20001116 Ver 1_More Info Received_20010116

SPANGLER
ENVIRONMENTAL, INC.
January 16, 2001
Mr. Todd Tugwell
6508 Falls of Neuse Rd.
Suite 120
Raleigh, NC 27615
RE: Action ID #199920576
VIA: Hand Delivery
TO
C,00
Dear Todd:

,. JAN 1 6 2001
Tci? U;',LITY Sc%T;rl
On behalf of North Carolina Golf Enterprises, Spangler Environmental, Inc. is transmitting this final proposed
modification to the Individual Permit associated with Action ID #199920576. Included within this package are:
• Amended text for pages 1 to 7 of the previously submitted permit modification. Please replace the old
pages as they are not relevant to the proposed mitigation areas in full;
• Two 11 x 17 inch designs, showing the entire property, that depict the proposed riparian preservation
mitigation areas with a calculations table indicating the mitigation credit and acreage present in each
proposed area. Please add these plans to the report with the other proposed mitigative treasures
associated with this permit modification.
These changes were made in accordance with your direction presented to me and our client's representative at a
November 16, 2000 meeting. At that time you stated that the Corps was requesting a mitigation ratio (for
preservation) nearing 10:1 for the stream impacts associated with this project and that the minimum buffer
width that could be accepted for mitigation was 25 feet. We have proposed herein a mitigation ratio over 1 1:1
and buffer widths up to 50 feet.
We sincerely hope that this level of detail is more that sufficient for your needs to process this permit
modification quickly as the optimal planting season for the wetland mitigation, stormwater detention, and
bioretention areas will soon disappear and we wish to give ourselves every chance for successful mitigation.
Sincerely,
Spangler Environmental, Inc.
sio
Scott Linnenburger
Project Manager
cc. Mr. Mark Black (North Carolina Golf Enterprises)
Mr. John Myers (Arland Community Development)
Land Planning • Permitting • Environmental Consulting • Construction Management • Expert Testimony
Post Office Box 387 Raleigh, NC 27602-0387 tel: [phone] fax: [phone] www.Spangler-SEI.com
Background and History
The Eagle Ridge Residential and Golf Course Community is located on the west side of Old
Stage Road, Wake County, North Carolina. The developer of this project previously requested
and received an individual permit from the Department of the Army on February 26, 1999 for the
permanent fill of 0.42 acres of wetlands and 1,1 15 linear feet of stream to facilitate development.
This project was filed as USACE Action ID Number 199920576 and NCDENR Division of
Water Quality project number 960722. The above-mentioned impacts were permitted by
NCDENR DWQ on September 21. 1999 and by the Department of the Army on February 7.
2000.
Project Purpose and Need/Alternatives Evaluation
On behalf of the Eagle Ridge Golf Course developer (North Carolina Golf Enterprises, c/o Mark
Black, 4800 Six Forks Road, Suite 100, Raleigh, NC, 27609), Spangler Environmental, Inc. is
seeking minor modifications to the previously issued individual permit. Three separate types of
impact are proposed in this modification: impacts to intermittent and ephemeral streams;
alternative location designation for created wetland area form the original permit authorization,
and authorization after-the-fact for incidental impact to low quality isolated wetlands.
Proposed Stream Impacts. Changes made to the layout of the golf course, due in part to the
required mitigation efforts of the initial Individual Permit authorization, as well as minor
construction changes made in the process of earth-moving, have necessitated the re-configuration
of golf holes throughout the Eagle Ridge Golf Course. The original authorization required par
changes on holes in the front-nine to accommodate stream relocation and associated riparian-area
preservation. As a result. holes 1 and 17 each have gained one stroke. An evaluation by
Spangler Environmental. Inc. the golf course operator and the owner/applicant of the original
authorization resulted in a re-configuration of the course that minimized impacts to wetlands and
streams, and to the recorded residential lots adjacent to the golf course property. Limiting
factors on the re-design of the golf course when the original authorization was issued included
the configuration of the adjacent residential subdivision, conservation easements. roadways and
utilities. that were all either sold and occupied, under construction, or in final review for local
engineering/planning department final design approval when the authorization was issued.
According to the project owner, these reconfigurations will allow the planned number of rounds
per day necessary to achieve economic benefit from the development, primarily by speeding-up
play. Based on the loss of rounds due to slower play that would result from not implementing
these modifications (the "no-build" alternative), a reduction in revenue of $300,000 to $400,000
annually could be expected, according to the course operator, North Carolina Golf Enterprises.
