SITE VISIT MEMORANDUM

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SITE VISIT MEMORANDUM

Project Name: Couper Farm Construction Observations Green Project No. 15002.030 Subject: Site Visit 3

Date / Time: 7/13/2017 (11:00 AM‐11:45 AM)

Location: On site

Weather: Sunny, 70°F

Prepared By: Tom Bigelow, Green International (Green) Attendees: Tom Bigelow (Green), Luke Boucher (Green)

Site Visit Summary:

Tom Bigelow (TB) and Luke Boucher (LB) performed a site visit at Couper Farm Estates on 7/13/2017. The Town received approximately 3‐inches of rain in approximately 90 minutes the previous evening. The Contractor was not on site at the time of the site visit. Equipment in use: No equipment in use Site Observations:  Green arrived on site at 11:00 AM. The roadway subgrade was wet and appeared to be saturated. As noted above, Littleton received approximately 3‐inches of rain the previous evening.  Standing water was observed in CB 20 and 21. It does not appear that the outlet pipes have been constructed from any catch basins; therefore, any water entering the basins is being retained within the structure. This does not appear to be groundwater. The frame and grates are set on top of the structures, approximately 1‐foot above the surrounding ground. The Contractor should investigate how water is entering these structures and confirm that sediment is not entering the structures in the same manner.  Signs of significant erosion were noted throughout the site.  Significant erosion was noted at the inlet and outlet of the temporary 18” HDPE culvert located at Couper Farm Sta. 10+50. Additional erosion was observed between Sta. 10+50 and Great Road. Stormwater appears to be sheeting from Great Road and from the nearby fields, concentrating at the embankment toe, resulting in erosive flows. Additionally, the temporary culvert appears to have been broken by the Contractor to install the water line, introducing additional sediment to the stormwater flow from the roadway surface. Green recommends the Contractor install erosion prevention and control measures at this location. Green also recommends the Contractor install the permanent culvert shown on the plans and stabilize the area as soon as possible.

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Site Visit 3 Couper Farm Construction Observations 7/13/2017 (11:00 AM‐11:45 AM) Green Project No. 15002.030

above. While this area is not flagged as a wetland, the developer should take measures to prevent sediment from discharging outside of the proposed limit of disturbance.

 It appeared some temporary sediment basins were constructed, particularly on either side of Infiltration Basin No 1 and No 2. The previous day’s storm appeared to have overwhelmed the temporary sediment basins. It appears that water from at least one of the temporary sediment basins had breached its wall and resulted in a significant sediment deposit in the adjacent wetland. The site’s perimeter controls were breached in numerous locations behind Lots 5 – 10. Silt fence had recently been installed; however, portions did not appear to be keyed into the ground, as is standard practice. This allowed water and sediment to bypass under the erosion controls. The Conservation Commission is aware of the situation and has since issued an enforcement order. The Developer has also retained the services of a wetland scientist to assist with remediation at this location and others on site.  A stockpile of loam was located up‐gradient of Infiltration Basin No. 2. No perimeter controls were present around the stockpile. It appears that material from the stockpile washed into Infiltration Basin No. 2. The Contractor should remove the excess material and the Infiltration Basin should be monitored to ensure stormwater still infiltrates though the basin bottom.

 Silt fence was installed downstream of the outlet of flared end 83, between Lots 13 and 14. Sediment appears to have overwhelmed the silt fence; however, additional perimeter controls are in place down‐gradient of the silt fence and did not appear to be breached. The Contractor should maintain and replace the erosion controls, as required.

 Due to inaccessibility resulting from the saturated soils, a review of erosion downstream of Infiltration Basins No. 3 and No. 4 was not performed.

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(Picture of the break in the temporary culvert at Sta 10+50 on Couper Farm Road.)

(Sediment in agricultural space (Open Space C) located south of Couper Farm Road)

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(Sediment from a temporary infiltration basin breaching the perimeter erosion controls and entering the flagged wetland) (Evidence of runoff from loam stockpile entering Infiltration Basin No. 2)

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(Erosion cut through embankment constructed near Lot 11) (Sediment at the outlet of flared end 83)