Below please find sections (approx. 5 pages) from the 22 page report by the most respected groundwater consultants in Connecticut.  Leggette, Brashears and Graham were "...formally retained by the Town of Weston on May 5, 2000 to conduct a water supply and aquifer impact assessment for proposed expansion of the well water supply at the Weston Public School Campus and Town Hall Complex."

"The scope of the study was established by a meeting with Town Administrator Roy Hill and Town Engineer John Conte on April 25, 2000 and confirmed by a written proposal on that date.  This preliminary investigation was commissioned in support of the Town's application to the Planning and Zoning Commission under Section 8-24 of the (Connecticut General Statutes) Zoning Code.  The study was requested to determine if a proposed expansion of the system to address an expected 25 percent increase in student population could be met by onsite water resources and whether that increase in groundwater usage would cause drawdown impacts to offsite residential wells" (page one).

For the purposes of keeping the public informed, "AboutTown" has uploaded the parts of L,G,B's report that are least technical and most clear to the casual reader.   There are 7 pages of tables and charts including information from published and unpublished sources.  Water demand estimates, fracture analysis and details about Town wells are provided. Some data is from the U.S.G.S. and available to all, and some is original to the records of the Westport-Weston Health District.

Relative to the present flexibility of new school location (off site) as indicated to the public by the Superintendent of Schools, more reports may have to be commissioned by the Town of Weston to determine groundwater availibility in other sub-watersheds in Weston.

SUMMARY (first two pages [ahead of page one])

The public schools campus of the Town of Weston is served potable water by a single water well completed in the metamorphic bedrock beneath the southern part of the site.  The well system serves the six school buildings as well as the Town Hall complex that lies to the south of the schools campus.  Present average water demands are about 18,000 gpd (gallons per day) on school days, and during maximum demand weeks are about 24,000 gpd on school days.

 School population forecasts indicate that an increase in student population of about 25 percent will occur in the next ten years, probably peaking in the eighth year.  It is proposed to build a new elementary school to house grades 3, 4 and 5, which will accommodate students presently in other elementary school buildings and the Middle School, and to make other improvements to existing school buildings.  The potable water demand can be expected to increase in general proportion to the increase in school population.  The school-day demand for potable water is expected to increase to an average of about 28,000 gpd, and to experience maximum daily demands on the order of 37,500 pd.

The well presently serving the system is 225 feet deep and reportedly produced about 114 gpm (gallons per minute) upon completion, and regularly produces 20,000 to 30,000 gpd to the system.  It is presently regulated by the Connecticut Department of Public Health (CTDPH) and is generally satisfactory but requires water treatment to control copper and lead within the distribution system.  The water system does not meet current Connecticut regulations in that a public water system of this type is required to have a minimum of two wells, each of which is capable of meeting the maximum daily demand of the system.  The drilling of a second well is part of the planned expansion of the water system.  Several high-yield wells exist on the site and are reported to be abandoned or limited to use for fire protection.  The possible use of one or more of these wells for the potable system should be investigated by yield and water quality testing, if their sites meet the requirements of the CTDPH, not only to save the cost of drilling but also to spread the ground-water withdrawal over the property.

The schools property and Town Hall complex comprise about 132 acres of gently rolling upland topography, and the sites are part of a subwatershed of about 190 acres, including the properties, with the additional acreage largely to the east.  Ground-water recharge to the till-covered bedrock within this watershed is about eight (8) inches of precipitation per year in years of normal precipitation, i.e., about 16 percent of the average annual precipitation.  For the watershed, this translates to about 41.3 million gallons per year, or the equivalent of about 113,000 gpd.  In a one-year-in-30 drought year, the recharge rate would only be about 63 percent of the normal year, or the equivalent of 71,000 gpd.

Planning yet to be finalized indicates that sewage from the schools property, presently returned to the ground onsite by septic systems, will likely be disposed to an offsite facility.  This will mean that 100 percent of the water usage will be what is known as "consumptive" water use, water that is removed from the local ground-water system.  At a practical level, this implies that water withdrawals from the bedrock aquifer within the watershed must be supported by natural recharge occurring within the watershed.

