The Conservation Commission on Tuesday rebuked the Charleswood School developer for a lack of “urgency” in addressing recent stormwater management violations.

Judy Day, the town’s conservation administrator, explained that on Oct. 16, she observed silt beyond the limit of work in the buffer zone heading into a jurisdictional pond. It was “just off of the worksite for the new Charleswood School,” located at 147 Hayden Rowe Street. She suspected that this was caused by heavy rains two days before.

On Oct. 20, Day said she saw additional silt in two areas, one “just north of that same pond” and the other above it.

While Day acknowledged that the builder “has made a lot of improvements to the site” since that time, another concern was a hole in a concrete drain pipe. The pipe carries an intermittent stream across the planned entrance of the school.

Earlier in the process, Day noted that there were “all sorts of conditions” in place regarding the excavation and replacement of the pipe. The old pipe was cut through during the placement of utilities.

Said Day: “Obviously not how it was meant to be handled.”

“The breach occurred during excavation for what is the utility duct bank,” said project manager Joe Amara.

Because the pipe was “compromised,” it was removed, he added. It was repaired on the day of the meeting. Within the next two weeks, “the permanent fix” for the pipe will be completed.

Regarding the two runoff areas, Amara said they occurred in areas where the roadway’s grade is being heightened. By the end of the construction season, the grade should be elevated 5-6 feet.

“It was an unfortunate event,” he added. “We do have the measures in place per the contract. But sometimes you’re not going to really see where the water is going to flow until the rain event.”

Chair Melissa Recos advocated for a temporary berm to be placed at the roadway site to stabilize the area. Amara said a temporary berm should be in place within two weeks.

“Why does it take two weeks to build that berm if we have good weather?” questioned co-vice chair Ted Barker-Hook.

Project superintendent Nicholas Brait said the berm could be built in a week and installed by a subcontractor within a week. The construction team plans on backfilling the area to stabilize the slope before installing a berm.

Replied Barker-Hook: “I just don’t sense the urgency from you guys that I feel to make sure all of this is buttoned up as soon as absolutely possible.”

Recos agreed. She noted that the commission was concerned about the project’s erosion control plans before it started because of the soil condition there.

Amara said he will discuss the temporary berm installation with the contractors on Wednesday so that “it is at the forefront of their attention.”

Vertex project manager Chris Eberly addressed the commission, noting that the firm’s performance regarding this situation is being documented daily.

“We have made this point of emphasis right from the beginning,” he stressed. “We know the commission’s concerns, and we have relayed them from the initial bid.”

He added that engineering firm Tighe & Bond was brought on as a third-party reviewer by the Planning Board. It will serve as the “eyes and ears” of the board.

75 South Street remediation hearing continued

The commission voted 5-0 to continue the hearing for remediation plans for 75 South Street, the site of an old electronics company near Interstate 495.

Consultant Joe Marquedant explained that the 4-acre parcel is at the corner of Hayward and South streets. The Valpey Fisher technology company built its facility there circa 1973. It made circuit boards.

He added that the owner, who purchased the property last year, understood that there is “hazardous waste on the site below grade as a result of the activities of Valpey Fisher.” The remediation plan calls for several “injections sites,” where chemicals will be introduced to break down the hazardous materials.

The injection sites will be 20-50 feet deep, according to Marquedant. There also will be “a handful of monitor wells.”

Contaminated soil will be put in a sealed container and removed, he said. Once the work is completed, the site will be capped.

Environmental remediation expert Jarrod Yoder explained that iron with emulsified vegetable oil and lactate will be injected “to facilitate biological activity.” Then microbes will be added that will degrade the hazardous materials.

He said it is “a lot safer” than injecting chemicals typically used in this type of process, such as permanganate. The microbes are nontoxic.

Wetlands consultant Joe Orzel questioned whether the project could qualify as a limited project for contamination and mitigation remediation work. The applicant will check into that and will report back at the Nov. 4 meeting. The hearing was continued until then.

Orzel documented invasive species on the site in case they can be removed in the future. Member Ed Harrow said an emphasis on removing invasives now should be made.

NOI for office building off Lumber Street approved

The commission voted unanimously to approve a notice of intent (NOI) for REC Hopkinton to build a proposed a one-story office and retail building off Lumber Street. The 3.46-acre site is fully vegetated and undeveloped. It is bordered by apartments to the northeast, Lumber Street to the west and Independence Place to the north.

Fifty-seven trees are planned to be removed, including 44 in the buffer zone, said consultant Sophia Esdale. Proposed mitigation will include the planting of 38 red maple, spruce, service berry and creeping juniper trees that are native to the area. An invasive species management plan was submitted.

Orzel noted that previous questions have been addressed by the applicant.

North Mill Street hearings continued

The commission continued two hearings on 12 North Mill Street until Nov. 4, as the developer presented alternative plans at the meeting. One hearing was for the initial proposal, while the other was for soil testing.

Developer Lou Petrozzi noted that the Board of Appeals approved his request for a variance for a 30-foot front-yard setback. This prompted him to create four alternative proposals to move the proposed home forward and out of the wetland area.

Recos noted that a potential vernal pool was not documented on the original plans. This prevented the commission from evaluating the alternatives until the plans are corrected.

A site walk is planned for Saturday.

Berry Acres boardwalks approved

An exemption request for two boardwalks proposed by the Trails Committee for the Berry Acres neighborhood was unanimously approved. Trails Committee member Sean Kimball provided schematics. He noted that the boardwalks are meant to connect this neighborhood to the school campus.