SW5120101_Add Info Request_20120201

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AA 11
MA
NCDENR
North Carolina Department of Environment and Natural Resources
Beverly Eaves Perdue
Governor
Mr. Eric M. Tweed, PE
CH Engineering, PLLC
3220 Glen Royal Rd.
Raleigh, NC 27617
Dear Mr. Tweed:
Division of Water Quality
Charles Wakild, PE
Director
February 1, 2012
Dee Freeman
Secretary
Subject: Request for Additional Information
Stormwater Project No. SW5120101
Cantonment Trailer Relocations
Granville County
The Division of Water Quality Central Office received a Stormwater Management Permit Application for
the subject project on January 30, 2012. A preliminary review of that information has determined that
the application is not complete. The following information is needed to continue the stormwater
review:
1. Please provide the revised calculations for the offset payments through EEP that reflect the
lower amounts discussed today on the phone,
2. The J4 Annex site and grading plans were not submitted. Please submit 2 copie .
Y ► /AS t ry G L. K D�> -*" G 0) - (2 b e - 21 z�I ?-
3. The impervious area and % BUA shown on the supplement form for bioretention cell (BR) #2 is
not consistent with that shown in the calculations and the upper portion of the table on SWU-
101, IV.10. Based on this inconsistency, it appears the volume provided in BR#2 is not large
enough for the 50.2% BUA (90,281 sf)..
4. A soils report must be provided that specifically states what the SHWT elevation is based on
boring(s) within each of the bioretention cell footprints. The determination is done based on
visual observations of mottling of the soil. The soils information submitted only states that no
groundwater was encountered during the time of the borings. Also, the borings need to be
shown on a map with respect to the proposed cells.
5. For BR#2, the temporary pool elevation shown on the supplement is 477.75', but it is shown
lower on the cross-section and calculations at 477.60', Please revise.
6. For both BR#1 and BR#2:
a. On the supplements, the separation of IWS & surface should be a depth in feet, not an
elevation.
b. The supplements state no IWS is used, but an IWS is shown on the cross-section and
nutrient tool.
c. The supplements and cross -sections need to state the elevation of the IWS.
d. The supplements show incorrect VFS lengths. There is no VFS proposed for BR#1, and
the VFS for BR#2 is 40', not 504'.
Wetlands and Stormwater Branch
1617 Mail Service Center, Rateigh, North Carolina 27699-1617
Location: 512 N. Salisbury St. Raleigh, North Carollna 27604
Phone: [phone] FAX: [phone]
internet: www.ncwaterquality.org
An Equal Opportunity lAffirmaove Action Employer
NorthCaroiina
Naturallff

Mr. Eric M. Tweed, PE
SW5120101 - Cantonment Trailer Relocations
Page 2 of 2
February 1, 2012
e. The supplements show incorrect planting media depths of 2.5'. Only 2.0' is shown on
the cross -sections.
f. The supplements show 0.5' of washed sand, but none is shown in the cross -sections.
g. The bottom of the planting media elevation is not shown consistently between the
supplements and cross -sections.
7. The bioretention cross -sections need the following information shown/detailed.
a. When proposing grass cells, sod must be specified along with grass species of the sod.
b. The media mix specification needs to be shown.
Please note that this request for additional information is in response to a preliminary review. The
requested information should be received by this Office prior to March 3, 2012, or the application will be
returned as incomplete. The return of a project will necessitate resubmittal of all required items,
including the application fee.
If you need additional time to submit the information, please mail or fax your request for a time
extension to the Division at the address and fax number at the bottom of this letter. The request must
indicate the date by which you expect to submit the required information. The Division is allowed 90
days from the receipt of a completed application to issue the permit,
The construction of any impervious surfaces, other than a construction entrance under an approved
Sedimentation Erosion Control Plan, is a violation of NCGS 143-215.1 and is subject to enforcement
action pursuant to NCGS 143-215.6A.
Any revised calculations or plans must be sealed, signed, and dated; and have a revision date shown.
Please reference the State assigned project number SW5120101 on all correspondence. If you have any
questions concerning this matter please feel free to call me at [phone], or at
[e-mail].
Sincerely,
Robert D. Patterson, PE
Environmental Engineer
Stormwater Permitting Unit
CC" SW5120101 File
ec: LTC Toni Coats, CFMO - NCNG
Danny Smith - Raleigh Regional Office

