20001195 Ver 6_More Info Letter_20080924

F F Michael F. Easley, Governor
`0?0 9QG William G. Ross Jr., Secretary
North Carolina Department of Environment and Natural Resources
C Coleen H. Sullins, Director
Division of Water Quality
September 24, 2008
DWQ EXP # 00-1195v6
Mecklenburg County
EXPRESS REVIEW ACCEPTANCE LETTER
Attn: Mr. Jerry Orr
Charlotte Douglas International Airport
Post Office Box 19066
Charlotte, NC 28219
Subject Property: CDIA SWMP for Area West of 2"d Parallel Runway
REQUEST FOR MORE INFORMATION
The Division of Water Quality (DWQ) has reviewed the stormwater management application form and
construction drawings submitted by Mr. Ron Geiger, PE of HDR Engineering, Inc. requesting a
modification to the stormwater management plan (SMP) dated March 15, 2007 and approved by DWQ on
March 22, 2007. The modified SMP is intended to meet Condition 9 of the modified 401 Water Quality
Certification for the subject project issued on March 1, 2008. The DWQ has determined that your
application will require additional information. Please provide the following information so that we
may continue to review your project and prevent return of your application as required by 15A
NCAC 211.0506:
Additional Information Requested
Please provide the items specified in the Required Items Checklist (RIC) for the newly proposed and
modified BMPS. These include:
a. Typical cross sections of the grass swales and filter strips with a table listing various
sections where changes occur, the lengths, longitudinal slopes, bottom widths, side
slopes, etc. For the grass swale, please indicate where check dams will be required on the
plans and show a cross section of the Swale with the check dam. In order to claim credit
for the grassed swales, the side slopes shall be 5 : 1 (H : V) or flatter.
b. Larger plan view and cross sectional detail of the bioretention as listed in the RIC. Please
specify the composition, permeability and Phosphorus Index (P-Index) of the soil media
on the plans.
c. Soil report based on in situ field testing at the proposed bioretention location indicating
the seasonal high water table (SHWT) elevation.
d. On the required items checklist, please indicate the page or plan sheet number where each
item can be found.
e. Supporting calculations such as drawdown time and underdrain sizing, etc. Please note
that the drawdown times reported on the first two lines of the bioretention supplement
form would be 8 hours and 16 hours respectively (totaling 24 hours on the third line),
given that the soil media has 1.5 in/hr infiltration rate and has underdrains.
NhCarolina
one
401 Oversight/ Express Review Permitting Unit
atura!!y
1650 Mail Service Center, Raleigh, North Carolina 27699-1650
2321 Crabtree Boulevard, Suite 250, Raleigh, North Carolina 27604
Phone: [phone] / FAX [phone] / Internet: httr)://h2o.enr.state.nc.us/ncvvetlands
An Equal Opportunity/Affirmative Action Employer - 50% Recycled/10% Post Consumer Paper
CDIA Mod_SWMP for Area West of 2"d Parallel Runway
Page 2 of 2
September 24, 2008
2. As discussed please divert, as much as possible, runoff from the roadway section between drainage
area to the bioretention and B02 Endwall through a grass swale into extended dry detention pond ED
6 for some treatment prior to leaving the site.
Operation and Maintenance (O & M) Agreement Plan for the Vacuum Sweeping of Pavement:
Since the SNIP for the entire site relies heavily on Vacuum Street sweeping, the following
recommendations are suggested to be included in your O & M Agreement Plan, taking into
consideration your literature review, and recent research findings by the Center for Watershed
Protection regarding pollutant (TS, TN, and TP) removal rates from vacuum sweeping in similar
settings. Please refer to the following website for more information:
hl!p://www.ewp.orgjResource Library/Center Docs/municipal/CBStreetS weeping. pd f.
Please include and/or modify the O & M Agreement Plan for this non-structural BMP as follows:
a. Require the frequency of the sweeping activity to be a minimum of twice a week.
b. Include a trash and leaf litter pick-up program.
c. Please emphasize that pavement sweeping should be carried out prior to 1" or more storm
events, when there is advance storm prediction.
d. Describe how the sweeper waste will be disposed of.
e. Include sampling and testing procedures to evaluate the effectiveness of the proposed
sweeping activity with respect to the pollutant removal credits assigned to it. Quarterly
reports shall be submitted to DWQ for review. Failure to reach within 10% of the
assigned pollutant removal credits shall require their replacement with DWQ-approved
BMPs.
Please respond within five (5) days of the date of this letter by sending two (2) copies of the above
information in writing. Please submit only the revised and/or requested information. The Express
Review Program is a process that requires all parties to participate in a timely manner. This letter only
addresses the application review and does not authorize any impacts to wetlands, waters or protected
buffers. Please be aware that any impacts, activities or services requested within your application are not
authorized at this time by the DWQ.
Please contact Joseph Gyamfi or Lia M. Gilleski at 919-733-1786 if you have any questions regarding, or
would like to set up a meeting to discuss, this matter.
Sinc e ,
Cyndi Karoly, Supervisor
401 Oversight/Express Review Permitting Unit
CBK/jg
cc: Steve Chapin, USACE Asheville Regulatory Field Office
Alan Johnson, DWQ Mooresville Regional Office
File Copy
Mr. Matt Matthews, DWQ - Wetlands & Stormwater Branch
Ron Geiger, HDR Engineering Inc., 128 S. Tryon St., Suite 1400, Charlotte, NC 28202