20130412 Ver 1_Prospectus Comments_Hoosier Dam_20140415

A
NCDENR
North Carolina Department of Environment and Natural Resources
Pat McCrory
Governor
April 15, 2014
Mr. Andrew Williams
U.S. Army Corps of Engineers
Raleigh Regulatory Field Office
3331 Heritage Trade Drive, Suite 105
Wake Forest, North Carolina 27587
Subject Property: Hoosier Dam Mitigation Bank
Prospectus Comments
Dear Mr. Williams:
John E. Skvarla, III
Secretary
DWQ Project # 13 -0412
Chatham County
We have reviewed the above - referenced document received in this office on February 21, 2014. Our
comments are as follows:
1. The majority of the proposed mitigation units (Table 3) are based on improving the water quality of
the Rocky River and its tributaries. Monitoring (both pre- and post - removal) should be performed to
assess water quality and aquatic function of the impounded reaches and their post - impoundment
condition. Physicochemical monitoring should follow up on temperature and nutrient data collected
and presented in the Prospectus.
Biological monitoring should focus on improvement of water quality through conversion from a
lentic to a lotic system. Parameters for monitoring should include macrobenthos and fish.
Performance standards should be crafted to document improvements in physicochemical parameters
and to the biotic community. Meeting each individual performance standard over the course of the
monitoring period should have an associated percentage of the total water quality improvement
credit.
DWR recommends consulting the Milburnie Dam Draft Mitigation Plan dated March, 2014 for an
example of performance standards and associated credit yield. While the performance standards and
credit yield presented in this plan may not be appropriate for the Hoosier Dam project, the concepts
may provide useful in development the Hoosier Dam mitigation plan.
2. The total proposed potential credit for the project raises a concern that has been the topic of
discussions among the IRT in the past. Specifically, if it is appropriate for the DE to allow for more
credit to be generated by a dam removal project than the amount of mitigation that would be required
if the dam was constructed now.
Division of Water Resources — 401 & Buffer Permitting Unit
1650 Mail Service Center, Raleigh, North Carolina 27699 -1650
Location: 512 N. Salisbury St. Raleigh, North Carolina 27604
Phone: 919 - 807 -63001 FAX: 919 - 807 -6494
Internet: www.ncwaterquality.org
An Equal Opportunity 1 Affirmative Action Employer— Made in part by recycled paper
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Mr. Williams
Hoosier Dam Mitigation Bank
Prospectus Comments
Page 2 of 2
The mitigation plan (Table 3) indicates the total maximum potential credit for the project is 24,105
LF (24,105 credits). The impounded reach of the river and associated tributaries has been calculated
to be 22,425 LF. If the project were proposed today, based on DE requirements on other
impoundment projects, the mitigation required would likely be as follows:
Impact Type Impact Amt (LF) DA Multiplier Mitigation Requirement
Fill (dam footprint) 200 LF* 2:1 400 LF
Inundation 22,225 LF 1:1 22,225 LF
Total Mitigation Required 22,625 LF
*Approximate based on aerial photography.
According to the proposed maximum potential credit from the mitigation plan, the Sponsor would
potentially be awarded 1,480 more linear feet of credit (24,105 — 22,625) than the mitigation that
would be required to permit the construction of the dam and impoundment of 22,425 LF of river and
tributaries. As this issue has not been resolved, this should probably be discussed by the IRT at the
next regularly - scheduled meeting.
3. Monitoring activities should also include stability monitoring of all formerly- impounded tributaries
proposed for credit. Lower of the water level after dam removal has the potential to expose
unvegetated stream banks, which could result in streambank erosion /headcutting.
4. The standard service area for mitigation banks in North Carolina is the eight -digit HUC in which the
bank is located. The location of the bank site at the southeastern end of 03030003 and its close
proximity to 03030004 makes the proposed service area feasible. DWR would support the primary
service area for this bank to include all of 03030003 and the Piedmont portion of 03030004.
5. We strongly encourage the bank Sponsor to continue to acquire property along the Rocky River and
associated bank tributaries, and inclusion of such lands within the bank conservation easement =..
We look forward to discussing and resolving these issues, as we believe the project has merit and
should provide documentable improvement of aquatic function within the impounded reaches.
Please feel free to contact Eric Kulz at (919) 807 -6476 if you have any questions regarding -these
comments.
Sincerely, `N
Karen Higgins, Supe r
401 & Buffer Permitting Unit
cc: Danny Smith, DWQ Raleigh Regional Office
File Copy (Eric Kulz)
Todd Tugwell — USACE Wilmington District