Alternative Scenarios Analysis & Site Evaluation

Based on the Technology Screening Report, the Mashpee Sewer Commission identified five different wastewater management scenarios for further evaluation.  They include leaving existing facilities in place and developing new facilities for unsewered areas, expanding existing facilities, assuming each Town in the watershed develops its own facilities using a standard percent nitrogen reduction for each community (called fair share), and centralized treatment.  The analysis of the fifth scenario using NITREX ™ technology in individual and cluster systems was prepared by Lombardo Associates.

Proposed sites discussed in this report are outlined below.

Click here to view the Alternative Scenarios Report

Scenario 1: Existing Facilities and New Facilities:  Continues operation of existing private WWTFs and constructs additional facilities to achieve nitrogen reduction.  New WWTFs are located at Sites 2, 4, 6 and 11 and new recharge locations are at Sites 1, 2, 4, 7 and 11.  The scenario assumes approximately 380 properties would be on new I/A systems.

Scenario 2: Upgrade and Expand Existing Facilities: Expands existing WWTFs to the extent feasible to address adjacent areas and enhance nitrogen removal.  The WWTFs sites are the same as Scenario 1.  The recharge sites are the same, except that Site 1 is eliminated.  The scenario assumes approximately 50 properties on new I/A systems.

Scenario 3: Nitrex™:  This scenario proposed cluster systems and individual I/A systems using Nitrex technology.

Scenario 4: Fair Share: An overall percent reduction of nitrogen for the Popponesset and Waquoit East watersheds is determined for each community to remove.  New WWTF sites are located at Sites 4, 6 and 11 and new recharge sites are at 4, 7 and 11.  The scenario assumes approximately 130 properties would be on new I/A systems.   Each Town would develop its own facilities rather than sharing facilities as in the other four scenarios.

Scenario 5: Centralized Treatment: Wastewater treatment takes place at a centralized (municipal) treatment plant.  A plant at Site 4 (in the Popponesset Bay watershed) would treat flows from both watersheds and recharge at multiple sites within the two watersheds.  Each of the existing private WWTFs (except New Seabury) would become a pumping station.  New Seabury would continue treating wastewater.  The Forestdale School would serve as a pumping station for flow sent to another new WWTF located on Site 11 in Sandwich.  The new WWTFs are located at Sites 4 and 11 and new recharge sites are 1, 4, 5, 7 and 11.  The scenario includes approximately 120 properties on new I/A systems. 

A site evaluation was also prepared for use with each of the five scenarios.  Thirteen sites were evaluated for treatment facilities and treated wastewater recharge.  Some were considered for recharge only; others were considered for both.  The evaluation included criteria such as ownership, land use, proximity to sensitive receptors such as schools.  Nine sites were carried forward for further development.  The sites and the potential uses are listed below.

Proposed Sites - click here

• Site 1 – Heritage Park Ball Fields – drip irrigation and subsurface infiltration
• Site 2 – Ashumet Road – open sand beds; wastewater treatment
• Site 4 – Transfer Station – open sand beds and subsurface infiltration; wastewater treatment
• Site 5 – High School Ball Fields – drip irrigation and subsurface infiltration
• Site 6 – Keeter Property – open sand beds; wastewater treatment
• Site 7 – New Seabury Country Club – drip irrigation and subsurface infiltration; wastewater treatment
• Site 11 – 168 Route 130 (Sandwich) – open sand beds; wastewater treatment
• Site 12 – Bartlett Property – open sand beds
• Site 13 – Adjacent to High School Parcel – open sand beds and subsurface infiltration