; and the storm drain maps
and inventory database were corrected.
In order to prioritize pipeline segments for rehabilitationl
replacement, an objective scoring system was devised to rate the
pipelines. Point scores were established for typical pipeline
defects such as eracks~ holes. open joints, roots; debris~
corrosion r and misalignment. The initial point scores were then
adjusted by impact factors related to land use; level of traffic,
and pipeline material and diameter. For example r a defective
pipeline segme.."Tlt located on an arterial street in a comm~rcial
district would be given a higher priority than a pipeline ~ith a
similar defect located on a local residential street because of the
greater potential for property damage and cOmmlllity disruption if
the pipeline were to fail. Using the standardized defect point
scores and impact factors, each segment of pipeline was aasigned a
condition score and ranked accordingly. The higher the pipeline's
score, the more severe its defects and the higher its priority for
rehabilitation or replacement.
-" .
Attachment 4
Storm Drain Maste_'t" Plan Technical Summary
~thoU9h the 1965 storm drain master plan is a valuable pl~~ing
tool, its usefulness is limited due to its static nature and the
lack of backgl-"o-..md data to support its findings. It is difficult
t~ recreat,e the technical basis for the: report and. it is. not
possible to examine alternative solutions to those proposed by the
consultant. In addition, due to the limitations of the analytical
t.ools available in 1965, the report only gives a snapshot
comparison of the peak stormwater runoff vs. pipe capacity at 3
given moment rather than a projection of how the system will
perform throughout the duration of a storm event. In order to
avoid the shortcomings of the 1965 storm drain master plan. sta!!
specified a dynamic computer-based model for the master plan
update. The computer model will give staff a much more powerful
tool that ean be used to evaluate multiple scenarios ~~d potential
solutions to drainage problems.
Approximately 25\ of the existing storm drai!l network. which
includes most pipelines 18' or larger in diarneter. was incorporated
into the computer model. These pipelines form ~he backbone of the
City'S drainage system and carry the bulk of ~he stormwater. It
would have been prohibitively expensive and only marginally
beneficial t.o include. pipelines smaller t;.han ~8· in the model. As
a result of the flexibility of the computerized format. staff has
the ability to add these pipelines to the model at a later time
during the design of individual improvement projects.
In order to evaluate a large municipal storm drain system. it is
necessary to bre~~ it down into manageable parts. The consultant
divided the City into individual drainage basins and identified
portions of the stCrtr. drain net",,·ork that serve eacb basin. These
individual drainage ~ystemsr identified as System AA through ZZ,
operate independently and were modeled separately. Figure ES-l cf
the attached Storm Drain Master Plan ex.ecutive 9U'r."Lmary (Atta.chment
2) contains a map identifying the individual dra~nage systems.
Relevant information about each dra.inage system, including length
and diameter ci pipeline. and pipeline and street elevations was
gather~d and inputted into the computer model. Land use
information i including zoning, slope. and amount of impervious area
was also collected.
Using the inputted rainfall data, land use information, and storm
drain system character.istics, the computer model predicted the
performance of each individual drainage system. The model
sinr..llates the rainfal1~ calculates: the runoff. and routes it
through the pipelines to a creek or the Bay. If a system cannot
accommodate the predicted flows~ the model predicts where and for
how long water will begin surcharging out of a catch basin or
manhole into the surrounding street. Those systems that exhibited
street pending were studied further for potential solutions.
"';:--. --------
->" ,;::":
<.
Attachmen, 5
Stonn Drain Condition Asses'i:ment Cost Brea.kdown
SCOPE OF WORK
Year 1 -Pipeline rehabilitatioo
Year 2 • Pipeline rehabilitation
Year 3 -Pipeline rehabilitaticn
Year 4 • Pipeline rehabililaJion
Year 5 -Pipeline rehabilitatioo
Year 6 -PipoIine roIWillitatiOll
Y..,. 7 -Pipeline rehabilitation
Year 8 • Pipeline rehabilitation
Year 9 • Pipeline rdlabilitation
YeaT 10 -Reinspoctioo of selected pipelines
TOTAL ESTIMATED PROGRAM COST
• All costs "'" in 1993 dollan.
ANNllAL BUDGET'
$ 760,000
$ 470,000 ..
