HomeMy WebLinkAbout2012-02-07 Planning Board Supplemental Materials (18)
Enright, Jean
From:Lisa Eggleston [lisa@egglestonenvironmental.com]
Sent:Thursday, January 26, 2012 12:26 PM
To:Tymon, Judy; Susan Harrington
Cc:mike.carter@gcgassociates.net
Subject:RE: Fountain Drive
Judy,
I was actually able to review all the revisions on the pdfs and they seem to address all of my
comments satisfactorily.
The pea stone diaphragm and the grass swale should be raked each spring, and the stone may need
to be periodically replenished. The sediment forebay will also need to be cleaned out on an annual
basis. These should be incorporated in the O&M plan.
Let me know if you have any questions or need anything else.
Lisa
Lisa D. Eggleston, P.E.
Eggleston Environmental
Please note our new mailing address:
32 Old Framingham Rd., Unit #29
Sudbury, MA 01776
tel 508.259.1137
fax 866.820.7840
lisa@egglestonenvironmental.com
From: jtymon@townofnorthandover.com
To: sharrington@gcgassociates.net; lisa@egglestonenvironmental.com
CC: mike.carter@gcgassociates.net
Date: Thu, 26 Jan 2012 12:07:59 -0500
Subject: RE: Fountain Drive
Susan,
Thanks for the update. Lisa, do you need a hard copy of the plans for a final review?
Judy
From: Susan Harrington [mailto:sharrington@gcgassociates.net]
Sent: Wednesday, January 25, 2012 12:05 PM
To: 'Lisa Eggleston'
Cc: Tymon, Judy; Mike Carter
Subject: RE: Fountain Drive
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Hi Lisa,
In response to your comments I have attached preliminary PDF copies of revised plans. Sheets revised and attached are
the Proposed Site Plan (Sheet 4), Detail Sheet II (Sheet 6 of 6), and Post Drainage Plan. Revised Post Drainage Hydro CAD
analysis is attached.
The following are your comments as they are addressed:
Rain garden design should be based on the total area that drains to it (e.g. at least a portion of the community
building roof), not just the pavement areas modeled. - Drainage design now includes half of the Community
Building roof. (Post drainage calcs attached)
Additional pretreatment is needed for the pavement runoff into the rain garden. For the sheet flow off the new
parking lot you could add a stone trench or pea stone diaphragm, followed by the grassed channel, or a forebay
in the rain garden. The piped discharge should also have a sediment forebay. – Pea stone diaphragm and
sediment forebay are added to design plan and detail sheet.
In order to provide adequate treatment, soil media in the rain garden needs to be at least 24 inches deep, and 30
inches if trees are proposed. –Soil media is revised to show 24” depth.
Based on our discussion of water levels in the area it appears that there will be adequate separation to
groundwater beneath the rain garden; the Planning Board can condition that confirmatory soil tests be done prior
to installation. – OK.
Based on the type C soils, the design infiltration rate should be a maximum of 0.27 in/hr using the Rawls table.
The model uses a rate that converts to 0.42 in/hr over the bottom area shown on the plan. –New hydrocad
calculations attached with summarys to show design infiltration rate of 0.27 in/hour is used.
Plan should show an overflow outlet/swale from the rain garden, consistent with the way it is modeled. As we
discussed, the outlet should be located and/or graded so that the flow is distributed overland toward the
catchbasin at the intersection of East Water St. and Davis St. –Proposed overflow weir is designed for Rain
Garden to direct any overflow to grassed area where it will flow overland towards existing catch basin rather than
flowing to East Water Street.
The berm around the rain garden as shown on the plan is not consistent with the 3:1 side slope shown in the
detail. – Overall grading in Rain Garden area is refined on plan. Rain garden depth is revised from a 6” to 9”
depth sloping up over 2.25’.
I suggest naturalizing the shape of the rain garden so that it just looks like a landscape feature. – Revised shape
to follow contours.
Snow storage for new parking areas should be addressed. – Locations shown on plan for new parking areas as
well as currently used location.
Where possible, I recommend directing the upgraded roof downspout/splash pads to flow to pervious areas of
the site and away from paved areas. – Note added to plan and detail sheet.
Please contact me with any questions or comments regarding this preliminary review submission.
Thank you,
Susan Harrington
From: Lisa Eggleston [mailto:lisa@egglestonenvironmental.com]
Sent: Friday, January 20, 2012 4:06 PM
To: sharrington@gcgassociates.net
Cc: Judy Tymon
Subject: Fountain Drive
Hi Susan,
Following up on our discussion this morning, here is a summary of my comments on the Fountain Drive project:
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Rain garden design should be based on the total area that drains to it (e.g. at least a portion of the community
building roof), not just the pavement areas modeled.
Additional pretreatment is needed for the pavement runoff into the rain garden. For the sheet flow off the new
parking lot you could add a stone trench or pea stone diaphragm, followed by the grassed channel, or a forebay
in the rain garden. The piped discharge should also have a sediment forebay.
In order to provide adequate treatment, soil media in the rain garden needs to be at least 24 inches deep, and 30
inches if trees are proposed.
Based on our discussion of water levels in the area it appears that there will be adequate separation to
groundwater beneath the rain garden; the Planning Board can condition that confirmatory soil tests be done prior
to installation.
Based on the type C soils, the design infiltration rate should be a maximum of 0.27 in/hr using the Rawls table.
The model uses a rate that converts to 0.42 in/hr over the bottom area shown on the plan.
Plan should show an overflow outlet/swale from the rain garden, consistent with the way it is modeled. As we
discussed, the outlet should be located and/or graded so that the flow is distributed overland toward the
catchbasin at the intersection of East Water St. and Davis St.
The berm around the rain garden as shown on the plan is not consistent with the 3:1 side slope shown in the
detail.
I suggest naturalizing the shape of the rain garden so that it just looks like a landscape feature.
Snow storage for new parking areas should be addressed.
Where possible, I recommend directing the upgraded roof downspout/splash pads to flow to pervious areas of
the site and away from paved areas.
Feel free to contact me directly if you have any questions. As we agreed, I will anticipate receiving electronic versions of
your revisions to review before you produce a final set of plans for the Planning Board hearing on Feb 7th.
Lisa D. Eggleston, P.E.
Eggleston Environmental
Please note our new mailing address:
32 Old Framingham Rd., Unit #29
Sudbury, MA 01776
tel 508.259.1137
fax 866.820.7840
lisa@egglestonenvironmental.com
Please note the Massachusetts Secretary of State's office has determined that most emails to and from municipal offices and officials are public records. For more
information please refer to: http://www.sec.state.ma.us/pre/preidx.htm.
Please consider the environment before printing this email.
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Please note the Massachusetts Secretary of State's office has determined that most emails to and from municipal offices and officials are public records. For more
information please refer to: http://www.sec.state.ma.us/pre/preidx.htm.
Please consider the environment before printing this email.
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