Tracy Lakes Stormwater Management Plan and Design

Tracy, CA

PACE provided engineering services for the inclusion of 3 man-made lakes in a proposed development located in Tracy, CA. The lakes, which are designated as C, F, and G, combine for approximately 9-acres and serve as both an aesthetic amenity for the community and as the development’s primary means of stormwater management. Our team conducted water balance and water demand analyses to determine non potable water requirements, calculate the make-up water required for lake operation, and evaluate average year and dry year conditions. Using the results of these analyses, PACE developed lake designs, grading plans, and evaluated flood impacts and level of flood protection provided to surrounding properties. A sediment management system was designed using hydrodynamic separators at each storm drain outfall, effectively removing debris from stormwater runoff before it enters the lake system. The planters along the lake’s edge provide water quality improvement by reducing the amount of sediment, settling particulate phosphorus and metals, providing denitrification and filtration, and biologically removing pesticides and hydrocarbons. Additionally, PACE prepared a stormwater management plan for the site in compliance with the 2015 Multi-Agency Post Construction Stormwater Standards Manual governing the City of Tracy. The lake system functions as a wet pond with extended detention, temporarily retaining stormwater during the 10- and 100-year storm events to reduce peak runoff flow rates and provide treatment and hydromodification control.

PACE also prepared the construction plans for all 3 lakes, including lake grading, recirculation piping, aeration, utility requirements, and the pump station. Water quality is maintained through recirculation, aeration diffuser pods spread throughout the lake, alum treatment, and a sediment management system preventing excess contaminants from entering. Our designs also include a stream and waterfall feature for lake C, further contributing to water quality management through increased recirculation and filtration. A single pump station serves all 3 lakes. Pump station plans include site grading, as well as the mechanical, electrical, and control equipment schematics.

Key Features:

• System of 3 man-made lakes covering 9-acres
• Hydraulic analysis of capture volumes and flood impacts using XP-SWMM
• Stormwater management integrated lake system
• Improved water quality management with recirculation, aeration, and alum treatment
• Sediment management at storm drain outfalls
• Pumped drainage
• Lake grading plan
• Stream and waterfall feature