20190865 Ver 1_SAW-2019-00835 Buffer Calculation_20210208

Strickland, Bev
From: Browning, Kimberly D CIV USARMY CESAW (USA)
<[e-mail]>
Sent: Monday, February 8, 2021 12:48 PM
To: Tugwell, Todd J CIV USARMY CESAW (US)
Cc: Davis, Erin B
Subject: [External] FW: Laurel Springs (SAW-2019-00835) Buffer Calculation
Attachments: Fig_11_WiderBufferResults_210205.pdf, Laurel Springs Buffer Calculation.xlsx
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FYI, I asked RS to re -run the buffer calculation for Laurel Springs using the revised buffer tool that exempts
terminal ends entering and exiting the project. Attached is the revised spreadsheet. It looks like it gave them a
gain of about 100 stream credits from the version they had in the draft mit plan.
Kim Browning
Mitigation Project Manager, Regulatory Division I U.S. Army Corps of Engineers
-----Original Message -----
From: Kenan Jernigan<[e-mail]>
Sent: Friday, February 05, 2021 3:38 PM
To: Browning, Kimberly D CIV USARMY CESAW (USA) <[e-mail]>
Cc: Ray Holz <[e-mail]>; Grant Lewis <[e-mail]>
Subject: [Non-DoD Source] Laurel Springs (SAW-2019-00835) Buffer Calculation
Hi Kim,
As part of your comments on the Laurel Springs Draft Mitigation Plan, you requested that the additional credit
from wider buffers be calculated from the newest version of the buffer tool, which accounts for the terminal
ends. I have attached the excel sheet and an updated figure for your review. This is our first shot at using the
new tool, and we are happy to discuss any issues at your convenience. Have a nice weekend!
Thanks,
Kenan

Kenan R. Jernigan
Project Scientist
Axiom Environmental, Inc.
218 Snow Avenue
Raleigh, NC 27603
[e-mail]
[phone]
https:Hurldefense.com/v3/_http://www.axiomenvironmental.org_;!!HYmSToo!Mt2lXUJSwrh-
OhkA9An7wWG_gvMgebSSgxA6GDZPvllZj-8a59wujf60NGFcJGg8quE$

f
Legend
Conservation Easement Boundary
Channel TOB
TOB-15ft
15-20ft
_ 20 - 25 ft
25-30ft
_ 30-50ft
50-75ft
-75-100ft
100 - 125 ft
_ 125-150ft
® Ineligible Buffer Area (Wetland Reestablishment Beyond 45 ft from TOB)
0 200 400
r
Axiom Environroenial, Inc.
Prepared for:
Project:
LAUREL SPRINGS
MITIGATION SITE
Avery County, NC
Title:
STREAM BUFFER
CREDIT
ADJUSTMENT
OUTPUT
\rl Drawn by:
KRJ
Date:
FEB 2021
.'� Scale:
41
1:2200
Project No.:
19-009
'`ok
Buffer Zones
less than 15feet
>15to 20feet
>20to 25feet
>25to 30feet
>30to 50feet
>50to 75feet
>75to 100feet
>300to 125feet
>325to 150feet
Max Possible Buffer
156596.25
53983.75
54376.25
54768.75
223000
265993.75
266386.25
266778.75
287581.25
Ideal Buffer
161982.14
54780.67
54365.47
54390.63
211885.48
258774.43
255325.63
253381.12
252860.16
Acutal Buffer
156496.49
51227.47
50181.69
49327.64
169766.9
145440.21
134349.17
123208.11
100737.85
Zone Multiplier(%)
50%
20%
15%
15%
9%
7%
6%
5%
3%
Buffer Credit Equivalent
1865.98
746.39
559.80
559.80
335.88
261.24
223.92
186.60
111.96
Percentage of Ideal Buffer
97%
95%
94%
93%
80%
56%
53%
49%
40%
$00
Feet
Credit Adjustment
-53.31
-39.55
-34.55
-41.83
269.11
146.82
117.82
90.73
44.60
Total Baseline Credit
Credit Loss in
Required Buffer
Credit Gain for
Additional Buffer
Net Change in
Credit from Buffers
Total Credit
3731.97
-169.24
1 669.1
499.86
4231.83
FIGURE
11

Wilmington District Stream Buffer Credit Calculator
Site Name:
Laurel Springs
USACE Action ID:
SAW-2019-01732
NCDWR Project Number:
2019-0865
Sponsor:
Restoration Systems
Number of Exempt Terminal Stream Ends':
5
County:
Avery
Minimum Required Buffer Width2: 30
Mitigation Type
Restoration (1:1)
Enhancement 1 (1.5:1)
Enhancement II (2.5:1)
Preservation (5:1)
Other (7.5:1)
Other (10:1)
Custom Ratio 1
Custom Ratio 2
Custom Ratio 3
Custom Ratio 4
Custom Ratio 5
Totals
Buffer Zones
Max Possible Buffer (square feet)-'
Ideal Buffer (square feet)6
Actual Buffer (square feet)'
Zone Multiplier
Buffer Credit Equivalent
Percent of Ideal Buffer
Credit Adjustment
Total Baseline Credit
3731.97
Mitigation Ratio
Creditable Stream
Include in Buffer
Buffered Stream
Credit From Buffered
Multiplier
Length
Calculations Baseline
Stream CreditLength
Streams
1
3296 Yes
3296.00
3296.00
3296.00
1.5
274
Yes
182.67
274.00
182.67
2.5
198
Yes
79.20
198.00
79.20
5
248
Yes
49.60
248.00
49.60
7.5
10
1245
Yes
124.50
1245.00
124.50
5261.00 3731.97 5261.00 3731.97
Riiffar Width 7nna Ifaat frnm nrrlinnry Hioh XA/ntar Mark)
Credit Loss in Required Credit Gain for Net Change in
Total Credit
Buffer Additional Buffer Credit from Buffers
-169.24 669.10 499.86 4231.83
1Number of terminal stream ends, including all points where streams enter or exit the project boundaries, but not including internal crossings even if they are not protected by the easement.
2Minimum standard buffer width measured from the top of bank (50 feet in piedmont and coastal plain counties or 30 feet in mountain counties)
3Use the Custom Ratio fields to enter non-standard ratios, which are equal to the number of feet in the feet -to -credit mitigation ratio (e.g., for a perservation ratio of 8 feet to 1 credit, the multiplier would be 8).
4Equal to the number of feet of stream in each Mitigation Type. If stream reaches are not creditable, they should be excluded from this measurement, even if they fall within the easement.
5This amount is the maximum buffer area possible based on the linear footage of stream length if channel were perfectly straight with full buffer width and no internal crossings. This number is not used in calculations, but is provided as a reference.
6Maximum potential size (in square feet) of each buffer zone measured around all creditable stream reaches, calculated using GIS, including areas outside of the easement. The inner zone (0-15') should be measured from the top of the OHWM or the edge of the average stream width if OHWM is not known. Non -creditable stream reaches
within the easement should be removed prior to calculating this area wtih GIS.
'Square feet in each buffer zone, as measured by GIS, excluding non -forested areas, all other credit type (e.g., wetland, nutrient offset, buffer), easement exceptions, open water, areas failing to meet the vegetation performance standard, etc. Additional credit is given to 150 feet in buffer width, so areas within the easement that are more than
150 feet from creditable streams should not be included in this measurement. Non -creditable stream reaches within the easement should be removed prior to calculating this area wtih GIS.