HomeMy WebLinkAbout20250566 33-35 Caroline St Site Plan Revised Dewatering Letter - 35 Caroline Dempsey Construction & Development
54 Minot St, Boston, MA 02122
July 14, 2026
To Whom It May Concern:
Based on two prior excavations, we believe we will not encounter any groundwater until
approximately 12’ 6” below grade on Caroline Street. Once we encounter the water table, water
will be funneled through crushed stone to one of the few local sumps in the site. There the water
will be tested for any chemicals before being pumped through a geotextile filter bag to filter out
any remaining silt. The geotextile bag will be placed right outside of the site barriers on top of
the storm drain on Caroline Street. Below are images from the prior excavations, rough sump
locations and diagram, and details of the geotextile bag.
Sincerely,
Cronan Dempsey
Dempsey Construction & Development
Local Sump Diagram
- Above is a rough diagram of how on-site sumps will look
- Sumps will include a perforated drainage pipe encased in crushed stone that will filter out
initial mud and silt and provide a space for water to be tested for any chemicals
- Sump pumps in the drainage pipe will then pump water to the final sump and/or directly
to the geotextile bag and into the Caroline St storm drain
Geotextile Bag Details
- A geotextile filter bag like the one pictured above will be placed over the storm drain on
Caroline Street to act as a final filter for the groundwater before it enters the drain.
- We plan to use a 2’ x 2’ or 3’ x 3’ bag like the one linked below
- https://www.grainger.com/product/ENPAC-Dewatering-Bag-36-in-x-36-38E778
Dempsey Construction & Development
Test Pit 1
- Water table encountered at 12’ 6” below grade on Caroline Street
Te st Pit 2
- Water table encountered at 12’ 6” below grade on Caroline Street
Dempsey Construction & Development
Excavation and Sump Locations