Washington Park Stormwater Capture Project - Engineering Design Services

Under the federal Clean Water Act, the National Pollutant Discharge Elimination System (NPDES) permit program regulates pollutant discharges to protect water quality. As part of this framework, Total Maximum Daily Loads (TMDLs) set the maximum allowable pollutant loads for waterbodies and allocate those loads among contributing sources, including municipal separate storm sewer systems (MS4s). The City of Pasadena’s MS4 conveys dry- and stormwater flows to receiving waters, including the East Side Storm Drain, Rubio Wash, and the Rio Hondo Channel, all of which ultimately discharge to the Los Angeles River and are subject to TMDLs for bacteria, trash, metals, sediments, and other pollutants of concern. Compliance with the Los Angeles County MS4 Permit requires the City to implement cost-effective, multi-benefit stormwater management projects that achieve pollutant load reductions and advance watershed health.

The City of Pasadena is leading the Washington Park Stormwater Capture Project to continue regional progress toward pollutant load reductions for bacteria and other priority pollutants in the East Side Storm Drain, Rubio Wash, and Rio Hondo watershed. Washington Park, located at the southeast corner of Washington Boulevard and El Molino Avenue, is uniquely positioned within the Rio Hondo watershed and offers substantial potential to improve water quality due to its proximity to existing storm drain infrastructure, its watershed linkage, and available city-owned space. A Project Feasibility Study, funded through the Los Angeles County Safe, Clean Water Program’s Technical Resources Program (TRP), has been completed and evaluated conceptual approaches for diverting stormwater from the adjacent East Side Storm Drain, filtering it through a pretreatment unit, and conveying it to an underground storage and groundwater recharge system. The preliminary concept evaluated in the study also explored opportunities for on-site bioretention/infiltration basins and gardens to enhance native vegetation and passive recreation opportunities. The Feasibility Study informs the RFP’s expectation that final design build upon the study’s findings while assessing additional alternatives that maximize water quality improvements, cost-effectiveness, and design efficiencies within site constraints.

The site is on public property owned by the City of Pasadena and is located within the Rio Hondo watershed. The drainage area for the project is approximately 527 acres and is located within the City of Pasadena. The drainage area is contributed by the City of Pasadena (77.3%) and the County of Los Angeles (22.7%).

The Project is located at 700 E. Washington Blvd. and is a 5.4-acre park that has single family homes to the west and south, homes and small commercial buildings to the north, and a banquet hall and multi-family apartments to the east.

The National Pollutant Discharge Elimination System (NPDES) permit issued by the California Regional Water Quality Control Board (RWQCB) requires the City to take steps necessary to reduce or eliminate pollution in stormwater runoff. In addition, the City is part of a group of 18 agencies who participate in the Upper Los Angeles River (ULAR) Enhanced Watershed Management Program which addresses NPDES compliance issues as a watershed region rather than as independent municipalities. Water in the Rio Hondo Channel, which is a major tributary of the Upper Los Angeles River, regularly exceeds the Total Maximum Daily Load for bacteria, heavy metals, and other pollutants set forth by the RWQCB.

The East Side Storm Drain is the City’s oldest and largest storm drain asset, former Woodbury Creek turned channelized conveyance system, continuing from it’s origin in Altadena directly through Washington Park, before connecting with several other drains. It drains approximately 527 acres of urban runoff that flows, untreated, to the Rubio Wash and subsequently to the Rio Hondo Channel giving the park the potential to provide a significant water quality and recharge benefit to Pasadena.