20081352 Ver 1_More Info Received_20081028

i
ALMG
LAND MANAGEMENT GROUP INC.
19W Environmental Consultants
October 24, 2008
TO: Mr. Chad Coburn
NC Division of Water Quality
127 Cardinal Drive Extension
08-1352
OCT 2 B 2008
Wilmington, NC 28405
Uksjk. - VvATER QUAU'(Y
WETLANDS AND STORMWATER BKWA
RE: NWP 12 Application; Additional Information
New Hanover County Northern Campus Regional Wastewater Collection System
New Hanover County, NC
Action ID# SAW-2008-02725 & DWQ# 08-1352
Dear Chad:
Thank you for your letter dated October 17, 2008 in which you request additional information about
the NWP 12 application we submitted for the New Hanover County Northern Campus Regional
Wastewater Collection System. Below is a response to each of your comments.
1. Your application states that you are applying for a Nationwide 12; however, the US. Army Corps
of Engineers stated in their letter from October 3, 2008 that this application does not meet the
terms and conditions required for a Nationwide 12. Please clarify.
We addressed the Corps' comments in a letter dated October 15, 2008 and believe that this project
meets the terms and conditions of a NWT 12. In our response (enclosed), we discussed why directional
drilling cannot occur and why a 50' wide construction corridor is needed for this project.
2. If you do wish to apply under a Nationwide 12 permit then you will need to modify the proposal to
meet the requirements for the corresponding Section 401 Water Quality General Certification 3699
(GC3699). The following items have been identified in the application that do not meets those
requirements:
a. Condition #19 requires the construction corridor (including access roads and stockpiled
materials) to be limited to 40 feet in width in wetlands. You have proposed a 50 foot construction
corridor.
The first page of GC3699 states that if the general conditions of this certification cannot be met,
written approval from DWQ is required. We understand that the work corridor is wider than what
the general conditions allow and submitted a check for $240 to DWQ with our original submittal in
order to obtain written approval from DWQ.
As we stated in our response to the Corps, a 50' corridor will be required to install this sewer line
due to the difficult working conditions. Large equipment will be required to excavate the required
trench, drive pilings, and move the large diameter metallic pipe into place. Additionally, in order to
www.lmgroup.net • [e-mail] • Phone: [phone] • Fax: [phone]
3805 Wrightsville Ave., Suite 15, Wilmington, NC 28403 • P.O. Box 2522, Wilmington, NC 28402
install the pilings connect to the pipeline, the excavation will be required to be dried. As material is
excavated, it will be placed around the excavation on all sides to provide a temporary dike around
the working area. It is estimated the area required to construct temporary dikes and move the large
equipment and materials through the area will require up to a 50' working corridor. It should be
noted the temporary dikes will only be constructed around the immediate working area and no
damming of the stream will take place.
b. Condition #20 requires that permanent, maintained access corridors be restricted to 1 5 feet in
width. You have proposed a 30 foot permanent easement with an additional 20 foot construction
corridor.
Condition #20 refers to maintained easements. As stated in the PCN form, the 30' permanent
easement across Prince George Creek will not be maintained.
3. Please provide a wetland restoration plait as required by Condition #22 of GC3699.
Enclosed is the restoration plan for this project.
4. Please re-submit your site plans on full plan sheets at a scale of no smaller than I"= 50 ' with
topographic contours shown.
Enclosed are plan sheets at a scale of I" = 50'.
5. Please submit a revised PCNfor this project.
No revisions to the PCN have been made since our original submittal.
Please contact me if you have any additional questions. Thank you for your assistance with this
project.
Sincerely,
im Williams
Wetland Scientist
Encl.
C: Mr. Frank Styers, Cape Fear Public Utility Authority
Mr. Michael Johnson, McKim & Creed
Ms. Kim Garvey, ACOE
Mr. Ian McMillan, DWQ
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October 15, 2008
TO: Ms. Kim Garvey
U. S. Army Corps of Engineers
P.O. Box 1890
Wilmington, NC 28402-1890
RE: NWP 12 Application; Additional Information
New Hanover County Northern Campus Regional Wastewater Collection System
New Hanover County, NC
Action ID# SAW-2008-02725
Dear Kim:
Thank you for your letter dated October 3, 2008 in which you request additional information about
the NWP 12 application we submitted for the New Hanover County Northern Campus Regional
Wastewater Collection System. Below is a response to each of your comments.
