Attachment A
SANCITY OF ffr JOSE CAPITAL OF SILICON VALLEY
STORM SEWER SYSTEM ANNUAL REPORT FY 2015-2016
Installation of Large Trash Capture Device
October 2016 City of San Jose Storm Sewer System Annual Report FY 2015-2016 CONTENTS . 1 1 I. HISTORY AND BACKGROUND 3 II. PROGRAM FUNDING 5 A. Adopted FY 2015-2016 CIP Budget Revenue 5 B. Adopted FY 2015-2016 CIP Budget Expenditures 5 C. Adopted FY 2015-2016 Operations and Maintenance Budget Expenditures 5 III. PROGRAM ACTIVITY 6 A. Storm Sewer Improvement Projects 6 B. Rehabilitation Projects 8 C. Existing Storm Pump Stations 9 D. Non-Construction Activities 10 E. System Management and Planning 10 1. Master Planning 10 a. Alviso and North San Jose Master Plan 10 b. Modeling for Flooding Areas 12 c. DOT Portable Pumping Operation for 2015-16 El Nino Season 15 d. Flow Monitoring 15 e. Modeling Coordination with Water District and Alameda County 15 f. Citywide Storm Drain System Master Plan Initial Results 16 2. Support Economic Development 23 3. Coordination with Santa Clara Valley Water District (District) 23 4. Neighborhood/Special Corridors 24 5. Rehabilitation of Pump Stations 24 6. Improving Annexation Areas 24 7. San Jose-Santa Clara Regional Wastewater Facility . 25 E. Sustainability/Green Vision 25 VI. OPERATIONS AND MAINTENANCE 27 V. CONCLUSION 28
Storm Sewer System Annual Report - FY 2015-2016 2 I. HISTORY AND BACKGROUND
The City of San Jose drains to two main water shed/drainage basin areas, Coyote Creek and Guadalupe River. Within the tributary areas to these watersheds, the majority of the City's storm sewer collection system benefits from the generally uniform topography of the Santa Clara Valley, allowing the majority of the water to be conveyed to the waterways using gravity lines with minimal use of pump stations.
The City's storm sewer network is a storm water collection system that includes more than 1,100 miles of storm sewer pipelines, 32,200 storm drain inlets, 1,510 storm outfalls, and over 4,500 miles of curb and gutter. Various channels, culverts, ditches, detention and debris basins make up the remainder of the system. The storm sewer system is designed to convey storm water away from developed areas to local creeks and rivers, and ultimately, to San Francisco Bay. An estimated 67 percent of the City's storm drainage system was constructed between 1950 and 1990.
Levees separate North San Jose from Coyote Creek and the Guadalupe River. These levees enable water levels in both waterways to rise to elevations higher than adjacent lands in North San Jose. In those instances, pump stations are needed to discharge storm runoff into the waterways. In the absence of pump stations, internal flooding would likely occur in various portions of North San Jose. The City owns and operates 30 storm pump station with various capacities, including the Cahill Pump Station recently relinquished to the City and previously operated and maintained by Caltrans and the Berryessa Pump Station constructed for the Flea Market Development. The larger pump stations drain areas located north of Highway 101 into the Guadalupe River. The smaller pump stations typically drain street underpasses. The construction dates of the smaller pumps range from 1928 to 1975, the majority of which are over 40 years of age.
Since the mid 1980's, the City's design standard requires that storm sewer systems be designed to convey a 10-year storm event (a storm large enough to have a 10 percent chance of occurring in any year). The 10-year event is widely recognized as a reasonable, safe standard, and is employed by numerous jurisdictions nation-wide. Prior to 1990, approximately 67 percent of the storm drains were designed for a 3-year storm event standard. In many areas that have been annexed to the City, the capacity is even less than a 3-year event. While all new developments are required to design their on-site storm system to accommodate a 10-year event, they are not required to address deficiencies of the downstream storm sewer system to which the developer connects.
• The Department of Public Works designs and builds storm sewer infrastructure funded through the City's Capital Improvement Program. Public Works also reviews and inspects storm sewer improvements constructed by private developers and other public agencies. The Storm Section is part of the Transportation & Hydraulics Services Division in Public Works. The Storm Section is tasked with the design and construction of improvements that maximize the efficiency of the existing storm sewer system to meet current and future needs, the design and construction of improvements that rehabilitate older deteriorated storm sewers and storm pump stations to extend useful life, design and construction of green infrastructure and trash reduction methods for stormwater quality improvements as required by regulatory agencies, master-planning of the City's storm sewer system to meet the future demands for conveyance, identifying and prioritizing the City's storm sewer capital investments, rehabilitation program and corrective maintenance activities.
Storm Sewer System Annual Report - FY 2015-2016 3 • The Department of Transportation performs day-to-day operations and maintenance of the collection system. • The Environmental Services Department is responsible for protecting the health of the South Bay watershed through regulatory programs that prevent pollution from entering the storm sewer system and waterways.
Citywide Watershed Map
Storm Sewer System Annual Report - FY 2015-2016 4 II. PROGRAM FUNDING
A. Adopted FY 2015-2016 CIP Budget Revenue
Primary sources of funding include transfers from the Storm Sewer Operating Fund, the Storm Drainage Fee, interest earnings, and joint participation revenues. The Storm Sewer Operating Fund provides funding for capital improvement projects and the federally mandated National Pollutant Discharge Elimination System requirements through Storm Sewer Service Charge fees.
Storm Drainage Fee (Fund 413 - $446,175) - Storm Drainage Fees are charged to developers for the privilege and benefit of land directly or indirectly discharging into the storm drainage system, and also for the benefits accruing to said land because of the existence of a city storm drainage system which collects and disposes of waters from other lands in the city. The fees collected may only be used for the construction, reconstruction and maintenance of the storm drainage system for the City of San Jose, and for acquisition of land for such system. The fee is based on land use and acreage.
Storm Sewer Capital Fund (Fund 469 - $30,582,491) - Funds for capital improvement projects are transferred from the Storm Sewer Operating Fund (Fund 446) and from the California Proposition 84 Storm Water Grant Program (SWGP) and Integrated Regional Water Management (IRWM) Implementation Grant Program. These funds are used for new or rehabilitated pump stations, new or replacement laterals, pipe, storm drain inlets, outfall rehabilitation, and projects that address water quality issues.
Joint Participation Revenues ($4,000) - This revenue comes from the City of Cupertino, when, in the late 1970s, City boundaries were redrawn and a portion of Cupertino's storm sewers system connects into San Jose's system before being conveyed downstream. This revenue covers maintenance and operations expenses for Cupertino's share of the system.
