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Red Morton Park Regional Stormwater Capture Project Redwood City, CA • Research existing record data consisting of record of surveys, parcel maps, tract maps and other recorded documents made available to the design team. • Request and review existing Geographic Information System (GIS), ground survey, aerial photogrammetry, and other electronic information available from the County. • Establish horizontal project control for the project moving forward based on the California State Plane Coordinate System, Zone 3 (NAD 83), and vertical control based on the San Mateo County benchmark system. Additionally, a basis of bearing and local site control will be established for future use. • Base map and 3-dimensional surface of Red Morton Field. The invert of the drainage culvert will be determined by topographic survey and as -built information because the invert elevation at the point of diversion will be of critical importance. Utility as-builts will be collected per Task 2.2 and incorporated horizontally and vertically into the existing site plan. Task 2.4. Geotechnical Evaluation The primary goals of the geotechnical exploration are: (1) to evaluate the feasibility of stormwater infiltration into subsurface soils, and (2) to provide geotechnical design and construction recommendations for the project improvements. The Consultant will perform the following tasks for the geotechnical evaluation: • Pre -mark proposed explorations at the site with white paint or wooden stakes. • Contact Underground Services Alert (USA) within 48 hours of the Consultant exploration. • Retain the services of a private utility locator to further mark underground utilities within the area of the Consultant proposed explorations. • Permit the Consultant explorations through San Mateo County, and coordinate with their staff as needed. Consultant assumes any City encroachment permit fees will be waived. • Perform additional field exploration at the site comprising of two geotechnical borings to depths of up to 50 feet. The Consultant will observe the drilling operations and log the subsurface conditions encountered. Soil samples will be taken at frequent intervals for visual classification and laboratory testing. Another team member will be onsite to perform infiltration testing concurrently. • Soil cuttings from the borings will be drummed in 55 -gallon steel drums and off -hauled from the site. • All exploration locations will be backfilled in accordance with recommendations set forth by San Mateo County. • Perform laboratory testing on the collected soil samples to better characterize the subsurface soil conditions. Consultant will perform strength testing, Atterberg limits, sieve analysis, and moisture/density, as necessary, based on the collected soil samples. • Summarize the borings, lab testing, and field-testing within boring logs that will be attached to the draft and final report. Based on the geological and geotechnical data gathered, Consultant will revise its geotechnical exploration report to address the following: • Suitability of the site for the proposed improvements • Physical properties of the typical soils encountered • Assessment of geological/geotechnical hazards at the subject site. • Discussion of treatment of geotechnical constraints such as loose/soft surface soils, existing fills, compressible soils, expansive soils, liquefiable soils, and lateral spreading, as necessary based on field exploration results. • Seismic design criteria • Grading and drainage recommendations • Grading, subgrade/drainage, temporary excavation and shoring recommendations for subsurface reservoir. • Foundation recommendations for the storage unit, diversion structure, pre-treatment units, and pump structures. ATTY/AGR.2020.309/Craftwater Inc (Page 14 of 34)