20061085 Ver 2_Emails_20061130

RE: Elementary School G (DWQ EXP No. 06-1085)
Subject: RE: Elementary School G (DWQ EXP No. 06-1085)
From: "Jay Guffey" <[e-mail]>
Date: Thu, 30 Nov 2006 12:03:22 -0500
To: "'Jay Guffey"' <[e-mail]>, <[e-mail]>
CC: "'Cyndi Karoly"' <[e-mail]>, "'Eddie MacEldowney"' <[e-mail]>
Cynthia or Cyndi,
I have another question concerning your comments about the bio retention
areas being undersized. I have attached a pdf file of the calculations of
the bio retention area size from Bill Hunts website
http://www.bae.ncsu.edu/to is/bioretention/desi n-sizing.html and I came out
with a required size that is smaller than what is provided. Also the pdf
file shows the calculations as suggested in the BMP Manual page 38 (2nd
paragraph) which gives me a greater size required than what is provided.
Which sizing calculations do you want?
Also please respond as soon as possible to the questions listed below. You
have given me a 5 day turn around and I would greatly appreciate your
response so I can adequately address your concerns.
Thank you.
Jay Guffey, EI
Davis-Martin-Powell & Associates, Inc
Engineering-Land Planning-Surveying
6415 Old Plank Road
High Point, NC 27265
Phone: [phone]
Fax: [phone]
www-dmp-inc.com
[e-mail]
-----Original Message-----
From: Jay Guffey [mailto:[e-mail]]
Sent: Wednesday, November 29, 2006 10:30 AM
To: 'Cynthia.vanderwieleCncmail.net'
Cc: 'Cyndi Karoly'; 'Eddie MacEldowney'
Subject: Elementary School G (DWQ EXP No. 06-1085)
Cynthia,
I got your letter yesterday afternoon and I have a few questions about your
comments.
1 of 3 12/4/2006 12:18 PM

RE: Elementary School G (DWQ EXP No. 06-1085)
1. The Operation and Maintenance Agreement is being worked on. An 0&M
agreement has been sent to you for the wet detention basin, but not for the
bio retention areas. From our email conversation the other day, DWQ does
not have a typical O&M Agreement for Bio retention areas like they do for
wet detention basins. I am in the process of gleaning material from the BMP
Manual and Bill Hunt's website per your suggestion. This as you have
indicated must be signed and notarized. We will get this to you as quickly
as possible. We can fax a copy to you once signed and forward the original
plus two copies when we get the signed original back from UCPS. Is this
acceptable?
2. Drainage Area 1 & 4 (Bio Retention) The ponding depth is shown as 6"
on the plans. The bio retention worksheets are confusing in the
description. The orifice invert out is the invert of the overflow pipe and
the outlet structure invert in is the invert of the overflow. Is the
permanent pool elevation the elevation of the mulch and the temporary pool
elevation the elevation of the throat of the overflow? Or do I need a
saturated zone meaning I will have the invert of the overflow discharge pipe
6" above the bottom of invert of the underdrain pipe into the overflow
structure?
3. Drainage Area 3 (Wet Pond) The forebay volume is 230 of the
permanent sediment storage. Previously, one of the comments said the
forebay was way oversized, but looking at the calculations for the forebay,
it appeared that the volume went from the bottom of the pond to the top of
the gabions and then from the gabions it included the whole volume of the
pond from the gabions to the permanent pool level. I can not get 200 of
the total volume in 2 feet (from bottom of pond to top of gabions). 200 of
the pond total volume is appox 13900 cubic yards. Even if 2 raise the
gabions 1 foot, then wrap them around the riser the volume would not meet
200. If I make the pond larger, (which is next to impossible due to the
property line location) I still run into the same problem, since a larger
pond would result in a larger total volume. Please provide me some guidance
on how you want this calculated. Do I determine the volume of the forebay
as if the gabions extended to the permanent pool level?
4. The SA/DA ratio used the permanent pool level minus the permanent
sediment storage which is 3 feet not 5 you have indicated. I can
re-determine the SA/DA using 5 feet, but this is different from how I have
had to design ponds for nearby municipalities. Have I been doing this
wrong for the past 5 years?
Also, is there anyway DWQ can issue a permit for construction with a
contingency that the storm water plan be completed prior to final approval?
The contractor has been instructed to stay out of the wetlands and streams
until approval has been granted and right now an agreement has been worked
out between the contractor and an adjoining landowner for access. But the
agreement expires as of Jan 1, and the building of the road is a top
priority for construction to continue.
Any clarification will be greatly appreciated. Thank you.
Jay Guffey, EI
Davis-Martin-Powell & Associates, Inc
2 of 3 12/4/2006 12:18 PM

