Res 1993-174 - Laserfiche WebLink

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1~3J 2. Conduct field studies of the San Marcos River to calibrate and verify the water quality model. Velocity, flow and depth relationships for the San Marcos River will be part of this field study. 3. Set-up Model. An appropriate USEPA or TWC approved computer modeling program will be selected and used to estimate water quality in the San Marcos River. The study segment will extend from its source to a point downstream of the WWTP. The downstream limit of the model will be based on the need to include points in the study segment where critical water quality conditions may occur. For example, for the dissolved oxygen (DO) evaluation, the study segment must extend as far downstream as the point(s) where the minimum DO concentration or usagu occur(s). 4. Calibrate Model. The model will be calibrated on the basis of hydraulic and water quality data. This will be achieved by adjusting model parameters until the simulated results compare reasonably close to the provided data. 5. Develop Effluent Criteria Scenarios. Three different wastewater treatment scenarios will be considered, including the existing NPDES permit restrictions and two hypothetical increased treatment scenarios. 6. Run Models. The water quality model will be used to evaluate the impacts of three effluent criteria scenarios on the water quality of the San Marcos River. The WWTP will be input as a point source to the model. Other significant point source discharges to the study segment identified in Task 1.c will also be included in the model. 7. Analyze and Present Results. The results of the modeling effort will be analyzed to identify critical water quality conditions that may occur in the San Marcos River for the various effluent criteria and treatment scenarios. Potential water quality problems and exceedance of water quality criteria will be identified. The results of the study, along with descriptions of the modeling procedures, data results, findings and conclusions, will be doc~mented in a working paper. E. Existing Facilities. 1. Review available plans, drawings and other information concerning existing treatment plant facilities. 2. Visit the plant site and discuss facilities and operations with plant staff. 3. Determine hydraulic adequacy, treatment capacity, and expansion potential of the existing facilities based on the projected wastewater quality and quantity criteria established above. 4. Prepare description of existing facilities, review with City and revise as required. 06/02/93 A-3