The Town of Sherborn seeks formal proposals from preferably New England-based certified lake management consultants to create a MassDEP approved 9-element Watershed Based Plan (WBP) for the 126-acre lake Farm Pond, inclusive of a comprehensive internal and external nutrient load analysis. If questions arise on completing the RFP, please send questions in written format only to the Town contact. Questions and answers will be posted publicly on the Town website as Addendum's to the RFP, with no mention of the source of the question(s). Please email Jeanne Guthrie when you obtain RFP documents so that any questions/addendums that may arise can be emailed to all who expressed an interest and obtained the documents. Farm Pond, a 126-acre kettle pond located approximately 20 mile west of Boston in the semi-rural Town of Sherborn (pop 4500) is a treasured natural resource enjoyed by many swimmers, sailors, boaters, fishermen, residents, and visitors. This MA Great Pond has an estimated contributing watershed of about 435 acres, no major surface tributaries (but potential minor wetland tributaries), and one small outlet stream flowing to the nearby Charles River. Except for a 12-acre Town-owned Farm Pond Reservation property, with a public beach, boat ramp, bath house, well, septic system, and paved parking lot, the rest of the watershed is privately owned. Approximately 30 residential homes lie within the largely forested watershed, all with private septic systems and private wells. Of these, about 20 properties have direct shoreline frontage. Information within the Town's existing 2015 Farm Pond Management Plan can be directly used to complete much of one of the nine MA WBP elements, Element A - Identification of the causes and watershed sources of nutrients, but some updated watershed and land use GIS mapping will be required. The following separate tasks have been identified as important steps in completing the MA WBP for Farm Pond. In addition, the RFP seeks to determine a key factor that the US EPA and MA WBP elements normally ignore: the contribution of in-lake nutrient sources from the phosphorus and nitrogen components trapped in the sediments from historical watershed inputs, that are now suspected to be released into the lake at a growing rate due to climate change (warmer water temperatures, leading to longer periods of water column stratification, causing larger water volume anoxic conditions, driving more substantial release of iron-bound phosphorus from the lake bottom). Lake water sampling: - On at least seven dates between April to October 2023 collect at least four vertical samples from a mooring point near the deep hole (typically 15 to 16 m depth). Sample # 1) 0.5 m depth, sample # 2) top of thermocline, sample # 3) just below thermocline, and sample # 4) 1 m above the lake bottom. All four samples to be analyzed for: Total Phosphorus (TP) and Total Nitrogen (TN). - On every field event collect at least one field duplicate sample and one field blank. - Top (#1) and bottom (#4) samples, along with field duplicate and field blank to be analyzed for ammonia-nitrogen and nitrate-nitrogen for each event. - Top (#1) and bottom (#4) from April and August events to be further tested for particulate and dissolved organic carbon (POC/DOC), manganese, iron, and alkalinity. - For each of the seven testing events a second top (#1, 0.5 m) sample to be taken and analyzed for chlorophyll-a. Outlet structure water sampling: At times of high lake water level a flow of water occurs over the man-made earthen berm located on the eastern side of Farm Pond, feeding the isolated lagoon that eventually drains into a small stream out to the Charles River. - Attempt to collect at least four water samples during the 2023 season at point of berm overflow, and have tested for TP and TN. If no flow is present, no samples need to be collected. The method of Contractor Selection has not been Determined at this time.
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