B. Adopted FY 2015-2016 CIP Budget Expenditures
The Storm CIP Program has a $52.3 million, 5-year budget. This level of funding allows three to four medium neighborhood improvement projects to be completed each year. It is important to note that the current level of funding in the Storm CIP program only addresses immediate needs for dealing with minor neighborhood drainage issues. It does not address long-term, system-wide needs stemming from significant development activities that have occurred over the past few decades and those planned for future years. The on-going Master Planning effort will provide a working document that establishes city-wide long-term solutions for any deficiencies or lack of efficiency within the storm sewer system.
C. Adopted FY 2015-2016 Operations and Maintenance Budget Expenditures
(Fund 446) - The annual ongoing operating and maintenance budget is approximately $8.2 million which provides funding for administration, engineering and maintenance.
Storm Sewer System Annual Report - FY 2015-2016 5 III. PROGRAM ACTIVITY
A. Storm Sewer Improvement Projects
A portion of the Storm Section's resources are allocated to the Storm Capital Improvement Project (CIP) Program for resolution of localized drainage problems, primarily in residential neighborhoods, neighborhood business districts and school zones. These projects typically address localized ponding and neighborhood drainage issues that can be corrected by extending or enhancing the existing storm sewer system. Improvement projects for fiscal year 2015-2016 include the following:
Wilson Avenue and The Alameda - Public Works General Engineering Contract for Underground Pipe Facilities 2014-2016 - (CPMS ID 7660) During the potential threats of El Nino, this project was identified by local residents who were experiencing significant localized flooding issues and notified the City to address improvements to the existing drainage system in this area. This project and Stockton Avenue and Lenzen Avenue project (later discussed in this report) are within existing storm drainage systems that are under significant capacity. As a result, the storm master plan team evaluated and determined major deficiencies in the Q2,08ja-i.gaBg storm sewer system that should be implemented to help minimize and/or eliminate flooding in this area.
Two large hooded inlets and two flat grate inlets with laterals were installed. The total construction cost of the project was $56,727 and the contractor under this General Engineering Contract was JMB Construction and was completed on February 9, 2016.
Warner Drive - Public Works General Engineering Contract for Underground Pipe Facilities 2014-2016 - (CPMS ID 7660)
A resident notified the City that during previous wet season a significant amount of stormwater from Warner Drive enters onto the resident's property that is located along the easterly downslope side where the roadway curves. The resident was very concerned about the potential threats of El Nino and was seeking the City's assistance.
City evaluated the existing drainage area and determined that this resident's house was at the low point along the vertical profile of Warner Drive and resolved the issue by extending a portion of the storm sewer main to install new inlets and laterals to minimize the amount of storm water runoff onto this resident's property.
Storm Sewer System Annual Report - FY 2015-2016 6 Approximately 140 linear feet of 15 inch RCP storm sewer pipe, one manhole and two regular hooded inlets with laterals were installed. The total construction cost of the project was $115,666 and the contractor under this General Engineering Contract was JMB Construction and was completed on April 15, 2016.
Joseph Avenue and Curtner Avenue - Public Works General Engineering Contract for Underground Pipe Facilities 2014-2016 - (CPMS ID 7660)
Last winter, due to the potential threats of El Nino, this project was identified by residents in the surrounding area that indicated localized flooding. Based upon upon the storm sewer modeling of existing conditions, the storm sewer system in this area experiences localized flooding when the outfall is submerged in the due to the rising water levels in Coyote Creek. This project installed 90 linear feet of 15 inch RCP pipe, manhole and two regular hooded inlets with laterals were installed to help reduce the localized flooding.
The total construction cost of the project was $111,873 and the contractor under this General Engineering Contract was JMB Construction and was completed on March 11, 2016.
Stockton Avenue and Lenzen Avenue- Public Works General Engineering Contract for Underground Pipe Facilities 2014-2016 - (CPMS ID 7660)
This project was identified by local residents who were experiencing significant localized flooding issues and notified the City to address improvements to the existing drainage system in this area. As a result, the storm master plan team evaluated and determined major deficiencies in the existing storm sewer system that should be implemented to help minimize and/or eliminate flooding in this area.
Due to a lack of storm sewer pipe system, many of the properties installed curb side pipes to drain towards the street curb and gutter. There were minimal amount of existing inlets installed along Lenzen Avenue and Stockton Avenue. As a result, the low point on the street was located near Pershing Avenue and Stockton Avenue. Based upon visual inspection and storm master plan model results, it was evident that this area experience significant amount of localized flooding that exceeded past the sidewalk onto the private property.
This project installed three large hooded inlets with laterals and two manholes along Lenzen Avenue and Stockton Avenue to the stormwater to enter into the storm sewer system as quickly as possible.
Storm Sewer System Annual Report - FY 2015-2016 7 The total construction cost of the project was $80,880 and the contractor under this General Engineering Contract was JMB Construction and was completed on March 25, 2016.
Piedmont Hills High School - Public Works General Engineering Contract For Underground Pipe Facilities 2014-2016 - (CPMS ID 7660)
This project was identified by Santa Clara Valley Water District (SCVWD) when a sinkhole was discovered within SCVWD property that is adjacent to stand seats near a football field on Piedmont Hills High School campus in east San Jose area. The sinkhole was in vicinity of a 48-inch City owned corrugated HDPE pipe. The Department of Transportation excavated a portion of the area to determine that the 48-inch corrugated HDPE storm sewer main was disconnected to the Santa Clara Valley Water District 54 inch flood control storm pipe. This was an urgent repair that needed to be accomplished prior to graduation on Piedmont Hills High School campus.
The total construction cost of the project was $44,686 and the contractor under this General Engineering Contract was JMB Construction and was completed on May 25, 2016.
B. Rehabilitation Projects
Alviso Storm Network Infiltration Control - 6753
This project was one of the first storm sewer condition assessment projects that Public Works managed and modeled this project similar to the sewer program. The Alviso area was chosen since it was prone to flooding and City has established annual funding for condition assessment appropriation has been established to regularly clean large diameter pipes in areas that are prone to flooding.
This project required CCTV inspection and cleaning of approximately 11,000 feet of storm sewer mains from 24-inches up to 48-inches in diameter in the Alviso area. The results will be used to establish a database for prioritization and development of future storm sewer repairs and rehabilitation projects and any structural defects will be corrected immediately.
Storm Sewer System Annual Report - FY 2015-2016 8 C. Existing Storm Pump Stations
The average age of the City's 30 storm sewer pump stations is approximately over 40 years. These facilities are listed in Table 1 shown below. The existing pump stations at Oakmead, River Oaks, Rincon I, Rincon II and Gateway were evaluated for adequate capacity using the 10-year storm event. Pump stations are generally considered adequate if there is sufficient pump capacity to discharge design runoff into the receiving waters or if excess flows can be stored without causing property damage.
