SW8021042_COMPLIANCE_20030424

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
SW��
DOC TYPE
❑CURRENT PERMIT
❑ APPROVED PLANS
❑ HISTORICAL FILE
COMPLIANCE EVALUATION INSPECTION
DOC DATE
�Y
YYYYMMDD

WET DETENTION POND ANALYSIS
FILE NAME
PROJECT #: SW8 021042
PROJECT NAME: Shallotte Villas
G:\DATA\WPDATA\WQS\POND\021042.WK1
REVIEWER: L. Lewis
DATE: 24-Apr-03
Receiving Stream: Shallotte River Class: SC HQW
Drainage Basin: Lumber Index No. LBR59 15-25-2-(7.5)
Site Area 4.61 acres
Drainage Areaf?0812>40 square feet Area in Acres 4.61
IMPERVIOUS AREAS
Buildings
Parking
Sidewalks
TOTAL
r
SURFACE AREA CALCULATION
% IMPERVIOUS 47.39%
Des. Depth 4
TSS: 90
Rational C
41983.00 square feet
43152.00 square feet
10026,00 square feet
square feet
square feet
square feet
95.1 1 00 square feet
Rational Cc= 0.11
SA/DA Ratio 4.09%
Req. SA 8215 sf
Prov. SA
VOLUME CALCULATION * place a "1" in the box if Rational is used
Rational ?*
Des. Storm
! 0
......
inches
Rv=
0.476
Bottom
17.38 msl
Perm. Pool
2 i 38
msl
Design Pool
22.5 msl
Storage met @elev 22.28 msl
Req. Volume
974:
cf
Vol. Prov. at DP
:.::.:9936.1
cf
ORIFICE CALCULATION
FOREBAY
Perm. Pool Volume=
26217.5
Req. Forebay Volume=
5243.5
Provided Volume=
5337.50
Percent=
Elevation Area
Inc. Vol. Acc. Vol.
21.38 8636.00
0.00
22.50 9096.00
9929.92 9929.92
Avg. Head =
0.53 ft
Q2 Area = 1.89
sq. inches
Flow Q2, cfs
0.046 cfs
Q5 Area = 0.76
sq. inches
Flow Q5, cfs
0.018 cfs
Orifice Area 1.23
sq. inches
No. of Orifices
- ............:....:1.;',
Q= 0.030
cfs
Diameter, inches
; ...,1.25'
weir H x W
in x
:......: ...
in
Drawdown =
3 ;days
Surface Area @DP =
9096 sq. ft.
Falling Head Drawdown =
5.3 days
COMMENTS
Surface Area , Volume and Orifice are within Design Guidelines

SHALLOTTE VILLAS - WET DETENTION POND
SHALLOTTE, BRUNSWICK COUNTY, NC
Permanent Pool
Bottom Elevation — 17.38 �� C E IVE D
Normal W.S.E. = 21.38 APR 0 l 2003
Average Depth = 4.0' l?yw�
�o�# SGucyGZIG¢Z
Surface Area = 8636 sf
% Impervious — 47.39% (95,161 sf Impervious Area, 200,812 sf Total Area)
SA/DA = 4.091 = 0.041 (90% TSS Removal - No Vegetated Filter Required)
Allowable DA = 8636/0.041 — 210,634 = 4.84 ac
Actual Area = 4.61 ac, therefore, 4.84 > 4.61 OK
1"Runoff Pool
Permanent Pool W.S.E
Runoff Volume (RV)
Volume
Drainage Area
1" Storage W.S.E.
= 21.38
0.05 + 0.009(% IMP)
0.05 + 0.009 (47.39) = 0.48 in/in
Design Runoff * RV * Drainage Area
= V * 0.48 * 4.61 * (1 / 12) = 0.184 ac-ft
Use 0.20 ac - ft = 8712 cf
0.20/((1 ")(0.48)(1/12)) — 5.00 ac > 4.61 ac OK
22.50 (volume = 8866.1 cf> 8712 cf) OK
(See Stage -Storage Table for Wet Detention Pond)
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SHALLOTTE VILLAS - WET DETENTION POND
SHALLOTTE, BRUNSWICK COUNTY, NC
Drainage To Pond
Design Pond wl Allowable Capacity of 4.61 ac of Drainage Area @ 47.39% impervious
tc = 5.0 min
I(10yr15min) = 6.93 in/hr
Impervious Area = 47.39%, C = 0.95
Pervious Area = 52.61 %, C = 0.30
Cc = 0.608
Q10 = Qp = CIA = 0.608 * 6.93 * 4.61 = 19.42 cfs

