HomeMy WebLinkAbout29_Example SCM Inspection Reports
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Store #: 1498 Greensboro, NC - COMPLETE Opened: 7/2/1991
Walmart Supercenter
3738 North Battleground Ave
Greensboro, NC 27410
(336) 282-6754
Summary of Issues: This item resulted from a municipally conducted annual inspection of the above
ground stormwater facilities, which include a retention pond and three bioretention cells. Regulators
noted mostly minor or cosmetic deficiencies during their site visit and have been agreeable to
permitting two installation phases to optimize some required replanting in spring 2020. Required Phase I
corrective actions include:
• Refresh lava rock groundcover as needed at Bio 1/Bio 2/Bio 3
• Replace any broken clean out caps at Bio 2 (none known)
• Redistribute or refresh riprap dissipater pad at Bio 3
• Address minor soil loss and refresh riprap inlet dissipater pad at Retention Pond
• Clean and mortar seal riser structure at Retention Pond
R+R has additionally noted the following minor items that should be repaired while onsite:
• Repair broken fence at corner of Bio 1
• Mortar seal broken curbs at either side of double slab top CI in fire lane (DCB-7)
R+R will submit the Phase II spring replanting scope separately and will work with the regulators to
identify and have approved some substitute perennial species that will better tolerate shade from the
maturing trees. The underground detention system is on a separate inspection system that is not part of
the municipal report; R+R has already submitted the required certified annual inspection report for that
portion of the facility for 2019.
This property also contains a portion of a natural creek that was partially buried under the Walmart
truck turnaround and expansion parking lot; the creek daylights through a 700’ long gabion channel on
the southern edge of the property and drains into the retention pond at the front corner. At least one
major erosion event at an upstream, off-property stormwater facility was the likely point source of
heavy sediment accumulation in the stormwater pipes, gabion channel, and southern half of the pond;
the creek also appears to be typical for the region and frequently carries loose sediment as part of its
normal state. Regulators have stated that the pond may need to be dredged in the next year or two but
for now, appears to be stable and does not require repair. Although the municipality is aware of the
upstream conditions and has indicated some tolerance for the natural creek behaviors, R+R
recommends a vac cleaning of the downstream pipes to retain enough fall through the underground
system and to prevent another sediment release into the channel.
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Scope of Work: R+R completed the out of scope maintenance by performing the following tasks:
Mobilized all equipment and labor to the site
Bioretention:
• Refreshed lava rock groundcover as needed at Bio 1/Bio 2/Bio 3
• Repaired broken fence at corner of Bio 1
• Replaced any broken clean out caps at Bio 2 (none known)
• Refreshed riprap dissipater pad at Bio 3, adding small quantity of new stone as necessary
Structure repair:
• Drew pond water down with filter pump
• Addressed minor soil loss and refreshed riprap inlet dissipater pad at Retention Pond
• Removed rooted tree and mortar sealed riser structure at Retention Pond
Catch basin repair:
• Mortar sealed broken curbs at either side of double slab top CI in fire lane (DCB-7)
Sediment removal:
• Used vac truck to remove accumulated sediment in 60” RCP segments between CB 20-MH 21
(approximately 135 linear feet of pipe, sediment may be 12”-18” deep at downstream end)
• Disposed of collected material in approved offsite facility
Demobilized
Driver for Corrective Action: Perform approved Phase I correction actions resulting from 2019 municipal
inspection; remove accumulated sediment within WM structures before it can release and impact
downstream assets or clog pipe
Retention
pond
Walmart
Store #1498
Bio bed #2
Bio bed #1
Bio bed #3
Underground
detention
Partially buried creek - gabion channel
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Refresh lava rock groundcover as necessary and any broken clean out caps at Bio 2 (below)
Bio 1
Bio 2
OCS
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Refresh lava rock groundcover as necessary and broken fence corner at Bio 1
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Refresh lava rock groundcover and restack/refresh outlet dissipater pad (below) at Bio 3
Bio bed #3
OCS
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Recommend mortar sealing broken curbs at either side of double slab top CI (DCB-7) in rear of building
Broken curbs DCB-7
Bio bed #3
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Backfill, compact, and refresh stone at inlet from MH 18G/Bio 2 (below)
Bio 1
Bio 2
OCS
MH 18G
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Backfill, compact, and refresh stone at inlet from MH 18G/Bio 2 (below)
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Debris and sediment pile up on riser trash rack and are cleaned during monthly maintenance (above);
sycamore tree has rooted inside riser structure, which should also be mortar sealed (below)
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Gabion channel is the downstream end of an undergrounded creek originating off property to the east,
which enters WM property at the headwall and runs through five structures (MH/JB/CB) via 60” RCP
before daylighting at the endwall. Surface flow then drains down through a long gabion channel to reach
the retention pond. Sediment is persistently washing into the WM pipes from the natural creek, which is
typical of piedmont creeks in that it carries a high volume of loose, clayey sediment, and from an
upstream, off-property stormwater asset in complete failure that sent a large quantity of soil and debris
downstream and directly into the Walmart pipe system.