The master plan recommended existing pump station improvements to increase reliability and redundancy, and to comply with FEMA flood hazard mapping requirements. These projects include installation of on-site backup power at the Rincon I, Rincon II, and Gateway Pump stations, and the replacement of pumps at the Oakmead Pump Station.
Table 1: Storm Sewer Pump Stations (Alphabetical Order)
Name Year Built Year Updated/Status Pump Stations 1. 87/Taylor 2005 N/A 2. Airport 1990 N/A 3. Alma 1955 2007 4. Almaden 1935 2000 5. Bascom 1958 N/A 6. Bird 1969 2007 7. Capitol 1990 N/A 8. Communication Hill 2009 N/A 9. Chynoweth 1988 N/A 10. Delmas 1934 2004 11. Forest 1961 1995 12. Gateway 1960 2014 13. Gold 1979 2003 14. Golden Wheel 2001 N/A 15. Hedding 1960 N/A 16. Hester 1928 N/A 17. Hope Street 1 1992 N/A 18. Hope Street 2 2008 N/A 19. Julian 1975 N/A 20. Liberty 1973 2007 21. Oakmead 1982 2013 22. Park 1966 2005 23. Rincon 1 1998 N/A 24. Rincon 2 2004 N/A 25. River Oaks 1979 2012 26. Skyport 2005 N/A
Storm Sewer System Annual Report - FY 2015-2016 9 27. Taylor 1939 N/A 28. Willow 1934 2005 29. Berryessa (Flea Market) 2016 N/A 30. Cahill 1939 2016 (in progress)
D. Non-Construction Activities
Non-construction activities for the Storm Sewer Section include oversight of storm sewer program management, Preliminary and Final Engineering design, construction management, updating GIS information, Storm Sewer Master Planning, Storm Sewer Permit Review and Inspection for Development and Outside Agencies, Public Art, Fee Administration, plan review for other sections and Divisions of Public Works, representing approximately $3,072,000.
E. System Management and Planning
1. Master Planning
a. Alviso and North San Jose Master Plan
The North San Jose Storm Drain Master Plan for North San Jose Development Policy and Alviso areas was completed and a final report was prepared by Schaff and Wheeler in June 2014. The Master Plan evaluated the storm drain system capacity under existing and 2040 General Plan land use conditions. A computer model using MIKE-URBAN software was developed to simulate the hydrology and hydraulics of the drainage system and to identify capacity deficiencies at a 10-year 24-hour design storm event.
The master plan identified minor, moderate and severe pipe deficiencies with reference to the predicted depths of street flooding caused by the deficient pipes. For minor deficiency, flooding depth would be less than 6 inches; for moderate deficiency, between 6 and 12 inches; and for severe deficiency, deeper than 12 inches. Drainage system deficiencies for both existing and 2040 General Plan land use conditions were identified.
The Master Plan recommended 55 improvement projects totaling approximately $131 million for flood protection. Among these projects, twelve (12) projects totaling close to $57 million are high priority projects.
This study and the proposed CIP is a starting point. PW will perform a more detailed master plan study to confirm the project limit and sizing, and conduct alternative analysis to find more affordable or effective improvements with information gathered as part of the design process.
As part of the citywide storm drain master plan study, North San Jose and Alviso systems will be included in the InfoWorks ICM model. Future capacity analysis of the storm drain system will be performed using this modeling tool.
Storm Sewer System Annual Report - FY 2015-2016 10 Alviso Area
The Alviso area model network included storm drain pipes of 12 inches in diameter or larger, with 294 manholes and 28,600 feet (5.4 miles) in length. The hydraulic model predicted flooding at over 180 manholes, of which about 100 manholes was predicted with more than 6 inches of flooding depth at a 10-year storm event.
The computer model confirmed known flooding locations, such as the most commonly flooded area at the intersection of Hope and Catherine Streets, and at the low-lying areas around Gold Street and Taylor Street.
In addition to identifying storm drain capacity improvements for the 10-year storm event, the master plan recommended improvements to alleviate the flooding impact due to interior system deficiencies at the 100-year event for 2040 General Plan land use scenario. The urgent need for the Gold Street Pump Station to be upgraded to 110 cubic feet per second (cfs) from the existing 30 cfs pumping capacity was confirmed. The study also recommended approximately 3,700 feet storm drain pipeline to be upsized or constructed new in order to minimize 100-year street flooding.
North San Jose Development Policy Area
Drainage pipes 15-inch in diameter and larger which accounts for more than 35 percent of approximately 49 miles of pipes in the study area were included in the hydraulic model. The North San Jose Policy Area is mostly occupied by pre-existing developments, with over 65 percent industrial land uses, but less than 10 percent open space/vacant land. The average percentage of impervious surface of existing developments is high and estimated at 80 to 90 percent. And the 2040 General Plan land use in North San Jose will likely maintain high percentage of impervious surface.
Stormwater runoff from the North San Jose is conveyed through storm drain networks and discharged to two channels, Coyote Creek and Guadalupe River. North San Jose's storm drain system is broken into five general drainage areas: Oakmead, River Oaks, Rincon/Charcot, East Coyote, and Brokaw.
The master plan study confirmed known flooding areas such as Charcot Avenue, Zanker Road, and Brokaw Road areas. The master plan also confirmed the need for a 300 cfs Charcot Pump Station previously identified in the 1999 North San Jose Storm Drain Master Plan Report. Most of the severe flooding would occur in Rincon/Chacot area and the area east of Coyote Creek.
The master plan recommended 47 CIP projects to provide flood protection for areas with storm drain capacity deficiencies. The projects were prioritized based on the severity of deficiencies. These projects include new or upsized pipelines, outfalls, new pump stations in Alviso and Charcot areas, and upgrade of existing pump stations for reliability and compliance with FEMA flood hazard mapping requirements.
Storm Sewer System Annual Report-FY 2015-2016 11 Out of the 47 storm drain system improvement projects, 42 are needed to address street flooding under existing land use conditions. Some of these 42 projects are sized to address increased flooding due to future land use growth. Approximately 113,000 feet of pipeline construction have been recommended for long-term 2040 General Plan land use condition, with 102,000 feet needed to minimize street flooding for existing conditions. Total capital improvement program for the North San Jose Policy Area will cost approximately $113 million, with roughly 40 percent or $45 million needed for high priority capital improvements.
b. Modeling for Flooding Areas
PW Master Planning Staff performed modeling analysis as requested by DOT for the historical known flooding areas. The preliminary model was used at the time of the analysis and the results are presented below for the Charcot/Zanker, Alviso, and Stockton/Taylor areas.
