20140705 Ver 1_Mitigation Plan comments_20160106

Strickland, Bev
From: Haupt, Mac
Sent: Wednesday, January 06, 2016 11:46 AM
To: 'Hughes, Andrea W SAW'
Subject: Selma Mill Mitigation Plan comments
Andrea,
Here are my comments on the Selma Mill Mitigation Plan:
1. Their stream design approach was good with the combination of analog and analytic methods and their
recognition of a sand bed system and the applicable sediment transport analysis (looked at a combination of
several methods)
a. However, in their stream hydrologic analysis Section 8.3.1.1 they did not include the references
(Citations in the References at the end) they referred to for the different regional curve regression
equations... not a big point but I went looking and did not find them...
2. 1 am assuming this is just a stream bank and does not have wetland, riparian buffer, or nutrient offset
credit ... saw some letters at the end where they were inquiring about buffer and nutrient offset credit. In
addition, there are wetlands on site, looks like mostly degraded, however, no mention of credit.
3. One wetland, wetland 2, appears to be the least degraded, however, their stream design is going right through
this area. This particular section is a priority 11 and appears to have about 2 feet of cut so it will definitely impact
this wetland and they did not discuss this at all in their plan. I thought at first this would be an issue for wetland
4 as well but it looks like this wetland is largely degraded. Nevertheless, there should be some discussion.
4. They are proposing to install small woody debris (SMD) through various methods. In addition, they state this is
for functional uplift, which I believe is a good thing, however, in their analysis they are looking at the small
woody debris in their reference stream and using that amount as a guide for their amount and placement. I
would think they need to do a quick analysis of SMD for the restoration site as well.
5. Headwater valley (HV) portion -I have two concerns about the HVs, one is the limits of grading and two, is the
cross-section typical seen on the plan sheets, 515. I guess both relate to the slope of the banks, I feel there
should be a much more gradual grading that extends out farther than the limits shown. The typical for the cross
section should have a flat channel bottom (the water will make its own channel) with very gradual slopes, I am
not sure of the grade, 8:1-10:1 ???
6. Extra stream credit with wider buffers -This particular area is the most concerning part of this project to
me. First of all, I am all for extra credit for wider buffers, however, the IRT really needs to come to grips with
how this is done. Specifically, we need to know the method and be able to reproduce it (check it)
ourselves. Even someone like me who is an ignoramus on GIS stuff. For this particular site, I question the
amount of extra credit that is being produced. First of all, we are talking about 895 extra credits, which is
significant. We need to see their method and be able to reproduce it. Secondly, it was interesting that there
were virtually no areas of negative credit. Thirdly, what about those areas with stream junctions, it looks like
they may have only counted one side for each but still with the amount of extra credit proposed, it is important
to work out these issues.
7. Hydrologic performance criteria for the HV- nothing specific is stated, what is the standard these days ? Is it flow
for 70% of the year? Still not crazy about that one...
8. Overall looks like a good project, my main concerns are with the HV design and the method for determining
extra stream credit due to wider buffer widths.
Thanks,
Mac

Mac Haupt, LSS
Stream & Wetland Mitigation Coordinator
401 & Buffer Permitting Unit
Division of Water Resources
Department of Environmental Quality
919 807-6476 office
u.:.lhu.pt ncdenir.gov
512 N. Salisbury Street, Suite 942-K, Raleigh, NC 27604
1617 Mail Service Center
Raleigh, NC 27699-1617
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