20080868 Ver 2_Draft of Flexible Buffer Mitigation Report_20080731

DRAFT Flexible Buffer Mitigation
Strategy Report
Beaufort County, North Carolina
Prepared for:
PCS Phosphate, Inc.
Highway 306 South
Aurora, North Carolina
July 2008
QjUl, 3 1 2008
C Mm F1 rNeyi Fbrn
aKind Associates, Inc.
©Kimley-Horn and Associates, Inc. 2008
MW - WATER OU BRANCH
Dg AND STORW
•
i
I•
Executive Summary
• In March 2006, PCS Phosphate, Inc. (PCS) sought a Major Variance from the Tar-Pamlico
• Buffer Rules from the North Carolina Environmental Management Commission (EMC) to
i be able to provide flexible forms riparian buffer mitigation associated with the planned
mine continuation in Aurora, North Carolina. The EMC did not approve the request at
that time, but did indicate willingness to reconsider the request if PCS could establish
i that its proposed mitigation sites would not be able to provide enough buffer mitigation
• credit by providing buffer restoration or enhancement (replanting existing stream
- buffers) as described in 15A NCAC 2B .0260. The Variance request was based on the
document titled Rationale and Methodology for Flexible Buffer Mitigation for PCS
i Phosphate Company, Inc. February 20, 2006 (Rationale). This document was updated
• and revised in the recently published PCS Final Environmental Impact Statement (FEIS)
i (Attachment 3).
• Since that time, PCS has identified its mitigation sites and has determined that the
i buffer mitigation credit need cannot be met using the methods described in the Rule
i (15A NCAC 213 .0260). As such, a Flexible Buffer Mitigation Strategy study was performed
by Kimley-Horn and Associates, Inc. to establish the Conversion Ratio (CR), a
i dimensionless number that associates a buffer area with the drainage area draining to it
as described in the Rationale. This dimensionless ratio is the amount of drainage area
i that drains through a buffer as diffuse surface flow or interflow (subsurface flow above
i the groundwater table). These drainage areas were measured based on the drainage
area that flows through a 1,000-foot-long section of buffer as described above at the
i three mine continuation sites: NCPC, S33, and Bonnerton. The average CR as well as the
average CR for each site are provided in Table 1 below.
The flexible buffer mitigation methods are described in the Rationale document. For
example, based on the average CR of 6.01, the flexible buffer mitigation method of
converting agricultural land to forest would yield 17.1 acres of buffer mitigation credit
for every 100 acres of agricultural land converted. Alternatively, based on the flexible
method of treating untreated agricultural runoff using stormwater wetlands, 146 acres
of untreated agricultural runoff could be treated to provide 10 acres of buffer mitigation
credit.
C nd Associates,
and Associates, Inc.
a
Table 1- Conversion Ratios
Table of Contents
Executive Summary .............................................................................................................. i
Introduction ........................................................................................................................ 3
Methods .............................................................................................................................. 4
Results ................................................................................................................................. 5
Discussion and Conclusions ................................................................................................ 6
References .......................................................................................................................... 9
List of Tables
Table 1- Conversion Ratios ................................................................................................ i
Table 2 - Summary of Results ............................................................................................. 3
Table 3 - Calculating the Equivalent Buffer Ratio from the Rationale ............................... 4
List of Figures
Figure 1- Alternative L Boundary Area Map .................................................................... 10
Figure 2a - NCPC Site Aerial ............................................................................................. 11
Figure 2b - NCPC Site LIDAR ............................................................................................. 12
Figure 2c - NCPC LIDAR Site 2 ........................................................................................... 13
Figure 2d - NCPC Aerial Site 2 .......................................................................................... 14
Figure 2e - NCPC LIDAR Sites 4, 5, and 6 .......................................................................... 15
Figure 2f - NCPC Aerial Sites 4, 5, and 6 ........................................................................... 16
Figure 2g - NCPC LIDAR Sites 7 and 8 ............................................................................... 17
Figure 2h - NCPC Aerial Sites 7 and 8 .............................................................................. 18
Figure 3a - S33 Site Aerial ................................................................................................ 19
Figure 3b - S33 Site LIDAR ................................................................................................ 20
Figure 3c - S33 LIDAR Sites 1 and 2 .................................................................................. 21
Figure 3d - S33 Aerial Sites 1 and 2 .................................................................................. 22
Figure 3e - S33 LIDAR Site 10 ........................................................................................... 23
Figure 3f - S33 Aerial Site 10 ............................................................................................ 24
Figure 3g - S33 LIDAR Sites 17, 19, 21, and 30 ................................................................. 25
Figure 3h - S33 Aerial Sites 17, 19, 21, and 30 ................................................................. 26
Figure 4a - Bonnerton Site Aerial ..................................................................................... 27
Figure 4b - Bonnerton Site LIDAR ..................................................................................... 28
Figure 4c - Bonnerton LIDAR Sites 1, 2, 3, 4, 6, 7, and 8 .................................................. 29
Figure 4d - Bonnerton Aerial Sites 1, 2, 3, 4, 6, 7, and 8 .................................................. 30
List of Attachments
Attachment 1: Field Notes Summary and Individual Site Data
Attachment 2: Photo Pages
Attachment 3: Rationale and Methodology for Flexible Buffer Mitigation for PCS
Phosphate Company, Inc. FEISAppendix I.
/ t? Fl Kjwky-Horn
?'? and Associates, Inc.

Introduction
PCS Phosphate, Inc. (PCS) is in the process of continuing its mining operation in Aurora,
. North Carolina. PCS has carefully selected the specific areas of mine continuation to
. avoid impacts to the natural resources on the three sites in which the continuation will
occur; however, due to the size and nature of the needed continuation, some impacts to
natural resources will be unavoidable. Some of these unavoidable impacts are proposed
for stream features and their associated riparian buffers (the area 50 feet from each
. stream bank) as designated by the North Carolina Division of Water Quality (NCDWQ).
- PCS has agreed to mitigate for these unavoidable impacts. As set forth in the Tar-
Pamlico "Buffer Rules" (15A NCAC 2B .0260), buffer mitigation is required to be buffer
restoration or enhancement (replanting of deforested buffers along streams) for such
projects. However, based on the currently proposed mitigation areas (and as a result of
- the mitigation ratios applied to the impacts), PCS will not have enough replanted buffers
• along its streams at the proposed mitigation sites to provide the required amount of
riparian buffer mitigation credit.
•
The stated purpose of protecting stream buffers in the Buffer Rules is primarily for
nutrient reduction. As such, to provide the needed additional mitigation, PCS is seeking
flexible forms of buffer mitigation that replace the nutrient-removing function of the
buffers. Such flexibility requires a Variance from the Buffer Rules by the Environmental
- Management Commission (EMC). PCS sought such a Variance in March 2006 as
documented in the Rationale and Methodology for Flexible Buffer Mitigation for PCs
Phosphate Company, Inc. February 20, 2006 (Rationale) This document was updated
and revised in the recently published PCS Final Environmental Impact Statement (FEIS)
(Attachment 3). The EMC did not grant the Variance at the time because it was
i determined that a definite need for flexibility had not been established. However, the
EMC did indicate that it would be willing to consider such a Variance if, after the
mitigation sites were determined and impact amounts were established, PCS could
show that stream buffer restoration alone at the mitigation sites would not provide
sufficient buffer mitigation credit. PCS has subsequently established its impacts and
• mitigation sites and determined that additional buffer mitigation is needed. As such,
- Kimley-Horn and Associates, Inc. (KHA) has gathered and analyzed the necessary data to
establish the numerical criteria proposed in the Rationale.
•
As described in the Rationale, it is necessary to establish a means of numerically relating
alternative means of reducing nutrients to that of restoring stream buffers. The concept
of the Conversion Ratio (CR) is described in the Rationale. The CR provides a means of
comparing the area that drains to a stream buffer in a diffuse manner (or through
. interflow) to an area of buffer. In this case, the Rationale proposes determining the
. average amount of drainage area that drains in a diffuse manner through 1,000-foot-
long sections of buffer (i.e., approximately 50,000 square feet of riparian buffer). This
drainage area is then divided by the area of the buffer to determine the CR. The buffers
reviewed to establish the CR (as well as the existing drainage area conditions) were
- located within the impact area of the Alternative L boundary, as described in the PCS

