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HomeMy WebLinkAbout1999-05-03 City Council (13)City of Palo Alto Manager’s Report TO:HONORABLE CITY COUNCIL FROM:CITY MANAGER DEPARTMENT: PUBLIC WORKS 9 DATE:MAY 3, 1999 CMR:227:99 SUBJECT: STORM DRAINAGE INFRASTRUCTURE IMPROVEMENTS REPORT IN BRIEF On March 3, 1999, staffpresented a report to the Finance Committee describing a proposal for financing the next phase of storm drainage improvements. During the Finance Committee’s review, questions were raised regarding the extent and severity of the existing drainage system deficiencies throughout the City, and the expected effectiveness of staffs recommended infrastructure improvements to address the known deficiencies. This report provides additional information to Council in response to the Finance Committee’s concerns. This report summarizes the most critical storm drain system deficiencies, as identified in two Storm Drain Master Plans and corroborated through service call records and records of flooded basements in February 1998, and staff’s recommended improvements to address the deficiencies. The report also contains more specific information about the storm drainage infrastructure improvement program and funding recommended in the March 2, 1999 report to the Finance Committee (CMR:147:99) and illustrates the relationship between the deficiencies and the recommended improvements. This supplemental information will assist Council in assessing the program’s benefits to the community. CMR:227:99 Page 1 of 10 BACKGROUND On March 3, 1999, staffpresented a report to the Finance Committee describing a proposal for financing the next phase of storm drainage improvements. The report discussed the current financial status of the Storm Drainage Fund; constraints on the City’s ability to increase property-related fees, such as the Storm Drainage Fee, as a result of Proposition 218; staff’s proposal for storm drain infrastructure improvements, an augmented operations and maintenance program, and work associated with San Francisquito Creek; and a long-term financing plan to fund future storm drainage needs through an increased Storm Drainage Fee. During the Finance Committee’s review, questions were raised regarding the extent and severity of the existing drainage system deficiencies throughout the City and the expected effectiveness of staff’s recommended infrastructure improvements to address the known deficiencies. This report provides additional information to Council in response to the Finance Committee’s concerns. DISCUSSION The deficiencies of the City’s storm drainage system are well-documented, as a result of engineering studies, observations by maintenance staff, and resident complaints. The initial Storm Drain Master Plan was prepared in 1965. Although the highest priority projects recommended in the Master Plan were constructed in the late 1960’s and early 1970’s, many of the Plan’s recommendations were never implemented due to a lack of funding. One of the first tasks completed following the creation of the Storm Drainage Enterprise Fund was an updated master plan. The 1993 Master Plan was prepared based upon current drainage system performance standards and with the use of modern computer modeling tools. Although more refined due to the use of sophisticated modeling techniques, the findings of the 1993 Master Plan are generally consistent with the 1965 Master Plan. Many of the previously identified problem areas are designated for drainage improvements in the updated Master Plan. Furthermore, the deficiencies identified through theoretical analysis in the two Master Plans are consistent with the real-life observations of the City’s maintenance crews and service calls received from localresidents during storm events. The attached map shows the spatial distribution of drainage system service calls received by the Public Works Operations Division over the past five years (Attachment A). Although staff has discussed in its past presentations to Council that the Storm Drain Master Plan identifies the improvements needed to enable the City’s storm drain system to convey the runoff from a ten-year storm, it is important to note that there are drainage problems (and resident requests for service regarding poor drainage) far more often than once every ten years. Some of the storm drains back up several times every winter, resulting in flooded streets and gutters. There is a strong correlation between the areas with the highest concentration of service calls and the problem areas identified in the two Master Plans. The most severe deficiencies are addressed by staff’s proposed drainage system improvements. CMR:227:99 Page 2 of l0 During the February 1998 San Francisquito Creek flood event, there were also a large number of flooded basements in areas outside the creek’s floodplain. The inability of the storm drain system to convey the local runoff contributed to the flooding of these basements. The attached map shows the location