The Carlisle Mosquito Online

Friday, September 19, 2008

BOH applies for grant to share school waste treatment plant

Last month the Board of Health (BOH)applied for a state grant for a revolving loan at 2% interest for the purpose of connecting the Carlisle School’s wastewater treatment facility (WWTF) to Gleason Library, other municipal buildings in the town center, or the Church Street elderly housing complex. Town Administrator Madonna McKenzie organized a meeting on September 12 of officials and possible interested parties, including representatives from the Selectmen, Board of Health, Library Trustees and Carlisle Public School, as well as the Carlisle Village Court elderly housing association.

McKenzie later explained that the idea to create a municipal sewage system is in the early stages, saying ,“This is very preliminary.” If the state awards the grant, the project would need Town Meeting approval. The first step, she said, was to ask the Carlisle School Committee whether it is interested in allowing others to share the WWTF.

According to Library Trustee Priscilla Stevens, who attended the meeting, the library’s septic system is over 50 years old and will need replacement in the next few years. She is interested in the opportunity to use the school’s WWTF and will bring the idea to an upcoming Trustees’ meeting.

Tom Raftery, one of the directors of Carlisle Village Court, also attended the meeting and later said that Village Court was approached this year by town officials, but the board of the elderly housing association has not yet decided whether it would vote to expand. He added, “Everybody’s in the fact-gathering stage.” The town’s Affordable Housing Trust had talked about commissioning a study to see if Village Court could be connected to the school’s WWTF, freeing up the land currently used for its septic system for additional affordable housing (“Engineer to evaluate feasibility of Village Court expansion,” Mosquito, July 4.) The feasibility study has not been done yet and Raftery said it was his understanding that the study would not be undertaken until it was known if the school would share the WWTF.

It is not known whether the Massachusetts School Building Authority (MSBA), which gave partial reimbursement for the wastewater plant’s construction, would favor use by the non-profit Carlisle Village Court. McKenzie said there is no intention of adding other non-municipal buildings at this time, though connecting Ferns store had been mentioned at one time.

How much capacity is available?

Any new use of the WWTF is limited by the capacity of the wastewater facility. According to the April 2006 Carlisle School Facilities Master Plan by HMFH Architects, Inc., the wastewater treatment facility was built in 2006 with a capacity to handle up to 13,500 gallons of effluent per day (gpd). The treatment plant is larger than needed by the current school population of 728 students and School Building Committee forecasts predict enrollments will not exceed this level for the next ten years. Current use by students and staff can be roughly estimated at about 8,800 gallons per day, or 65% capacity, using the Master Plan’s figure of ten gallons per day per person. This would indicate that on schooldays, up to about 4,700 gpd capacity remains unused. School is in session 180 days per year and the BOH grant application lists an actual average flow over 25 months of only 1,671 gpd.

During the summers, there are fewer people on campus and the school has resorted to “feeding” the system pet food in the summers to keep it operating properly. McKenzie said that the cost of pet food was small compared to the cost of linking more users to the wastewater plant. One summer, sewage was trucked in from the Fenn School summer program, but the BOH no longer allows that practice.

Raftery said that exact data is not known for the Carlisle Village Court’s septic effluent rate. However, a rough estimate can be made, based on the state Title 5 minimum requirement of 100 gpd septic system capacity per bedroom. Given this, the 18 bedrooms currently in the elderly housing complex might need approximately 2,000 gpd.

Another question, McKenzie noted, is whether the school’s WWTF was designed to handle residential waste. Also, the library’s septic effluent rate is not yet known. There were, she said, more questions than answers at this point. Raftery said, “The meeting was well worth it, because it brought people together to share facts and better understand the questions to be addressed.” ∆

© 2008 The Carlisle Mosquito