3
?? Kir?ey-Horn
?? and Associates, Inc.
FEIS and as shown in Figure 1. Table 1 (p. i) summarizes the results of the study. The
sites within the Alternative L boundary include the NCPC site, the Bonnerton site, and
the S33 site.
Mpthnric
In order to establish the CR as described in the Rationale, 1,000-foot sections of stream
buffer were identified on each side of every stream within Alternative L (Figures 1- 4d).
Stream reaches less than 1,000 feet were excluded. The Rationale describes randomly
selecting and evaluating 21 such buffer sections. It was decided to select seven sections
from each of the three tracts since each tract would represent a different phase of the
mine continuation. The buffer sections were selected using the random number
generation function in Microsoft Excel 2007. The Figures (2a - 4d) show the selected
sections in red. However, it was necessary to replace the selected sections nos. 9 and 10
at the Bonnerton tract with those from an un-buffered stream because of the beaver
impoundment in the vicinity of nos. 9 and 10 that prevented field verification of the
LIDAR features.
The drainage areas that flow diffusely into each 1,000-foot buffer section were
identified using LIDAR mapping in ArcMap (GIS software). These maps as well as aerial
maps were uploaded into sub-meter GPS units with display screens adequate to provide
accurate orientation relative to the LIDAR field maps and aerials. The drainage areas
were field verified by walking each length of buffer and various transects of the
potential drainage areas to verify the accuracy of the LIDAR mapping. Additionally,
drainage break-lines or channelized drainage features directly connected to the stream,
through the buffer, effectively bypassing the stream buffer were identified. To establish
the presence of such a bypass, the following criteria had to be met:
• The channelized feature had to pass completely through the buffer and outlet
directly into the stream. If the channel stopped short of the stream within the
buffer, it was not considered to be bypassing.
• The channel had to be clearly defined with evidence of concentrated flow. Shallow
swales were not considered to bypass flow.
• The feature had to continue beyond the buffer such that it intercepted and bypassed
drainage area outside of the buffer.
• The feature had to be positioned in the landscape such that it obviously intercepted
runoff and interflow from the drainage area.
Where drainage break-lines could be evaluated (such as in open forest or agricultural
fields), the break-lines were confirmed using the GPS unit. Break-lines were hand-drawn
on the field maps. In some of the cutover areas, field conditions made it impossible to
evaluate the break lines. In such cases, the locations of break points were confirmed by
walking transects perpendicular to the drainage features shown in the LIDAR maps in
the GPS units. This method was used to generally confirm the accuracy of the LIDAR
4 Kidd-Horn
'mj and Associates, Inc.
mapping. The general locations of any ditches not identified by IIDAR were hand-
sketched on field maps using the GPS units to identify the locations.
A combination of field notes and recent aerial imagery obtained from Beaufort County
were used to confirm the conditions of the drainage areas. Each drainage area was
assigned a category or combination of categories as follows:
• Forested
• Cutover forest
• Agriculture
• Silviculture
These categories could be used to establish assumed riparian buffer removal efficiencies
should studies ever be developed that determine removal efficiencies based on the
characteristics of the drainage area. To date, studies that have been conducted to
determine removal efficiency have been associated with buffers along agricultural
fields. Based on previous discussions with NCDWQ, the removal efficiencies for total
nitrogen and total phosphorus of buffers that drain agricultural fields is considered to be
85%. For urban or developed watersheds, 50-foot buffers are considered to remove 20%
total nitrogen and 35% total phosphorus (according to the NCDWQ Water Quality BMP
Manual).
Calculations were conducted based on the Rationale document.
Results
Results of the study are summarized for each tract as well as on an aggregate basis in
Table 2. The results of each 1,000-foot buffer length are provided in the figures and
Attachment 1. Specific details are provided for how each drainage area was determined
as well as the field conditions that affected the determinations.
Table 2 - Summary of Results
Bonnerton Site NCPC Site S33 Site Average
Conversion Ratio 4.65 8.25 5.13 6.01
% Drainage Area in Forest 77.10% 55.54% 22.50% 56.15%
Drainage Area in
Recent Cutover 22.90% 44.46% 28.89% 35.32%
Drainage Area in
Agriculture 0% 0% 48.60% 8.54%
Drainage Area in
Silviculture 0% 0% 0% 0%
The drainage area to each buffer ranged from a low of 1.13 acres for S33 site 30 to a
high of 18.8 acres for S33 site 17. The average drainage area for all three sites is 6.99
5 G = Fj Kimley-Horn
and Associates, Inc.
acres. The CR was obtained by dividing each of these drainage areas by the
corresponding buffer area.
Discussion and Conclusions
The results of this study have established a Conversion Ratio (CR) based on the
Rationale document. Using the CR and the calculations described in the Rationale, it is
possible to determine the buffer mitigation credit that could be achieved by providing
nutrient-removing stormwater best management practices (BMPs) or by converting
agricultural land to forest, for instance.
Riparian Buffer Credit Though Forest Conversion of Agricultural Land
Based on previous discussions with NCDWQ, buffers surrounded by agricultural fields
are considered to remove 85% of nitrogen and phosphorus that enters the buffer
through stormwater flowing in a diffuse manner. Buffers in urban settings (e.g., forested
filter strips) are considered to remove 20% total nitrogen and 35% total phosphorus.
Since the 85% removal rate would be the more conservative number in this case, it has
been applied to the calculations described in Table 3 below (see Table 1 of the
Rationale) to determine the Equivalent Buffer (EB) Ratio for nitrogen and phosphorus
removal:
Table 3 - Calculating the Equivalent Buffer Ratio from the Rationale
Calculations to Determine the Equivalent Amount of
Riparian Buffer Credit Achieved By Converting TN (lbs/ac/yr) TP (lbs/ac/yr)
Agricultural Land to Forest (Equivalent Buffers)