HW
EW
60” RCP
MH 19
MH 4
CB 20 MH 21
Off-property
18” RCP outlet
is in failure
Retention
pond
Walmart
Store #1498
Creek
Daylighted creek section – outlets to WM pond
Underground
creek section
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Off-property upstream outlet is in complete failure, with massive previous blowout and soil loss
(photos above taken from same place by turning camera)
WM headwall
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View of upstream natural creek bed with high volume of loose sediment
Off-property
18” RCP outlet
is in failure
WM headwall
Creek
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Start of undergrounded creek segment through WM pipes (below)
HW
EW
60” RCP
MH 19
MH 4
CB 20 MH 21
MH 19 MH 4
HW
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Exterior of HW where natural creek enters WM stormwater pipe (above);
interior of MH 4 looking out of HW where large debris has washed into pipe (below)
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Dry pipe junction from stormwater system but rapid flow from buried stream inside MH 19 (above);
only small sediment accumulation in upstream pipe run between HW-CB 20 (below)
Off property
inflow WM stormwater
pipe is dry
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Increasing sediment over long pipe run between downstream CB 20-MH 21;
recommend vaccing this segment to ensure that WM pipes do not release sediment downstream
152’
53’ 83’
193’
HW
EW
60” RCP
MH 19
MH 4
CB 20 MH 21
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Interior of MH 21 looking out of EW where sediment has deeply accumulated (above);
exterior of EW where undergrounded creek exits WM pipes to the daylighted gabion channel (below)
202’
Deep sediment
in 60” RCP
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Refreshed lava rock groundcover and broken clean out caps at Bio 2
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Refreshed lava rock groundcover in Bio 1
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Repaired broken fence section on each side of Bio 1
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Replenished lavarock groundcover and restacked/refreshed outlet dissipator pad in Bio 3
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Set up molds to form shape for joints and curbs at double slab top CI (DCB-7)
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Mortar sealed curbs and joints at double slab top CI (DCB-7)
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Refreshed riprap dissipator at MH 18G/Bio 2
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Mortar sealed voids in riser structure
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Crew setting up to remove sediment in the 60” RCP from CB 20 to MH 21
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Jetting and sediment removal in process
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Sediment buildup and sediment removal
Note shovel
for cleanup
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Sediment removed from 60” RCP from CB 20 to MH 21
BMP Environmental
Store Lake Jeanette Orthodontics
Location Greensboro, North Carolina
Job Type MS4
Date 2022-04-14
Weather Bright Clear Overcast Rain
Temperature <32 32-50 50-70 >70
Rain 24H Dry <.25" .25"-1" >1"
System Type Bioretention Constructed Wetland
Dry Detention Basin Grass Swale
Level Spreader Infiltration Basin
Riparian Buffer Permiable Pavement
Proprietary Device Sand Filter
Underground S/D Wet Detention Basin
Other:
Comments:
This report is for the underground Sand Filter #1 located to
the right of the above address along N. Elm St.
The system was entered and inspected. The (3), 60" UD pipes
contained between 0"-4" of sediment; less than an amount where
removal is needed. The filter media was clear with surface
discoloration less than 1/2". The sand chamber had some leaves
and trash present. This was removed and the media was raked
level. There's a sump on the upstream side of the weir. This
area contain about 12" of sediment. Some remaining storage
capacity exists so cleanout would probably be needed by the
next inspection cycle. The outfall area contained a mixture of
vegetated, woody and clear areas with the underdrain pipe being
clear.
BMP Environmental Inc. Page 1 of 5
Sand chamber Sand chamber
UD pipes at the weir Sump located at the weir with
12" of sediment
same 1 of 3, 60" UD pipes
BMP Environmental Inc. Page 2 of 5
2 of 3 UD pipes 3 of 3 UD pipes
UD upstream manifold section
Splash pad entering the filter
chamber
BMP Environmental Inc. Page 3 of 5
Profile of the filter media Media profile
Media profile Media was raked clean
Trash was removed Daylight of the underdrain pipe
BMP Environmental Inc. Page 4 of 5
Outfall area
BMP Environmental Inc. Page 5 of 5
BMP Environmental
Store Lake Jeanette Orthodontics
Location Greensboro, North Carolina
Job Type MS4
Date 2022-04-14
Weather Bright Clear Overcast Rain
Temperature <32 32-50 50-70 >70
Rain 24H Dry <.25" .25"-1" >1"
System Type Bioretention Constructed Wetland
Dry Detention Basin Grass Swale
Level Spreader Infiltration Basin
Riparian Buffer Permiable Pavement
Proprietary Device Sand Filter
Underground S/D Wet Detention Basin
Other:
Comments:
This report is for system #2, as identified in our 9-14-19
report. This system is located underground adjacent to the Lake
Jeanette Orthodontics building. The system contained water
within the UD and Sand Filter areas at the time of inspection.
We were able to probe and sample some limited areas such as the
splash pad and sump located just upstream of the media chamber/
weir. Sediment was measured at approximately 1". The filter
media was also sampled with no measurable sediment present.
Trash and leaves were removed from the outfall area along with
a few smaller trees. The underdrain was located within the
dissipater and a steady output of water was noted. Based on the
observations performed, the system dewaters slowly but the
filter media appears to be hydraulically conductive based on
the outflow observed. See photos.
BMP Environmental Inc. Page 1 of 2
System outfall area Sediment measurements taken
Interior of the filter chamber UD pipes
Steady outflow from the
underdrain
Underdrain pipe location
BMP Environmental Inc. Page 2 of 2