SHALLOTTE VILLAS - WET DETENTION POND
SHALLOTTE, BRUNSW ICK COUNTY, NC
P = 4.2
CN = 80
S = (10001CN) = 2.5
Q* — ((P-0.2S)^2)1(P+0.8S) = 2.21 in
Tp = Voll(1.39Qp) _ ((2.21 *4.61 ac)/(1.39* 19.42))/((1 ft/l 2 in)(43560 sflac)
(1 min160 sec)) — 22.65 min

I
SHALLOTTE VILLAS - WET DETENTION POND
SHALLOTTE, BRUNSWICK COUNTY, NC
Stage -Storage Table for Wet Detention Pond
Surface
Incr
Accum
Contour
Area
Volume
Volume
Stage
CSD
(C-D
(S) (cfl
(Z) (ft)
17.38
4635
0
0
0
18.38
5532
5083.5
5083.5
1
19.38
6506
6019
11102.5
2
20.38
7544
7025
18127.5
3
21.38
8636
8090
26217.5
4
22.50
9096.2
8866.1
35083.6
5.12
b =
ln(S2/S1)/ln(Z2/Z1)
= 1.18
Ks =
S2/(Z2^b)
— 5107
Si — Ks*Zi^b
S (Temporary Pool Elevation) — 5107(5.12A1.18) = 35,083.6 of
(22.50' = Z=5.12')
Therefore the storage between the Temporary Pool Elevation and the Permanent Pool
Elevation = 35083.6 - 26217.5 = 8,866.1 of

SHALLOTTE VILLAS - WET DETENTION POND
SHALLOTTE, BRUNSWICK COUNTY, NC
Stage -Storage Table for Wet Detention Pond Forebay
Surface
Incr
Accum
Contour
Area
Volume
Volume
Stage
(ffi
ss 0
Cf
S c
(Z) (ft)
17.38
927
0
0
0
18.38
1434
1180.5
1180.5
1
19.38
2051
1742.5
2923
2
20.38
2778
2414.5
5337.5
3
b
ln(S21S 1)/]n(Z21Z 1)
= 1.37
Ks =
S2/(Z2^b)
= 1185
Forebay Volume at the Vegetated
Shelf = 5337.5 cf =
20.36% of the Total
Permanent Pool Volume of
26,217.5 cf

SHALLOTTE VILLAS - WET DETENTION POND
SHALLOTTE, BRUNSWICK COUNTY, NC
Orifice Size Calculation:
Q = Cd(A)((2gh)^0.5)
use l .25"
Cd = 0.60
A = 3.1416((1 in/ (1.25 ft/ 12 in))^2)/4 w 0.0085 sf
g = 3 2.2 ft/sec^2
h = 1.1272 = 0.56'
Q = 0.6(0.0085)((2*32.2*0.56)^0.5) = 0.0306 cfs
Time to drain 8866.1 cf = 8866.1/0.0306 = 289,742 sec
80.5 hr
48 < 80.5 < 120 OK
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SHALLOTTE VILLAS - STORMWATER NARRATIVE
The purpose of this project is to develop an elderly housing facility in Shallotte, North Carolina,
on White Street. The site will be stripped and graded as depicted on the subject plans. The
approximate disturbed area is 4.1 acres. See limits of construction on the project on the subject
plan. Drives, parking areas & drainage construction will be in accordance with standards of the
NCDOT and the Town of Shallotte.
Public water and sanitary sewer will be provided by the Town of Shallotte.
Site Description
The topography of the site has slight sloping grades from north to south. Runoff will be handled
by one 1 basic storm drainage system which is a piped system which runs along the western
portion of the site and discharges directly to the wet -detention pond. The subject area to be
disturbed is presently cleared lands with undergrowth. The site is bordered on the west, north and
east by vacant lands and sparse development, and on the south by White Street.
The US Conservation Soil Survey maps classify the soils as follows;
(1) The subject site appears to be covered by Fo (Foreston Loamy Fine Sand). The slopes of
this specific area are typically - nearly level. This moderately well drained soil is on
slightly convex interstream areas. Permeability is moderately rapid and the available water
capacity is moderate.
Planned Erosion and Sediment Control Features
(1) Temporary gravel construction pads will be used at the areas shown on the subject plans.
(2) Silt fencing will be used as deemed necessary during development of the project.
(3) Drainage swales with appropriate liners will be used as shown on the subject plans.
(4) Temporary Block Inlet Protection, sediment traps, rock dams, swales and wet detention
ponds will be used to collect runoff as shown on the subject plans.
(5) Drainage outfalls will have outlet stabilization as shown on the subject plans
(6) Seeding of all disturbed areas will be accomplished as phases of construction are
completed.
RECEIVED
APR 0 7 2003
DWQ
PRod #