of flooded basements outside the San Francisquito Creek floodplain during the February 1998 flood (Attachment B). Although the recommended drainage improvements would not have prevented all of these flooded basements, since the February 1998 storm was categorized as an 80-year storm and was far larger than the ten-year storm model used to develop the improvements, the flooding would certainly have been less severe and widespread. The discussion which follows summarizes the most critical storm drain system deficiencies, as identified in the two Master Plans and corroborated through service call records and records of flooded basements in February 1998, and staffs recommended improvements to address the deficiencies. The recommended improvements are sorted into related groups of projects, based upon a common geographic location or project type. Most of the projects fall into one of two major categories: 1) construction of replacement or parallel pipelines to increase the capacity of the storm drain network, or 2) pump station improvements (this category includes capacity upgrades to existing pump stations, construction of new pump stations, or connection of existing storm drains to pump stations to improve the storm drain system performance). The project summaries include the "Priority Group" of the improvements, as cited in the March 2, 1999 staff report to the Finance Committee (i.e. Priority Group 1 projects have "critical priority" and Priority Group 2 projects have "moderate priority"). If the proposed Storm Drain financing plan is backed by Council and approved by the ratepayers, the storm drain infrastructure improvements will be constructed in the order that they are listed in Attachment A of the March 2, 1999 report. A. PUMP STATION EVALUATION AND UPGRADES ($2.38 MILLION) PRIORITY GROUP 1 Current Condition The storm runoff from a large portion of Palo Alto cannot flow by gravity into the local creeks at numerous times during a normal rainfall year. Because of the relatively flat slopes and low elevation of the eastern part of the City, the storm drains serving this area are significantly lower than the creeks, particularly when the creeks are flowing full during a storm event. As a result, storm runoff from these storm drains must be pumped into a creek by way of a pump station. Pumps are also required at localized low spots such as roadway underpass structures. There are six primary City-owned storm water pump stations throughout Palo Alto (see Attachment C). These stations are critical components of the CMR:227:99 Page 3 of 10 City’s storm drain system: Failure of one of these stations would result in significant flooding over a widespread area., In 1995-96, staff implemented a capital improvement project to upgrade pumps, motors, and controls at the City’s storm water pump stations, recognizing that station capacity upgrades might be required in the future to accommodate increased flows if the storm drain system were improved to convey the runoff from a ten-year storm. An important component of the project was the upgrading of the stations’ monitoring and remote telemetry system. This system monitors the performance of each of the pump stations and transmits the information to a central computer located at the Utility Control Center. The system has provided a wealth of information regarding pump station performance, including pump run times, wet well water levels, and pump cycling patterns. Staff has been able to take advantage of this information to identify further modifications that should be made to the pump stations to improve their performance. Staff has also identified improvements at each of the stations that are needed to improve worker safety and station reliability and efficiency. Recommended Solution The recommended infrastructure improvements include both operational (capacity) and safety-related upgrades to the City’s storm water pump stations. B.NORTHEASTERN PALO ALTO ($19.87 MILLION) PRIORITY GROUPS 1 AND 2 Current Condition University Avenue, E1 Camino Real, Seale Avenue, and San Francisquito Creek in the northeastern portion of the City roughly bound some of the most severe and chronic ponding problems. This entire 1250-acre area drains through a single 96" outfall pipe into San Francisquito Creek downstream of Highway 101 (see Attachment D). There are longstanding chronic drainage problems throughout this area (many of the deficiencies were identified in the 1965 Storm Drain Master Plan). The drainage problems fall into two basic categories. In the upstream portions of the watershed, the storm drainpipes are undersized, as this system was designed in the 1930’s and 1940’s. During even moderate storms (2- to 5-year intensity storms), water ponds in the streets and floods intersections because the amount of runoff exceeds the capacity of the underground pipe network. The downstream portion of the drainage system was upgraded in the early 1970’s, when the 96" outfall pipeline was constructed. Over