10/18/2011 SEWER COMMISSION Minutes

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�iii►' locations were not available.The balance of flow would either be managed within the watersheds or remain as flow from septic systems. This second table outlines where/how each part of the project planning area is proposed to be served in the future under this option,and where the treated effluent from that area would be recharged in order to meet the TMDLs. In Option 1B the future flows are more dispersed with eastern Mashpee(around Willowbend) receiving the largest portion of the flow,with other large recharges at Sites 4,6,and the Backroads parcels. Again some of the smaller WWTF's would remain with a higher treatment level.This Option also assumes that all of Sandwich's flow remains within the project planning area,and Barnstable's flows are treated within the planning area as well. This Option does consider that the%portion of Falmouth west of the Moonakiss/Quashnet River is removed from the project planning area(similar to Option 1 A). Figure 2 shows the location and discharge areas summarized on the Table. 3 Preliminary Findings Leading to MEP Model Runs The results of this analysis were then entered into existing MEP"Rainbow Spreadsheets"that were updated to show the recharges based on the tables summarized above.The preliminary results are shown in the attached Table. Because this is not the official model run by the MEP,the impact on the various watersheds is considered approximate and will need verification through the MEP model run,however the results show that distribution of the nitrogen loads should be within the allowable thresholds. It is important to note the following caveats: • The focus of this step is to identify the discharge locations and volumes so they can be incorporated into a scenario including considerations for maximum month and peak day conditions required for facilities design. . All these options are based on the assumption that private facilities will be owned and operated in the future,by the Town or District.Town/District should continue with negotiations with all of these facilities. All these options are based on the assumption that the recharge sites can accommodate the flows (at all conditions: average,maximum month,peak day);the Town/District will need to verify this as part of preliminary design;final design,or as an amendment to this project. . This assumes that Towns will manage their respective loads or be willing to enter into agreements regarding regional facilities. . Nitrogen concentrations from septic systems at 23.63 mg/L are based on MEP/DEP findings. . Nitrogen concentrations from I/A systems are assumed to be 19 mg/L based on current MassDEP permitting and the findings of the Barnstable County study; however it is understood that some of these facilities may be able to achieve much higher treatment performance,however a conservative approach was selected. 4 R I 5 E