20060922 Ver 2_Stormwater Info_20070817

~1~~ELAND and KAUFFMAN, INC. o ~ _ o q a ~ ~ ~
EMGl~S • LAl1~5CAPE /`~RQ~ECTS
August 16, 2007
To: Mrs. Annette Lucas
NC Division of Water Quality
2321 Crabtree Boulevard
Raleigh, NC 27604
[phone]
Re; Wa/-Mart Supercente~ #1179-02
Buncombe Counfy, NC
As discussed in the email I sent to you dated 8-16-07, I have enclosed the Operation and
Maintenance agreement for the Wet Detention Ponds and BioRetention Basins, for the above
referenced project. This was accidentally left out of our original submittal package. Please insert
this along with our original submittal for approval. Thank you.
Should you have any questions or need additional information, please call me directly at (864)
282-3039.
Thank you,
Todd Burnett
Freeland & Kauffman, Inc.
Enclosures
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209 West Stone Avenue • Greenville, South Carolina 29609 • Telephone [phone] • Fax [phone]

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WET DETENTION POND & BIORETENTION BASIN
OPERATION AND MAINTENANCE PLAN
Project Name: Wal-Mart Store #1179-02
Permittee: Wal-Mart Stores East, LP
Address: 2001 SE 10th Street, Sam Walton Development Complex
Bentonville, AR 72716-0550
Phone No: 479-273-4000
WET DETENTION PONDS:
Maintenance of Embankments
A. Vegetation
The embankment has a ground cover of fescue, which if properly maintained
will prevent erosion of the embankment and provide an easy surface for
inspection. The grass will be most difficult to obtain in the area subject to
water level fluctuation below the top of the riser.
Re-Seeding -periodically re-seeding may be required to establish grass
on areas where seed did not take or has been destroyed. Before seeding,
fertilizer (12-12-12) should be applied at a minimum rate of 12 to 15
pounds per 1,000 SF. The seed should be evenly sewn at a rate of three
pounds per 1,000 SF. The seed should be covered with soil to the depth
of approximately'/". Immediately following the planting, the area should
be mulched with straw.
^ Trees & Shrubs -trees, shrubs, and other landscape vegetation should be
permitted only as shown on the approved planting plan.
^ Mowing -grass mowing, brush cutting and removal of weed vegetation
will be necessary for the proper maintenance of the embankment. All
embankment slopes and vegetation of spillways should be mowed when
the grass exceeds 8" in height. Acceptable methods include the use of
weed ships or power brush cutters and mowers.
^ The soil in vegetated areas should be tested every 3-5 years and
adjustments to the soil amendments be made to sustain vigorous plant
growth with deep, well developed rooted systems.
^ Control of invasive, exotic plants (cattails, etc.) that would hinder the
reestablishment of woody vegetation or native wetland grasses and

planting should be controlled by a licensed pesticide operator in
conjunction with all applicable regulations.
^ If algae blooms begin to occur, installation of floating aerators may be
required in both the main pond/constructed wetlands and forebay. (Algae
blooms are not typically anticipated with this type of wet pond)
^ "Do not mow" signs shall be placed and maintained around the perimeter
of the pond/constructed wetlands surface to prevent indiscriminate
mowing of the aquatic vegetation on the littoral shelf.
B. Erosion
Erosion occurs when the water concentrates causing failure of the vegetation
or when vegetation dies and sets up the environment for rill erosion and
eventually gullies from the stormwater runoff. The berm should be inspected
for these areas. Proper care of vegetative areas that develop erosion is
required to prevent more serious damage to the embankment. Rills and
gullies should be filled with suitable soil compacted and then seeded.
Methods approved by NCDENR should be used to properly establish the
grass surface. Where eroded areas are detected, the cause of the erosion
should be addressed to prevent a continued maintenance problem.
Frequently problems result from the concentration of runoff to one point of the
embankment crest instead of a uniform distribution of runoff. This can be
corrected by reshaping the crest to more evenly distribute the runoff to areas,
which are not experiencing erosion problems. The top of the berm should not
be allowed to be used for pedestrian or bicycle traffic.
Abutment Areas -the abutment is the line formed where the embankment
fill comes into contact with the existing slope. Runoff from rainfall
concentrates in these gutter areas and can reach erosive velocities
because of the steep slopes. If a normal stand of grass cannot be
maintained on the abutments, additional measures may be needed such
as jute matting to provide for the establishment of a good ground cover.
Upstream Embankment Slope -Erosion problems can develop on the
upstream face of the berm due to the fluctuation of water level in the pond.
This is a result of a combination of wave actions and ground saturation,
which occurs from the elevated water levels. The erosion generally
occurs as the water level falls and the saturated ground becomes
subjected to the wave action. If erosion becomes a problem, it may
necessitate the installation of a stone armoring along the zone subject to
fluctuating water level. This would consist of 18" of NCDOT Class B stone
for erosion control underlain with Mirifi 140 geotextile fabric. It should be
centered at the point of the erosion problem and covering an area 2'
above and below the approximate center of the eroded area.

