WSMU_MRSV_Major Variance Request_19970924

ADDITIONAL INFORMATION FOR MAJOR VARIANCE REQUEST
FROM THE TOWN OF MOORESVILLE
SHOE ENTERPRISES TRACT, NC 150
as requested by the
EMC Water Quality Committee
9-24-97
The following information regarding the Mooresville, NC/Shoe Enterprises, LLC major variance
request is being provided to clarify important issues addressed at the 9-10-97 EMC Water
Quality Committee meeting. The proposed enhancements to the original watershed detention
site plan are being submitted at the request of the Committee by the applicant. The applicant
feels that a balance between natural and engineered BMPs which exceed regulatory requirements
has been demonstrated for this unique site. Based on these enhancements and the clarifying
information shown herein, the applicant requests the Committee recommend approval of the
proposed major variance request.
Attached for the Committee's review are the Town of Mooresville wet-detention pond bonding
and maintenance procedures which will govern this site.
1. The applicant would like to refer the Committee to research by Wendell Gilliam, Soil
Scientist at NCSU, Raleigh, NC on natural buffers. His research indicates that a 50'
natural buffer offers the greatest benefits in preserving water quality. Gilliam's work
focuses on the effect of natural buffers in rural settings in watersheds where large tracts
drain to rivers and streams. Although not directly related, his conclusions provide a
valid consideration when determining the impact on water quality of small commercial
sites where maximum treatment techniques are employed.
2. The regulations embrace the principle that the run-off from the first one inch of rainfall
collects the majority of non-point source pollution during that rainfall. Each additional
inch of rainfall collects increasingly less non-point source pollutants. The design
requirements for the wet-detention pond are based on this principle.
All run-off from impervious areas on the applicant's site will be collected and managed
in a wet-detention pond which has been designed to 1.3 times the volume specifications
required in the watershed regulations. Due to the larger detention pond, the applicant's
storm water collection and management system offers greater protection than provided
by other projects using wet-detention under the High Density Option.
3. The subject site is distinguished from other sites using wet-detention under the High
Density Option. Problems in accurately predicting up-gradient run-off volumes are
eliminated due to the fact that all run-off up-gradient from the site is being diverted away
from the applicant's site by up-gradient topography and existing commercial
development. The fact that the subject tract is only 9.080 acres in size and is not
impacted by run-off from other areas up-gradient from the site is of extreme importance.

When up-gradient run-off volumes are eliminated, the combination of detention and
buffer techniques employed by the landowner provides more than adequate protection to
the impacted watershed. With this greater ability to accurately predict run-off volumes
affecting the site and the detention pond, the Commission can have greater confidence
in allowing variances under this type of circumstance.
4. The buffer area as shown on the applicant's site plan will be designed to include the
optimal plantings of trees, shrubs and ground cover as recommended by the Division of
Water Quality. It should be noted that the only run-off to be treated by the planned
buffer will be rainfall on the planned buffer. All other rainfall will be treated by
wet-detention. The beneficial effect of using a 100' buffer versus a 50' buffer, given the
applicant's site storm water design, is negligible.
5. Attached is an analysis of surface water treatment efficiency for the applicant's site. It
should be noted, that the applicant's site is designed with a collection system comprised
of 6" rolled curb and gutter and other interior storm water collection measures which will
collect all runoff from impervious areas on the site. Three site design configurations are
compared. 1.) The volume of a one inch rainfall treated by a similar size site developed
under the "Typical High Density (HD) Option w/1" Rainfall Detention" on which the
maximum 70% impervious area has been developed is shown for comparative purposes.
2.) Also shown is the volume of a one inch rainfall treated by the applicant's site (64%
impervious area) if the standard detention pond design were used, "Applicant's Site w/1"
Rainfall Detention". 3.) Lastly, the volume of rainfall treated by the applicant's site
(64% impervious area) using the proposed detention pond design of 1.3 times that
required by regulation design standards, "Applicant's Site w/1.3" Rainfall Detention" is
shown.