This potential loss in revenue is due to a combination of a loss of concession revenue, equipment
rental revenue, and loss of approximately 10 to 15 tee times per day due to slower play caused by
the existing course configuration.
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SPANGL,ER
ENVIRONMENTAL, INC.
Alternatives to the specific impacts in this proposed modification have included creation of
topographic modifications to the course to create grassed "berms" to prevent golf balls from
being lost in the intermittent streams and water hazards associated with the proposed
modification impacts. However, factors such as roadway sight-line/safety concerns for cart paths
on hole 17. and the nutrient impact expected from drainage of run-off from behind the
constructed berms into the streams, resulted in these alternatives being identified as not feasible
from safety, environmental, and economic perspectives.
The proposed stream modifications are to streams that have little aquatic habitat function and
have been previously defined by the Corps as "insignificant streams." Each of these streams is
typically dry in the summer, except during storm events. Each of these streams lacks a
floodplain, and high flows are currently being contained within the banks. Therefore, each
provides little flood attenuation value, which will become an issue as the surrounding
development is completed and the impervious percentage of the property increases. They
function primarily as storm water and nutrient conveyance channels. Additionally each stream is
above headwaters, does not require the maintenance of a Neuse Riparian Buffer, and is located
within a golf course fairway. This situation will provide for little habitat heterogeneity, as the
riparian area will be maintained in short grass to the bank of the stream. In short, the current
stream condition affords little positive flood attenuation, water quality, or habitat value.
All three of these values will be improved with the design alterations. Controlling the flow near
the headwaters of the watershed will attenuate downstream flows and thus reduce downstream
channel erosion. The increased quantity of floodplain vegetation in the bio-retention area and
preservation of vegetated riparian corridors around the site will increase nitrogen and phosphorus
uptake and decrease the amounts of these nutrients that leave the site toward Swift Creek. The
addition of the vegetation in areas that would have been maintained as short grass will provide
wildlife habitat. landscape heterogeneity, and aesthetic features to the site.
Alternative Location fora Portion of Wetland Mitigation in Original Authorization. This
proposed modification is proposed as an additional area for mitigation activity to compensate for
wetland impacts associated with the original individual permit authorization. In the original
authorization. a littoral "shelf' of emergent vegetation was proposed as wetland area to be
created during the course of building the aesthetic pond adjacent to the golf course and
residential subdivision. A condition of this mitigation effort was to record deed restrictions and
conservation easements on this littoral zone (consisting of three feet upslope and downslope of
the mean ordinary pool elevation around the circumference of the pond). Because of the various
stages of development of the residential subdivision and the dozens of potentially effected
properties, combined with the fact that the ordinary pool elevation will have seasonal fluctuation,
the portion of the conditional approval for the littoral shelf associated with deed restrictions has
been determined to be unfeasible. Therefore, the area of wetland creation required by the
original authorization is now proposed to be made larger by an amount equivalent in area to the
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SPAN L,ER
ENVIRONMENTAL, INC.
littoral shelf, to ensure that acreage of created acres is consistent with the original application.
No design changes are necessary to facilitate this modification, and available area within the
conservation easement area for wetland creation in the original authorization is available. The
qualitative effect of this modification is that additional, higher quality forested wetlands will be
created in addition to the littoral shelf. The quantitative effect is that the forested wetlands will
be the only area of mitigation associated with the mitigation quantities authorized in the original
permit authorization.
After-the-Fact Incidental Fill. An isolated scrub-shrub wetland area in the middle of the fairway
of hole 12 in the golf course has been inadvertently impacted with grading and construction
associated with course construction. This area of four one-hundredths of an acre was not a
permitted activity in the original authorization. Mitigation in the form of additional forested
wetland creation in an amount.equivalent to the impact is proposed.
Summary. The proposed modification activities involve increasing the extent of on-site wetland
mitigation, piping a portion of one intermittent stream, and relocating a small reach of
intermittent stream to provide additional riparian area protection from golf course run-off. Off-
line, wetland-based water quality/storm water control structures and habitat improvement
measures are proposed in each of the stream modification areas for the purpose of mitigating any
loss in wetland function. Furthermore, stream preservation is proposed by establishing
conservation easements along the riparian area of certain intermittent streams in the golf course.
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SPANGLER
ENVIRONMENTAL, INC.