Charcot/Zanker Area
The storm drain system in the Charcot area collects serves approximately 500 acres that drains through the intersection of Charcot Road and Zanker Road and outfalls to Coyote Creek. This is opposite of ground slope with the highest at point Coyote Creek. In a large storm event, water cannot drain by gravity from the Charcot area into the creek because the creek's water level is higher than the level of the adjacent land. This causes the outfall structure's flap gate to close, forcing water to back out of drainage system in the lower portions of the Charcot area, resulting in street flooding. Recently, the December 11,2014 storm backed up the existing storm sewer system and flooded intersections, parking lots and a nearby business.
Staff performed hydraulic modeling for this area using the latest InfoWorks model to identify temporary and long-term solutions to minimize flooding. The model indicates that the 42- and 48- inch system between Junction Avenue and Zanker Road has a limited capacity of 8 to 16 cfs, although the downstream pipes can convey up to 84 cfs. With the results from the hydraulic model and field experience, PW worked with DOT and Santa Clara Valley Water District to set up a total of three 12-inch portable pumps (one 12-inch pump was used for redundancy) to handle approximately 22 cfs for this area that will help shorten the flooding time and reduce the flooding depth, even though it would not provide total relief to the area for the 10-year event.
For this reason, constructing a new 300 cfs Charcot Pump Station has become a high priority improvement that will pump stormwater from the Charcot area to the Coyote Creek. The master plan study indicated that all high priority projects are needed to solve existing capacity deficiencies, and over 80 percent, or 8,600 out of 10,400 feet of high priority pipeline improvements are located in this area. Approximately $37 million is needed for the high priority improvements for the Charcot area, including the construction of a new 300 cfs pump station.
Alviso Area
The storm drain system in Alviso has a primary pump station at Gold Street with a pump capacity of 30 cfs. The station can keep up with a small storms similar to a 2-year event. Under a larger storm, the pump station would be overwhelmed and stormwater would be back up and begin to
Storm Sewer System Annual Report - FY 2015-2016 12 pond and flood at low-lying areas. DOT is deploying portable pumps at Archer Street/State Street, Liberty Street/State Street, and Hope Street/Catherine Street when rainfall intensity is predicted to be greater than a 2-year event.
To prepare for the El Nino season in the winter of 2015/2016, staff evaluated the Alviso storm drain system using the Info Works model to identify an effective temporary pumping plan for up to a 10-year storm event and a backup pump deployment plan when rainfall intensity increases.
After considering the result from the modeling analysis and the field experience from storm drain maintenance crew, DOT concluded that the existing standard portable deployment plan will be suitable for a small flooding causing storm event, and that a backup plan would include additional pumps at Gold Street/Catherine Street and immediate upstream of Gold Street Pump Station. The number of portable pumps at these locations may increase to keep up with greater rainfall intensity.
The long-term solution to alleviate the street flooding in Alviso area is to construct the 110 cfs pump station near Gold Street and Catherine Street. Upsizing the existing Gold Street Pump Station was not feasible for two reasons (1) lack of area on the existing pump station property to build a new 110 cfs storm sewer pump station and (2) the duration to construct a new 110 cfs storm pump station would require the decommission of the existing storm sewer pump station. The new storm pump station will have the pumping capacity to handle the 100-year event. The City is in the final design and permit phase for a new 110 cfs Alviso Storm Sewer Pump Station and force main project. The City intends to keep the existing Gold Street Pump Station operating during the construction of the new pump station. The old Gold Street Pump Station will be used as a backup pump station after the new pump station is built. The design started in April 2014 and it is anticipated to award in April 2017, pending environmental permitting approval from regulatory agencies. The project construction is anticipated to complete in 2018.
Stockton/Taylor/Cinnabar Area
Also during the December 11, 2014 storm, DOT experienced several flooding issues near Cahill pump station and Taylor Street underpass. Staff began to further evaluate the existing system to understand the capacity constraints.
There are 18-inch and 30-inch storm mains on Taylor Street and Stockton Avenue that serve approximately 270 acres and eventually discharges through an existing 8 ft. by 3 ft. outfall culvert to the Guadalupe River. A pump station with 4.4 cfs capacity was installed to provide drainage for the Taylor underpass. In the 1970s, a 30-inch pipe was constructed at Schiele Avenue to supplement a parallel existing 16-inch storm drain, and a 30-inch stubout was built at Stockton Avenue, possibly for future improvements further downstream. However, the extension was never been constructed along Stockton Avenue.
Public Works conducted a preliminary computer hydrologic and hydraulic modeling analysis of the system using the May 14, 2015 storm. The model showed that the system could convey a 2-
Storm Sewer System Annual Report-FY 2015-2016 13 year event with a capacity of approximately 35 cfs. But the May 14, 2015 storm event would generate more than 77 cfs of stormwater runoff from the Stockton-Taylor drainage area. The model confirmed the flooding at Pershing Avenue and Taylor underpass that was observed by DOT and residents.
Also, Public Works installed three flow meters in these systems during the 2015-2016 El Nino season: GUA34 at Stockton/Villa Avenues, just upstream of the Stockton/Taylor intersection, GUA 31 at West Taylor and Irene Streets, approximately 1,000 feet upstream of outfall, GUA_32 at Cinnabar and Montgomery Streets. The flow monitoring data confirmed the model results and field observations.
South of the Stockton-Taylor system is the Cinnabar-Stockton-West Santa Clara-Cahill Pump systems. The Cahill Pump Station was constructed by the State in 1939 with 4.4 cfs capacity for the underpass drainage and has sufficient capacity to address a 10-year rainfall event. The station was last rehabilitated in 1975 and the current pumping system is in need of replacement. The Cahill PS rehabilitation project will began in summer 2016 with anticipated completion in February 2017 to replace the two existing pumps and install a diesel powered emergency pump. Both the Cinnabar-Stockton system and West Santa Clara system are at a 2- to 3-year design.
During the May 14, 2015 storm, this system was greatly surcharged and flow was backed up to the intersection of the Alameda and Stockton and caused flooding. The flooding at the Cinnabar/Stockon area would further compromise the Stockton-Taylor system as shown in the hydraulic model, due to the topography on Stockton Avenue generally sloping down north westerly.