The comparison shows that the applicant's proposed site development plan with an
oversize wet-detention pond will provide 4,867.92 cubic feet more treatment volume than
if developed with a wet-detention pond designed to regulation standards. It also
demonstrates that the applicant's proposed site design with oversized detention will
provide 3,346.70 cubic feet more treatment volume than a similar size site developed to
the maximum with a standard wet-detention pond.
Conclusion.
In this case, the issue of changing the size of the buffer, 50' versus 100', is less
important than the effectiveness and efficiency of the storm water collection and
treatment systems. The applicant's plan provides greater than maximum collection and
treatment effectiveness and efficiency in its design. The applicant seeks a variance from
the buffer demands of the regulations due to the uniqueness of his site and that he
exceeds the efficiency and effectiveness demands of the regulations. The applicant's
variance request clearly presents a development plan which preserves the spirit and the
intent of the ordinance, protects the general health and welfare of the community and
shows that substantial justice will be done for all concerns by granting the requested
variance.
2

B.K. Barringer & Associates, P.A.
Comparative Analysis of Treatment Volumes
Presented for Shoe Enterprises, LLC by B.K. Barringer & Associates, P.A.
September 15, 1997
Typical HD Option Applicant's Site Applicants Site
Item w/1" Rainfall Detention w/1" Rainfall Detention w/1.3" Rainfall Detention
Factor/CFS SF Factor/CFS SF Factor/CFS SF
Gross site size 9.08 395,524.80 9.08 395,524.80 9.08 395,524.80
Impervious area in % 70.00% 64.00% 64.00%
Impervious area in SF 276,867.36 253,135.87 253,135.87
Impervious area run-off coefficient 0.95 0.95 0.95
Impervious Area Run-Off 20,879.58 19,089.90 24,816.87
Wet detention efficiency rating 0.85 0.85 0.85
Treated Rainfall in Cubic Feet 17,747.64 16,226.42 21,094.34

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Annual Inspection/Maintenance Procedures
1.) Annual Inspection: Annual inspections shall be scheduled by the Town of Mooresville and
Owner on the first of June of each year.
2.) Inspection Activities:
a.) Testing of the emergency drain pipe valve.
b.) Visual inspection of drawdown orifice.
c.) Visual inspection of the trash rack at the intake orifice.
d.) Visual inspection of the emergency spillway.
e.) Visual inspection of the pond rim and slopes.
f.) Measurement of the wet pond depth(distance from the permanent pond drawdown
orifice invert to bottom of basin) at the dam end of the detention pond.
g.) Visual inspection of all stormwater structures on the served site feeding the detention
pond.
h.) Visual inspection of the total site drainage basin for adequate ground cover to
stabilize site.
i.) Visual inspection of upstream(off-site)areas feeding into the site drainage basin for
potential off-site sedimentation sources.
3.) Maintenance Activities, if required:
a.) If the permanent pond depth is measured to be less than 2',the pond shall be drained,
cleared of sediment to a depth specified in the original construction documents and
disposed of off-site. Off-site disposal based on sediment analysis. Pond to be
reseeded as required to prevent erosion.
b.) Riser mechanism shall be cleaned and repaired as necessary to bring the mechanism
up to functional condition as originally specified.
c.) Uniformly grade and stabilize any disturbed areas on the remainder of the site.

Section 14.12 Enforcement
1. These regulations shall be enforced by the Zoning Administrator
(refer to Section 11.1 -11.4 of this Ordinance). In addition to his other
duties, the Zoning Administrator shall keep records of the Town's
utilization of the provision that a maximum of ten (10) percent of the
WS-II BW Balance of Watershed be developed with non-residential
development to a maximum of seventy (70) percent built-upon
surface area, provided such developments are located in an EX-I or
CU EX-I zoning district. The Zoning Administrator shall keep records
on the.total amount of acreage available under this option, total acres
approved for this option, and site specific information on each
development employing said option including: location, acres, site
plan, use, stormwater management plan, etc.
2. The Zoning Administrator shall maintain a file on all applications for
minor and major variances. A copy of information pertinent to any
minor variance application request (including minutes of the hearing,
findings made by the Board of Adjustment, actions taken by the
Board of Adjustment, names and addresses of all persons giving
evidence at the public hearing) shall be submitted annually during the
last week of December to the Division of Environmental
Management, Supervisor of the Classification and Standards Group.