Drainage Area and Respective Stormwater Management Features
Drainage Area #1 Wet -Detention Pond
Area #1 incorporates only drainage from the entire site. The drainage will be captured in catch
basins and routed to the wet -detention pond; and by a diversion berm along the front and along
the eastern boundary of the site. The wet -detention will will be constructed with a Riser/Barrel
assembly to pass the 10 year-5 min storm event. An emergency spillway will be provided that will
pass the remainder of the 100 year - 5 min storm, that is not passed through the Riser/Barrel
assembly. Due to the nature of the site topography, proposed development, a four (4) foot
Permanent Pool Depth was utilized. All requirements outlined in Form SWU-102 have been
adhered too. See Form SWU-101 for Drainage Basin information.
Please note that a landscaping berm will be developed along the western property boundary to
direct offsite drainage to an existing ditch at the northwestern corner of the subject site.

SHALLOTTE VILLAS - STORMWATER NARRATIVE
The purpose of this project is to deveiop an elderly housing facility in Shallotte, tiTorth Carolina,
on White Street. The site will be stripped and graded as depicted on the subject plans. The
approximate disturbed 'r::a is 4.1 acres. See limits of construction on the project on the subject
plan, Drives, parking areas & drainage construction will be in accordance with standards Of the
NCDOT and the Town of Shallotte.
Public water and sanitary sewer will be provided by the Town of Shallotte.
Site Description
The topography of the site has slight sloping from north to south. Runoff will be handled by
three 3) basic storm drainage systems: one i is a piped system which runs along the western
oomon of the site anti eis .+acres. directly to the wet -detention pond, two f 2 is a swale in the
central eastern portion of the site, three 3 is a swale in the southeastern portion of the sit;,. The
subject area to be disturbed is presently cleared lands with undergrowth. The site is bordcred on
the west, north and east by vacant lands and sparse development, and on the south by White
Street.
The US Conservation Soil Survey maps classifv the soils as follows:
(1) The subject site appears to be covered by Fo (Foreston Loamy Fine Sand). The slopes of
this specific area are typically - nearly level. This moderately well drained soil is on
slightly Convex in: 7stream areas. Permeability is moderately rapid and the available water
capacity is moderate.
Planned Erosion and Sediment Control Features
(1) Temporary gravel construction pads will be used at the areas shown on the subject plans.
(2) Silt fencing will be used as deemed necessary during development of the project.
{ �) Drainage swales with appropriate iiners will be used as shown on the subject plates.
(4) Temporary Block Inlet Protection, sediment traps, rock dams, swales and wet de€ention
ponds will be used to collect runoff as shown on the subject plans.
(�) Drainage outfalls will have outlet stabilization as shown on the subject plans
(6) Seeding of all disturbed areas will be accomplished as phases of construction are
completed.