Cropland loading* _
13.4
5.3
Wooded land loading* 1.59 0.33
Nutrient load reduction by converting agricultural land to 11.81 4.97
forest
(cropland loading less the wooded land loading)
Nutrient load reduction by a 50-foot forested riparian 13.4 x 0.85=11.39 5.3x0.85=4.51
buffer from runoff from cropland
(nutrient loading multiplied by the 85% nutrient removal
efficiency rate for TN and TP*)
Equivalent Buffer (EB) Ratio 11.81/(11.39) = 1.03 4.97/(4.51)
= 1.10
* From NCDWQ's B. Everett Jordan Reservoir, North Carolina Phase I Total
Maximum Daily Load
The Equivalent Buffer Ratio (EB) is established for whichever of the two ratios (TN or TP)
is less. In this case, the EB ratio for nitrogen is less at 1.03. The following equation is
used to determine the buffer credit from forest conversion: (CR = Conversion Ratio, EB =
Equivalent Buffer Ratio, FC = Area of forest conversion)
Buffer Mitigation Credit = FC*EB/CR
= FC*1.03/6.01 (see Table 1, p.i)
=FC*0.171
6 Kimley-Horn
C and Associates, Inc.
Based on the equation above, 100 acres of forest conversion would provide 17.1 acres
or 744,876 square feet of buffer mitigation.
Buffer Mitigation Credit Using Stormwater BMPs
Two factors must be considered to establish the amount of credit that could be applied
to the use of stormwater BMPs to replace the function of riparian buffers. The first
factor is the use of the CR as described above; the second is the removal efficiency of
the BMP versus that of a riparian buffer. The use of BMPs would only be applicable
where currently untreated stormwater would be entering a stream from active
agricultural or otherwise developed land. Also, the removal efficiencies of the BMP or
BMPs in the series would need to exceed that of a functioning 50-foot riparian buffer in
the Tar-Pamlico Basin. The use of a BMP or series of BMPs to treat untreated
stormwater would replace the function of the riparian buffers. Using the CR would
provide the means to establish the mitigation credit based on the drainage area.
Following are the steps used to establish the mitigation credit:
1) Using the CR, the buffer mitigation credit required can be established as an
equivalent drainage area of acreage to be treated.
2) A BMP or series of BMPs would be selected that is appropriate for the watershed to
treat the existing untreated stormwater. Again, it is assumed that the watershed is
currently in agriculture or otherwise developed.
If the BMP or series of BMPs does not have the same or greater percent nutrient-
removal capability of a buffer, then the lack of removal efficiency can be accounted for
by treating a larger area. The size of the drainage area to be treated would be
determined by dividing the percent removal efficiency of a buffer by the percent
removal efficiency of the BMP and multiplying the result by the equivalent drainage
area determined by using the CR. This would result in the same nutrient removal rate
based on loading as would occur if the BMP(s) had the same removal efficiency as a
buffer.
Example: If 10 acres of buffer mitigation credit were required, the baseline drainage
area determined by the CR would be calculated as follows:
Drainage Area (acres) = CR x 10 acres of credit required
The average CR of 6.01 (from Table 1) would result in a baseline drainage area of 60.1
acres.
If a stormwater wetland designed to the 2007 NCDWQ Stormwater BMP Manual were
used, the removal efficiency of the device is considered to be 40% total nitrogen and
35% total phosphorus. If 85% total nitrogen and 85% total phosphorus removal is
assumed for the existing buffers, then phosphorus becomes the target nutrient since
the wetland removes 35% as opposed to 40% total nitrogen. As such, it would be
necessary to provide a factor of 2.43 (85°/x/35%) more acreage. Therefore, the following
calculation indicates the drainage area that would have to be treated to provide the
equivalent of 10 acres of buffer credit:
7 Kimsey-Horn
??? and Associates, Inc.
Drainage Area (acres) = 2.43 x 60.1 acres = 146 acres to be treated with a
stormwater wetland to provide for 10 acres of buffer mitigation credit.
Based on the above study, a numerical method of establishing flexible riparian buffer
mitigation credit for mitigation activities other than replanting of un-forested buffers as
prescribed in 15A NCAC 2B .0260 can be established if approved by the EMC. The
numerical method is based on the actual field conditions at the proposed impact site
(Alternative Q. The field exercise revealed that the effectiveness of the existing buffers
had been strongly impacted in many cases by various land altering activities that
resulted in ditches and other features which intercept surface and subsurface flow and
bring it directly to streams. The field exercise also anecdotally established the
effectiveness of LIDAR in conjunction with aerial mapping in predicting field drainage
conditions. However, the specific conditions of the drainage features as they enter the
buffer did require field verification. Also, nutrient removal rates and efficiencies were
used from studies and other sources that were conducted in very different conditions,
but were acceptable to NCDWQ at the time. Additionally, the numbers used in the
calculations above should be conservative in regards to the amount of flexible buffer
mitigation that would be required and, as such, be favorable to NCDWQ. Literature
reviews conducted back in 2006 did not reveal published or otherwise available data
that could further define the removal rates and efficiencies described above.
The numerical methods provided by this study provide PCS with a means of determining
the amount of mitigation that can be provided using the flexible mitigation methods
converting agricultural land to forest and treating untreated runoff using NCDWQ
stormwater practices that are considered to remove total nitrogen and phosphorus.
8 C Kidey-Horn
and Associates, Inc.
References
North Carolina Division of Water Quality (September 2007). B. Everett Jordan Reservoir,
North Carolina Phase I Total Maximum Daily Load, Final Report.
North Carolina Division of Water Quality Best Management Practices Manual, NCDWQ,
July 2007.
PCS Phosphate - Final Environmental Impact Statement,
http://www.saw.usace.army.mil/WETLANDS/Projects/PCS/feis.html
9 Kin*-Horn
'm and ksociates, Inc.
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NCPC Buffer Area
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Title NCPC' Site l-IDAR
Project PCS Buffer Assessment
Beaufort County, North Carolina
PC'S Phosphate

Date Project Number Figure
7,2x 08 U I R ?'_Oll00 26
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NCPC Buffer Area
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Title NCPC L1DAR Site 2
Project PCS Buffer Assessment
Beaufort County, North Carolina
PCS Phosphate Date Project Number Figure
7/25/08 018520000 2c
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Beaufort County, North Carolina
PCS Phosphate Date Project Number
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Title NCPC LIDAR Sites 3, 4, 5, and 6
Project PCS Buffer Assessment
rrcpnrcd r?,r_ Beaufort County, North Carolina
PCS Phosphate Date Project Number Figure
7/25/08 018520000 2e
P;?gc ; Prepared by Jush Allen
Prepaaad I or. Project
PCS Phosphate
Paec 16
PCS Buffer Assessment
Beaufort County, North Carolina
Date
7/25/08
Project Number Figure
018520000 I 2f
Prepared by Josh Allen
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Title I NCPC Aerial Sites 3, 4, 5, and 6
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PCS Phosphate
Page 18
PCS Buffer Assessment
Beaufort County, North Carolina
Date
7/25/08
Project Number Figure
018520000 I 2h
Prepared by Josh Allen
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Title I NCPC Aerial Sites 7 and 8
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PCS Buffer Assessment
Beaufort County, North Carolina
Date
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Project Number Figure
018520000 3d
Prepared by Jush Allen
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Title I S33 Aerial Sites I and 2
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Title I S33 Aerial Site 10
Prepared For:
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Pagc 24
I PCs Buffer Assessment
Project
Beaufort County, North Carolina
Date
7/25/08
Project Number Figure
018520000 I 3f
Prepared by Josh Allen
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Project PCS Buffer Assessment
Prepared h°r. Beaufort County, North Carolina
PCS Phosphate Date Project Number Figure
7/25/08 018520000 3g
Page 25 Prepared by Josh Allen [C/1 _ _