Section 14.13 High Density Option
A. General Requirements
In any designated WS-II, WS-Ill, or WS-IV watershed, any development (other
than a single-family residential development) may occur using the high density
options subject to approval by the Town Board under the rules and guidelines
herein outlined. The use of the high density option for any particular project shall
be subject to Town Board approval and, where deemed necessary by the Town
Board, may be submitted to the Division of Environmental Management's Water
Quality Section for review and recommendation.
Except for Planned Residential community (PRC) zoning, the use of the high
density option for any single-family residential development shall be prohibited.
B. Hiah Density Options Development Standards
The Town Board may approve a project using the high density option (other than
one for a non-PRC single-family residential development) consistent with the
following standards:
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1. If the area proposed to be developed lies in a designated WS-II
Balance of Watershed Area watershed, engineered stormwater
controls shall be used to control runoff from the first inch of rainfall for
development which contains a built-upon area of 12-30 percent.
2. If the are proposed to be developed lies in a designated WS-IV
Critical Area watershed, engineered stormwater controls shall be
used to control runoff from the first inch of rainfall for development
which contains a built-upon area of 24-50 percent.
3. If the area proposed to be developed lies in a designated WS-IV
Protected Area watershed, engineered stormwater controls shall be
used Zoning Administrator shall keep records on the total amount of
acreage available under this option, total acres approved for this
option, and site to control runoff from the first inch of rainfall for
development which contains a built-upon area of 24-70 percent.
C. Application
An application for authorization to use the Hiah Density Option shall be
sinned by the applicant and the consulting engineer and shall also be
accompanied by the following:
1. Two reproducible copies of the development plan within the drainage
basin containing all applicable and required information.
2. Two reproducible copies of the plans and required specifications of
the stormwater control structure.
3. When required by law, written verification that a soil erosion and
sedi',-nentation control plan which has been approved by the
appropriate State agency.
4. A separate fee shall be required for submittal of any high density
option application. Said fee shall be in accordance with a fee
schedule adopted by the Town Board. No application for high
density approval will be considered complete unless accompanied
with the requisite fee.
D. Inspection Fees
Inspection of all stormwater control structures will be conducted: (i) prior to
approval of the high density option for any project; (ii) annually once the
stormwater control structures have been approved by the Town, and: (iii)
any time after improvements, modifications or changes to said structures
have been made by the owning entity. A fee, in accordance with a fee
schedule approved by the Town Board, shall be required to be paid by the
owning entity prior to each such inspection being conducted.
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verification. The total cost of the stormwater control structure shall
include the value of all materials such as piping and other structures;
seeding and soil stabilization; design and engineering; and grading,
excavation, fill, etc. The costs shall not be prorated as part of a layer
project, but rather shall be priced as an individual project.
2. Once the stormwater control structure(s) has been constructed and
inspected in the manner provided in Section 14.13(G) of this
Ordinance, and approved by the Town Board, the Town Board may
authorize the release of up to seventy-five percent (75%) of the
surety bond or other equivalent device outlined in Subsection F(1) of
this Ordinance. The remaining portion of the surety bond or
equivalent device may be released to the owning entity in
accordance with Section 14.13(H)(1)(c).
3. Prior to said release, however, the applicant shall be required to
deposit with the Town either cash or similar instrument approved by
the Town Board in an amount equal to fifteen percent (15%) of the
total construction cost [as defined in Subsection (F)(1)] or one-
hundred percent (100%) of the cost of maintaining, repairing or
reconstructing said structure over a twenty (20) year
period, whichever is greater. The estimated cost of maintaining the
stormwater control structure shall be consistent with the approved
operation and maintenance plan provided by the applicant as
outlined in Section 14.13(E).
G. Default
1. Upon default of the applicant to complete the stormwater control
structure as spelled out in the performance bond or other equivalent
security, the Town Board may obtain and use all or any portion of the
funds necessary to complete the improvements based on actual
construction costs. The Town Board shall return any funds not spent
in completing the improvements to the owning entity.