The capacity improvement alternatives for this area were evaluated. The most cost-effective solution would be to construct a 54-inch storm drain on West Julian Street from Stockton Avenue and connect to the existing 54-inch Julian pipeline and the outfall system, and to construct a 30- to 54-inch pipe on Stockton between Schiele and the Alameda to convey stormwater to Julian. The project would involve approximately 4,500 feet of new pipe. Some remaining flooding at Taylor/Stockton intersection can be alleviated through a 2,300 foot, 30-inch diversion pipe from this intersection to the Hedding Street system at Elm Street. Potential utility conflicts or constructability issues under UPRR/Caltrain crossing will need to be further evaluated.
The model showed that the drainage capacity is not only limited the pipeline system, but also further reduced when the river flow level rises above the outfall. According to the Santa Clara Valley Water District's HEC-RAS model, the river elevation at the Taylor outfall would be at 58 feet at a 2-year event and would reach 61 feet at a 10-year event. Currently, the top of the outfall opening is at 53 feet, thus the outfall would be submerged during a small storm event. A pump station may be required as part of the capacity improvement for this system, and will be evaluated with the master plan study.
Storm Sewer System Annual Report - FY 2015-2016 14 Funding to design and construct the improvement is not available in the current 5-year CIP. DOT and PW staff are re-evaluating the existing maintenance and operation practice to identify options to provide temporary relief.
c. DOT Portable Pumping Operation for 2015-16 EI Nino Season
Although the total rainfall was greater than that of an average year, there were no large storm events during the 2015-16 El Nino season. The biggest storm events occurred on January 6, 2016 and March 3, 2016. Both storms had less than 1.3 inches of rain in a 24-hour period and could be categorized as less than a 1-year event. During this El Nino season, in addition to the temporary pumps that were installed at Cahill Storm Pump Station, PW installed a total of three 12-inch temporary pumps at the Charcot/Coyote Creek location. DOT deployed the pumping plan in Alviso, however none of the three locations experienced significant flooding.
d. Flow Monitoring
Flow monitoring is an essential component of hydraulic modeling from which flow and rainfall data are collected for the calibration and verification of the H&H model.
The storm events of 11/19/13, 2/6/14 and 2/26/14 were the largest storm events during the 2013 2014 wet season and were used for model calibration. However, these events were small and were less than 2-year return frequency, and little or no pervious area runoff would be resulted from these storms. Therefore, a second season flow monitoring was needed at most of the original 2013-2014 sites and a few alternate locations to the unsuitable first season sites. Total of 75 flow meters measuring depth and velocity were installed by mid-October 2014 and additional 10 flow meters were installed in January 2015. The rainfall measurement system also included 25 rain gauge sites for the wet weather season between October 2013 and April 2014. During this period, the meters collected flow data for a very large storm on December 11, 2014. This storm was measured as a 10- to 50-year event for the 24-hour duration at various locations in the City. This storm was used to calibrate the pervious area runoff generating parameters.
During the 2015-2016 El Nino season, staff deployed 80 flow meters and 16 rain gauges throughout the storm drain system for from October 2015 to April 2016 to capture flow data in the storm drain system. The biggest storm events occurred on January 6, 2016 and March 3, 2016 with less than 1.3 inches of rain in a 24-hour period. These less than 1-year return frequency events were not used for model calibration.
e. Modeling Coordination with Water District and Alameda County
The City has been coordinating and collaboratively working with the Santa Clara Valley Water District (District) on the modeling effort and data needs. The Water District is responsible for the modeling of the county's river/creek system, and the City is responsible for the modeling of the City's urban drainage pipeline and pumping systems. The two agencies and the neighboring Alameda County Flood Control District worked together to share the knowledge and experience in stormwater runoff volume and routing
Storm Sewer System Annual Report - FY 2015-2016 15 methodologies, loss method, land use percent impervious, and other parameters for hydrologic and hydraulic (H&H) modeling.
The City integrated District's riverine system model City's Infoworks ICM storm system model and used the District's stream gauge and high water mark data to verify the integrated H&H model. The City has also applied the District's recently modified design rainfall depth equations for the design storms for the master plan study. Collaboratively, the City provided the calibrated urban drainage model and other related data to the District for their recent Lower Silver Creek and Berryessa/Penitencia Creeks floodplain studies. The collaboration between the City and the District has the cost-saving benefit to both agencies, and allows each agency to focus on their respective studies.
f. Citywide Storm Drain System Master Plan Initial Results
Hydrologic and Hydraulic (H&H) Model of Storm Drain System
The citywide storm drain system's dynamic H&H model was developed using the InfoWorks ICM (integrated catchment model) software. The model included pipes 24 inch and larger using City's GIS datasets, as-builts and survey data, and incorporated the Water District's HEC model files into the H&H model. The model included over 40 percent of the storm drains or over 540 miles of pipeline system, 634 outfalls, 29 pump stations, and over 180 miles of river/creek system. All LID (Low Impact Development) and HM (hydro-modification) projects currently installed and documented were included in the H&H model - 257 LID features and 7 HM facilities total. Figure 1 shows the pipe, pump station and outfall network included in the model.
Storm Sewer System Annual Report - FY 2015-2016 16 Model Pipes GIS Pipes Model Outfalls GIS Outfalls Model Pump Stations GIS Pump Stations Guadalupe Watershed City Service Area Coyote Watershed Creeks San Thomas Aquino Watershed
Figure 1: Urban Drainage System Included in the H&H Model
Storm Sewer System Annual Report - FY 2015-2016 17 Three major watersheds, Guadalupe River, Coyote Creek, and San Tomas Aquino/Calabazas Creeks, over 580 square miles of drainage area was included in the H&H model, with approximately 20 percent of it inside City's Urban Growth Boundary (UGB). The drainage area was delineated into 7,000 sub-catchments, with sizes ranging from less than one acre to over 1,000 acres. Inside UGB, average sub-catchment size is around 14 acres; and outside UGB, average is over 500 acres. The drainage size, land use type and associated percent of impervious, soil type, initial loss, and other hydrologic and hydraulic factors were included in each sub-catchment for computation of runoff flow responding to rainfall.
Through collaborative effort, City staff and the Water District worked out the methodologies for runoff calculations and percent of impervious area values for various land use types. Both agencies will use the same methodologies in future modeling studies of urban system.
Calibration and verification were performed to validate and verify the model's accuracy. Calibration methodology included applying actual rainfall events to the model and adjusting the model parameters so that the resulting flows match the measured flows. Rain and flow data for two wet seasons (2013-2014 and 2014-2015) were used for the calibration. In addition, the calibrated model was validated using observed creek levels, and flooding data and complaints for recent storm events.
Existing System Performance at Existing Flow Conditions
The calibrated model was run for 3- and 10-year 24-hour design storm events to review existing system deficiencies. The 15-minute interval design storms based on the Water District's design storm depths were selected for the master plan study.
