20070972 Ver 1_Staff Comments_20070615 (1384)

Adkin Branch Stream Restoration Project (Lenoir) 07-0972
Subject: Adkin Branch Stream Restoration Project (Lenoir) 07-0972
From: Annette Lucas <[e-mail]>
Date: Fri, 15 Jun 2007 12:10:19 -0400
To: eric Kulz <[e-mail]>, Tammy L Hill <[e-mail]>
CC: John Dorney <[e-mail]>
Eric & Tammy,
I have reviewed this project and spoken with Lin Xu of the EEP. Here were my
observations regarding the stormwater devices:
- Sand filters: In order to comply with the DWQ BMP Manual as well as good
engineering practice, the seasonal high water table must be at least two feet below
the bottom of the sand filter. If the water table level is appropriate, then the
design is acceptable; however, I would suggest that a greater load of TN could be
removed at a lower cost with bioretention areas. If the water table level is not
appropriate, then a different type of BMP must be used; I would suggest a pocket
wetland.
- Constructed wetland: Please verify that John Dorney gave them permission for this
pseudo-in-line constructed wetland. If so, then we need to determine whether the
EEP is required to design the wetland in accordance with the DWQ BMP Manual. If
the wetland design must be in accordance with the BMP Manual, then it will need to
be redesigned and more information will need to be provided per the Extended
Detention worksheet on the 401 Unit web site. If the design does not have to
comply with the DWQ BMP Manual, then I will leave it to your judgment about whether
you think it will work. I've never seen a design like that - it certainly is
creative!
Annette
1 of 1 6/15/2007 12:26 PM