time the performance of this system has deteriorated due to excessive siltation in San Francisquito Creek. The siltation has reduced the capacity of the creek, resulting in higher water levels in the creek during storm events. The higher creek levels, in turn, prevent the storm drain system from draining freely, causing the pipes to back up and pond into the streets and gutters. Chronic street ponding occurs initially on the 500 block of Greer Road and then spreads to the Hamilton Avenue, Hilbar Lane, Rhodes Drive, Channing Avenue, Heather Lane, and Walter Hays Drive areas. These areas remain ponded until the water level in the creek drops enough to allow the 96" pipe to drain freely again. CMR:227:99 Page 4 of l0 Recommended Solution Many of the recommended infrastructure improvements address the drainage deficiencies in this watershed area. Installation of a pump station at the 96" outfall and construction of a new pump station and outfall into the Creek at Newell Road will alleviate the downstream area system backups. This work will have to be carefully coordinated with the Santa Clara Valley Water District as well as the cities of Menlo Park and East Palo Alto in order to avoid any negative flooding impacts on San Francisquito Creek. The Newell Road, Harker Avenue, Lincoln Avenue, Kellogg Avenue, Pitman Avenue, and "System BB and CC" replacement and parallel pipelines will all address upstream drainage system deficiencies. The highest priority pipeline projects will improve the system performance by diverting runoff from existing undersized storm drains. Th~se "diversion" pipelines will allow the existing pipelines to remain in service and will also provide improved local drainage on streets where they are constructed. At a later stage in the drainage infrastructure improvement program, remaining undersized pipelines will be replaced or a second parallel pipeline will be installed to augment their capacity. Projedt Name Priority Group Relocate & pump 96" outfall in SF Creek 1 Newell Road pipeline, outfall, and pump station 1 Harker Street pipeline 1 Lincoln Avenue pipeline 1 Professorville replacement/parallel pipelines 1 Kellogg Avenue pipeline 2 Pitman Avenue pipeline 2 Green Gables replacement pipelines 2 TOTAL Cost ($M) $3.71 $3.62 $2.41 $2.25 $1.78 $1.70 $3.71 $0.69 $19.87 C.MATADERO PUMP STATION WATERSHED ($8.87 MILLION) PRIORITY GROUPS 1 AND 2 Current Condition A large portion of southeastern Palo Alto drains to Matadero Creek by way of the Matadero Storm Water Pump Station. The watershed area is roughly bounded by Seale Avenue, Highway 101, Barron Creek, and Alma Street (see Attachment D). Most of this. 1200-acre area drains through a network of trunk pipelines to a pump station located adjacent to Matadero Creek, just upstream of West Bayshore Road. Much of the land in this area, particularly the eastern portion near Highway 101, is lower than the creek water level during storm events. Without the pump station, this land would be unable to drain until the creek recedes, several hours after the rainfall stops. Problems in this watershed include undersized pipes, the capacity of the pump station itself, and several areas that are not connected to the pump station. CMR:227:99 Page 5 of 10 Recommended Solution The recommended infrastructure improvements include Upgrades to the Matadero Pump Station, the addition of pipelines to connect the Clara Drive area to the pump station, and the construction of replacement or parallel pipelines for several of the trunk pipelines feeding the pump station. Clara Drive currently drains to Matadero Creek by gravity. Water ponds in the ’street during even moderate storm events, with the extent of the ponding increasing with the creek level. Connection to the pump station will allow Clara Drive to drain regardless of the creek level. The Master Plan analysis showed that several of the large trunk pipelines that drain to the Matadero Pump Station (including Loma Verde Avenue, the former Seale-Wooster Canal north of Colorado Avenue, and the former Sterling Canal east of Maddux Drive and Kenneth Drive) are undersized and need to be replaced with larger pipelines or supplemented with parallel pipelines. Project Name Matadero Pump Station upgrade Connect Clara Drive to pump station Loma Verde/Seale-Wooster/Sterling pipelines Priority Group Cost ($M) 1 $1.19 1 $0.55 2 $7.13 TOTAL $8.87 CHARLESTON TERRACE/GREENDELL/GREENHOUSE/SAN ANTONIO AVENUE AREA ($4.44 MILLION) PRIORITY GROUPS 1 AND 2 Current condition The Charleston Terrace, Greendell, Greenhouse, and a portion of Greenmeadow neighborhoods, and San Antonio Avenue between Charleston Road and Alma Street are served by a 36" storm drain that flows by gravity into Adobe Creek behind Bibbits Drive. This 280-acre watershed is roughly bounded by Adobe Creek, Nelson Drive, Ferne Avenue, Alma Street, San Antonio Avenue, and East Charleston Road (see Attachment D). Once the water level in Adobe Creek rises to a depth of approximately four