20001195 Ver 6_Stormwater Info_20101103

PA
NCDETIR
North Carolina Department of Environment and Natural Resources
Division of Water Quality
Beverly Eaves Perdue Coleen H. Sullins Dee Freeman
Governor Director Secretary
November 3, 2010
Mr. Jerry Orr, Airport Director
Charlotte Douglas International Airport
P. O. Box 19066
Charlotte, NC 28219
DWQ #: EXP 00-1195v6
Mecklenburg County
Subject Property: CDIA Area West of 2°d Parallel Runway - Stormwater Management Plan
RE: PAVEMENT SWEEPING ACTIVITY REPORT
Dear Mr. Orr:
On October 20, 2010, the 401/Wetlands Permitting Unit of the Division of Water Quality (DWQ)
received your report dated October 13, 2010 for the pavement sweeping activity conducted on October
12, 2010. The report contains the description of the equipment used and testing procedure, the discussion
of the test results, as well as future testing and monitoring protocol. The sweeping activity was conducted
to determine the operating parameters (primarily the speed of the equipment) that could achieve the TSS
removal efficiency acceptable to meet the pollutant removal requirement of the 401 Water Quality
Certification and the corresponding Stormwater Management Plan (SMP) approval. The DWQ has
reviewed the report and has the following comments:
1. The percentage of sediment removed should be determined separately for the two speeds to align with
the main objective of the tests, which was to determine the speed that yielded an acceptable TSS
percent removal. As you recognize that each lane was swept at a different speed, the pollutant
removal efficiency computed for the combined sweeping would not represent any particular speed.
As a result, the DWQ recommends the following revisions to the calculations:
a. The 1001bs native load prior to adding the 500lbs was determined during one lane pass,
and so 100lbs must be used as the initial load in each lane. Assuming a uniform spread of
sediments, there is a total of (250 + 100) lbs of sediments in each lane.
b. At IOmph, the percentage of Total Solids removed is: 140/(250+100) = 40%
c. At 7.5mph, the percentage of Total Solids removed is: 280/(250+100) = 80%
d. From the calculations above, there is a remarkable drop off in the amount of total solids
collected from 80% to 40% as the speed is increased from 7.5mph to l Omph. Based on
the results of this test alone, the DWQ would accept an equipment speed less than or
equal to 7.5mph.
2. The proposed future testing and monitoring procedures described in your report are acceptable. It is
understandable that, in order to establish an effective and agreeable protocol, several sweeping
activities must be conducted at the actual site under varying conditions and operating parameters to
generate sufficient data and information. Please notify the DWQ as soon as the testing and monitoring
begins at the actual site and submit quarterly report of data and analysis to DWQ for review. The
DWQ will work with you to obtain an appropriate set of parameters (operating speed, amount of
401 Oversight/Express Review Permitting Unit
1650 Mail Service Center, Raleigh, North Carolina 27699-1650
Location: 2321 Crabtree Blvd., Raleigh, North Carolina 27604
Phone: [phone] FAX: [phone]
Internet: http://h2o.enr.state.nc.us/ncwetlands/
NonrthCarolina
?aturaltr?
An Equal Opportunity 1 Affirmative Action Employer
CDIA- Pavement Sweeping Protocol
Page 2 of 2
November 3, 2010
overlap and frequency of sweeping) that will at least meet the TSS pollutant removal efficiency
required by your permits.
Please revise the report as described above and respond by sending two (2) copies of the revised report.
This letter only addresses the review and does not authorize any impacts to wetlands, waters or protected
buffers.
Please contact Joseph Gyamfi at 919-733-1786 if you have any questions regarding or would like to set up a
meeting to discuss this matter.
Sincerely,
9, Ian McMillan, Acting Supervisor
401 Oversight/Express Review Permitting Unit
IJM/jg
cc: File Copy
Alan Johnson, MRO
Ron Geiger, HDR Engineering, Inc., 128 S Tryon Street, Suite 1400, Charlotte, NC 28202