20080868 Ver 2_Staff Comments_20081106

[Fwd: Buffer Mitigation Credits - Guidance Documents related to Di...
Subject: [Fwd: Buffer Mitigation Credits - Guidance Documents related to Ditches]
From: Eric Kulz <[e-mail]>
Date: Thu, 06 Nov 2008 08:47:55 -0500
To: Coleen Sullins <[e-mail]>, John Dorney <[e-mail]>, Matt Matthews
<Matt. Matthews@ncmai l.net>, Amy Chapman <[e-mail]>
Folks;
Please note the attached that Jim Stanfill sent regarding buffering ditches for riparian buffer credit. We may need
to make a clear policy decision that applies to everyone. I have not been allowing private sector banks to buffer
ditches for riparian buffer credit. Nutrient offset credit only.
Eric
Eric W. Kulz
Environmental Specialist
401 Oversight and Express Permitting Unit
2321 Crabtree Blvd., Suite 250
Raleigh, NC 27604
Phone: [phone]
Fax: [phone]
Subject: Buffer Mitigation Credits - Guidance Documents related to Ditches
From: Jim Stanfill <[e-mail]>
Date: Wed, 05 Nov 2008 11:42:06 -0500
To: Eric Kulz <[e-mail]>
CC: Marc Recktenwald <[e-mail]>, Suzanne Klimek <[e-mail]>,
Kelly Williams <[e-mail]>, Guy Pearce <[e-mail]>
Eric,
We have started looking for some of the older correspondence on Buffer accreditation when buffering ditches.
Right off the bat, we have found language in several documents.
The first document is the never signed but operating memo that the program utilized as guidance for a number of
years -- I am referring to the October 23, 2002 DWQ memo. In that memo the following statements are written:
"Definitions
<>Riparian Buffer Restoration: Defined as woody vegetation being absent or sparse (less than 100 stems per acre
that are greater than or equal to five inches at breast height) measured within 50 feet of surface waters. Restoration
of woody vegetation along ditches that deliver runoff directly to waters classified in accordance with 15A NCAC
213.0100 and are not part of an existing nutrient reduction program can be approved for mitigation provided that
this activity addresses the predominant source of pollutants into the system. "
The memo also contained the following:
• Where riparian buffers are restored along intermittent and perennial streams, the stream must be
stable. In situations where the stream is unstable, a stream restoration/enhancement or stream
bank stabilization plan must accompany the riparian buffer mitigation plan unless documentation
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[Fwd: Buffer Mitigation Credits - Guidance Documents related to Di...
can be provided to show that this activity is not required.
• Where riparian buffers are restored along ditches, the ditch must not be actively eroding. In
addition, the water table within the ditch should be within three feet of the surface. Permanent
water control structures as well as ditch plugs can be used to achieve this depth.
• Artificial berms along ditches or channeled streams greater than three feet in height as measured
from the ground surface should be leveled to allow for more successful vegetation survival.
• Any surface contours that would prevent diffuse flow across the buffer must be graded to allow
for diffuse flow.
• Surface drainage across the buffer, which is not diffuse flow, must be managed to become and
remain diffuse flow.
Also the published DWQ Buffer Interpretation/Clarification #2008-017 references the use of ditched streams as
buffer mitigation. It states:
"3) The mitigation plan must be consistent with the NCEEP's "Guidelines for Riparian Buffer Restoration"
located at http://www.nceep.net/news/reports/buffers.pdf unless otherwise approved by DWQ."
The "Guidelines for Riparian Buffer Restoration" includes "Criteria for Priority Riparian Buffer Restoration
Projects." The section states:
" The following characteristics are intended to provide general guidance when identifying sites and are not
intended to exclude sites that may have merit based on other criteria:
• Woody vegetation absent or sparse (less than 100 stems per acre that are >= 5 inches diameter at breast
height) measured within 50 feet of intermittent and perennial streams, lakes, ponds, and shorelines.
• Adjacent to headwater streams or those streams defined as first, second, or third order
• Project length greater than 1,000 feet (for projects implemented by the EEP)
• Ditches, gullies, or evidence of concentrated flow within 50 feet of intermittent and perennial stream, lakes,
ponds, and estuaries.
• Adjacent source of nitrogen including cropland, pasture, golf course, residential development, ball fields,
etc.
• Water table depth within three to four feet of surface as determined by characteristics of soil cores."
A more recent document is the Reduction of buffer credits due to non-diffuse flow:
http://h2o.enr.state.nc.us/ncwetiands/documents/DiffuseFlow.pdf
This document clearly states how buffer credits can be achieved on ditches and includes diagrams.
These documents include direct references for the development of buffer mitigation credits along ditches that flow
directly into intermittent, perennial or modified streams.
I will keep you posted as we find more references.
Jim Stanfill
Ecosystem Enhancement Program
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