PC_S Phosphite Date Project Number
7/25/08 018520000
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M Bonnerton Buffer Area
Title Bonnerton Site LIDAR
Project PUS Butler Assessmem
Beaufort County, North C'arohoa
PCS Phosphate
Date
7;25,08
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Project Number
01R.'-0000

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7/25/08 018520000 4c
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Prepared l:or: Project
PCS Phosphate
rag, 30
PCS Buffer Assessment
Beaufort County, North Carolina
Date
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Project Number Figure
018520000 4d
Prcpar,d by Josh Allen
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Title I Bonnerton Aerial Sites 1, 2, 3, 5, 6, 7, and 8 1

Attachment 1- PCS Flexible Buffer Mitigation Field Notes Summary
The following is a synopsis of the field notes gathered during the field verification to determine
stream buffer drainage areas.
NCPC Buffer Site 2 - Part of the drainage area was intercepted by a ditch creating a gap in the
. drainage area.
NCPC Buffer Sites 3 and 4-This site included natural drainage features that intercepted flow.
However, there was no evidence of channelized flow as these areas entered the buffer,
so the drainage area was included. This was, in part, due to the fact that the spoil piles
blocked the flow, allowing infiltration and/or lateral flow. The drainage areas were cut
- off by roads to the north and west. Site 4 did have a road (along the west) with a ditch
that at first appeared cut off drainage; however, there was a pipe beneath the road that
allowed the drainage to pass back into the drainage area.
NCPC Buffer Site 5 - This site was in forest but included an extensive ditch system that
- intercepted flow at the top and to the north of the site. This created gaps and limited
• the size of the drainage area. There were also ditches along the roads to the north and
east.
NCPC Buffer Site 6 - The LIDAR reflects the topography observed. This area was cutover with no
evident ditches.
• NCPC Buffer Sites 7 and 8 - Both sites were in recent cutover. However, ditch systems were
• field verified, which can be observed using the LIDAR. This accounts for the gaps in the
drainage areas.
S33 Buffer Sites 1 and 2 - Much of the potential runoff and interflow was intercepted by
ditches that did not appear very clearly on the LIDAR images. This accounts for the gaps
in the drainage areas. This area was recently cutover.
- S33 Buffer Site 10 - The site's drainage area is bounded to the east and south by agricultural
fields The field edges have been ditched and pass through the buffer at the northern
and southern extents of the reach The field ditches run along the wood line such that
the entire buffer area is wooded.
S33 Buffer Sites 17, 19, and 21-The drainage areas for this site were in agricultural fields that
- have field ditches that appear to penetrate the buffer based on the LIDAR mapping;
however, the site review revealed that some of the ditches stopped short of the stream,
allowing infiltration within the buffer. Some of the ditches did penetrate the buffer.
Flow directions of the ditches were also field assessed (using wrack lines, etc.). All of the
above features account for the drainage areas shown.
- S33 Buffer Site 30 - Much of the drainage area was intercepted by roadside ditches. The road
. was in the buffer of the stream, which was on the north side of the road. This greatly
diminished the actual effectiveness of the buffer. However, some of the drainage area
was considered to flow diffusely over the road or to be treated by the "buffer," which
included the road.
. Bonnerton Buffer Site 1-There are a number of ditches that intercepted the stormwater prior
• to entering the buffer resulting in the large gaps shown in the drainage area.
Bonnerton Buffer Site 2 -This site includes old home sites with drainage ditches that intercept
flow, resulting in the gaps in the drainage area.
Bonnerton Buffer Site 3 -This site is bound to the west by an abandoned farm road with
ditches that intercepted flow. This with an additional ditch limited the size of the
drainage area.
Bonnerton Buffer Site 5 - This site had a network of ditches presumably from old agricultural
fields that intercepted flow and carried it through the buffer.
Bonnerton Buffer Site 6 - Part of the drainage area was intercepted by ditches that can be
observed on the LIDAR map and were verified in the field.
Bonnerton Sites 7 and 8 -These sites are not actually a buffered stream because the stream
was not shown on the USDA Soil Survey or USGS Topographic Map; however, the stream
was determined to be a jurisdictional stream by both the USACE and NCDWQ.
Nevertheless, the stream was used in place of the randomly selected sites 9 and 10 (and
their drainage areas) because that stream and its buffers were completely impounded
by beaver activity. The extent of the impoundment created a completely different buffer
on the main stem of the system. As such, a 1,000-foot-section of the above stream was
used in the original sites' place. The replacement Buffer Site 8 was bounded by roads
and a ditch, and the replacement Buffer Site 7 is bound by an existing paved road to the
south/southeast and a ditch to the northwest that intercepted flow.

Buffer ID
Drainage Area ID
Landuse Buffer Area
(ft') Buffer Area
(acres) Drainage Area
(ft') Drainage Area
(acres) Drainage Area per 1000
ft of Stream
Drainage Area/Buffer Area
2 A FOREST 261307.55 6.00
2 B FOREST 12896.72 030
51110.99 1.17 6.29 5.36
3 A 50% CUT-OVER/50% FOREST 478315.44 10.98
49912.06 1.15 10.98 9.58
4 A FOREST 318846.84 7.32
51038.31 1.17 7.32 6.25
5 A FOREST 761308.07 17.48
52480.58 1120 17.48 14.51
6 A FOREST 4703.70 0.11
6 B FOREST 10019.11 0.23
6 C CUT-OVER 486985.51 11418
51074.53 1.17 11.52 9.82
7 A CUT-OVER 223365.94 5.13
7 B FOREST 23301.31 0.53
49274.99 1.13 5.66 5.01
8 A CUT-OVER 356497.01 8.18
49539.13 1.14 8.18 7.20
I lAverage 9.6 8.25
S33 MAter nneccrr t

Buffer ID
Drainage Area ID
Landuse Buffer Area
(ft') Buffer Area
(acres) Drainage Area
(ft) Drainage Area
(acres) Drainage Area per 1000 ft
of Stream
Drainage Area/Buffer Area
1 A CUT-OVER 57736.75 1.33
1 B CUT-OVER 56768.22 1.30
49260.97 1.13 2.63 2.32
2 A CUT-OVER 107717.90 2.47
2 B CUT-OVER 11031.57 0.25
50578.63 1.16 2.73 2.35
10 A FOREST 172840.29 3.97
50705.22 1.16 3.97 3.41
17 A AG FIELD 818822.53 18.80
49985.95 1.15 18.80 16.38
19 A AG FIELD 389629.86 8.94
19 B AG FIELD 16615.47 038
191 C AG FIELD 9054.89 0.21
50004.95 1.15 9.53 8.31
A AG FIELD 1860.89 0.04
21 B FOREST 47343.50 1.09
P C AG FIELD 10607.29 0.24
D AG FIELD 11830.42 0.27
E AG FIELD 13833.27 0.32
F AG FIELD 13115.55 0.30
21 G G AG FIELD 8993.27 0.21
49998.55 1.15 2.47 2.15
30 A CUT-OVER/ROAD 49428.75 1.13
50009.50 1.15 1.13 0.9
verage 5.89 5.13
Rnnnerrnn rtueor o«occ...e..r