Preliminary Model Results for the 3-year Design Event The model of the 3-year design event predicted flooding at 550 manholes (out of 13,700 manholes modeled) or about 3.7 percent of the modeled system - 360 located in Guadalupe, 115 in Coyote, and 75 in San Tomas Aquino and Calabazas watersheds. Maximum flood depth of 6 inches or deeper were predicted at 170 manholes, or roughly 1 percent of the modeled system. Figure 2 presents the model results of the 3-year design storm event.
The H&H model also showed storm drain deficiencies (at full-pipe capacity) for existing system flow at 13 percent of the pipes. But if all bottlenecks were improved to provide free flow conditions, roughly 22 percent of the existing storm drain would become deficient at the resulted unrestricted flow.
Preliminary Model Results for the 10-year Design Event For the 10-year 24-hour design storm event, the H&H model predicted flooding at 1,770 manholes or about 12.6 percent of the modeled system - 1170 in Guadalupe River, 440 in Coyote Creek, and 160 in San Tomas Aquino and Calabazas Creeks watersheds. Over 602 of these manholes, or roughly 4 percent of the modeled system would have more than 12 inch of maximum flood depth. The preliminary model results of the existing system at the 10-year design storm event are shown in Figure 3.
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Y?%x vvii'i- \ \ '--.VVv C z-v/ v,?v\V.VvV V\} £ A50'Jf < h.-> \v\ * \ \ >•» * \V , /{, M ? r.^^x yyyt. v YffT' Z XV; J ;-"-^^g'V\X ^ \ "•***!%. v •3 y k W- % )\X/^d T-r—r *• vt , v " OCa n 4- V t, ,„*«;£&£V> ' Tfm jb®,3Ji \ J J Ji$y y\YSt\v^S <\ iVtBSBEE" CPEi^ -/>'!•J ) ,«r; ffhk iV * V" i ». i tj£ ' 5" w [ r' r ,11 "*,•.' ^ '• w if L-t .l t*»v, 4 X' J :"• i L.i^7 % - ^jrX ~'iJ-- • • r \% I-1 5 ffl I \-^L ''Vnx - , - '-V •rV^V-V~1 ^--JXiXK x. / Yx ,1 ._ , ( \___J»1 J >--"—x ' s * ' \ "* Ct* a |. ''-t l'"-I -s X "V Figure 3: Preliminary Model Results of Existing System at the 10-year Design Storm Event Storm Sewer System Annual Report - FY 2015-2016 20 The results indicated that about 31 percent of modeled pipes would be deficient at existing system flow. Roughly 41 percent would become deficient if the system could be without bottlenecks. In other word, about 60 percent of the system has the full-pipe capacity for the 10-year design storm event. Compared to the merely 33 percent of the pipes constructed at the 10-year standard, the existing system has performed far better than expected. This may be attributed to the general use of Rational Method and conservative values of percent of impervious area. The proper use of Rational Method should be to predict design peak flow rates from small urban watershed up to 50 acres. The Rational Method is a rather conservative method when compared with the unit hydrograph methods which are used in computer models. Preliminary High Priority Capacity Improvement Locations For the master plan study, the performance criteria is set to maintain the hydraulic grade line (HGL) in the system below the ground surface for the 10-year 24-hour design storm event. A total of 56 areas were identified city wide where the HGL was above the ground surface causing flooding. For this reporting period, staff focused on the areas with flooding on surface exceeding 6 inches during a 3-year storm event. New upgraded pipe sizes for the deficient system were identified to the predicted improve the flooding condition. This was the first step of looking into potential solutions to providing flood protection in high level flooding areas. The preliminary high priority CIP projects were size to maintain the HGL at pipe crown if feasible for the 10-year 24-hour design event, and up to creek levels if the creek level was affecting the upstream HGL. Figure 4 illustrates the locations of the preliminary high priority projects, which upsizing existing storm drains and outfalls, and pump station improvements. Five locations were identified with improved or new pump stations, including Alviso, Charcot, Snell, Santa Teresa and Bluefield pump stations. Table A presents the preliminary planning-level cost estimates for these high priority projects. TABLE A: PRELIMINARY HIGH PRIORITY CIP TO ADDRESS MAJOR CITYWIDE FLOODING LENGTH COUNT OF COUNT OF COUNT TOTAL PROJECT COST OF PIPES MANHOLES OUTFALLS OF PUMP (2016 Million$) UPSIZED REPLACED STATIONS (MILES) GUADALUPE 21.6 414 14 4 $98.0 COYOTE 5.9 139 3 1 $30.0 OTHER 4.0 88 5 0 $8.0 TOTAL 31.5 641 22 5 $136.0 During the next reporting period, staff will refine projects to address the remaining high level flooding areas, as well as refine projects to alleviate areas with flooding of less than 6 inches. The preliminary cost of an overall capacity improvement program to remove citywide flooding could be over $500 million. Storm Sewer System Annual Report - FY 2015-2016 21 TTwJ S-'~\ A\d>" y* /> Y/J$r \ \ .«; / ' 1 I.j M AfSJSkiv|N\f y In ^-fn "'( -4i j 1H< Tzar a v.v'W • #. ; __ N v r ;0 r1 > rJj ..i-U-.J \yl__ " y P-- X>/ w. ' / , ! I.J3 i i S sW rS r ^•J . , '#.- y )"^T / • it\V& km LA X V/VN -1 - rVi-fW^ViL * -'4Qy \\ s"~^ ^J£' ''dJV 'X, H T^N. y A -j.4 l_! '--^-i—, '1 ^\ £& ~xf+—'•:-•.'~' -'-v i / *>J] 11V \jl Nf> / '•>'. '•1 '• FX , f>X Y' -••• .^I r fvo ,, •< > s High Priority CIP Pump Stations < p. - •' W'vr^o ! * -V? Y#^ . : *f\ / \ \ High Priority CIP Pipes Hr •* i\ • *v% / ••«•. \ It/xS > X .c-\ i I- Existing Pipes "J" * 1i IS-.* Vv.^ * 4>A, v V V V Creeks Sounds: Esri. HERE, DeLome^rrtifmap. increment RCffp,, GEBCO. U3GS,A FAO, NPS, NRCAN, GsoBase. IGN, Kaclpster NL, Onjnance Survey Esri Japan, M.E.TI, City Service Area Esr; China [Hcng Kcng), sw?sstapo>Mapmylndia, © OpenStreetMap contributor^* ^ and tine GIS User Community Figure 4: Preliminary High Priority Capacity Improvement Locations Storm Sewer System Annual Report - FY 2015-2016 22 Next Steps The model results presented in this report were for existing land use scenario. The master plan study will review the system performance under near-term and long-term General Plan 2040 land use scenarios. In addition to the pipe upsizing alternative initially reviewed, staff will perform alternative analysis to identify cost-effective solutions and optimize the capacity improvement projects with potential inline or offline storage. Suitable green infrastructure projects will be evaluated and considered in the capacity improvement projects to provide water quality benefit. Regional facilities to provide retention or detention of storm water flows will be identified and evaluated as alternatives to the conveyance projects. Preliminary high priority projects' scopes and cost estimates will be refined and will cover other high level flooding areas during the 10-year storm events. Projects to relieve remaining flooding areas will be identified and their costs estimated. The draft report will be prepared for the master plan study with prioritized CIP projects. 2. Support Economic Development Working with Development Services Division, the Master Plan staff reviewed the storm drain capacity for development projects. Because the storm drain model is still under development, the review was done by evaluating the existing capacity against the runoff calculated using the Rational Method in Excel spreadsheets. The partial list of development projects that staff conducted capacity reviews included Santa Clara BRT, Agnews, Communications Hill, Cannery Park, Santana West, and 715-739 West Julian developments. 