Why is the Town testing Jameson Field as a potential leaching field?

Background

For many years, there has been discussion about the issue of considering municipal sewer to the Town Center. The 2001 General Plan noted the difficulty of maintaining septic systems on small lots without impacting groundwater quality, and noted that there had been discussion about a small wastewater treatment plant to serve the area. There also has been speculation about whether Jameson Fields would be a suitable site for a leaching field for a shared septic system or wastewater treatment plant. Knowledge of whether this is an important asset or not is of critical importance to the potential of the Town Center. Any potential use of the fields for this purpose would be subject to much further analysis and votes of the Town.

The newly adopted 2019 Master Plan addresses water and septic issues. It notes that "locations of many Town Center wells and septic fields, which were installed many years ago before today's stricter standards were in place, no longer would be allowed, and they pose a potential health risk. Options for current businesses are limited as there is little room for expansion of septic capacity. Indeed, ground water supplies are currently vulnerable to contamination by existing septic systems. It also states that, in addition to a potential health threat, "it could threaten town finances by forcing expensive emergency infrastructure remediation."

The Select Board appointed the Town Center Options Committee (TCOC) in 2014 to study the technical and financial options available to add water supply and/or wastewater management systems. The TCOC work to date shows further development of the Town Center is constrained by septic disposal capacity and water supply.

One of the recommendations of the Master Plan is to:

C. Support and guide the TCOC with resources needed to complete the analysis of the technical feasibility and projected costs of installing and maintaining a public water and/or septic system within a strictly limited Town Center district.

Previous studies have considered the possibility of a wastewater treatment plant serving the Town Center. The Town worked with Metropolitan Area Planning Council (MAPC) and the Charles River Watershed Association (CWRA) to study the "smart sewer" concept in 2013. The TCOC consultant also prepared a cost estimate for a wastewater treatment system. Both of these efforts lacked the essential information of whether Jameson Field had any capacity to serve as a leaching facility for any wastewater treatment system. A nonbinding vote in the 2007 Town election favored encouraging the formation of a water and/or sewer system to serve the Business district by a 2-1 margin.

Current Efforts

In 2018, a proposal for a private development included the option to locate a wastewater treatment facility leaching field at Jameson Field that would be paid for, in part, by the developer. Several financing options were discussed but the discussions never advanced beyond the preliminary concept stage. However, the discussions did bring to light the fact that no one knows whether using the fields as a leaching area is technically feasible, before even considering financial feasibility.

Some knowledge of the Jameson Field is already available. It is currently the leaching area for the Pine Hill School septic system as well as the Pine Hill School stormwater management system. It also serves as the leaching area for the Fire Station septic system. The Fire Station leaching area is raised due to high groundwater, but the Pine Hill School system is not raised.

Regarding the potential development of a municipal water and/or wastewater system for the Town Center, the Master Plan also states that "The successful solution will depend on the residents' ability to define and agree upon specific additions and changes that are consistent with their shared vision of the future of the Town Center."

Due to the factors stated above, the Planning Board decided that any discussions about the future of the Town Center hinged on whether or not there is technical feasibility of locating a leaching facility at Jameson Fields. Therefore, at the meeting of the Sherborn Select Board of May 23, 2019, the Planning Board asked the Select Board to authorize funding to conduct limited preliminary soil testing that could potentially determine either that a leaching facility was not feasible or whether enough promise could be found to justify additional testing. The Select Board authorized the funding and asked the Planning Board to spearhead the effort.

With input from members of the Planning Board, Board of Health, Town Center Water Options Committee, DPW Director and Town Planner, a local engineering firm familiar with the Town was asked for a proposal. After considering the opportunity, the firm declined because, while it had extensive experience with septic systems, it believed its lack of experience in analyzing conditions for a wastewater treatment facility led to the conclusion that a firm more experienced with such facilities would serve the Town better.

An RFP was drafted and sent to three firms with experience working in Sherborn and with designing wastewater treatment plants. Two proposals were received and both offered excellent credentials. After much review and consideration Stantec was selected.

With some coordination among DPW, Board of Health and Stantec, the testing day was scheduled to be on November 5. DPW supplied an excavator and Stantec provided a certified soil evaluator. Three test pits were dug and soil logs were prepared for all three pits down to 12-15 feet. No groundwater, ledge or impervious soil was encountered to those depths.

The test results indicated highly permeable soils with fast perc rates of under 2 minutes per inch at all three sites. The soil logs also indicate one area at Test Pit #2 with a "Redoximorphic Feature" at 30" from the surface. This can be an indication of high ground water. However, the certified soil evaluator at Stantec states that "Stantec does not believe the observed "Redoximorphic feature" is an indication of high groundwater but rather is an indication of variegated colors. This test pit was done adjacent to forested hill." In any case, monitoring pipes have been installed at all three test pits and will be monitored in the next few months through Spring to determine if groundwater rises within the pits.

Conclusion

While not definitive, the initial test results do not preclude consideration of Jameson Fields as a leaching area for a wastewater treatment facility. The soils are very permeable. Groundwater does not appear to be an issues based on these results but the monitoring pipes that were installed will need to be checked periodically, especially during wet times of year, before a conclusion can be made on that. Capacity has also not been determined. More testing and substantial analysis is required before any decisions could be made.