MARK THOMAS & COMPANY, INC. (6) - Laserfiche WebLink

Home Browse Search

SCOPE OF SERVICES future proposed conditions. There will need to be confirmation if the Interstate 5 sump to the north outputs it's pumped flow to a pipe that leads to the south to the project site to join the main drainage pipe. This includes a site visit to the project site to review the watershed and the Caltrans pump station. Based on topographic data, the improvement plans, and confirmation of the drainage patterns to the site through coordination with Orange County Flood Control District and Caltrans, Tetra Tech WTR will conduct a series of analyses based on the OCPW Hydrology Manual (OCHM) methodology generating high confidence flows (per the OCHM Addendum) for flood control design purposes that will include the following: A Hydrology Study. This will include an existing condition baseline study of the watershed, flow paths, concentration points, and routing delineations based on topography and pipe dimensions/elevations. It also includes land use, and land cover per the Orange County hydrology manual and available Orange County geomatics data. Rational Method Analysis. Using the hydrology input, the rational method will be implemented in AES to determine time of concentration and designed discharges for the 10, 25, and 100 year events which aligns with both the City of Santa Ana and Orange County Public Works (OCPW) requirements. Unit Hydrograph Analysis. Using the hydrology input, a unit hydrograph method will be implemented also to determine volumes discharged to the proposed pump station. WSPG Analysis. Pipe hydraulics will be conducted using the Los Angeles County 2018 WSGP software for all the proposed pipe systems that lead to the proposed pump station and pump station outlet pipe to the existing storm drain system. If the Caltrans pump on Interstate 5 to the north discharges into the project area, an evaluation of that pump system and resulting outflows will be included based on provided data. CITY OF SANTA ANA SANTA ANA BOULEVARD GRADE SEPARATION MARK THOMAS • Street Flow/Catch Basin analysis. Street flow hydraulics of the existing roadway and catch basins will be analyzed for the roadway hazard during design storm events. • Proposed Condition Alternative Measures. Conceptual designs will be developed to minimize storm flows to the proposed project grade crossing and associated pump station location. This will evaluate measures that may include diverting flows around the project site, detaining water in basins or offline catchments, and stormwater infiltration. • A technical memorandum will be prepared, summarizing the baseline existing condition of the project drainage area and include study assumptions, results, and findings for each task previously listed to inform the pump station proposed design and potential alternative measures that could be incorporated to limit the pump station sizing. After review and incorporation of the results of the baseline study by the project design team and PUMP station design team, a proposed condition analysis will be performed incorporating new grading, drainage patterns, and pump station and pipe locations, etc. This will include: • Proposed condition Hydrology Study • Proposed condition Rational Method Analysis • Proposed condition Unit Hydrograph Analysis • Proposed condition WSPG analysis to include HEC-HMS for modeling the pump station functionality • Proposed condition Street Flow/Catch Basis analysis, and • Proposed condition Technical Memorandum 7.3.2 Pump Station (inclusive of structure, electrical, mechanical, SCADA) and Retention Basin The design of the pump station and retention design includes the following: