20051360 Ver 2_Staff Comments_20060524

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Michael F. Easley, Governor
William G. Ross Jr., Secretary
North Carolina Department of Environment and Natural Resources
Alan W. Klimek, P.E. Director
Division of Water Quality
May 24, 2006
Mr. Russ Overton
Town of Cary
P.O. Box 8005
Cary, NC 27512
Dear Mr. Overton;
RE: Cumulative Impact analysis for Town of Cary road projects
Town of Cary Morrisville Parkway Extension
DWQ # 2005-1360
Wake County
On November 30, 2005, the Division met with you, your consultants and the US Army
Corps of Engineers to discuss issues related to cumulative impact of the proposed Morrisville
Parkway Extension in Cary, NC. The meeting was in response to DWQ's letter of October 28,
2005. At the meeting, the Town of Cary representatives asked DWQ to consider whether the
October 2005 report entitled "Secondary and Cumulative Impacts Master Mitigation Plan -Cary,
North Carolina" prepared by CH2M Hill would be sufficient to address DWQ's cumulative impact
issues as outlined in the 401 Certification rules (15A NCAC 2H .0506 (b) 4 and (c) (4)) as well
as DWQ's working draft policy on cumulative impact (dated October 3, 2002).
In response to that request, I have carefully read the above-mentioned report. The
report does an excellent job of documenting and describing Cary's comprehensive, wide-
ranging water quality protection measures from stream buffers to stormwater management. The
only technical question that I have is whether the stream buffers also require diffuse flow as
required for the Neuse and Tar-Pamlico buffers that DWQ administers. Please clarify this issue
in your response.
With respect to DWQ's cumulative impact requirements for the 401 Water Quality
Certification Program, those rules require that the Certification address whether downstream
water quality will be affected by any growth that is likely to occur as a result of the project.
DWQ's interim cumulative impact policy dated October 3, 2002 requires a quantitative analysis
for projects that are likely to result in growth and that affect 300(d) waters. As you know in our
meeting in November, we discussed the fact that this project will open additional, presently
undeveloped areas to growth and the streams that drain from this road have been designated
as 303(d) waters. Therefore, a quantitative analysis is required to demonstrate that the land
use measurements that Cary has presently in place are sufficient to protect downstream water
quality. Since the report discussed above is a qualitative analysis rather than a quantitative
analysis, it will not be sufficient to address DWQ's cumulative impact policy. In order to
expedite this quantitative analysis, we will be glad to meet with you to discuss the model to be
used, the area to be modeled, the timeframe for the model and the water quality parameters to
be modeled.
401 Oversight/Expn;ss Review Permits Unit
1650 Mail Service Center, Raleigh, North Carolina 27699-1650
2321 Crabtree Boulevard, Suite 250, Raleigh, North Carolina 27604
Phone: [phone] FAX [phone] Internet: http://h2o.enr.state.nc.us/ncwetlands
N °e Carolina
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An Equal OpportunitylAffirmative Action Employer- 50% Recycledll0% Post Consumer Paper

We understand that the cumulative impact report noted above (dated October 2005) was
done with the guidance and direction of DENR coordinated by Ms. Melba McGee as discussed
in the MOA between Cary and DENR dated July 26, 2005. As outlined above, this report is
helpful in addressing cumulative impacts for the 401 Certification Program but does not meet
our requirement for a demonstration (e.g., using quantitative modeling) that these land use
management measures will protect downstream water quality since the report is a qualitative
description of these measures. It is possible that if you decide to model several additional,
representative watersheds that would be required to have a quantitative analysis and if these
modeling exercises demonstrate that Cary's land use management measures protect
downstream water quality, that the Division could make a determination that the existing land
use measures provide adequate protection for downstream water quality. In that case, the
report (and the supplemental modeling) could adequately address cumulative impact issues for
Town of Cary projects throughout your Extra-Territorial Jurisdiction (ETJ) for the 401
Certification and Isolated Wetland Permitting programs. If you would like to pursue this more
generic process, please contact me at 733-9646 to begin discussions to design this study.
Thank you for your patience for this response. I was very tardy in reviewing your report
and I apologize for that delay. If you have any additional questions, please call me at 733-9646.
Cc:
Melba McGee, DENR
Monte Matthews, Raleigh Field Office US Army Corps of Engineers
Cyndi Karoly
John Hennessy
Ian McMillian
Leila Goodwin, CHZM Hill
Glenn Dunn, Poyner and Spruill
Mike Babuin, Town of Cary
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