Calculation of Proposed Stream Impact Modifications
Location Fill/Impact
Hole l 130 ft. stream filled (130 ft. relocated, 90 ft. created)
Hole 17 315 ft. stream culverted
Mitigation 445 ft. stream impact, to be mitigated by:
• 220 ft. of stream realignment (including 0.14 acre bioretention
area which will eventually convert to forested wetlands) for
hole 1 modification,
• 3,520 linear feet (6.06 acres) of riparian buffer preservation
mitigation credit (though buffer is preserved along 5,485 linear
feet of stream) and 0.08 acre wet detention basin for hole 17
modification.
Note regarding stream mitigation:
As the function of these streams is primarily nutrient and stormwater conveyance. it is proposed
that the acreage impacts are mitigated in the form of providing riparian buffer/stream
preservation through on-site deed restrictions. Such areas will help to detain nutrients and
encourage stormwater sheet flow. Coupled with the existence of the on-site wetland creation
area and pond, the vegetated riparian zones will improve the water quality of the site.
Riparian zones up to 50 feet in width will be preserved in perpetuity throughout the site through
deed restrictions. These areas, along with stream length buffered, mitigation credit. and acreage
calculations are included on the attached site maps. Many of these areas have not previously
been disturbed and will be left in their current state. Others may undergo minor enhancement
(coniferous plantings without cutting existing trees) in the 20 feet to provide year-round wind
and visual buffer. Area "G" will be planted in a low-growing (less than 10 feet at maturity) mix
of Piedmont shrubs as it lies within a golf course fairway. The only additional modifications to
the preserved riparian areas will take place if there is for safety considerations of course and
residential users.
The preservation areas were chosen where were found the maximum amount of land available
within the property and along a stream without imposing a restriction to golf course play. As
stated by the Corps, buffer width would have to meet or exceed 25 feet. Credit was calculated by
stream length in linear feet where buffer would be preserved. Where buffer could only be
preserved on one side of the stream due to property lines, every attempt was made to increase the
width to 50 feet. However, for the sake of calculating mitigation credit, each foot was
discounted by half in these circumstances.
SPANGLER
ENVIRONMENTAL, INC.
In total 3.520 feet of riparian buffer preservation mitigation credit has been proposed to offset the
impacts associated with piping 315 feet of stream. This is an 11:1 mitigation ratio, which is in
keeping with the mitigation ratios instituted for impacts previously permitted for the
development of this property. Where the 315 feet of intermittent, "insignificant" stream did not
provide nutrient removal and climatic moderation through its adjacent riparian area as such an
area was not required. the proposed mitigation areas provide nutrient removal treatment and
climatic moderation over 5,485 linear feet of stream and a total of 6.06 acres of wildlife habitat.
This is a vast net gain in terms of both stream/riparian function and value.
Hole 1 (see attached drawings)
The projected activity in this area is to relocate 130 feet of the intermittent stream channel to the
outside of the historic toodplain, outside the golf fairway, in the vicinity of lots 315-317. A
270-foot low flow channel will be maintained that is slightly smaller than the existing stream in
cross-sectional area. The channel width will be reduced to 1 foot and the banks will be sloped to
reduce the possibilities for bank erosion. The decreased cross-sectional area will promote
overbank flooding during periods of storm flow.
Surrounding the relocated stream, a 0.14-acre, shallow, contained bioretention area will be
created. This vegetated area will attenuate storm flows and provide some storage before
emptying back into the stream. A riprap lined trapezoidal narrow constriction will be
constructed on the downstream end of the mitigation area that restricts the flow from this area.
The area will be planted with Benda nigra and a few Platanus occidentalis lining the banks of
the relocated channel to provide shade and stability. Behind these species a mixture of oaks
(Quercus michauxii, Q. nigra, Q. bicolor, and Q. phello.s) will be planted that can withstand
short periods of inundation. 55 trees will be planted, providing a canopy density of 400
stems/acre. In essence, a bottomland hardwood floodplain forest will be created that is very
similar in composition to the Swift Creek floodplain forest downstream of the project area.
The estimated stormwater detention volume of the bioretention area is 5,044 ft3 (37,732 gal).
The actual volume will be based on as-construction dimensions. This detention volume equates,
roughly, to a 1-inch rainfall across the contributing watershed area. Flow will be constricted
with a narrow, riprap lined trapezoidal channel at the outlet of the bioretention area. The bottom
width of the channel should be 3 ft. Channel sideslopes should be 3:1 or 4:1 depending on the
type of soil encountered. The channel depth at this location is approximately 3 - 4 ft. Class "B"
riprap, or equivalent, should line the entire channel and a riprap apron should be placed upstream
and downstream of the constriction. The apron should extend upstream and downstream a length
equivalent to 3 times the channel width. Woven geotextile fabric will be placed under the riprap
to minimize the potential for "piping".