1. The plans and description submitted with your September 3, 2008 PCN does not illustrate
avoidance and minimization to the maximum extent practicable because you did not adequately
address Regional Condition 4. 1, Directional Drilling or Boring, requiring the use of directional
drilling,boring to the maximum extent practicable. , Please provide evidence that it is not
practicable to directional drill/bore this high quality resource or modify your PCN.
As mentioned in the PCN form, the proposed wastewater collection system consists of a regional
pumping station with gravity collection lines which collect flow from the surrounding area. The service
area of the regional pump station encompasses areas to the north and south of Prince George Creek,
subsequently a gravity sewer crossing of the creek will be required regardless of which side of the creek
the pumping station is on. Gravity sewer mains must be laid to a consistent grade between manholes.
Although directional drilling can install pipe below obstructions and water bodies, directional drilling
can not achieve a consistent grade as is required for a gravity sewer pipeline. The other trench-less
alternative considered was a bore & jack installation of steel casing which the 24" carrier pipe could be
inserted through. Although bore & jack casing installation can be installed to grade with reasonable
accuracy, it is not likely a bore of this size and length could be installed to the required accuracy. An
additional concern with trench-less installation is flotation. Due to the standing water present during wet
periods and likelihood of poor native soils above the pipe, the buoyant force of an empty pipe will be
greater than the weight of the soil above the pipe. Note the proposed design utilizes driven timber piles
with additional stone placed above the pipe to provide solid structural support and anchorage to resist
flotation.
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3805 Wrightsville Ave., Suite 15, Wilmington, NC 28403 • P.O. Sox 2522, Wilmington, NC 28402
2. You do not meet the terms of Regional Condition 4.3, Work Corridor Restrictions, and provided no
explanation as to why a 50 foot construction corridor was requested.
A 50' corridor will be required to install this sewer line due to the difficult working conditions. Large
equipment will be required to excavate the required trench, drive pilings, and move the large diameter
metallic pipe into place. Additionally, in order to install the pilings connect to the pipeline, the
excavation will be required to be dried. As material is excavated, it will be placed around the excavation
on all sides to provide a temporary dike around the working area. It is estimated the area required to
construct temporary dikes and move the large equipment and materials through the area will require up
to a 50' working corridor. It should be noted the temporary dikes will only be constructed around the
immediate working area and no damming of the stream will take place.
3. You did not submit a restoration plan as required by Regional Condition 4.7, Restoration of
Wetland Areas Using Native Vegetation.
Enclosed is the restoration plan for this project.
4. The drawings that you submitted indicate that a 30 foot permanent easement will be maintained
and an additional 20 foot construction corridor will be used. Asper Special Condition 20 (h) and
Regional Condition 4.8, Compensatory Mitigation for Permanently Maintained Corridors,
Compensatory Mitigation for all impacts to forested wetlands will be required including any
temporary construction areas due to the high quality of this resource and the long term nature any
impacts to forested wetlands.
As stated in the PCN form, the 30' permanent easement across Prince George Creek will not be
maintained. Both Special Condition 20 (h) and Regional Condition 4.8 state that mitigation is only
required if these easements will be permanently maintained. Because this easement will be allowed to
revegetate, we do not believe that mitigation should be required.
5. This office does not have information pertaining to the wetlands f lagged by ECS Carolinas, LLP as
indicated in your August 18, 2008 submittal of additional information for the Jurisdictional
Determination. Without this information, this office cannot verify the wetland delineation of those
areas.
According to the letter and map enclosed, Ms. Jennifer Frye met with staff of the Clark Group on May
15, 2007 to evaluate this area. Ms. Frye agreed with the wetland line as flagged and called these
wetlands isolated. Please note that the northern part of the original project area that was delineated is no
longer part of this project. The sewer line will tie into the cul-de-sac on the school property.
6 This impact area may be used by anadramous fish. As such, unless you provide evidence to the
contrary, if any type of permit is issued in the future for this area, you will be subject to the date
restrictions in Regional Condition 1. 1, Anadramous Fish Spawning Areas.