Drainage Area #1 Wet -Detention Pond
Area # l incorporates offsite drainage from the west and western half of the subject site. The
drainage will be captured in catch basins and routed to the wet -detention pond, The wet -
detention will will be constructed with a Riser/Barrel assembly to pass the 10 year-5 min storm
event. An emergency spillway will be provided that will pass the remainder of the 100 year - 5
min storm, that is not passed through the Riser/Barrel assembly. Due to the nature of the site
topography, proposed development, a four (4) foot Permanent Pool Depth was utilized. All
requirements outlined in Form SWU-102 have been adhered too. See Form SWU-101 for
Drainage Basin information.
Please note that a landscaping berm will be developed along the western property boudary.
Drainage Area #2 (Swale)
Area 42 incorporates the central and eastern portion of the site. The drainage will be captured in
a swale :and discharged to the wet. -detention pond. See Form SWU-101 for Drainage Basin
information.

State of North Carolina
Department of Environment
and Natural Resources
Wilmington Regional Office
Division of Land Resources
Land Quality Section
Michael F. Easley,Governor
William G. Ross Jr., Secretary
October 14, 2002 :jiJ Q /0 7 L
NOTICE OF RECEIPT OF EROSION & SEDIMENTATION CONTROL PLAN
Shallotte Villas Association Ltd. Partnership
Mr. James B. Smith
3800 Raeford Road
Fayetteville NC 28304
Dear Mr. Smith:
This office has received a soil erosion and sedimentation control plan for the project listed below which was
submitted as required by the North Carolina Sedimentation Pollution Control Act (NCGS 1 13A-57(4)).
Please be advised that this Act requires that all persons disturbing an area of one or more acres of land must
obtain approval of a soil erosion control plan prior to the commencement of said land disturbing activity (NCGS 1 13A-
54(d)(4)). The act further states that this plan must be filed a minimum of 30 days prior to the activity and the
approving authority must approve or disapprove the submitted plan within 30 days of receipt. Failure of the approving
authority to approve or disapprove the submitted plan within the 30 day period will be deemed approval of the plan.
Commencement or continuation of a land -disturbing activity under the jurisdiction of this Act prior to the approval of
an erosion and sediment control plan is a violation of the Act.
A copy of any erosion and sediment control plan which could involve the utilization of ditches for the purpose
of dewatering or lowering the water table is forwarded by this office to the Division of Water Quality (DWQ). It is
suggested that you contact the Division of Water Quality at [phone] if the ditches shown on your plan will
lower the water table.
The approval of an erosion and sediment control plan is conditioned on the applicant's compliance with Federal
and State water quality laws, regulations and rules.
If you have questions, please do not hesitate to contact this office
appreciated and we look forward to working with you on this project.
Sincerely,
Carol N. Miller, CPESC
Assistant Regional Engineer
CNM/bfr
cc: Harvey Allen, P.E.; Allen -Allen & Associates, P.A.
WiRO-LQS
PROJECT NAME:
Shallotte Villas
PROJECT NUMBER:
BR-03098
LOCATION:
White Street - Brunswick County
RIVER BASIN:
Lumber
SUBMITTED BY:
Allen -Allen & Associates, P.A.
DATE RECEIVED BY LQS:
October 11, 2002
Your cooperation in this matter is
127 Cardinal Drive Extension, Wilmington, N.C. 28405-3845 a Telephone [phone] • Fax [phone]
An Equal Opportunity Affirmative Action Employer

.
li
STORMW ATER MANAGEMENT FLAN
''VET DETENTION POND OPERATION & MAINTENANCE
SHALLOTTE VILLAS
SHALLOTTE, BRUNSWICK COUNT Y, NC
OCI'OBER, 2002