Based on the historical record and the expected increased demand for potable water, as well as the ground-water recharge available to the bedrock aquifer under normal or extreme drought conditions, LBG concludes that the supply can readily be provided by two to three wells on the site without causing adverse drawdown impacts to neighboring private wells.  The same cannot be said at this time for large-scale irrigation of athletic fields, but further definition of these needs may indicate that a reasonable level of seasonal irrigation can be supported.

Under a relatively new interpretation of the Connecticut regulations governing public water supplies, the expanded water system will come under the joint regulatory control of both the CTDPH and the Connecticut Department of Public Utility Control (CTDPUC).  If the future water demands on the system exceed 50,000 gpd in any 24-hour period, the system would also come under a permit process of the Connecticut Water Diversion Policy Act, administered by the Connecticut Department of Environmental Protection (CTDEP).  LBG strongly recommends that every effort be made to keep the maximum daily water demand below 50,000 gpd to avoid this costly, time-consuming and burdensome regulatory process.

A full-scale study of irrigation water demands is beyond the scope of the present study but preliminary information has indicated possible demands for irrigation water on the order of 50,000 to 100,000 gpd.  Although recognizing that any irrigation water demand is highly seasonal, with peak demands in the months that school is not in full session, this is a serious issue that may overdraw the ground water supply available to the site, as well as involve a Water Diversion Permit application to the CTDEP.  A detailed study of irrigation water demands should be made before any commitment to irrigation of athletic fields is made.

The data indicate that the area in general is considerably better than average for obtaning highly satisfactory well yields from reasonable well depths, a finding that is consistent with the drilling results on the school campus site.  A cluster of relatively low yield wells at greater than average depths was noted in the western part of the Nimrod Farrns Road area, to the northwest of the campus, for reasons that are not known.

CONCLUSIONS (pages 9 and 10)

1. The available information makes clear that the Weston Schools Campus can support the present potable water demands and the demands of the 25-percent increase in projected student population.

2. Based on the estimated recharge to the bedrock aquifer in both normal and extreme drought conditions, this level of expansion will not cause adverse drawdown impacts to offsite wells.  This conclusion includes consideration of the likely removal of school septic systems from the property with sewage being discharged to an offsite location.

3. No commitment to extensive irrigation of athletic fields should be made until a thorough study of irrigation water needs and their timing through the growing season is made.

4. It appears clear that the potable water demands of the planned expansion will keep the water demand of the School Campus water system below 50,000 gpd, so that no Water Diversion Permit will be required.

5. At a minimum, one additional well of at least 30 gpm capacity will be needed to comply with the regulations of the CTDPH and the CTDPUC, both of which agencies have regulatory authority over public water supplies of this nature.

RECOMMENDATIONS (pages 10 and 11)

1. The metering of water use that was initiated in January should be continued indefinitely to establish more reliable figures for water use on an average, maximum week and maximum-day basis, to provide a more reliable basis for design flow figures for approval by the CTDPH and CTDPUC.

2. Before a commitment is made to drilling a new well, consideration should be given to testing one or more of the wells previously drilled on the campus for yield and water qualitv if these well sites are acceptable to the CTDPH as appropriate public water supply well sites.  These wells are nicely spread over the property, and the past chloride impacts of the salt pile on the Town Garage property have probably been largely attenuated by dilution.

3. The well site previously selected and field-approved by the CTDPH is acceptable as a backup well location in our viewpoint.  If none of the existing wells are acceptable for use in the potable water system, LBG would prefer to see the backup well site farther to the north on the property, so that the supply wells could be operated alternately, an operational program that would minimize any possible offsite impacts.  This approach may not be necessary but is regarded as a prudent alternative.
 

4.  If extensive irrigation of athletic fields is planned, a detailed and in-depth study of irrigation water needs and timing is required.  Such a study will require coordination among the designer of the athletic fields, an irrigation system designer/installer and a hydrogeologist.

LEGGETTE, BRASHEARS & GRAHAM
 

R. G. Slayback,
Chairman

cmp
May 31, 2000

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