C. Seepage
Detection -Seepage may vary in appearance from a soft wet area to a
flowing spring. It may show up first as only an area where the vegetation is
more lush and darker green. Cattails, reeds, mosses and other marsh
vegetation often become established in a seepage area. The downstream
abutment areas where the embankment fill and natural ground interface are
very common locations for seepage. Also the contact between the
embankment and the spillway conduit is a very common location, which is
generally attributed to poor compaction around the conduit. Due to the way in
which conduits are put in, this is generally most evident on the embankment
slopes. The natural foundation area immediately downstream of the dam
abutment should also be inspected to ensure that "piping" is not occurring
underneath the embankment. "Piping" may appear as a "boil" evident as
spring carries soil. The soil usually deposits around the boil area and is
evident by the sedimentary deposits accompanying it. Seepage can also
occur into the spillway conduit through cracks in the pipe or improperly sealed
joints. These can be seen by observing the conduit when the water level is
high. The movement of the water itself is not dangerous, but if soil particles
are being carried with it, then it can create a shortcut for the piping of soil.
This might show up on the upstream face of the embankment roughly along
the line of the conduit itself.
D. Cracks, Slides, Sloughing and Settlement
Cracks -the entire embankment should be inspected for cracks. Short,
isolated cracks are usually not significant, but larger cracks (wider than
'/"), and well-defined cracks, indicate a serious problem. There are two
types of cracks: transverse and longitudinal:
Traverse cracks appear crossing the embankment and indicated
difference of settlement within the embankment. These cracks provide
avenues for seepage and piping could develop.
Longitudinal cracks run parallel to the embankment and may signal the
early stages of slide. In recently built structures, these cracks may be
indicative of poor compaction or poor foundation preparation resulting
in consolidation after construction.
Slides -Slides and slumps are serious threats to the safety of an
embankment. Slides can be detected easily unless obscured by
vegetation. Arch shaped cracks are indications that slides are slipping or
beginning to slip. These cracks soon develop into large scarps in the
slope at the top of the slide.
^ Settlement -settlement occurs both during construction and after the
embankment has been completed and places in service. To a certain
degree this is normal and should be experienced. It is usually the most

