Agmt14 Environmental Science Associates

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_ _ • Relative role for source control management and storm water BMPs to complement the management of hydraulic flushing times. Source control measures in combination with circulation and flushing enhancement may provide the most cost effective approach to meeting water quality goals. • Sea level rise planning horizon — Since the Lagoon's hydraulic exchange is partially a function of the Bay water levels,future management should consider vuinerabilities caused by sea level rise and possible adaptation strategies. Consultant shall deliver memorandum refining the project definition by: (1) providing an inventory of existing hydraulic features, (2) describing a conceptual model that links hydraulic conditions to water quality and maintenance concerns,and (3)states the perFormance criteria for the proposed modifications. Subtask 1-3 Field Survey and Lagoon Observations Based on the inventory of relevant hydraulic features and processes refined in Subtask 1-1, Consultant shall conduct a field survey to verify the location, elevation, and geometry of key hydraulic features (culverts, inlets, tide gates).The ground survey will prioritize structures and features for which as-built documents or other recent survey data is unavailable or suspect. The ground survey wiil also include a limited number of points intended to verify the accuracy of the as-built documents reviewed under Subtask 1-1. Consultant shall install five salinity and water level gages at key locations across the Lagoon which will collect time-series data for 3-4 weeks.The data collected by these gages wili support the development and calibration of the hydraulic model under Task 2. Each gage location will inciude both a water level and salinity sensor.The gages will be instailed at representative locations to characterize conditions across the Lagoon. Consuitant recommends that during the lagoon observation period, the Lagoon operators consider a temporary change from the current season's water level to the out-of-season water level. This switch will provide a larger dynamic range in Lagoon water levels and salinity against which to verify model predictions. Consultant shall develop a tentative plan for this switch and coordinate the timing of the change relative to the weather forecast and Lagoon use. If r�nement of the project definition (Subtask 1-2) identifies larger uncertainties about the relationship between Lagoon hydraulics and water quality conditions, Consultant must receive prior written authorization from the City Engineer to authorize additional work to expand the data collection effort. Additional data might include water quality sensors that also measure temperature and dissolved oxygen and/or a dye study. An expanded data collection effort is not part of the scope of work and fee estimate of this agreement and may create additional considerations, such as permitting and public perception of dye releases. Recent hydrographic surveys to plan dredging and to confirm post-dredging conditions are assumed to sufficiently characterize the Lagoon bathymetry that no additional hydrographic data is required. Consultant shall provide an engineering memorandum describing existing site conditions based on field observations and the review of as-built documents. The memorandum shall also describe the field data collection conducted by the Consultant.The memorandum shall include a description of the data collection methods,with descriptions of the gages and survey equipment used, the location and duration REV:04-09-14 VR Page 10 of 16 ATTY/AG R.2014.048/ESA_88464