,Sh/S! tot o 1
February 1, 2012
Robert Patterson, PE
NCDENR — DWQ
512 N. Salisbury St, 9"' Fir
Raleigh, NC 27604
RE: Camp Butner Cantonment Area
Stormwater Review
Revised Calculations & Supplement Forms
R1m@mO%q[91
FEB - 12017
VVETZAN S AN STORMWATER BRANCH
Dear Robert,
Per our phone conversations, I have updated the two Bioretention Basin Supplement
Forms to include the correct acreage and flow rates. These previously reflected earlier
design information which has now been corrected.
I also have received the updated Jordan Falls Nutrient Tool that you sent and pasted the
project data into it. I also got the same results you mentioned on the phone. This will
affect the buy down amount.
Attached are PDF versions of:
➢ Revised Suppleihent Form for Basin I
➢ Revised Supplement Form for Basin 2
➢ Revised Jordan/Falls Nutrient Accounting Too (Version 2,0)
Sincerely,
Eric Tweed, PE
CH Enginecriing, PLLC
919-788-0224
\oCAP,0//
SEk
m 3220 Glen Royal Road, Rolelgh, NC 27617 - TEL [phone] • FAx [phone]

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ENGINEERING
1-3-11
Robert Patterson, PE
Environmental Engineer
DWQ Stormwater Permitting Unit
Subject: Cantonment Trailer Relocations
Falls Lake Strategy Stormwater Permit
Granville County
Dear Mr. Patterson:
UO
JAN 3 0 2012
DENR' WAFER QUALITY
WETLANDS AND STOWIdWATER BRANCH
I've received the comments from October 7, 2010 and have made changes to the plans
and calculations to address the stormwater issues. Note that these plans have also
changed in the interim to meet some additional requirements of the Owner. Both the
DWQ comments and Owner changes have been addressed in the resizing of the
stormwater facilities.
To address your comments, please see below:
1. The TN and TP targets of 2.2 and 0.33 cannot be met with the proposed
stormwater treatment facilities. A buydown will be made in order to offset the
difference in what we are able to achieve and these numbers.
2. Acknowledged. A new supplemental sheet DWQ2 has been added to address
this.
3. The BUA area from the .I4 Annex site is listed on the DWQ1 sheet and will be
treated by excess capacity in the basins at the main site.
4. Contour labels have been added around the BMPs to help.
5. The DA delineations have been adjusted to include the bioretention cells. The
SWU-101 has been updated to show this.
6. This berm has been removed.
7. Additional calculations have been provided to show these items.
8. A new LSNFS supplement form is enclosed.
9. The missing volume has been added to bioretention 92 supplement form.
10. Calculations are included that show the overall site's pre and post flows from
the one-year 24-hr storm.
1 I. The soils report has been performed by subconsultants and is included.
12. Requested corrections have been made to SWU-101.
13. The referred to hole has been removed from`the calculations.
14. More detail for the level spreader splitter box is provided.
15. Additional details are also provided for the bioretention basins including the
note to have t1Te contractor grout the hole closed from the skimmer.
16. In the Nutrient Load Accounting Tool: the areas have been made consistent
and the soil group has been changed to C. The Cell size calculations are
provided but sizes are now different than the last ones due to changes.
■ 3220 Glen Royal Road, Raleigh, NC 27617 • TEL [phone] • FAX [phone]

A new application fee is enclosed. The contractor was instructed to proceed no further
than the construction entrance and silt fences. The erosion control plan is also being
resubmitted to Land Quality due to the Owner's changes since the overall disturbed area
did increase above the next threshold.
Sincerely,
Eric Tweed, PE
CH Engineering
Cc: Jack Johnson - NCNG

