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After the CONSULTANT received notice -to -proceed for WO No.5, the OWNER requested that three additional modeling simulations be conducted to determine the withdrawal flow split between the north and south wellfields. Also, the OWNER requested approval from the SJRWMD to use the existing calibrated groundwater models developed by the CONSULTANT in 2016 for the 2020 CUP modification. On January 13, 2020, SJRWMD provided approval for the use of the model but requested that a revised/updated groundwater modeling plan be submitted to the District for review and approval. Amendment 1 was issued to provide the three additional modeling simulations and revision of the 2016 groundwater modeling plan. In addition to North County and South County wellfields, the OWNER is now considering three other groundwater withdrawal alternatives. The first alternative is to move the additional requested allocation to a potential new UFA wellfield on County -owned property in the western part of the County to distribute the pumping, reduce groundwater level drawdown and reduce the potential impacts to existing legal users of the UFA. The second alternative is to move a portion of the requested allocation to the Avon Park Permeable Zone (APPZ) located below the, UFA at both the north and south wellfields. The third alternative will consider pumping from the County's existing wellfield at an interim allocation based on short-term projected demand. The OWNERS withdrawal allocation under their exiting CUP is 12.84 mgd from 2021-2031 and does not provide for any growth in demand over this time period. This alternative would provide County time to analyze the first two alternatives and finalize the one to satisfy County's long-term water supply needs. Additional modeling simulations are therefore necessary to determine whether these three new wellfield alternatives will cause any adverse impacts to water resources, environmental resources, and other existing legal users. This Amendment has been developed to provide the additional groundwater modeling services requested by the OWNER. SCOPE OF WORK The following is a description of the work to be provided under this Amendment. TASK 1- ADDITIONAL GROUNDWATER MODELING SIMULATIONS The CONSULTANT will perform three additional groundwater model simulations with the modified ECFM to determine if the three new wellfield alternatives will cause any adverse impacts to water resources, environmental resources, and other legal users. The modified ECFM model was used during previous permit modification attempt in 2016 and has been approved by SJRWMD for use in support of the current CUP modification. The three groundwater modeling simulations will be performed using the End -of -Permit (EOP) withdrawals for all permitted users and OWNER wells pumping at the requested allocation increase. A detailed description of these three simulations is listed below: 1. Simulation 7 (SIM7) — Existing North County and South County wellfield wells will be pumping at their current permitted allocation of 12.84 mgd. The requested additional allocation of 10.34 mgd to will be withdrawn from the proposed West County wellfield. The combined withdrawals from the existing and proposed wellfields will be 23.18 mgd. Other legal user wells within the model domain pumping at their current EOP withdrawal rate, except for the agricultural use wells whose EOP allocations will be adjusted to 5 in 10 -year factors provided by SJRWMD. Smith Page 2 Of 6 jj3005_Fxhlbits.doa