Agenda Packet_2023-06-20 - Laserfiche WebLink

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Scope of Work Task 1: Research and Site Reconnaissance JS&TM will provide preliminary engineering services to collect and review existing background data. Data collection includes right-of-way documents, existing utilities plans, soils, and geologic information, "as -built" construction drawings for the lake, park and existing nearby utilities, existing hydraulic and master plans of drainage, irrigation plans, previous project reports, and proposed development plans. A field reconnaissance investigation of the project study area will be performed. The field investigation will include an onsite meeting with COSA Public Works staff to get input on observed issues with the lake, discuss objectives, and discuss needs for improved maintainability of the lake facilities. Our research will also include review of available city records regarding water usage of the lake, power consumption of the lake pumps and aerators, lake maintenance records (algae removal, fish kills, wildlife issues, etc.). JS&TM will also perform field inspections of the existing facilities to assess the current condition of each component system of the lake. This will include assessing the current condition of the following lake facilities: • lake liner (obtain in -situ liner samples) • lake wall • recirculating stream liner system • existing pumps • lake skimmers • lake fill control valve • accessible aeration equipment • existing pump vaults and electrical panels and controls • lake perimeter landscape • lake access paths • fishing/angling facilities • signage • seating areas • trash receptacles • water quality control facilities • maintenance access provisions JS&TM subconsultant (Converse Consultants) will identify and document the historic groundwater table using the USGS Water Data Website, the California Department of Water Resources SGMA Data Viewer Website, and historic groundwater information from USGS Water Supply Papers from the early 1900's. Converse Consultants will provide recommendations for future groundwater elevation beneath the site based on nearfield wells and trends. Converse Consultants will obtain 2-3 soil samples under the guidance of JS&TM and provide sieve analysis of soil samples in general accordance with ASTM Standard D6913. JS&TM will prepare a water balance analysis for the lake system accounting for lake inputs and withdrawals to determine the expected lake water use compared to actual water usage. This analysis will provide an accurate assessment of the condition of the existing lake liner. The water balance accounting will account for the following water inputs and withdrawals: • direct precipitation • precipitation runoff inflow • evaporation Thornton Pa 1 y ounce17 — 31 6/20/2 8