Buffer ID
Drainage Area ID
Landuse Buffer Area
(ft') Buffer Area
(acres) Drainage Area
(ft') Drainage Area
(acres) Drainage Area per 1000
ft of Stream
Drainage Area/Buffer Area
1 A FOREST 33044.63 0.76
1 B FOREST 65063.10 1.49
1 C FOREST 90088.95 2.07
1 D FOREST 3045.28 0.07
52035.71 1.19 4.39 3.68
2 A FOREST 153049.04 3.51
2 B FOREST 105167.50 2.41
50318.84 116 5.93 5.13
3 A FOREST 121446.10 2.79
3 B FOREST 4239.63 0.10
48109.44 1.10 2.89 2.61
5 A FOREST 59696.77 1.37
5 B FOREST 160129.35 3.68
50834.30 1.17 5.05 4.32
6 A FOREST 294058.81 6.75
50273.96 1.15 6.75 5.85
7 A FOREST 162768.70 3.74
51889.40 1.19 3.74 3.14
8 A FOREST 4974.94 0.11
8 B MARSH 9917.23 0.23
8 C FOREST 9553.76 0.22
8 D CUT-OVER 378992.61 8.70
51406.43 1.18 9.26 7.85
Average 5.43 4.65

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Summary Table :Bonnerton Sit e NCPC Site S33 Site Average of A ll Sites
Conversion Ratio (CR) 4.65 8.25 5.13 6.01
% Drainage Area in
Forest 77.10% 55.54% 22.50% 56.15%
% Drainage Area in
Recent Cutover 22.90% 44.46% 28.89% 35.32%
% Drainage Area in
Agriculture 48.60% 8.54%
% Drainage Area in
Silviculture
Conversion Ratio
Drainage Area per 1000 ft (Drainage Area/Buffer Area)
PCS Average 6.99 6.01
Attachment 2 - Photo Pages
Photo Pase I
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Photograph 1: NCPC Site 2 Example of ditch that intercepts flow in forest.
I- 112k
Photograph 2: NCPC Site 3 - Example of drainage feature not considered to intercept flow.
Title Attachment 2: Project Site Photographs
Prepared For Prepared By
Project PCS Aurora, NC
PCS Phosphate Date Project Number Wey-Hom
7/25/08 p I K??0000 and Assoaates, Inc.
Photo Pape 2
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Photograph 3: S33 Sitc I L'.xaniple of ditch that cnded pnoi, to reaching stream. Considered to
be treated by buffer.
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Photograph 4: S33 Site 17 - Another example of ditch that ended prior to reaching stream.
Title Attachment 2: Project Site Photographs
Prepared For Prepared By
Project PCS Aurora, NC

PCS Phosphate Date Project Number
Kimley-Horn
7/25/08 018520000 and Associates. Inc.
Photo Page 3
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Photograph 5: S33 Site I and 2 Stream.
i, F I1.a17,, ? ti '; 1e n. t f
0 .w.. "yt r ..
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Photograph 6: Bonnerton Site 7 and 8 Stream.
Title Attachment 2: Project Site Photographs
Prepared For Prepared By
Project PCS Aurora, NC
PCS Phosphate rl=Fl
Date Project Number Krnfay-Horn
7/25/08 0 ( 8520000 and Associates, Inc.
Attachment 3
RATIONALE AND METHODOLOGY FOR FLEXIBLE BUFFER MITIGATION
FOR PCS PHOSPHATE COMPANY, INC.

Rationale and Methodology for Flexible Buffer Mitigation for PCS Phosphate Company,
Inc.
By Todd St. John, Kimley-Horn and Associates, Inc.
and Jeff Furness, PCS Phosphate
. Part 1: General Information
1. Applicant: PCS Phosphate Company, Inc.
2. Project Name: Rationale and Methodology for Flexible Buffer Mitigation for PCS
Phosphate Company, Inc.
- 3. Requested Variance from Environmental Management Commission

Part 2: Demonstration of Need for a Variance

- PCS Phosphate Company, Inc. (PCS) is in the process of seeking agency approval to continue its
mine operation in Beaufort County, North Carolina. As part of this process, the U.S. Army Corps
of Engineers has developed a Draft Environmental Impact Statement, a Supplemental Draft
- Environmental Impact Statement, and a Final Environmental Impact Statement (FEIS) regarding
the proposed impacts in the mine continuation area. It is anticipated that a Section 404 Individual
• Permit application and associated Section 401 Water Quality Certification application will be
authorized that allows specific unavoidable impacts to jurisdictional streams and wetlands and to
riparian buffers protected under the Tar-Pamlico River Basin Rules. Avoidance and minimization
• of impacts to natural resources, including protected riparian buffers, and the selection of
alternatives for analysis are being identified through multiple and regular interagency and
stakeholder meetings held over the past seven years as part of the Section 404/401 Permit
application process. This variance request is only intended to request flexible forms of riparian
buffer mitigation for any riparian buffer impacts that may be approved as part of the Section
• 404/40 1 Permit application process. However, this variance request is not to request approvals
for any riparian buffer impacts as part of the mine continuation. Despite an extensive search of
the Pamlico hydrologic unit (Figure 1), there may be a shortfall of suitable sites available for
• buffer restoration.

- Section 15A NCAC 2B .0260 "Tar-Pamlico Basin - Nutrient Sensitive Waters Management
"
Strategy: Mitigation Program for Protection and Maintenance of Riparian Buffers
specifies three
- options for providing compensatory buffer mitigation. These are: 1) payment of a fee to the
Riparian Buffer Restoration Fund, 2) donation of real property and restoration, or 3) enhancement
. of non-forested buffer.

- PCS has performed an exhaustive search for available tracts of land that have the potential for
restoration or enhancement of non-forested buffer, including reviews of all available mapping
(USGS and county soil surveys), LIDAR data, and field reconnaissance. Through this process
PCS has identified a number of sites that may yield sufficient stream and wetland restoration
credit to satisfy their anticipated stream and wetland compensatory mitigation needs for the L
Alternative. Based on the proposed buffer impacts and the ratio applied to such impacts under
. PCS Compensatory Mitigation Plan 2 FEIS Appendix I
Attachment 1