RE: Elementary School G (DWQ EXP No. 06-1085)
Engineering-Land Planning-Surveying
6415 Old Plank Road
High Point, NC 27265
Phone: [phone]
Fax: [phone]
www-dmp-inc.com
j guffeyc~dmp-inc . com
BIOCELL SIZING.PDF '~ Content-Type: application/pdf
', Content-Encoding: base64
3 of 3 12/4/2006 12:18 PM

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Elemegtary School G (DWQ EXP No. 06-1085)
Subject: Elementary School G (DWQ EXP No. 06-1085)
From: "Jay Guffey" <[e-mail]>
Date: Wed, 29 Nov 2006 10:29:51 -0500
To: <[e-mail]>
CC: "'Cyndi Karoly"' <[e-mail]>,"'Eddie MacEldowney"' <[e-mail]>
Cynthia,
I got your letter yesterday afternoon and I have a few questions about your
comments.
1. The Operation and Maintenance Agreement is being worked on. An 0&M
agreement has been sent to you for the wet detention basin, but not for the
bio retention areas. From our email conversation the other day, DWQ does
not have a typical 0&M Agreement for Bio retention areas like they do for
wet detention basins. I am in the process of gleaning material from the BMP
Manual and Bill Hunt's website per your suggestion. This as you have
indicated must be signed and notarized. We will get this to you as quickly
as possible. We can fax a copy to you once signed and forward the original
plus two copies when we get the signed original back from UCPS. Is this
acceptable?
2. Drainage Area 1 & 4 (Bio Retention) The ponding depth is shown as 6"
on the plans. The bio retention worksheets are confusing in the
description. The orifice invert out is the invert of the overflow pipe and
the outlet structure invert in is the invert of the overflow. Is the
permanent pool elevation the elevation of the mulch and the temporary pool
elevation the elevation of the throat of the overflow? Or do I need a
saturated zone meaning I will have the invert of the overflow discharge pipe
6" above the bottom of invert of the underdrain pipe into the overflow
structure?
3. Drainage Area 3 (Wet Pond) The forebay volume is 230 of the
permanent sediment storage. Previously, one of the comments said the
forebay was way oversized, but looking at the calculations for the forebay,
it appeared that the volume went from the bottom of the pond to the top of
the gabions and then from the gabions it included the whole volume of the
pond from the gabions to the permanent pool level. I can not get 20% of
the total volume in 2 feet (from bottom of pond to top of gabions). 200 of
the pond total volume is appox 13900 cubic yards. Even if I raise the
gabions 1 foot, then wrap them around the riser the volume would not meet
200. If I make the pond larger, (which is next to impossible due to the
property line location) I still run into the same problem, since a larger
pond would result in a larger total volume. Please provide me some guidance
on how you want this calculated. Do I determine the volume of the forebay
as if the gabions extended to the permanent pool level?
4. The SA/DA ratio used the permanent pool level minus the permanent
sediment storage which is 3 feet not 5 you have indicated. I can
re-determine the SA/DA using 5 feet, but this is different from how I have
had to design ponds for nearby municipalities. Have I been doing this
wrong for the past 5 years?
Also, is there anyway DWQ can issue a permit for construction with a
contingency that the storm water plan be completed prior to final approval?
The contractor has been instructed to stay out of the wetlands and streams
until approval has been granted and right now an agreement has been worked
out between the contractor and an adjoining landowner for access. But the
agreement expires as of Jan 1, and the building of the road is a top
priority for construction to continue.
1 of 2 12/4/2006 12:18 PM

Elementary School G (DWQ EXP No. 06-1085)
Any clarification will be greatly appreciated. Thank you.
Jay Guffey, EI
Davis-Martin-Powell & Associates, Inc
Engineering-Land Planning-Surveying
6415 Old Plank Road
High Point, NC 27265
Phone: [phone]
Fax: [phone]
www-dmp-inc.com
~[e-mail]
2 of 2 12/4/2006 12:18 PM