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economically feasible and that land is available for acquisition, Phase 2 would include the detailed modeling efforts to determine if sufficient surface water is available from the surrounding canal system to supply the reservoir. Phase 2 tasks will include: 1. Preparation of a modeling approach technical memorandum for submittal to and review/approval by St. Johns River Water Management District (SJRWMD) prior to commencing modeling activities. 2. Unless already available from the local drainage districts and property owners, it is anticipated that survey services will be required during this Phase to identify critical elevations, distances and property boundaries. The survey data will be used in development of the project models. 3. A stormwater runoff and routing model will be needed to define the hydrology and hydraulics (H&H) of the Sebastian River Improvement District (SRID) canal system. Consultant requested and received a copy of the recently updated H&H model (using the advanced Inter -Connected Pond Routing software) from the water improvement district for simulating surface water inflows into the reservoir. This H&H model will need to be capable of performing continuous simulations of surface water flow in the canal system over a 20 to 30 year time period to capture low, average, and high flow conditions in the surface waters providing flow to the reservoir. If the SRID H&H model is a storm event based model, the model will need to be revised by Consultant to simulate continuous flows. 4. Upon approval of the approach, Consultant will develop an operations model utilizing STELLA, a widely used systems model for evaluating inflows, outflows, and storage components of systems similar to that proposed by the County. The STELLA model will be used to perform a continuous simulation of the proposed reservoir operations over a 20 to 30 year period. The model will account for historical rainfall patterns as well as take into account surface water inflows from the SRID canals, evaporation, seepage, and other releases from the reservoir (water supply and emergency overflow) on a daily basis over the 20 to 30 year time period. 5. Modeling results will be used to quantify the amount of surface water that can be anticipated during drought conditions, average rainfall conditions, and during high rainfall periods. This information will then be utilized to refine the reservoir sizing evaluation performed in Phase 1. The result may be that the size of the reservoir presented in Phase 1 based on the maximum demand (population projection based) would be reduced based on actual, available flow. 6. The modeling summary will be submitted to SJRWMD for review and comment, and modeling will be updated if needed based on comments received. Actual permitting activities would be performed during Phase 3, in conjunction with final design efforts. 7. Once the modeling is accepted by SJRWMD, the County would move forward in acquiring the land for the project (both reservoir construction and rights-of-way for the necessary transmission piping). Phase 3 — Final Design, Permitting and Construction Once the modeling is complete, a refined reservoir size is determined, and land is acquired, final design and permitting activities can commence. The initial step would be to develop a preliminary design report in which a treatment process is selected to treat surface water from the reservoir. To do this, A-3 )jt429REVS (2).doc.docx 105