the Tar-Pam buffer rules, a deficit of appropriate buffer restoration sites to compensate for these
impacts may occur.
Based on the above discussion, an adequate amount of riparian buffer restoration sites may not
be available under a strict interpretation of the buffer rules. The lack of available riparian buffer
restoration sites has created a hardship for PCS. As such, PCS herein requests the ability to
comply with the Tar-Pamlico Buffer Rules and to protect water quality in the river basin through the
use of flexible forms of buffer mitigation.
In order to obtain such flexibility, PCS herein requests the following:
(1) a major variance from 15A NCAC 2B .0259 and .0260 in regards to compensatory
mitigation; and
(2) EMC approval of a methodology for determining the type and amount of flexible
mitigation required as opposed to a specific mitigation plan;
As part of this variance request, review and approval of the specific mitigation is delegated
by the EMC to the Division of Water Quality Staff based on this method if approved by the
EMC.
Findings of Fact:
Hardship -
The first 15 years of the L Alternative have approximately 32 acres of buffer impact which
translates to 77 acres of buffer mitigation required once the ratios (3:1 for Zone 1 impacts and
1.5:1 for Zone 2 impacts) are applied. Since May 2004 PCS has conducted an exhaustive search
using its own staff and three consulting firms including Environmental Banc and Exchange, LLC
(EBX), an environmental mitigation banking company that specializes in identifying and securing
real estate for compensatory mitigation purposes, CZR Incorporated, an environmental consulting
firm with longstanding expertise with lower coastal plain wetland, stream, open water and natural
systems assessment and restoration and, and Kimley-Horn and Associates, Inc., for its expertise
in mitigation design and regulatory issues. Through this exhaustive mitigation site search, PCS
has secured approximately 28 acres of potential and available riparian buffer restoration sites.
Therefore, it may not be possible to secure enough appropriate riparian buffer restoration sites. This
has created a hardship for PCS. An additional hardship is that failing to meet the buffer mitigation
requirement could also delay the permitting process which is already critically time constrained.
Purpose and Intent of the Buffer Rules -
15 A NCAC 2B .0259(1) states in part, "The purpose of this Rule shall be to protect and preserve
existing riparian buffers, to maintain their nutrient removal functions, in the entire Tar-Pamlico
Basin." The existing riparian buffers are shown in Figures 2, 3 and 4. As part of the Section
404/40 1 Permitting process, DWQ staff will require that a determination of no practical
alternatives be demonstrated in order to impact any protected riparian buffers. Additionally, it is
also anticipated that stormwater control measures will be required by DWQ for the proposed mine
continuation site to maintain water quality. PCS does not anticipate a need at this time for a
variance from 15 A NCAC 2B .0259 based on the proposed impacts. However, PCS is requesting
a variance from 15A NCAC 2B .0260(6) and 15 A NCAC 2B .0259(10) in order to be allowed to
provide flexible forms of mitigation that replace the nutrient removal functions of the impacted
buffers. By providing alternative means of nutrient removal as compensatory mitigation for
riparian buffer impacts, PCS proposes methods with a goal to improve the total nitrogen (TN) and
total phosphorus (TP) removal functions of the buffers, which is consistent with the general
purpose and spirit of 15A NCAC 2B .0259 and .0260.
PCS Compensatory Mitigation Plan 3 FEIS Appendix I
Attachment 1
Public Safety and Welfare, Water Quality and Substantial Justice -
As described herein, PCS proposes the following methods to replace the nutrient removal
functions of the riparian buffers that may be impacted by the proposed mine continuation:
• Conversion of existing untreated cropland into forest and riparian headwater
system mitigation as described in the recent DWQ and USACE publication,
"Information Regarding Stream Restoration with Emphasis on the Coastal
Plain" (April 4, 2007).
• Stormwater best management practices (BMPs) that remove nutrients from
currently untreated urban (developed areas) and agricultural runoff.
• Other similar quantifiable means of nutrient reduction.
• Other potential sources of mitigation credit may include support and funding of
activities such as research into the effectiveness of wider buffers in developed
areas.
PCS would not request credit for agricultural or silvicultural BMPs if required by other rules
administered by DWQ. As such, none of mitigation activities provided by PCS could be applied
towards any required county nutrient management or reduction requirements. PCS also agrees
that riparian buffer preservation and wastewater (as opposed to stormwater) treatment would not
be acceptable as riparian buffer mitigation in the context of the variance as proposed.
Additionally, DWQ staff would review and approve any specific requests for mitigation credit.
Part 3: Water Quality Protection
For any kind of compensatory mitigation of natural resources it is important to replace the desired
functions that would be removed by the impact to that resource. In the situation of riparian buffer
impacts in the Tar-Pamlico Basin as stated in the Purpose of the Tar-Pamlico Buffer Rules, the
important functions are related to maintaining the nutrient removal capabilities of the riparian
buffers (1 5A NCAC 2B .025 9). As described previously, PCS seeks to implement flexible buffer
mitigation that will meet or exceed the nutrient loading reductions and resultant water quality
benefits of the impacted riparian buffers. The goal of this method of determining flexible methods
of buffer mitigation described is focused on the replacement of that function, especially for total
nitrogen (TN) and total phosphorus (TP). The mitigation techniques described below would also
replace hydrologic and hydraulic functions of riparian buffers. The methodology is intended to be
specific to the proposed PCS Phosphate mine continuation.
Buffer Mitigation Credit from Riparian Headwater System Stream Restoration
At most of the mitigation sites identified by PCS, there will be an opportunity to use the
"Information Regarding Stream Restoration with Emphasis on the Coastal Plain" (April 4, 2007)
publication from DWQ and the USACE. In the case of riparian headwater system stream
restoration credit can be provided for the length of the riparian headwater system regardless of
whether a defined channel with a wetland or wetland only forms, as long as there is flow. When
flow is documented and the riparian headwater system is used for linear stream restoration
credit, PCS proposes that a 50-foot forested zone around the riparian headwater system be
considered as buffer restoration also. This is reasonable since the forested zone around these
swampy headwater systems that flow slowly in the eastern North Carolina coastal plain will
provide the same nutrient removal functions as a riparian buffer around blue line streams.
Additionally, 50-foot buffers would count as buffer mitigation credit on restored streams under
normal circumstances.
PCS Compensatory Mitigation Plan 4 FEIS Appendix I
Attachment 1
Method for Converting Treated Drainage Area into Buffer Mitigation Credit
The methodology involves two primary steps:
1) Calculation of the functional buffer impact from the proposed mine continuation; and
2) Calculation of the function of the proposed mitigation practice.
. Two of the potential mitigation activities that PCS Phosphate would like to consider using for
riparian buffer mitigation credit are to treat currently untreated stormwater runoff from agricultural
- fields through the use of stormwater best management practices (BMPs) and conversion of
- agricultural fields to natural forest (upland and/or wetland). The main purpose for maintaining the
riparian buffers in the Tar-Pamlico Basin is to reduce nutrients (nitrogen and phosphorus) that
. enter the basin through runoff. Both of the above activities could provide the nutrient reduction
function of riparian buffers. In order to establish the amount of buffer mitigation credit these
activities would provide, a method to equate buffer mitigation requirements that are in units of
- square feet of buffer into a drainage area for that buffer must be established. The following is
such a method that would be directly applicable to the proposed PCS Phosphate mine
continuation site.

