Photo 1: Typical 4 Weephole

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1 April 25, 2008 MEMORANDUM To: Shelly LeClaire Milford Highway Department From: Tom Jenkins, P.E. Baystate Environmental Consultants, Inc. RE: Results of Field Inspection of Charles River Culvert Potential Illicit Discharge BEC Project No Baystate Environmental Consultants, Inc. (BEC) completed the fieldwork component of the Charles River culvert investigation on Thursday, April 24, A three-person team of engineers entered the downstream portal of the culvert, and walked the entire length of the culvert to its upstream mouth, just north of Main Street. In general, we found the 900±foot long culvert to be in excellent condition. Based on our observations, the culvert construction and alignment appear to have been completed in substantial conformance with the original construction documents provided to us by Mike Santora. BEC acquired water samples from the Charles River immediately upstream of the culvert and immediately downstream of the culvert. We also obtained water samples from numerous (15±) weep holes that were found to be actively discharging. These weepholes were installed on both the left and right sidewalls of the culvert, spaced approximately every 10 feet. Approximately 2/3 of the weepholes were damp or had discernible flow with anticipated iron staining (see Photo 1). Approximately 1/3 of the weepholes were completely dry. The dry weepholes were predominately found in the middle third of the culvert. Page 1 of 5 Photo 1: Typical 4 Weephole Underneath Main Street, a 36 RCP storm drain entering the culvert from the west was observed to be discharging at a rate of approximately 25 gallons per minute (see Photo 2). Immediately prior to our

2 field work, Milford had experienced several days of dry weather. The most recent date of precipitation greater than 0.1 inches was April 12, 2008, according to the National Weather Service. Thus, this discharge was not from any precipitation event and is believed to be non-stormwater. It is likely that the discharge was primarily groundwater. Water quality test results, expected within the next several days, are expected to support this preliminary conclusion. Photo 2: Discharging 36 RCP Storm Drain Under Main Street The most disturbing observation made was a 4 cast iron pipe entering the culvert from the east, approximately in line with the centerline of Main Street (see Photo 3). This pipe entered the culvert approximately 2 feet above the culvert invert, thus placing the iron pipe about feet below the exterior grade. This pipe was observed intermittently by BEC for a period of about 90 minutes, during which time it discharged continuously at approximately 2-5 gallons per minute. The color of the discharge ranged from a light cloudy gray to a very dark, almost opaque black (see Photo 4). Staining around the pipe entry point is black, gray, and white, and an intermittent odor of sewage was noted. There is a weephole located about 18 upstream of the iron pipe, at slightly lower elevation, which had minimally discernible flow. Other weepholes are located approximately 10 feet upstream and ten feet downstream of the iron pipe discharge. Page 2 of 5

3 Photo 3: Suspected Illicit Discharge, Entering Culvert From the East, At Centerline± of Main Street Photo 4: Dark Black Color of Discharge from 4 Iron Pipe The Milford Sewer Department (MSD) was contacted, and John Mainini and several other members of his department arrived at the scene. Mr. Mainini and 2-3 others walked up the culvert from the downstream end to observe the flowing pipe. BEC took two water samples in bottles provided by the MSD, which they took to be analyzed at their facilities. BEC acquired samples for our own testing, to be performed by a Massachusetts certified laboratory. The MSD installed a bladder-type plug into the cast iron pipe in an attempt to stop flow. The plug was effective at stopping almost all of the flow, but a small trickle remained. The plug was in place for about 5 minutes, when the flow in the adjacent weephole was noted to increase dramatically. Our conclusion was that by stopping the flow from the iron pipe, the liquid was being diverted to other flow paths and then out the weephole. Soon, the bladder plug was removed. Page 3 of 5

4 Mr. Mainini indicated that the MSD would return over the next few days and place a temporary plug in the iron pipe and adjacent weephole, and wait a few days to see if any upstream problems or complaints developed. If no obvious problems were encountered, the MSD would then seal both the iron pipe and the adjacent weephole with hydraulic cement to eliminate the discharge. Based on observations of the type of construction, the 4 iron pipe was installed at the same time as the culvert. The pipe entered the culvert at a boxed-out penetration of the culvert sidewall, formed directly into the concrete pour (see Photo 5). It is our opinion that this discharge has been active for the entire period that the Charles River culvert has been in place, approximately 50 years. Photo 5: 4 Iron Pipe Entry Detail Eliminating this discharge will be an important step forward for the Town of Milford in its efforts to address water quality concerns in the Charles River. BEC is concerned that by plugging the iron pipe exit point and the adjacent weephole, the source of the discharge will not be adequately addressed, and the flowage will otherwise find its way into the Charles River, most likely by transference to the upstream or downstream weepholes. We urge Milford to investigate this discharge fully, determine its source, and divert the source into the municipal sewer collection system for treatment at the WWTP. Page 4 of 5

5 As soon as water quality results are available, BEC will provide a complete report of our findings. We felt the issue of the apparent illicit discharge described above deserved immediate reporting to you. Please contact us if we can provide any other interim information. Page 5 of 5