3. Coordination with Santa Clara Valley Water District (District) Approximately 20 percent (or 250) of the storm outfalls are in need of rehabilitation in order to maximize operational capacity and minimize maintenance requirements. The range of improvements needed include flap gate repair, vegetation removal, sediment removal, riprap repair, bank erosion repair, channel dredging, and/or outfall structure and pipe reconstruction. The City does not have a comprehensive outfall program to address the widespread planning and funding needs, environmental and regulatory permitting requirements, and mitigation and monitoring plans that would be necessary to implement a robust and long-term program. Currently, repairs to existing outfalls are considered on a case-by-case basis; when possible the City has been collaborating with the District to implement select projects through their Stream Maintenance Program or Five-Year Capital Improvement Program. This approach will continue to be used to rehabilitate outfalls in conjunction with ongoing District river and creek channel improvement projects (Coyote Creek, Guadalupe River, Los Gatos Creek, Lower Silver Creek, Thompson Creek, etc.) Storm Sewer System Annual Report —FY 2015-2016 23 City staff has closely coordinated with the District on the progress of the City's storm master plan development. Staff provided results of the North San Jose and Alviso area storm drain master plan study to the District. Potentially, the City would like to partner with the District to improve the storm sewer system in those areas to 10-year and 100-year storm event standards. The Water District has requested the City to assist them in their flood protection studies of Lower Silver Creek, Ross Creek, Upper Penitencia Creek, and Canoas Creek by making these areas' modeling the highest priorities of the City's modeling project. 4. Neighborhood/Special Corridors The citywide master planning effort is expected to yield the data necessary to plan and estimate Storm Capital Projects. Currently, most storm system improvement projects are identified and selected for implementation based on public complaints and City staff observation, as well as historical knowledge of chronic/re-occurring drainage problems. These improvement projects are funded by the Storm Sewer Capital Improvement Program (CIP). Priority for funding of storm improvement projects through Neighborhood/Special Corridors funding is based on proximity to public gathering centers, such as schools, community centers, libraries, etc. 5. Rehabilitation of Pump Stations As noted above, the City owns and operates 30 storm pump stations with various capacities. The majority of the City's 30 pump stations are over 40 years old. Although the majority of the storm pump stations have been rehabilitated within the last 20 years, Public Works continues coordination with the Department of Transportation to develop and implement a plan for prioritizing the rehabilitation of the City's storm pump stations. 6. Improving Annexation Areas In April 2006, the San Jose City Council launched a three to five year program in which the City of San Jose will annex the remaining "islands" (or "pockets") of less than 150 acres of unincorporated County of Santa Clara land. Unincorporated islands are governed by and receive services from the County even though they are completely or substantially surrounded by incorporated, or City lands. Upon annexation, the land use and general governing responsibility changes from the County of Santa Clara to the City of San Jose. This change enables residents in these County islands to receive urban services from the City rather than the County. The addition of these pockets to the City service area increases the demand on existing City storm infrastructure. The total impact of the annexation to the storm program is unknown, but County pockets typically lack underground storm sewer pipes and tend to experience various problems related to ponding. In addition the lack of curbs and gutters does not address the current standards for protection from overland release (streets are designed to capture the effects of the 100-year storm or failure of the storm sewer system). The city-wide master planning effort is expected to identify any deficiencies or needs for improvements within the recently annexed County pockets. Storm Sewer System Annual Report - FY 2015-2016 24 7. San Jose-Santa Clara Regional Wastewater Facility Storm Drain System Model A dynamic H&H model using Infoworks ICM software was developed for the Regional Wastewater Facility's (RWF) internal drainage system as part of the RWF's CIP effort. The RWF site is located within the Citywide Storm Sewer Master Plan currently under development, but the RWF model was developed separately to allow analysis to a higher level of detail. The goals of the modeling effort were to create a H&H model, evaluate the performance of the existing drainage network and to identify deficiencies and potential solutions. The stormwater analysis was completed in December 2015. Model results confirmed RWF staff observations of areas within the stormwater system that do not meet level of service criteria. Potential solutions were developed to address the identified deficiencies. Eighteen individual deficiencies were identified and prioritized to allow RWF staff to split the recommended solutions into phases to spread the implementation over a period of time. Two alternative packages of projects were developed to resolve these stormwater deficiencies, either alternative costing an estimated $9 million. A funding strategy is being developed for incorporation into the CIP budget. Flooding Study In addition to stormwater modeling, a flooding study was conducted to better understand impacts associated with regional flooding and heavy rainfall at the RWF. Completed in April 2016, the study analyzed numerous 100-year and 500-year flooding scenarios, coupled with the cumulative impacts of projected sea-level rise. 100-year flood protection for the RWF and surrounding community will be provided with the Shoreline Levee, soon to be constructed by the Corps of Engineers. Further analysis is required to estimate the potential flooding impacts at the RWF due to riverine flooding should the Coyote Creek or Guadalupe River overflow their banks or levee systems during a 500-year event. Staff is working with Water District staff to identify the potential for flooding at the RWF during a 500-year river flooding event. Understanding the risks of 100- year and 500-year events is important due to the critical nature of the facility, the unique topography of the South Bay and recognized design standards for critical infrastructure. E. Sustainability/Green Vision The Federal Clean Water Act requires the City to operate under a National Pollutant Discharge Elimination System (NPDES) municipal stormwater permit for the discharge of stormwater to surface waters via the City's storm sewer collection system. On November 19, 2015, the Water Board adopted the second Municipal Regional Stormwater NPDES Permit for the San Francisco Bay Region that became effective January 1, 2016. It regulates 76 municipalities, counties, and flood control agencies in the Bay Area and specifies actions necessary to reduce the discharge of pollutants in stormwater to the maximum extent practicable and to effectively prohibit non- stormwater discharges into the municipal storm sewer system to protect local creeks and the Bay. The City complies with the stormwater NPDES permit requirements by administering a comprehensive Stormwater Management Program, led by the