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City of Santa Ana On -Call Stormwater Project Design Services RFP No.: 20-102 City of Torrance Stormwater Basin and Treatment Wetlands Enhancement This project received awards from the American Public Works Association (APWA), American Society of Civil Engineers (ASCE), Englneering News -Record (ENR), California Stormwater Quality Association (CASQA), and Storm WaterSolutlons magazine. CWE designed two treatment wetlands, two infiltration basins, and 300 feet of pressured storm drain piping to retain, treat, and infiltrate stormwater runoff to help the City comply with the Santa Monica Bay Beaches Bacteria Total Maximum Daily Load (TMDL). CWE performed a topographic and boundary survey of each basin and coordinated a geotechnical investigation for the design of earthwork, pipelines, structures, other site improvements, and infiltration capabilities of three basins. A wetlands sustainability analysis was performed to evaluate dry -weather inflows, evaporation, evapotranspiration, and infiltration, and ensure the long-term functionality of the wetlands system. CWE conducted a hydrologic analysis using the Modified Rational Method (MODRAT) in Watershed Modeling System (WMS) to evaluate the reservoir routing and pumping from the interconnected wetlands/detention basin system under Capital Flood and Standard Urban Stormwater Mitigation Plan (SUSMP) conditions. Water quality modeling determined the reduction in pollutant loads. The estimated annual pollutant load reduction for this project is 91 %. Using the stormwater for irrigation reduces the potable water demand by approximately 2,800,000 gallons annually. The project included designing and preparing construction documents for the proposed improvements, including: site grading, roadway paving, recycled water line, and piping plans; retaining walls; park lighting and signage; stream channel and infiltration basin design; trails, viewing areas, and landscaping details; a water -tight system for irrigation; inlet and outlet structures; bridge structures; culverts, 20-cfs flood control pump station, and several irrigation pump stations, and other control structures; electrical and mechanical plans; and Supervisory Control and Data Acquisition (SCADA) plans. The project also included placement of new trash sweeping signage and catch basin screens throughout the basin subwatersheds. The project included coordination with the Los Angeles County Flood Control District (LACFCD). Special consideration was given to protect the burrowing owl and legless lizard habitat. CWE performed legless lizard surveys prior to and during construction. Specifications per Greenbook and special provisions and estimates were prepared. CWE also provided construction management and support services. Contact: John Dettle, Engineering Manager, (310) 618-3059, jdettle@torranceca.gov with 446 acre-feet of runoff annually r� City of San Fernando Regional Park Infiltration CWE provided design services for the City of San Fernando Regional Park to install an underground manufactured infiltration system underneath the existing park and replace the baseball field and irrigation system. Six different alternatives were developed and evaluated to maximize benefits while reducing capital cost and ongoing life cycle cost. The infiltration system serves a drainage area greater than 950 acres and recharge groundwater sources CWE recommended upsizing the system and doubling the -17- CW=