HomeMy WebLinkAboutCLA-6182Z - PW Drainage Letter 2024-12-17Page 1 of 4
December 17, 2024
CLA Engineers, Inc. | 317 Main Street, Norwich CT 06360 | 860.886.1966 | www.claengineers.com
December 17, 2024
Leonard Bunnell, Mayor
John Carlson, Director of Public Works
Meredith Badalucca, Assistant Planner
Town of Montville
310 Norwich-New London Tpke., Uncasville, CT 06382
Via Email: lbunnell@montville-ct.org
jcarlson@montville-ct.org
mbadalucca@montville-ct.org
RE: Town Public Works Facility – Drainage Modifications
CLA-6182Z
To All,
CLA has previously consulted with John Carlson for the replacement of the existing drainage pipe
that runs through the Public Works garage building at the Maple Avenue facility. The existing
pipe is highlighted in yellow on Picture 1. The existing pipe appears to be a 15” corrugated metal
pipe, presumed to have been installed prior to 1970. A PVC pipe section has been inserted into the
inlet due to the deterioration of the metal pipe, and the section from the building to the discharge
is corrugated polyethylene pipe.
The attached Picture 2 is an excerpt from the 1970 Connecticut airphoto showing a garage in place,
what appears to be the swale along the driveway that collects stormwater runoff from the hill along
Maple Avenue, and presumably a culvert or conveyance for the stormwater to discharge through
the garage building. In our opinion, due to the age and continuous use of the stormwater system,
the Town would have a prescriptive right to use and maintain the existing drainage system.
Public Works wishes to replace the metal pipe through the garage building, and remove the existing
catch basin from within the garage bay. Picture 1 depicts the garage, catch basin, and subject
piping. This work will provide several benefits:
1. Older metal pipes typically rot along the bottom flow line, and commonly cause clogging
problems or potentially complete failure of the pipe. This preemptive pipe replacement
work will allow the Public Works staff to perform the work under normal controlled
working conditions and not under an emergency situation if the pipe clogs or fails
completely.
2. Removing the catch basin from within the garage removes a potential source of pollution
from the storm drainage system. Vehicle washdown water, snow melt, or fluids from the
trucks are common sources of pollution within garages. A trench drain is present within
this garage bay intended to collect this runoff and discharge it to the sewer system.
CLA Engineers, Inc.
Civil Structural Survey
317 MAIN STREET NORWICH, CT 06360 (860) 886-1966 (860) 886-9165 FAX
Page 2 of 4
December 17, 2024
CLA Engineers, Inc. | 317 Main Street, Norwich CT 06360 | 860.886.1966 | www.claengineers.com
However, the existing catch basin is located in close proximity to the trench drain and
could potentially collect the polluted runoff and discharge it through the stormwater
system. The removal of the catch basin will eliminate this possibility.
The replacement of the existing pipe and removal of the catch basin does not change the
contributing watershed to the drainage system or to the outlet. Therefore, there is no change in the
amount of stormwater that will discharge from the system.
Public Works staff has started the replacement piping work by installing a new culvert outlet and
a new manhole at the rear of the garage building (shown in green on Picture 1). The new manhole
appears to be on the Town property. It appears that the new discharge piping is on property now
or formerly Central Vermont Railroad. The manhole and discharge pipe are not connected to the
existing drainage system and are not currently active. Public works has ceased work on the project
at this time.
While in our opinion the Town has the right to use and maintain the existing pipe discharge, it is
not clear whether the Town has the right to install a new outlet. In a brief review of the land
records, a formal easement or rights were not found.
We recommend the following:
1. Remove the newly installed discharge pipe and restore the surface to the pre-existing
condition.
2. Reconfigure the newly installed manhole to discharge to the existing corrugated
polyethylene pipe at the rear of the building, thereby reusing the exiting discharge piping
that is currently in place. This work could remain on Town property.
The drainage pipe replacement work through the building is located on Town property and can be
performed at any time. Increasing the pipe size to 18” through the garage building is prudent for
future planning. As previously noted, the contributing watershed remains unchanged; the change
in pipe size through the garage building will have no impact to the amount of stormwater discharge.
Please feel free to call me at our office or email khaubert@claengineers.com with any questions or
if you require additional information.
Very truly yours,
CLA Engineers, Inc.
Kyle Haubert, P.E.
Page 3 of 4
December 17, 2024
CLA Engineers, Inc. | 317 Main Street, Norwich CT 06360 | 860.886.1966 | www.claengineers.com
Picture 1 - Excerpt from Existing Conditions
Page 4 of 4
December 17, 2024
CLA Engineers, Inc. | 317 Main Street, Norwich CT 06360 | 860.886.1966 | www.claengineers.com
Picture 2 - 1970 CT Airphoto