Hole 17 (see attached drawings)
The modification would culvert a maximum of 315 feet of the stream within the playable area of
the fairway of hole 17. Actual project impacts may be less, and will depend upon the
SPANGLER
ENVIRONMENTAL,, INC.
construction constraints and final grading of the golf hole. This impact has been minimized from
previous concepts, which included culvert being placed in over 500 feet of this stream. Flow out
of the culvert will be directed into a 0.075 acre stormwater detention wetland located upstream of
the nearby roadway. This feature is designed as an according to the specifications outlined in the
North Carolina Department of Environment and Natural Resources Division of Water Quality
Stormwater Best Management Practices to provide for 85% total suspended solids treatment. An
inlet pool and outlet pool. both located out of the stream channel, are each 3 feet in depth to
allow for settling and controlled outflow, respectively. The remainder of the area is designed as
a combination of shallow and deep marsh. The shallow marsh will have a depth of less than 9
inches during periods of maximum storage and will be planted with a mixture of Hibiscus
moscheutos,.luncus effuses, Cur,?,x spp., and Polvgonum spp. that are able to withstand periods of
drought. The deep marsh will be planted with a mixture of Sagittaria latifolia. Peltandra
virginica. and :Vuphar lutea. Planting densities, schedules, and erosion control methods will be
identical to those previously approved for the nearby wetland creation area.
The storm water detention wetland was designed using the methodology outlined by NC
DEHNR "Stormwater Best Management Practices" guidance document. A conservative
estimate of 10% impervious area was used. Based on Table I.1 in the guidance document, at a
permanent pool depth of 3 ft. and a watershed drainage area of 12.5 acres, the surface area to
drainage area ratio is given as 0.59 for 85% pollutant removal efficiency. This requires the
surface area for the detention wetland to be at least 0.074 ac. (3,213 ft'). The calculated volume
of the detention wetland, using the equation as provided in the guidance manual, provides a
volume of 0.14 ac-ft. (6,098 ft').
Rv = 0.05 + (0.009)*(] 0) = 0.14 in/in
Volume = (1 in)*(0.14 in/in)*(1 ft/12 in)* 12.5 ac = 0.14 ac-ft
A riser pipe will be placed at the outlet pool to control the depth in the storm water detention
wetland. Based on a 1-hour duration rainfall intensity and a 10-year return period design storm,
the estimated peak discharge is 9.6 cubic feet per second (efs). This discharge requires a barrel
and riser size of 15 inches in diameter for adequate flow, provided an effective trash rack is
placed at the riser inlet. The riser inlet elevation will be set to 2 feet below the top berm
elevation. An emergency spillway approximately 6 to 8 inches deep and 10 to 15 feet wide will
be constructed to route excess flow around the berm into a riprap-lined swale upstream of the
roadway. This will protect the road grade from being undermined during very large storm
events.
SPANGLER
ENVIRONMENTAL, INC.

Calculation of Proposed Wetland Mitigation Location and Incidental Fill
Modifications
Location Fill/Impact
On-Site Pond 0.00
Hole 12 0.04 ac. filled.
Mitigation 0.19 ac. additional wetland creation and preservation in previously
approved wetland creation area at upstream end of pond
On-Site Pond
The projected activity in this area is to relocate the mitigation afforded by a three-foot wide
aquatic bench (littoral "shelf') around the pond, 0.15 acres, into the wetland creation area at the
headwaters of the pond. There is a concern that fluctuating water levels in the pond will
intermittently leave the bench out of the water, perhaps for long periods of time. This would not
conform to the idea of an aquatic bench and could be construed as not being in compliance with
the conditions of the permit. Furthermore, due to the number of property owners adjacent to the
pond, the deed restriction/conservation easement on this three-foot wide bench has been
determined to be logistically unfeasible. To provide on-site mitigation for these impacts, the on-
site mitigation area and conservation easement for this area is proposed to be expanded.
Hole 12
0.04 acres of wetland that is in the largest wetland unit located on Sheet 17 of the IP application
have been filled. Design attempts to avoid this portion of wetlands did not leave ample fairway
width. Mitigation for this impact can be fulfilled in the on-site wetland creation area, as it has
been expanded from 0.63 acres to 0.85 acres.
Contacts
Please contact Scott Linnenburger of Spangler Environmental, Inc. (919-546-0754) if you have
any questions regarding this request for a minor modification of the Individual Permit associated
with Action ID 9199920576.
SPANGLER
ENVIRONMENTAL, INC.