20141132 All Versions_Staff Report_20090903

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NCDENR
North Carolina Department of Environment and Natural Resources
Division of Water Quality
Beverly Eaves Perdue Coleen H. Sullins
Governor Director
MEMORANDUM
To: Steve Brown, Project Engineer, NCDOT
Through: Brian Wrenn, Supervisor, Transportation Permitting Unit, NCDWQ
From: Polly Lespinasse, Mooresville Regional Office, NCDWQ
Dee Freeman
Secretary
September 3, 2009
SUBJECT: Elevation of R -2501, US 1 from Sandhill Road (SR 1971) to Marston Road (SR
1001), Richmond County
The merger team met on three (3) separate occasions, to discuss bridging decisions (Concurrence Point 2A)
and avoidance and minimization (Concurrence Point 4A) for the above referenced project. The first meeting
was September 18, 2008. The merger team agreed at that time to have an on -site meeting to look at the
impact areas and proposed structure locations due to the amount of time that had elapsed since the original
site evaluations. The field meeting to evaluate these sites was held on November 12, 2008. The merger team
visited several structure locations and concurred with NCDOT recommendations on seven (7) of the nine (9)
proposed structures. Additionally, the merger team recommended that NCDOT staff further evaluate bridging
alternatives at Structures 7 and 8 prior to achieving concurrence on CP2A14A.
On August 20, 2009, the merger team reconvened to discuss NCDOT's recommendations for bridges at
Structures 7 and 8. The merger team concurred with NCDOT's recommendation to provide a 450' bridge on
South Prong Falling Creek and Wetland 26 (W26), also known as Structure 7. However, the merger team
could not reach concurrence on the proposed structure at Falling Creek at the McDonalds Pond Restoration
Site and Wetland 37 (W37), also known as Structure 8. Due to the team's inability to reach concurrence on all
bridging alternatives, the merger team decided not to sign a "partial" concurrence form. NCDOT has decided
to elevate the selection of the bridging alternative at Structure 8 only to the Merger Management Team
for resolution. NCDOT has requested that the merger team members prepare and submit a brief stating their
position. The information below represents NCDWQ's position on the project.
NCDOT prefers the construction of 120' bridges over Falling Creek and W37 (Structure 8). NCDWQ prefers
the construction of 480' bridges over Falling Creek and W37 (Structure 8).
DWQ staff has thoroughly reviewed all of the documentation associated with the project and offers the
following:
Falling Creek and W37 are part of an Ecosystem Enhancement Program (EEP) mitigation site. The site
consists of restoration, enhancement and preservation of streams and wetlands. The stream, which runs
throughout the mitigation area, is highly braided and very stable.
Mooresville Regional Office
Location: 610 East Center Ave., Suite 301 Mooresville, NC 28115 One
Phone: [phone] Fax: [phone] Customer Service: 1- 877 -623 -6748 NorthCarolina
Intemel: www.ncwaterquality.org
An Equal Opportunity 1 Affirmative Action Employer— 50% Recycled110% Post Consumer paper NaNrallil

Mr. Steve Brown
Page Two
According to NCDOT staff, the wetland rates as "high" for all parameters defined by the NCWAM manual.
The wetland area appears to be very successful with the proliferation of well - established native species
and very limited invasive species present. The area also contains unique microtopography throughout,
which provides many types of habitat for different aquatic and non- aquatic species. Due to the highly
successful nature of the wetland and stream system, NCDWQ recommends limited impacts to preserve as
much of the existing nature of the site as possible. As any impact in the area will compromise a portion of
the integrity of the system, NCDWQ staff believes it is our responsibility to support an alternative that will
reduce that amount of impact and preserve as much of an intact system as possible.
As stated above, the existing stream system is highly braided. NCDOT stated that the construction of 120'
bridges over the mitigation site will not span all the braided portions of the stream. NCDOT is proposing
two (2) 36 " equalizer pipes in the bridge fill slopes, on both sides of the bridge, for wetland connectivity.
Based on this information, NCDWQ staff is concerned that the construction of the shorter bridge span may
not accommodate the required hydraulic conveyance for this type of natural system and may create a
"bottleneck" effect. This could lead to ponding on both sides of the bridge as well as a modification to the
type of wetland /stream system which currently exists. NCDOT staff proposed for discussion, during the
August 20, 2009, merger team meeting, the installation of culverts adjacent to the bridge to provide
hydraulic passage for the braided stream. DWQ staff believes that the installation of the shorter bridge with
additional culverts to provide hydraulic passage does not demonstrate sufficient avoidance and
minimization measures as it would lead to additional fill impacts associated with culvert(s) installation and
slope fill as well as impacts which may be incurred due to aligning the stream(s) with the culvert(s).
NCDWQ staff is concerned about the amount of fill that would be required if the 120' bridge spans were
constructed. Based on the existing site conditions, the soils in the area seem unsuitable (field observations
indicated they are spongy and unconsolidated for a depth of at least three feet) for construction and would
require the excavation of the existing soils in the area directly under the road and possibly to the toe of the
fill slopes. In addition to the excavation and "wasting" of these soils, new fill would be required to stabilize
the area, further increasing the costs of the road. The merger team was only provided with the cost of
various bridge lengths, therefore, it is unknown whether the costs associated with soil
suitability /constructability were evaluated by NCDOT.
NCDOT staff stated during the merger team meeting that bridge costs for this project were consistent and
based on a standard cost per foot amount. Based on the information provided in the merger packet,
NCDWQ staff is unable to determine cost per foot for bridge construction. For example, at Structure 7, the
245' bridge costs $12,292,800 for a per foot cost of $50,174. The cost for a 450' bridge is $14,165,000 for
a per foot cost of $31,477. Similarly, at Structure 8 the cost of a 120' bridge is $1,147,000 for a per foot
cost of $9,588. The cost for a 480' bridge is $4,267,000 for a per foot cost of $8,889. In addition, the cost
to construct bridges at Structure 8 is considerably less than the cost to construct bridges at Structure 7.
NCDWQ would recommend that NCDOT please clarify how the bridge costs were determined.
Based on the information outlined above, NCDWQ staff supports the construction of 480' bridges at Structure
8.
If you have any questions or require additional information, you may contact Polly Lespinasse (704) 235 -2190
or Brian Wrenn (919) 733 -5715. Thank you.