S 480,000
$ 480,000
$ 480,000
$ 480,000
$ 480,000
$ 480,000
$ 480,000
$ 70.000
$4.7 million
AlI..!Chmem 6
Siorm Drai:l Masrer Plau COS! 9reakdown
SCOPE OF WORK
Priority 1 protects
Yeu I
Year 2
Year 3
Year 4
Year S
Y=6
Year 7
y.,. 8
Yoar9
YcarIO
Year II -
Year 12-
You 12-
Year 1:;-
Year 14-
Year IS-
Yeor16-
Ormc SlIe<t (SysiemS ITIWW)
La Do""" S<=< (Sy"<m XX)
Nowoll Road (System CC)
Harker Avenue (System CC)
Linc.lJln AvcmJe (System BB)
Dana Avenue (Sys"'" Cc/BB)
Louis Road (Symm GO)
W.vcIley S<=t (System GO)
Middlefield Road (S)',,.m GO)
San Amonio Rood (System MId)
Middkfield Road (System MId)
Hoathtt r..ne (Sy."'" EE)
East Meadow Drive (Sy ..... NN)
Pitm3n Avenue (Sy""" CC)
Soolhple oeighborbood (Sy""," DO)
Kellogg Avenue pipcliue (Symm BB)
California Avmue (System 11)
Emborcadero Road (System ZZ)
East Charleston Road (Sys<= QQ)
Batron Av...., (SIJUm XX)
ParI< lIoulovan! (Sysiem ZB)
l.aguoa Avenue (System XX)
81 Cemro S<=t (System XX)
Hillvfew A,'eDlle (S)"st ... KKJ
Hillview Avenue (Syzum ZA)
Lyrum Avenue (System AA)
Chaucer Avenue (System BA)
Transport _ (Syst= 00)
La DomJa S<=< (Syzum UU)
Prigriry 3 pmj~
Year 16-
YQI' 17-
Year IS
Year 19-
Year 20-
Year 21 -
Year 22-
Y .... 23-
Yt2r 24-
Year 2S
Y .... 26-
Year 27-
ChpMing Avenue (SysUm CC)
_ Road (SyJUm BB)
Amar.mta Avenue (Syzum m
Sy ..... GG nplaoemenr pipelines
System GG nplw:mem pipelines
S) ... em GG nplw:mem plpeliDc$
Sy ... ", GG rtplac<men! pipelineo
S)'SIem GG repla=noU pipelines
System GG 'eplacemenl pipelines
System GO replacemont pipelines
MatadcIo Pump Station upgrade
Ar.Istr.Idcro Road (System WW)
Seale Avenue (S)'SICm DD)
Page Mill Road (System II)
SUBTOTAL
SUBTOTAL
SUBTOTAL
TOTAL ESTIMATED MASTER PLAN PROJECTS COST
$ 2.00 M
2.00 M
2.00M
1.90 M
1.40 M
2.2SM
2.2SM
1.75 M
2.IOM
3.ooM
1.60 M
0.95 M
$ 23.2 M
$ 0.55 M
i.9O M
1.9S M
1.80 M
O.3OM
$ 6.5 M
S LSSM
2.15 M
2.00M
2.00M
2.DOM
2.00M
2.00M
2.20M
3.ooM
2.40 M
2.00M
!&.M
$ 24.8 M
$ 54.S M
\
"
lIliliIx
El:cttic (~KWH)
W ..... (14CCF)
Gas (IOOJH)
Sewer
Refuse
Storm DraiD
User Tax -. -
TOTAL
Attachment 7
Typical Residential Utility Bill Comparison
(Based on System Average Charg .. )
93-94 94-95
IlliI I!ill l..l.WI
.24.27 524,27 $0,00
31.65 28.98 (2.67)
41.48 46.48 5,00
13.89 13.89 0.00
28.60 33.75 S.IS
3.25 4..25 t.OO
4.87 4.99 0.12
W1.l2l 1WJl 1UZ
.LI2ilI
0.0\11
-8.4\11
12.1 \II
0.0%
!8.0%
30.8%
2.4"
~
'~
:' "1 "··'Y
/' . / !
i
".