Environmental Services Department. Other City Departments such as Public Works and Planning ensure adherence to Storm Sewer System Annual Report - FY 2015-2016 25 permit requirements for private development and municipal projects through plan preparation, review and inspection. The Departments of Transportation, Public Works, and Parks, Recreation and Neighborhood Services are responsible for operation and maintenance of City stormwater facilities. The City's Stormwater Program is comprised of a variety of program elements, including inspection and enforcement; outreach and education; municipal maintenance activities; controls on new development projects (private and public); and activities to address specific pollutants such as trash, mercury, and copper. Public Works is actively involved in the following elements of the Stormwater Program: 1. Green Streets Pilot Projects Provision C.3 (New Development and Redevelopment) of the MRP requires development projects to address both soluble and insoluble stormwater runoff pollutant discharges and prevent increases in runoff flows to local water bodies through the implementation of low impact development (LID) techniques. The goal of LID is to reduce runoff and mimic a site's predevelopment hydrology by minimizing disturbed areas and impervious cover and then infiltrating, storing, detaining, evapotranspiring, and/or biotreating stormwater runoff close to its source. As part of the Storm Sewer Master Plan study, the storm water conveyance and water quality impacts on the downstream water bodies due to the City's discharges and actions under normal and peak flooding conditions will be evaluated. A LID siting tool has been developed by the San Francisco Estuary Institute and San Francisco Estuary Partnership as part of GreenPlan Bay Area project, a collaborative effort between several Bay Area municipalities, including San Jose, to identify feasible locations for Green Infrastructure/LID projects. Phase I of the GreenPlan Bay Area project was completed with a LID siting tool and a watershed model to evaluate potential runoff reduction through an optimized number of LIDs. In an effort to support compliance with the MRP and facilitate future development in San Jose by creating treatment "credits", the City has secured grant funding for four green street retrofit pilot projects; Martha Gardens Green Alleys Pilot Project, Park Avenue Green Avenue Pilot Project, Ocala Avenue Green Street Project, and Chynoweth Avenue Green Street Project. Green elements included in these projects consist of bioretention areas, or "rain gardens" that function as a soil and plant-based filtration measure, and pervious pavers and infiltration trenches which will allow stormwater run-off to infiltrate into the ground. Total costs of the projects are approximately $6.7 million, including approximately $5.2 million in grant funding, and approximately $1.5 million in matching funds. Construction of the Martha Gardens Alleyways project began in FY 14-15 and was completed in FY 15-16. Construction of the Park Avenue, Ocala Avenue, and Chynoweth Avenue projects is scheduled for FY 16-17. The Park Avenue and Ocala Avenue projects are both being constructed in coordination with a Department of Transportation grant funded multi-modal project. Due to delays with the multi-modal projects the construction completion dates for the Park Avenue and Ocala Avenue green street projects are expected to be delayed beyond the current dates. Storm Sewer System Annual Report - FY 2015-2016 26 2. Trash Load Reduction Provision C.10 of the current MRP requires that trash loads from separate storm sewer systems be reduced by 70 percent by 2017, 80 percent by 2019, and 100 percent by 2022. The MRP includes specific requirements for installation of full trash capture devices that cumulatively treat runoff from 30 percent of Retail/Wholesale Land that drains to the storm sewer system (approximately 895 acres). The City installed nine large trash capture devices (hydrodynamic separator units) in 2011 and 2012 within the Coyote Creek and Guadalupe River watersheds which cumulatively treat more than 1,200 acres, exceeding MRP requirement. During FY 2014-2015, the Storm Section worked with the Environmental Services Department and the Department of Transportation to identify locations and to determine accessibility and maintenance needs for installation of an additional six full trash capture devices which are scheduled to be constructed by the end of FY 2016-2017. During FY 2015-2016, the Storm Section worked with the Environmental Services Department and the Department of Transportation to evaluate an additional eight sites. Of those sites, six were selected and design of those systems is currently underway with the goal of installing devices at these additional six locations by the end of FY 2016-2017. VI. OPERATIONS AND MAINTENANCE Funded directly from the Storm Sewer Operating Fund, the day-to-day maintenance and operations of the 1,150 miles of storm sewer collection system is primarily the responsibility of the Department of Transportation (DOT). Functions performed by DOT generally include the following: ® Cleaning and removing debris from the City's storm drain inlets at least once per year ® Repairing localized failures and deficiencies in the City's storm sewer mains, laterals and inlets • Inspecting and performing minor routine maintenance at City outfalls • Inspecting and maintaining 30 storm pump stations, which include the annual cleaning of wet wells and the repairing of pumps and other pump station facilities • Inspecting and maintaining storm water quality devices within the City's right-of-way, which include Connector pipe screens (CPS), Hydro Dynamic Separators, (HDS) and landscaped based treatment facilities • Sweeping more than 60,000 curb miles of streets to minimize contaminants from entering into the storm system and waterways • Responding to and resolving more than 1200 storm related calls every year In preparation for the El Nino storm season, the Department of Transportation increased maintenance activities ahead of the storm season and before predicted large events. Activities include: • Preparing portable pumps for the Alviso area; • Cleaning and removing debris from the City's storm laterals in the Alviso and downtown area; Storm Sewer System Annual Report - FY 2015-2016 27 • Cleaning and removing debris from the City's storm mains (less than or equal to 24" in diameter) in the Alviso area; • Sweeping problematic debris hotspots before the rain's arrival; • Cleaning and removing debris from storm drain inlets at various hotspots. V. CONCLUSION The City's Storm Sewer System is a significant infrastructure asset that has taken more than a century to construct. The overall system provides effective drainage for the protection of life and property, and is increasingly becoming a mechanism for treating polluted runoff and protecting local creeks, rivers, and the San Francisco Bay. However, as with any long-term asset, routine maintenance and rehabilitation are required to keep the system performing efficiently. Funding levels in recent years have been adequate for addressing small, nuisance issues, but the investment required to rehabilitate aging facilities and address chronic flooding issues is significant. The master planning effort will assess the condition and investment needs for the entire system and will develop the funding strategies to keep the system functioning efficiently. Storm Sewer System Annual Report - FY 2015-2016 28