1) Select 21 random, representative samples of 1,000-foot (by stream length) sections of 50-foot
wide stream buffer from streams mapped as subject to the buffer rules by NCDWQ in the
three areas proposed for PCS Phosphate Mine Continuation sites. The 21 samples will
represent the areas proposed for mine expansion. Next, measure the square footage of the
buffer selected for each of the 21 sites. Delineate the drainage area that drains by diffuse flow
through the selected buffer section. Figures 2, 3, and 4 show the mine sites with the buffered
streams highlighted in blue. Areas that drain through the buffers by channelized flow will not
be included as part of the drainage area. Actual drainage patterns for each of the 21 study
sites will be verified in the field. Also, the extents of the drainage areas that drain by diffuse
flow to the buffers at each site will be delineated using sub-meter accuracy GPS. PCS will
develop a specific method for selection of the 21 sites for written approval by NCDWQ. PCS will
conduct the field measurements.
2) Once the amount of buffer area and drainage area are determined, a ratio of the average
drainage area per unit area of buffer can be established. This ratio will be called the
Conversion Ratio or CR. The CR can be used as a basis for establishing buffer mitigation
credit.
3) PCS will submit the results to NCDWQ for review and written approval.
Calculation of Flexible Mitigation Function
Removal Efficiency of Existinq Buffers
PCS originally proposed an assumed removal efficiency of 30% for existing riparian buffers as it
relates to the following flexible buffer mitigation practices. NCDWQ maintains that buffers in
agricultural situations remove 85% total nitrogen (TN) and that 30% removal efficiency only
relates to urban situations. PCS believes that using an 85% buffer removal efficiency would likely
still create a hardship as it would approximately triple the amount of land required for the
following two flexible mitigation options as compared to using a removal efficiency of 30%. As
such, it was decided that the removal efficiency used in the following calculations will be based
on the removal efficiency of the buffers in the areas where the land is impacted.
PCS Compensatory Mitigation Plan 5 FEIS Appendix I
Attachment 1
Visual inspection of the proposed impact sites reveals that, for the most part, the areas directly
draining to the buffers are forested. At present, NCDWQ has not determined a nutrient removal
rate for riparian buffers that receive diffuse flow runoff from forested areas. As such, PCS will
conduct a review of available literature in an effort to establish an appropriate removal rate. PCS
will prepare a report and present the results for written approval to NCDWQ. Using the drainage
areas of the 21 randomly selected sites described above, the amount of forest cover compared to
the amount of agricultural drainage area will be determined. Using this information, an average
removal efficiency rate will be established based on the prorated amount of forest cover
compared to that of the agricultural cover. The final efficiency rate method of determination will be
approved by NCDWQ in writing. Because of the time constraint hardship that PCS is facing, it will
be necessary to determine a removal efficiency rate in a timely manner. If a rate cannot be
agreed upon within 60 days of receipt of the report from PCS regarding the removal efficiency of
buffers that serve forested areas then the matter will be sent to the Director of the Division of
Water Quality to establish a removal rate. This rate will only apply to the flexible buffer mitigation
variance for PCS.
Buffer Mitigation Credit Using Stormwater BMPs
In order to establish the amount of credit that could be applied to the use of stormwater BMPs to
replace the function of riparian buffers, there are two factors that must be considered. The first
factor is the use of the CR as described above; the second is the removal efficiency of the BMP
versus that of a riparian buffer. The use of BMPs would only be applicable where currently
untreated stormwater would be entering a stream from active agricultural or otherwise developed
land. Also, the removal efficiencies of the BMP or BMPs in series would need to exceed that of a
functioning 50-foot riparian buffer in the Tar-Pamlico Basin. The NCDWQ Stormwater Unit
considers that riparian buffers remove 30% of the total nitrogen (TN) and 30% of the total
phosphorus (TP) (see Updates to Stormwater BMP Efficiencies, NCDWQ, September 8, 2004).
The use of a BMP or series of BMPs to treat untreated stormwater would replace the function of
the riparian buffers. Using the CR would provide the means to establish the mitigation credit
based on the drainage area. The following describes the steps used to establish the mitigation
credit:
1) Using the CR, the buffer mitigation credit required can be established as an equivalent
drainage area of acreage to be treated.
2) A BMP or series of BMPs would be selected that is appropriate for the watershed to treat the
existing untreated stormwater. It is assumed that the watershed is currently in agriculture or
otherwise developed.
3) If the BMP or series of BMPs does not have the same or greater percent nutrient removal
capability of a buffer, then the lack of removal efficiency can be accounted for by treating a
larger area. The size of the drainage area to be treated would be determined by dividing the
percent removal efficiency of a buffer by the percent removal efficiency of the BMP and
multiplying the result by the equivalent drainage area determined by using the CR. This would
result in the same nutrient removal rate based on loading as would occur if the BMP(s) had the
same removal efficiency as a buffer.
Buffer Mitigation Credit by Converting Agricultural Uplands into Forest
PCS anticipates the possibility of acquiring parcels that comprise entire localized watersheds in
order to implement stream and wetland mitigation. Some areas of this land may be useful for
stream and wetland mitigation. However, there would also be the opportunity to take the land out of
agricultural production and convert it into upland (non-wetland) or wetland (if it is not used
PCS Compensatory Mitigation Plan 6 FEIS Appendix I
Attachment 1
otherwise for mitigation) forest. This land use conversion would reduce the amount of nutrients
exported off of the land, subsequently reducing the amount of nutrients entering streams. As
such, a mathematical model can be used to determine the appropriate amount of buffer mitigation
to allow for this conversion of agricultural land into forested land. The amount of buffer mitigation
credit would be based on the nutrient removal functions of buffer replaced. The model would be
based on information provided in NCDWQ's Tar Pamlico River Basin: Model Stormwater Program
for Nutrient Control. The basic premise would be to use mass balance information to compare the
difference in nutrient loading from farm land to that of forest. This difference would be compared
to the difference in loading from agricultural land that flows through a 50-foot wide riparian buffer.
As such, converting agricultural land to forest could be numerically compared to providing a
riparian buffer for that same amount of land. The results could be used to determine an
equivalent buffer value and ultimately be converted to an equivalent buffer credit amount using
the CR. The development of the proposed mathematical model as follows:
Calculations to Determine the Equivalent Amount of TN (Ibs/ac/yr) TP
Riparian Buffer Achieved By Converting Agricultural Land (Ibs/ac/yr)
to Forest (Equivalent Buffers)
Cropland loading* 13.4 5.3
Wooded land loading* 1.59 0.33
Nutrient load reduction by converting agricultural land to forest 11.81 4.97
or "LRF"
(cropland loading -wooded land loading)
Nutrient load reduction by a 50 foot forested riparian buffer 13.4xR 5.3xR
from runoff from cropland or "LRB"
(nutrient loading x nutrient removal efficiency rate (R) for TN
and TP*)
Equivalent amount of riparian buffers based on nutrient load 11.81/(13.4xR) 4.97/(5.3xR)
reduction (= LRF/LRB) Equivalent Equivalent
Buffer Ratio Buffer
Ratio
x From NUUVVU's study of the Jordan Lake Watershed.
The conversion can be valued using the Equivalent Buffer Ratio for whichever ratio (TN or TP) is
less.
To determine the buffer mitigation credit achieved by reforestation, the following model would
be employed:
CR = Conversion Ratio (see above)
EB = Equivalent Buffers
DA = Agricultural land converted to forest (areas of agricultural land converted to wetland forest
will be credited only as wetland mitigation or as buffer mitigation, not both)
Buffer Mitigation Credit*CR = EB*DA
PCS Compensatory Mitigation Plan 7 FEIS Appendix I
Attachment 1

