WQMC Proposal for Sewer Outfall Pipe

With reference to the recent local / public discussions regarding Falmouth Water Quality Management Committee’s (WQMC) proposal for a sewer effluent outfall pipe into Vineyard Sound, and more specifically with reference to WQMC chairman Steve Rafferty’s presentation at our August 5th annual meeting, please find below additional background information on this proposal and lastly a series of questions and answers raised by members at our annual meeting.

For the town link to the most recent presentation on outfall pipe planning by Wastewater Superintendent Amy Lowell, click here (4/3/23 Ocean outfall as the preferred effluent disposal alternative).

For the town link to the Water Quality Management Committee which provides additional information, click here.

Mr. Rafferty said he was grateful to have the opportunity to speak directly to FHMNA members at our annual meeting. Fellow WQMC member John Waterbury took notes at the meeting and has listed the FHMNA members’ questions below. The responses are the best recollection of Stephen Rafferty.

Kite Park Outfall Location – Q & A from FHMNA 2023 Annual Meeting

Q1. Would outfall preclude electric cables?
A1. I did not know the specifics of required vertical/horizontal separation of the outfall pipe from the Electrical cables but believed that there would be some required value. It would be to the Town’s advantage to “reserve” the location of the outfall.

Q2. How long would project take?
A2. Anticipate that directional drilling would require a three month period. The pipeline from the Treatment plant would look like a typical sewer/water main project with the project site moving at a rate of 200 feet per day.

Q3. Could the unsewered portions of the height be sewered?
A3. With land-based disposal there would not be any spare capacity to sewer additional areas. With an outfall there could be spare capacity but the allocation of that capacity would be up to overall Town planning/decisions.

Q4. What is the size of the outfall?
A4. Conceptual plan has a 24-inch diameter outfall pipe.

Q5. Why is our neighborhood being picked on?
A5. The analysis of best location and lowest cost identified the Heights as having best geology and bathymetry for an outfall pipe.

Q6. What happens if the treatment plant fails?
A6. Current treatment plant upgrade is adding a level of tankage and equipment redundancy to increase reliability. In the event of an emergency situation, the existing sand infiltration beds would still be available for backup usage, although this seems unlikely. The treatment plant has operated continuously since initially constructed.

Q7. What is scale of excavation for horizontal drilling?
A7. A desirable footprint for the equipment, pipe etc. would be 200ft by 200ft. The actual excavation for the directional drilling would be roughly 20 feet by 40 feet. Comment – I noted that one element of construction would be the assembly of 2300 linear feet of fused pipe. This could occur on Grand Avenue but would be easier and less disruptive to utilize Worcester Court for a two-week period to assemble. The Pipe would then be towed out into the Sound.

Q8. What would be in Kite Park when completed?
A8. All pipe and appurtenances would be below grade.

Q9. What is the size of the pipe back to the plant?
A9. Conceptually the pipe is sized at 16 inches diameter. This is the same size as the water main that was installed on Main Street and Davis Straits a few years back.

Q10. Do we ever need to worry about beaches being closed?
A10. The currents in the Sound run east west and below the surface do not flow towards the shore. The modelling indicated full mixing at the 1000-foot distance. We are looking at a 2300-foot distance to get 300 feet beyond the ell grass. Under a range of modelling scenarios, we never saw any flow to the beaches.

Q11. If we worked from Worcester Court would it eliminate the power cables?
A11. Can not state that unequivocally. Noted that from Worcester Court we would need to directionally drill a greater distance and overall project cost would go up $4 million to $6 million.

Q12. Would the project require a pump station in the Heights?
A12. There is no need for a pump station in the Heights for the outfall.

Q13. How far is the pipe off shore?
A13. Conceptual location is 2300 feet off shore from Kite Park. There is a buoy, looks a little like a lobster buoy at the location that is collecting data on Dissolved Oxygen, Temperature and other basic water quality parameters. Comment – noted that the treatment plant is 131 feet above sea level and as conceptually configured the plant’s effluent would flow by gravity for the current design flows under consideration.

Q14. Will there be flow to the beaches?
A14. No.

Q15. What funding is anticipated at this Fall’s Town Meeting.
A15. An article to fund marine borings, an analysis by USGS of the outfall’s impact on the Sagamore Lens (the groundwater source on the upper cape), as well as surveys of marine conditions is anticipated. The working group is currently getting price quotes to have a definitive amount to request.

Q16. Will a review of the deeds be necessary?
A16. Yes. While a layout that only utilizes the layout of Grand Ave is feasible it could take more time than using Kite Park. A review of the deed will be done and if the deeds language makes it necessary to go to the Legislature for a special act to use Kite Park we would consider doing that.

Q17. Why not go further off shore?
A17. For the necessary dilution and protection of the shore line further off shore than the 300 feet beyond the ell grass is not scientifically needed. To go significantly further off shore bigger and more costly equipment would be required. There is no apparent need to go further off shore.