pronounced at the location of the maximum foundation depth or
embankment height. Excessive settlement will reduce the free board
(elevation between the water surface and the top of the dam). Any areas
of excessive settlement should be restored to original elevation and
condition to reduce the risk of overtopping. A relatively large amount of
settlement (more than 6") within a small area could indicate serious
problems in the foundation or perhaps the lower part of the embankment.
Settlement accompanied by cracking often precedes failure.
What to do if seepage, cracks, slides or settlement are detected: If any of
the above items are detected there may be signs of significant problems,
which could lead, to failure of the structure. A geotechnical or civil
engineer should be consulted regarding the origin of these problems and
for the assessment of the appropriate solutions for the correcting item. If
the professional is not immediately able to inspect the berm, then the
bottom drain should be opened and the water level lowered to remove the
risk of failure until a professional can observe these problems.
E. Rodent Control
Generally in a developed, urban environment, rodents are not a problem.
Rodents such as groundhogs, muskrats, and beavers are attracted to dams
and reservoirs and can be quite dangerous to structural integrity and proper
performance of the embankment and spillway. Groundhog and muskrats
thrive on burrowing in the manmade earth embankments, which become
pathways for seepage. In the event that burrows are detected within the
berm, then the rodents should be dealt with by removal.
II. Maintenance of Spillways and Control Structures
A. Inspection of Spillway Conduits
Discharge conduits at the basin should be inspected once a year. Conduits
should be visually inspected by actually entering the conduit a sufficient
distance between the riser structure and the outlet to check all the joints.
Because the outlet works tie into street storm sewer system, catch basins and
pipes. Conduit should be inspected for proper alignment (sagging),
elongation and displacement at joints, cracks, leaks, surface water, surface
wear, loss of protective coating, corrosion and blocking. Problems with
conduits most often occur at joints and special attention should be given to
them during inspection. Joints should be checked for gaps caused by
elongation or settlement and loss of joint filler material. Open joints can
permit erosion of the embankment material and possibly the piping of soil
material through the joints. Catch basins should be checked for signs that
water is seeping along the exterior surface of the pipe where it enters the
catch basin. A depression in the soil surface over the pipe may be signs that
soil is being removed from around the pipe.

What to do if problems are detected with the spillway: retain the
assistance of a civil engineer or geotechnical engineer qualified in the
design of embankments to perform an inspection of the berm. If in doubt,
lower the water surface elevation of the pond/constructed wetlands until
such time as a qualified professional can perform an inspection.
B. Trash-racks on Outlet Structure
The riser structure for this pond is the only outlet structure. The intake
structure has been fitted with atrash-rack to prevent debris from entering the
spillway structure. Most of the runoff entering the pond comes in through
grated inlets, which have essentially provided filtration of the runoff and
should limit the size of the debris that enters the basin to floating debris,
which will most likely pass through the trash-rack. The opening between the
trash-rack and riser is smaller than the opening of the outlet pipe. The intent
is that any debris, which passes through the trash-rack, will be easily passed
by the pipe outlet.
Maintenance should include periodically checking the rack for rusted or
broken sections and repairing as needed. The trash-rack should be checked
routinely to ensure that it is properly functioning and to remove accumulated
debris.
III. Operation
A. Emergency/Maintenance Drain
A separate 12" dewatering orifice (with valve located on the interior of the
outlet structure) is provided in the even the permanent pool needs to be fully
drained. This drain will work by gravity. Draining, when required for
maintenance, sediment removal, etc. shall be done under the supervision of
an engineer or landscape architect knowledgeable about the wetland
plantings and their protection. Generally, when draining the pond, it should
be drained slowly. Rapidly lowering the water level in the pond can cause
permanent damage to the embankment and must be avoided, except in an
emergency situation.
B. Record Keeping
Maintenance and inspection of the pond should be recorded as follows:
Annual Inspection -Inspections will be done to verify: 1) Trees/shrubs are
not growing in pond embankment, 2) Trash is not preventing proper outlet
structure performance, 3) Erosion of the slopes and at the discharge is not
occurring, 4) Discharge conduit at the basin is in good condition (free of
cracks, poor alignment, etc.), and 5) No piping is occurring.

Inspection Reports - a collection of written inspection reports should be
kept on record, with copies provided to the owner.
^ Observations -all critical observations should be recorded. Where
periodic inspections are performed following significant rainfall events,
these inspections should be logged into a Periodic Inspection, Operation &
Maintenance Form.
^ Other Operation Procedures -the owner should maintain a complete and
up-to-date set of plans (Record Drawings) and all changes made to the
berms over time should be recorded on the record drawings.
C. Sedimentation and Dredging
Sedimentation from establishing areas tributary to the pond will eventually
result in the reduction of the retention pool, and eventually will need to be
removed. The frequency of this sediment removal can be reduced by
ensuring that the site areas around the building are stabilized with a
vegetative ground cover to effectively restrain erosion. This would include a
periodic application of fertilizer and other treatments necessary to promote a
stable groundcover and minimize sedimentation to the pond. The
maintenance on this pond requires that when the sediment level (as
measured from the low orifice (6"diameter) to the bottom of the permanent
pool is less than 3 feet, the pond must be drained and sediment must be
removed, with the pond being restored to its original configuration. Generally,
the dredging process begins with the removal of as much water as possible
from the deposited silt, so the collected material can be excavated with
conventional equipment for trucking offsite. The removed material should be
hauled offsite to a suitable landfill site or mounded somewhere on site and
stabilized with a groundcover sufficient to restrain erosion.