AttachlD8nt 8
S1UItM DItAINAOIl JIOItHCASl'
PAGE 1 Of 2
ArlIItJII\dtlpBudI VRI VR2 YR.) VR.. VI' YRt YR"f YIU Yft.9 YR.I" YIlU ytln Y"-l'} VIU,
92-93 11]-94 I ~-9' '~-96 9IS-tJ t1-9lI 98-99 99~OO 00-01 Ol-~ OZ-(;J 03-04 o,-~ 6:'-06 M-m 01-"
--------------------'~--,------------I-------------,------------,----------.. ----------------------... ---.------------.-------------
MQltthly Pl_. Rile
Projected Rille Il'I(Ir_1I1
Rl!.VBNUP.8
(~uiIOftin s..ft:. -.... fI
Rue halI'CUII Impact
fllillrallnr',(lftle ..... ,.... ...
TOTAL RnVbNUR.'I
OPBRAl1NG JPIDII'IHlI
DBR"J' ~HRVIc8
CAPITAL PRO()R.uiS (I)
(".undilion ane .. menl
On-pnl~.I1"
"'_I" Plln Pf"lN:U
$j.2$
""
,.60'
•
I~.
•
1.1~9
.. ,
177
o , ... ,
o
$)", S04.1~ ~.H $4.2!I ".,J 1~_~3 ",U ,',oM .',oM $"1.46 110.01 SIM1 $lIIm ioIHIt SIJ.OO
"" "" ... 096 .~ "" ... "" ow, 0':If, .l'f9(. 0';11 ~ JO'1io 09E.
1,6~6 I
.1
'" •
11i~6
.'II]
" 9..19."1
~". o
77
o
2.1~ 2,169
o ~'I
7" n
o 9,46.'J
2)110 'l~'ZIJ 2.1'10
o 0 ~1I1
100 100 100
• o 0,.412
'Il00
•
'16
o
,.."
•
']6
],1107 :'1.140
I.,1J] 0
1)1) I/O
(I 11..111 •
',lU ll.li24 2.J.t1 2,24' tl.:M2 2,~2J 1,911 I'IJM ),9.0 ),9"] 16.-~.JZl
1.002 1.078 1,114 I,I~O \,1!19 1.2211 t,l~ 1.304 1~1A(I 1,371 1,416 1.4~ti
, .. .w. 1,Illi I,IO!! 1,10) UIJ4 1,917 I,'H" ),00' ].0)2 l,O]3 ",m
o 1 '" ... ...
1 .. 1R..1 I J,14'1 no ~
o I 100 2.0):) 2.000
1
'" ,.,
2,2.'1
m , ..
~,lOl
-,\(19
"7
'.'"
"" ~3 nz
U'I 61] Ml
2'.767 U~f) 2.18j
• u
6'12 1)1)2
2,1112 ',m
M~
•
III~
.• ,140 6,682
J~'.2 0
I!U l~
o 1OJ84 •
."i,.l2J 17,249 6.fI20
1.497 1_~40 I~,"
'.1 I!! .,117 ~,120
II o o
11, '" ,,.
2.281 2.103 IfU4
'IOTAL nxPBNDln1l.ns j,9M l.Qtt..~ It""? .'1.210 ."i,2'l"l :'1,62) 11,417 6.02,) 1,IAli M41 1~1 1,90 10,419 8,tiHl 8 .. ~?4 IO .. B"I
-------------------.-------.. -.-----... 1 ------.--------------------. --.. ---. -----....... ----.--------------------.------.-----.. ' -----""----.-.
Tr¥"<PrQIIII:' ".eM,
IISIl. gesininl811lAnCl1
IlSR. P.ndi"l A.lance
(1.22!1) (1.l69) I
1
lSI] 1..1111 I
6:m
"
1.,1211 '" 6,814
(2.'lI'il) (1,oorJ) 6,'1l9 (3 .. 1'7) (3,103)
1't,814 'Il'«l '42 7~'81 4,1J:2"
l,8!10 '" 7,'181 .... 92'
A,IV( (4"'\1$) (J.n') ..... ' (."IJl96) (J.2l!1) 8.6"1.'1 (l,41.'!)
92, 9,11.' ',617 .. , 9.J~ .,]1Il '" 9,6]1
9,ln .,61'1 '" 9,lM '»' .,. 9.tiJI 6.216 ---_ ...... -........................... _ ........................ _ .... -........................ --_ .. , .................... __ .. _-_ .. _--_ ......... _ ............... _--_ ....................... -
Note 1) Includes all projects recommended in the Storm Oraln Condition Assessment and Master PIM.
, .. -'~.
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• ... i ~ f
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