• Project Selection Process
As part of this variance request, PCS is requesting that the EMC delegate the approval of the
specific flexible buffer mitigation projects to DWQ staff. Using the previously described
- methodology, it is anticipated that the majority of flexible buffer mitigation will involve providing
measures that directly reduce nutrient input. However, DWQ has requested that PCS consider
- other alternatives for flexible mitigation such as research into the effectiveness of wider buffers in
developed areas. Nevertheless the majority of the projects will require securing land.
Mitigation Projects Requiring Land Acquisition
- For projects that involve the use of BMPs or conversion of agricultural land to forest, the land on
which the projects will be implemented will be protected by a conservation easement or other
perpetual protection mechanism. As such, the first step in this process is to identify land that can
- be secured in that manner. PCS has already secured several tracts of land that it proposes to use
for mitigation. PCS has the ability to provide conservation easements or declarations of
- restriction for these sites as required by NCDWQ. NCDWQ will establish a method of nutrient
- accounting along with the Local Advisory Committee to keep track of PCS' activities.
NCDWQ has also requested that PCS seek to identify urban BMP retrofit sites for untreated
- stormwater runoff. NCDWQ has developed a Stormwater Outfall Database that identifies
untreated stormwater outfalls in areas such as Aurora, Bath, and Belhaven. In such cases, PCS
- can approach these municipalities or property owners to assess the feasibility of BMP retrofits. It is
anticipated that the main issues will be the provision of adequate land for BMP implementation
and securing that land in perpetuity. Another situation where the use of BMPs would be possible
• is to provide treatment as offline BMPs in Water Management Districts. The BMPs could be
located adjacent to drainage canals and provide treatment of low flow and first flush events.
However, it is important to note that this possibility has not been discussed with the Water
- Management Districts. Also, there are additional FEMA and drainage maintenance issues that
would have to be evaluated in order to assess the possibility of providing the BMPs.

The general process for identifying flexible buffer mitigation projects that involve securing land
would be as follows:
1) PCS will identify a proposed project and location. The identification may be
accomplished by the following methods:
a. Through the mitigation site search process performed by PCS, with a site visit
by DWQ staff.
b. Use of DWQ's Stormwater Outfall Database.
c. A public process to seek possible BMP retrofit sites through:
i. Local environmental groups
ii. DHS sanitary surveys
iii. Others
2) PCS will provide its preliminary findings and plans to DWQ's Central and Washington
Regional Offices including:
a. Location of the proposed mitigation activity,
b. Method of flexible mitigation,
c. Preliminary calculations to identify the potential buffer mitigation credit per the
methods described herein,
d. Information to substantiate that the activity is not required by other
rules administered by DWQ.
e. A credit release schedule and monitoring and maintenance plan.
PCS Compensatory Mitigation Plan
Attachment 1
FEIS Appendix I
3) DWQ will review the proposal within 60 days of receipt and either request additional
information, approve or deny the request. DWQ may also request an additional site
review as part of the additional information required.
4) If NCDWQ denies the project proposal or if PCS believes it has submitted sufficient
information for NCDWQ to either accept or deny the project proposal after two rounds of
submittals, then the proposal shall be brought before the Director of the Division of
Water Quality. The Director or the Director's designee shall accept or deny the proposal.
If the proposal is denied by the Director or the Director's designee then PCS can bring
the proposal to the EMC Water Quality Committee to accept or deny the project
proposal.
5) If the concept project is approved by DWQ, PCS will seek to secure the site (if not
already secured).
6) PCS will apply for any permits or approvals needed such as a Section 404/401
permits or certifications if needed to implement the project.
7) PCS will notify the representative of the Local Advisory Committee (LAC) established
under the Tar-Pamlico Agriculture rule, 15A NCAC 2B .0256, who is responsible for
carrying out annual accounting activities for the LAC, in writing of the activity and nutrient
reduction benefits and credit that will be achieved as a result of the activity. This
representative is currently a Soil and Water District Technician whose job responsibilities
include annual agriculture rule accounting. The Technician will be responsible for
ensuring that none of the credit from these activities will be applied towards the LAC's
agriculture rule nutrient reduction progress calculations. PCS will only be responsible for
notifying NCDWQ and the LAC.
8) Once all approvals are received, PCS will construct, monitor, and maintain the project per
the preliminary plan.
9) PCS will provide and keep a ledger for all of the flexible mitigation projects that it will
submit as part of its annual report. The ledger will include:
a. The total potential buffer mitigation credit for the project,
b. The credit release schedule and amounts,
c. The amount and date of approved credit,
d. The amount and date of impacts applied to that credit.
10) PCS will provide protection in perpetuity through a conservation easement or other
means.
Other Flexible Mitigation Options
Based on comments from DWQ staff, other activities can be considered for buffer mitigation
credit. One such activity is conducting research into the effectiveness of providing wider riparian
buffers in developed areas. The challenge with using such activities for mitigation is determining the
appropriate amount of mitigation credit that should be applied. Since PCS would not be the most
appropriate institution to conduct such research, it is recommended that a university or similar
institution be identified to actually conduct the research. The recommended process for
determining the buffer mitigation credit that could be derived from such a project is as follows:
- Identify, with input from DWQ, an appropriate research institution.
1) Determine the scope and resources needed for the study.
- 2) Evaluate anticipated benefits based on the scope of the research.
3) Negotiate with DWQ staff the credit that would be achieved through providing the
research.
Other flexible mitigation plans that provide quantifiable nutrient reduction measures would be
evaluated by DWQ and PCS on a case-by-case basis.
PCS Compensatory Mitigation Plan 9 FEIS Appendix I
Attachment 1
Sample Applications:
Agricultural - At present, the best opportunities for riparian buffer mitigation are on parcels of land
that are currently in agriculture. Most of these areas are drained by an agricultural ditch network
system. Typically, the ditches in these networks are not buffered and the fields in between are
crowned which allows runoff to directly enter the ditch system. This runoff usually them flows into
larger ditches or jurisdictional waters that do not provide the same opportunities for treatment as
a natural forest and stream system would. Figure 5 demonstrates how providing riparian buffer
restoration, converting agricultural land to forest, and providing BMPs to treat runoff from
untreated agricultural fields can be implemented. In this example, part of the area that is
reforested would qualify for wetland restoration which would not be used for riparian buffer
mitigation. However, the portion that is not used for wetland mitigation would be used as buffer
mitigation. In any event, the land would be converted from agricultural crop production to forest by
filling the ditch network and planting appropriate native forest tree and shrub species. Also, the
BMPs would be placed in strategic areas to intercept or receive diverted flow from the collection
ditches providing treatment to otherwise untreated runoff.
Urban - Figure 6 demonstrates how a BMP could be located at a stormwater outfall that drains a
developed area. In this example, the feasibility of the placing a BMP at the location shown has
not been studied, nor have any landowners been identified or contacted. However, PCS could
identify such stormwater outfalls and determine the feasibility of retrofitting a BMP to treat the
stormwater runoff. In this case, the drainage area has been estimated at approximately 100 acres,
and 2.5 acres may be sufficient to create an appropriately sized BMP.
PCS Compensatory Mitigation Plan 10 FEIS Appendix I
Attachment 1
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Title Example Application ot'Tar-Pamlico Flexible Buffer Mitigation Practices in Agricultural Lands
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