The applicant agrees to the restrictions listed in Regional Condition 1. 1, specifically that work within
Prince George Creek and its adjacent wetlands will be conducted outside of February 15 and June 30.
Please contact me if you have any additional questions. Thank you for your assistance with this
project.
Sincerely,
Kim Williams
Wetland Scientist
Encl.
C: Mr. Frank Styers, Cape Fear Public Utility Authority
Mr. Michael Johnson, McKim & Creed
Mr. Chad Coburn, DWQ
Mr. Ian McMillan, DWQ
RESTORATION PLAN
Cape Fear Public Utility Authority
Northern Campus Regional Wastewater System
New Hanover County, NC
The Cape Fear Public Utility Authority (CFPUA) plans to install approximately 6,440 linear feet of 10-
inch through 24-inch sewer main within existing and proposed utility easements and NC DOT R/W, as
well as a wastewater pump station in New Hanover County, North Carolina. This project will provide
wastewater service to the New Hanover County School Board of Education's Northern Campus
Middle & Elementary Schools. Approximately eight total acres are estimated to be disturbed during
construction. Disturbance will be limited to a 50' wide corridor along the pipeline route and limits as
shown around the proposed pump station site. The project will be constructed along slopes ranging
from 0% to 8.7%. Land use in adjacent areas is comprised primarily of light residential and industrial
areas.
CFPUA is applying for a Nationwide 12 permit to install a gravity sewer line that will temporarily
impact 0.736 acre of 404 wetlands and 50 LF of stream as it crosses Prince George Creek. The
proposed wastewater collection system consists of a regional pumping station with gravity collection
lines that collect flow from the surrounding area. The service area of the regional pump station
encompasses areas to the north and south of Prince George Creek, subsequently a gravity sewer
crossing of the creek will be required regardless of which side of the creek the pumping station is on.
Gravity sewer mains must be laid to a consistent grade between manholes. Although directional
drilling can install pipe below obstructions and water bodies, directional drilling can not achieve a
consistent grade as is required for a gravity sewer pipeline. The other trench-less alternative considered
was a bore & jack installation of steel casing which the 24" carrier pipe could be inserted through.
Although bore & jack casing installation can be installed to grade with reasonable accuracy, it is not
likely a bore of this size and length could be installed to the required accuracy. An additional concern
with trench-less installation is flotation. Due to the standing water present during wet periods and
likelihood of poor native soils above the pipe, the buoyant force of an empty pipe will be greater than
the weight of the soil above the pipe. Note the proposed design utilizes driven timber piles with
additional stone placed above the pipe to provide solid structural support and anchorage to resist
flotation.
Silt fencing is shown on the drawings at numerous locations for sheet flow protection and is to be
placed primarily down-slope of the proposed construction. Gravel filter inlet protection is to be
provided at storm drain inlets. Details are shown on the construction plans for correct installation of
all erosion control measures.
A 50' corridor will be required to install this sewer line due to the difficult working conditions. Large
equipment will be required to excavate the required trench, drive pilings, and move the large diameter
metallic pipe into place. Additionally, in order to install the pilings, the excavation will be required to
be dried. As material is excavated, it will be placed around the excavation on all sides to provide a
temporary dike around the working area. It is estimated the area required to construct temporary dikes
and move the large equipment and materials through the area will require up to a 50' working corridor.
It should be noted the temporary dikes will only be constructed around the immediate working area
and no damming of the stream will take place.
The sewer line will be installed in increments across the creek and its adjacent wetlands. As each
segment of the pipe is installed, the excavated area will be returned to grade and the contractors will
move onto the next segment. It is anticipated that each segment will take one or two days and that all
work in wetlands will be complete within 30 to 60 days. After this work is complete, the area will be
seeded with a wetlands seed mixture.
After construction, a 30' wide permanent easement will be maintained by periodic mowing where
accessible. Please note that the easement across Prince George Creek and its adjacent wetlands will not
be mowed due to the wet terrain. Manholes are located at the limits of the inaccessible area to allow
pipeline maintenance from either side of the wetlands.
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