2. Upon default of the owning entity to maintain, repair and, if
necessary, reconstruct the stormwater control structure in •
accordance with the approved Operations and Maintenance Plan,
Town Board shall obtain and use any portion of the cash security
outlined in Subsection (F)(3) to make necessary improvements based
on the actual costs borne by the Town to make such improvements.
H. Inspections
1. Inspections of Newly Constructed Stormwater Structures
All new stormwater control structures shall be inspected by the Town
after the owning entity notifies the Zoning Administrator that all
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2. Annual Inspection of Stormwater Structures
a. All stormwater control structures shall be inspected by the
Town on an annual basis to determine whether the structures
are performing as designed and intended. Records of
inspection shall be maintained on forms approved or supplied
by the North Carolina Division of Environmental Management.
Annual inspections shall begin within one year of approval of
the Town Board's approval of the filing date of the deed for the
stormwater control structure. A fee, in accordance with a fee
schedule adopted by the Town Board shall be charged to the
owning entity for annual inspections (and re-inspections)
made. A copy of each inspection report shall be filed with the
Zoning Administrator.
b. In the event the Town's report indicates the need for corrective
action or improvements, the Zoning Administrator shall notify
the owning entity of the needed improvements and the date by
which such improvements are to be completed. All
improvements shall be consistent with the adopted Operations
Plan and specifications. Once such improvements are made,
the owning entity shall forthwith contact the Zoning
Administrator and ask that an inspection be made.
Vegetation and Grounds Management
1. Landscaping and grounds management shall be the responsibility of
the owning entity of said structure(s). However, vegetation shall be
not established or allowed to mature to the extent that the integrity of
the structure(s) is in any way threatened or diminished, or to the
extent of interfering with any easement or access to the structure.
2. Except for routine landscaping and grounds maintenance, the owning
entity shall notify the Zoning Administrator prior to any repair or
reconstruction of the structure. All improvements shall be consistent
with the approved Plan and specifications for that structure. After
notification by the owning entity, the Town staff shall inspect the
completed improvements and inform the owning entity of any
required additions, changes, or modifications needed to complete
said improvements. A time period for making such changes shall
also be stipulated by the Town. A fee, in accordance with a fee
schedule adopted by the Town Board, shall be charged to the owning
entity for each inspection (or re-inspection) made.
J. Stormwater Control Structure Specifications
1. All stormwater control structures shall be designed by either a North
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agreement described in Section 14.13(E) of this Ordinance.
4. A description of the area containing the stormwater control structure
shall be prepared and filed, consistent with Section 14.13(1)(2) as a
separate deed, with the Register of Deeds along with any easements
necessary for general access to the stormwater control structure,
should ownership (and maintenance) of the stormwater control
structure be transferred to another person, firm, or entity. The
deeded area shall include the detention pond, vegetative filters, all
pipes and water control structures, berms, dikes, etc., and sufficient
area to perform inspections, maintenance, repairs and
reconstruction.
K. Town Board Approval Process
The Town Board shall either approve an application for the high density
option, approve the application with fair and reasonable conditions, or
disapprove such an application based upon the criteria contained in this
Ordinance.
1. If the Town Board approves the application, such approval shall be
predicated upon the developer and the Town entering into a binding
Operation and Maintenance Plan as indicated in Section 14.13 (E)
and the posting of a surety bond or other equivalent security in a
manner as provided in Section 14.13 (F). Such approval shall be
indicated on the application and on both copies of the plans
submitted with the application.
If the Town Board approves the application, a copy of the application
and one copy of the plans shall be returned to the applicant.
2. If the Town Board disapproves the application, the reasons for such
action shall be sent by first class mail by the Zoning Administrator to
the applicant within five (5) working days of the date of disapproval.
The applicant may make revisions or changes to the application and
submit a revised plan for approval. If the resubmitted plan is
submitted to the Zoning Administrator within sixty (60) days of the
date of denial, the application fee will be waived.
Section 14.14. Effective Date
The effective date of the regulations contained in Article 14 and all defined words
in association therewith to be added to Section 4.2 shall be July 1, 1993.
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