MCDEN
North Carolina Department of Environment and Natural Resources
Division of Water Quality
Beverly Eaves Perdue Coleen H. Sullins Dee Freeman
Governor Director Secretary
October 7, 2011
Mr. Eric M. Tweed, PE
CH Engineering, PLLC
3220 Glen Royal Rd.
Raleigh, NC 27617
Subject: Falls Lake Strategy Stormwater Perm it"Application Return'
Cantonment Trailer Relocations
Application Return #1280
Granville County
Dear Mr, Tweed:
The Division of Water Quality received your Stormwater Management Permit Application for the
subject project on September 16, 2011. After a preliminary review the submittal was found to be
substantially incomplete. Per DWQ requirements and policies, this office is hereby returning the
subject application package as incomplete.
The application is incomplete based on the following items:
✓ 1. The required TN and TP targets of 2.2 and 0.33, respectively, are not being met. The plan
must be modified to meet these targets, or provide for offsite treatment or offset payments
through EEP.
�2. It is very difficult to determine what is existing versus proposed on the plans. Please clarify.
—3. Please clarify how much existing is treated in lieu of how much new BUA is in the )4 Annex site.
Please show this on sheet DWQ1.
V-14. Please label the proposed contours in and around the BMPs.
V5. The DA delineations for each BMP should include the area of the bioretention cell also. The DA
map labels must also match the DA labels on SWU-101. The delineations should be shown on a
full size plan and follow the proposed grading. Please revise accordingly.
'6. It is not clear what the purpose of the berm is on the southwest side of bioretention #2. If it is
to divert the clean water from the wooded area around the cell, it's current layout does not
provide for this. Please clarity/revise.
•%-�7. The supplement forms are merely a tool for summarizing final design results. Please provide
supporting calculations for the bioretention cells and LSNFS. This includes treatment volume
calculations using the simple method, provided volume, drawdown, underdrain sizing, LS
sizing, etc.
Wetlands and Stormwaler Branch O
1617 Mail Service Centel, Ralek;h, North Carolina 27 699-1617 One
N ne Carolina
Locziion: 512 N. Sa}isbury St. R leigh, Narth Carolina 2760--
Pho^a:919-R'7-63001FAX: 9V-807-64�"4Customer Sew°ce 1-87 523-6748 AMA
Inte -..el www. cwaterquality.w. j
ffi "oua; Oppoft --My 1 Attirmahve A-t',on Emplc ^r

Mr. Eric M. T%need, PE `
Page ? of 3 ;
OctoLer7, <911
1"'8. The required LSNFS supplement form was not provided.
✓ 9. The volume provided item on the supplement form for bioretention #2 was left blank. Please
complete.
-10. Calculations must be provided that demonstrate that the new development does not result in a
net increase in peak flow leaving the site from predevelopment conditions for the one-year, 24-
hour storm event.
11. A soils report must be provided that states what the SHWT elevation is based on boring(s)
within each of the bioretention cell footprints. This should also provide soil type information.
The SHWT elevations were left blank on the supplement forms, and must be completed.
^-12.On SWU-101:
a. In IV.10. - Please fillout 1 DA column for each of the bioretention cell DAs.
b. In IV.10. -The Proposed BUA and % Impervious rows should include the total final
existing to remain + new BUA.
c. 4 through 8 should only be based on the project area, not the whole of Camp Butner.
This project area should be delineated on the plans.
v13. On sheet C3, please explain what 4" hole the note is referring to. Other than the underdrain
orifice, there should not be any other openings in the outlet structure until the overflow
elevation is reached.
✓14. Please provide a detail for the splitter box located upstream of the LS.
-� 15. The bioretention details need more information shown/detailed. They should show all
necessary parts of the cells.
�a. When proposing grass cells, sod must be specified along with grass species of the sod.
Wb. The underdrains need to be shown with detailed info (elevations, slope, etc.).
a, c. The media mix specification needs to be shown.
vd. The washed stone layer needs to be shown with detailed info.
-e:- Clarify whether the sand elevation shown is the top or bottom of the sand layer?
+-f. A note should be included that addresses grouting/sealing of the orifice used for the
skimmer.
✓16. Regarding the Nutrient Load Accounting Tool:
a. The DA and impervious areas shown in the tool are not consistent with that shown on
the supplement forms, plans, and SWU-101. Please make all consistent.
b. What area is the 406,259 sf in the Total Development Area referring to? This should be
the same area used to address comment 12.c. above.
c. The soil survey shows that the site soils are HeB. This should be confirmed in the soils
report requested above. HeB is a group C soil, not a B as used in the tool. Please
change to a C in the tool.
d-_ Please show an supporting Calrs_how _ynti_calCu-I-atedthells.-1..16
(0.58+0.58) and 1.46 (0.73+0.73) were used, however they don't appear to be that
large based on the other size info provided in the application.
It may be helpful to go through these in a meeting. Please let me know if you would like to schedule
something.

-�Mr. E i is M. Tweed, PE
Page of 3
October 7, 2`)11
Until a State Stormwater Permit is issued for this project, the construction of any impervious surfaces,
other than a construction entrance under an approved Sedimentation Erosion Control Plan, is a
violation of NCGS 143-215.1 and is subject to enforcement action pursuant to NCGS 143-215.6A.
Please note that when re -applying, a full new application package must be submitted, along with a
new application fee. All original signed documents are enclosed.
If you have any questions concerning this matter, please contact me at [phone], or
[e-mail].
Sincerely,
xl�eq-
Robert D. Patterson, PE
Environmental Engineer
DWQ Stormwater Permitting Unit
Enclosures
cc: LTC Toni Coats - NCNG-CFMO
Raleigh Regional Office - Danny Smith
SPU files