BIORETENTION BASINS:
Records of maintenance items to include dates, inspector's name, type of maintenance,
etc. shall be kept and made available to Division staff upon request. Maintenance
activities shall be performed as follows:
1. Inspect the bioretention area system for soil and mulch erosion, vegetated cover
and general condition after every significant runoff producing rainfall event and at
least monthly. Remove trash as needed.
2. Repair eroded areas immediately, re-seed, re-plant, and re-mulch as necessary
to maintain good vegetative and mulch cover.
3. Remove accumulated sediment as needed to maintain good infiltration (1" to
2"/hr.). When the filtering capacity diminishes substantially (e.g., when water
ponds on the surface for more than 24 hours), the top few inches of material
must be removed and replaced with fresh planting soil material. Regardless of
infiltration capacity, accumulated sediment in the bioretention basin shall be
removed when the depth is reduced to 75% of the original design depth. The
system shall be restored to the original design depth without over-excavating.
Over-excavating may cause the required water table separation to be reduced
and may compromise the ability of the system to perform as designed. Removed
sediment shall be disposed of in an appropriated manner and shall not be
handled in a manner that will adversely impact water quality (i.e. stockpiling near
a storm water treatment device or stream, etc.)
4. Replace, or add additional mulch as needed. Removal of the old mulch layer
before applying the new layer is recommended every 2 to 3 years.
5. Prune trees and shrubs and removed debris on an annual basis. Grassed
vegetation should not exceed 6 inches in height.
6. Treat all diseased trees and shrubs whenever needed. Remove and replace all
dead and diseased vegetation considered beyond treatment every 6 months.
7. Replace support stakes yearly (in the spring). Replace deficient stakes or wires
whenever needed.
8. Soil testing shall be conducted every 3-5 years to determine pH and any
accumulation of toxins in the planting media. Lime or other alkaline substances
shall be applied as recommended per the soil test and toxic soils shall be
removed, disposed of properly and replaced with new planting media.

9. All components of the bioretention area system shall be maintained in good
working order.
10. If the Division determines that the system is failing, the system will immediately
be repaired to original design specifications. If the system cannot be repaired to
perform its design function, other storm water control devices as allowed by
NCAC 2H.1000 must be designed, approved and constructed.
J. Chris Callaway
I, l~ hereby acknowledge that I represent the financially
responsible party for maintenance of these Bioretention Basins and Wet Detention
Ponds. Wal-Mart Stores East, LP, will be responsible for the performance of the
maintenance as outlined above, as part of the Stormwater Management Permit received
for this project. I agree to notify DWQ of any problems with the system or prior to any
changes to the system or responsible party.
Signature: L~/f Date: 0 "f:~ -©`7
Name: ~ -5 ' 7l
Title: ~~~~; r-c~! ~~ ~ ~ sv ~f~~: ~~~ r~
I, ~~ d t~~ , a Notary Public for the County of P,.~ ~~iJ
State of s g5 ,hereby certify that _
S CkriS L'alla~ personally appeared before me this day and
acknowledged the d execution of the foregoing bioretention basin maintenance
requirements.
Witness my hand and seal, this ~~day of lc, u-.5
20~.
Notary
My Commission Expires rXJ a~~ l ~--
" NOTARY SEAL "
7rina L, Brown, Notary public
Benton County, State of Arkansas
My Commission Bxpires 2/2$~2a12
Approve .. ~ s c~ ,
by _
WAL-M LEGAL DEPT.
Date: ~st _