feet, the 36" pipeline cannot drain by gravity. Subsequently, water begins ponding on Bibbits Drive and Gailen Avenue, and extends upstream in the drainage system. Several of the storm drains that feed into the 36" pipeline are also undersized and subject to backup. Recommended Solution The recommended infrastructure improvements include the construction of an 1,800-foot extension of the of 36" storm drain to connect it to the existing Adobe Creek Pump Station, a new diversion pipeline on Middlefield Road, and parallel pipelines for several storm drains that feed into the 36" pipeline. Connection of this watershed’s drainage system to the pump station will allow the streets to be drained regardless of the creek level. The Middlefield Road pipeline will divert runoff from the undersized San Antonio Avenue storm drain. New CM .R:227:99 Page 6 of 10 parallel pipelines along East Charleston Road and Montrose Avenue will supplement existing undersized storm drains. Project Name Priority Group Extend 36" outfall to Adobe Creek Pump Station 1 E. CharlestoniMontrose parallel pipelines 2 Middlefield Road diversion pipeline 2 TOTAL Cost ($M) $1.05 $2.75 $0.64 $4.44 E.ALMA STREET ($1.21 MILLION). PRIORITY GROUP 1 Current Condition There are several locations along southbound Alma Street where storm runoff drains onto Peninsula Corridor Joint Powers Board railroad property and is absorbed into the ground. When the ground becomes saturated, water begins to pond onto the roadway, creating hazardous driving conditions. There are few underground storm drains in these areas to collect the runoff and convey it to a creek. Recommended Solution The recommended infrastructure improvements include the construction of several new catch basins along the southbound side of Alma Street and installation of approximately 4,400 linear feet of new storm drain pipelines to properly drain the street. F.SOUTHGATE NEIGHBORHOOD ($1.78 MILLION) PRIORITY GROUP 2 Current Condition The Southgate neighborhood, bounded by Churchill Avenue, the Peninsula Corridor Joint Powers Board railroad property, Park Boulevard, and E1 Camino Real, drains to a single storm drain inlet at the comer of Mariposa and Sequoia Avenues (see Attachment D). There are no underground storm drain pipelines to serve the neighborhood, and there are many sections of uneven curb and gutter that pond water during rain events. Recommended Solution The recommended infrastructure improvements include the constmction of additional storm drain inlets, new pipelines, and curb and gutter repairs to eliminate street ponding in the Southgate neighborhood. This project will also accommodate runoff from the Palo Alto High School property. G. CHAUCER STREET ($0.18 MILLION) PRIORITY GROUP 2 Current Condition Storm runoff ponds at the intersection of University Avenue and Chaucer Street during heavy CMR:227:99 Page 7 of 10 storms. The runoff is conveyed to San Francisquito Creek via a 10" storm drain on Chaucer Street. The ponding occurs when the creek rises to a level high enough to prevent the storm drain from emptying freely. Recommended Solution The recommended infrastructure improvements include the replacement of the Chaucer Street storm drain with a 21" pipeline fitted with a flapgate. The larger pipe will provide increased underground storage for storm runoff while the creek is running high, and the flapgate will prevent the creek waters from flowing back up into the pipeline and into the street. These improvements will greatly reduce the occurrence ofponding at the University Avenue/Chaucer Street intersection. H. BAYLANDS/EMBARCADERO ROAD ($1.13 MILLION) PRIORITY GROUP 2 Current Condition Periodic street ponding occurs along Embarcadero Road east of Highway 101 due to undersized storm drain pipelines. These pipelines drain to the Airport Storm Water Pump Station. Ponding occurs because the existing pipes are not large enough to convey the peak storm runoff to the pump station. Recommended Solution The recommended infrastructure improvements include the replacement of 400 linear feet of 12" pipe with 18" pipe at the intersection of East Bayshore and Embarcadero Roads and the installation of 1,400 linear feet of new 24" pipe. These improvements will increase the capacity of the drainage system serving the Embarcadero/East Bayshore intersection and will provide a more direct route for storm runoff to the Airport Pump Station. Project Name Parallel pipelines Increase capacity at E. Bayshore/Embarcadero Road Priority Group Cost ($M) 2 $0.65 2 $0.48 TOTAL $1.13 I.EAST MEADOW CIRCLE ($0.60 MILLION) PRIORITY GROUP2 Current Condition Periodic street ponding occurs along East Meadow Circle during heavy storms. The runoff is conveyed to Barron Creek via an 18" storm drain, fitted with a flapgate. The ponding occurs when the creek rises to a level high enough to prevent the storm drain from emptying freely. Recommended Solution The recommended infrastructure improvements include the installation of pipelines to