HomeMy WebLinkAboutApplication Files_82693_pg0791 Mr.Jeffrey Doolittle,P.E.
Town of South Windsor
Project No.: 72189
November 11,2011
Page 5
Response: To properly function as a stormwater treatment device,deep-sump catch basins were designed
as off-line structures. This will prevent the re-suspension of sediment during high intensity
storm events. In order to incorporate deep sump catch basins into the design of CT Studios,
tee connections into the main drainage lines is necessary. Stormwater piping will be
constructed using HDPE materials fabricated specifically for the ability to connect via tees.
VHB has extensive experience working this product and has not witnessed any clogging or
joint failure issues created due to the use of these tees.
Comment 20: There needs to be a catch basin or leak-off on the north side of the road at the low
point by Infiltration Basin 1.
Response:. A curb break has been added to the site plans at this location. (C-8)
Comment 21: Infiltration Basin 1 needs a stone lined inlet,low level outlet and overflow spillway
or provisions.A berm should be considered for the north side of this basin to prevent
any water overflowing onto properties to the north.
Response: Infiltration Basin 1 was designed using HydroCAD software to ensure that up to and
including the 100-year design storm could be accommodated by the basin. Incoming surface
water velocities do not require stone inlet protection. Permanent erosion control fabric will be
installed within the inlet swale and sediment forebay to prevent scouring. Should a storm
event larger than the 100-year design storm occur,Catch Basin 28 has been designed as an
emergency overflow into the subsurface infiltration system.
Comment 22: Check the TF elevation for CB-31.It appears this should be E1.59.5.
Response: The rim elevation of CB-31 has been revised to 59.9. Invert elevations have also been lowered
to.accommodate constructability.
Comment 23: The underground infiltration system galleys need to be specified and designed for H-
20 heavy traffic loads.I suggest the northeast infiltration basin be moved further
north so it's not under the road.The number of chambers and/or length of infiltrator
rows need to be called out.
Response: The underground infiltration system is proposed to be constructed of Stormtech MC-3500
chambers. These units are designed to withstand heavy traffic loads. With 24 inches of
compacted cover(as specified for CT Studios),these units are designed to withstand a
dynamic wheel load of up to 16,000 lbs,which is required to meet H-20 loading.
The number of chambers in each row has been added to the site plans.
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