CMR:227:99 Page 8 of 10 connect the East Meadow Circle storm drains to the Adobe Storm Water Pump Station. Connection to the pump station will allow East Meadow Circle to drain regardless of the creek level. J.INSTALL PIPELINES TO ELIMINATE SIPHONS ($3.33 MILLION) PRIORITY GROUP 2 Current Condition The existing storm drainage system includes approximately 45 siphons located at various points throughout the City. A siphon consists of a pair of drain inlets connected by a short length of underground pipe designed to convey storm runoff across an intersection. Runoff flows into the upstream drain inlet, through the pipe beneath the roadway, and back out and up into the gutter at the downstream inlet structure. Leaves and debris chronically accumulate in the pipe, often leading to blockages.. Siphons also generate complaints related to odor problems, since the pipe remains filled with standing water after the storm ends until it evaporates. As a result, siphons must be cleaned more often than other components of the drainage system, and siphon blockages frequently cause intersection flooding. Siphons were constructed in the past as an inexpensive means to convey water from one side of a street to the other, but they should be eliminated as part of the upgrade of the City’s storm drain system. Recommended Solution The recommended infrastructure improvements include the installation of approximately 9000 linear feet of 12", 15" or 18" diameter pipes to connect the siphons to existing storm drains. Once the siphons have been connected to the storm drain system, storm runoff will flow into the drain inlets and be conveyed all the way to a local creek via the underground drainage network. K.CONDITION ASSESSMENT REPAIR PROJECTS ($4.16 MILLION) PRIORITY GROUP 1 Current Condition The City’s existing storm drain system has been constructed incrementally over the past 75 years. Portions of the system are at or near the end of their useful life. The 1993 Storm Drain Condition Assessment report contains a consultant’s assessment of the condition of the existing storm drain system and recommendations for repair or replacement of deteriorated storm drain pipelines, drain inlets, and manholes. A portion of the recommended work has already been completed, and Council gave its conceptual approval for the balance of the condition assessment repairs in 1994. Recommended Solution The recommended infrastructure improvements include the completion of the replacement and repair projects recommended in the 1993 Condition Assessment report. CMR:227:99 Page 9 of t0 In addition to the costs for the capital improvements listed above and the proposed improvements in operations and maintenance activities described in the March 3, 1999 report to the Finance Committee, Council should also be aware that the cost of the Storm Drainage Fund’s water quality protection programs will rise in the coming years as a result of several recent developments. The United States Environmental Protection Agency has announced its intention to list San Francisco Bay and San Francisquito Creek on its Clean Water Act Section 303(d) list of"impaired" water bodies for which action plans must be developed. This will result in the need to conduct a Total Maximum Daily Load (TMDL) study of the Creek and to develop a plan to reduce the pollutant loadings allocated to controllable sources. The Santa Clara Basin Watershed Management Initiative (a stakeholder planning group for the lower South Bay Watershed) has also just selected San Francisquito Creek as one of three creeks in the Santa Clara Basin on which to conduct a watershed assessment. The cost of these studies and related data collection and monitoring costs may be shared by the Santa Clara Valley Water District and other agencies participating in the recently created San Francisquito Creek Joint Powers Authority. It will be in the best interest of Palo Alto, however, to take an active role in these processes in order to have input towards their outcome, including possible new requirements placed upon the City to implement improved pollution control measures. Additional costs for water quality program enhancements can be accommodated in the proposed Storm Drainage Fund financing package presented to the Finance Committee, to the extent that significant new requirements are not imposed by regulators in the future. ATTACHMENTS Attachment A: Map Attachment B: Attachment C: Attachment D: of drainage system service calls received by the Public Works Operations Division over the past five years Map of flooded basements outside the San Francisquito Creek floodplain during the February 1998 flood Map of watersheds of storm water pump stations Map of watersheds with storm drain system deficiencies and staff’s recommended drainage improvements PREPARED BY: Joe Teresi, Senior Engineer DEPARTMENT HEAD: /~ /~. GLENN S. D! irector of] CITY MANAGER APPROVAL:/" JUNE City Manager orks cc: Utilities Advisory Commission CMR:227:99 Page 10 of 10 ©©