DETENTION POND OPERATION AND MAINTENANCE:
The purpose of this section is to provide the owner with guidelines to help maintain the permanent
wet detention pond. Wet detention ponds must be maintained
by the property owner as needed to ensure there proper functioning.
Periodic inspections and maintenance are key factors in preserving the functionalit), of wet detention
ponds. Detention ponds are not self maintaining systems, and over time the efficiency of the pond to
remove pollutants will diminish. Trapped sediments and other pollutants can potentially reduce the
volume and treatment capacity of the pond.
Besides inspecting and maintaining the pond components pertaining to water quality, attention must
also be paid to the structural components which sustain the hydraulic functionaliry of the pond as
well.
Maintenance is also important to prevent the decline in the appearance of the pond Unhealthy
conditions (such as noxious vegetation, trash, etc.) may occur within and around the pond. which may
affect the aesthetics and economic value of the surrounding property.
VEGETATIVE GRowrH:
Trees and other woody vegetation are not permitted on the top slopes or dam embankments. Large
root systems from woody vegetation can weaken the dam structure and provide seepage pathways.
Thick vegetative cover can also provide a haven for burrowing animals such as the groundhog. These
animals can create a network of burrows in the dam embankments that can significantly weaken the
dam. by creating seepage paths, which may eventually lead to dam failure.
The earthen embankment should at all times maintain a healthy grass cover, which is free of brush.
This type of cover, if properly maintained, will prevent erosion of the embankment and provide an
easv surface for inspection. Good grass cover should also be maintained around the pond perimeter
to prevent excessive sediment from entering the pond. Grass should be properly fertilized even,
March and October (or as required) to ensure a substantial grass stand is continuously present.
Grass mowing, brush cutting and removal of weed vegetation will be necessary for the proper
maintenance of the embankment, The embankment slopes and spillway should be mowed when the
grass exceeds eight (8) inches in height. Mowing of the dam embankments should occur, at a
minimum, once every 6 months to prevent woody vegetation growth and cover for burrowing
animals. Acceptable methods include the use of weed whips, power brush cutters and mowers. All
rip -rap areas should be treated with a herbicide as required to control any plant materials that may
develop.
The embankment and adjacent slopes of the pond should be periodically (at least once every two
years) limed, fertilized and re -seeded in the fall after the growing season. Consult the North Carolina
State Cooperative Extension Service of the local Soil &. Water Conservation district office to
determine the appropriate lime and fertilizer requirements.
Trees and other woody vegetation should not be allowed to grow on the earthen pond embankment.
Anv vegetation, which inhibits the operation of the pond, should be removed.
PAGE 2

All erosion gullies noted during the growing season should be backfilled with topsoil, re -seeded and
protected until the vegetation is established. Proper care of these areas is required to prevent more
serious damage to the embankment.
All bare areas and pathways in the embankment should be properly seeded and protected in order to
eliminate the potential for erosion.
All animal burrows noted during the mowing operation should be backfilled and compacted,
iIMeasures should be taken to eliminate animals from the area.
Trash and vegetative floatables (grass clippings, leaves, limbs, etc.) should be cleaned from the pored
surface and surroundings periodically to promote a healthy, aesthetically pleasing environment. and
to prevent blockage of the pond outlets. Studies have shown that people are less likely to litter ponds
that are aesthetically pleasing and support wildlife.
EROSION:
Unsuitable fill material, inadequate compaction, and/or poor stabilization of earth structures can result
in accelerated erosion where high runoff velocities exist. High velocities usually occur on steep pond
embankments, at pond inlet and outlet discharge areas, and where the water is constricted to channel
floe'. The entire pond area should be inspected quarterly for signs of erosion, paying special attention
to the following areas.
Embankments: if pond embankments are not kept well vegetated with grasses, rill erosion (small
channels formed in the embankment due to poor grass cover) may occur. Rill erosion can be repaired
by filling the small channels with suitable soil, compacting, and seeding. It may be necessary to
install temporary erosion control (such as excelsior matting) along heavily eroded areas to allow the
repaired areas to stabilize. It is especially important to inspect for and immediately repair any erosion
on the dam embankments.
Pipe Inlet and Outlet areas: Where erosion causes the undercutting of the dow-rtstream end of pipe.
the undercut should be stabilized immediately to prevent the end pipe section from "breaking" off.
Eroded areas should be filled with good compatible soil and covered with geotextile and riprap.
Open Channel Flow: Eroded areas should be seeded and protected with temporary matting. If
erosion continues, a more robust lining (riprap) should be used.
SEEPAGE:
The dowristcam side of the embankment should be inspected for evidence of significant seepage at
least quarterly. Seepage can emerge anywhere below the normal pool elevation, including the
downstream slope of earth dams, areas beyond the toe of the dam, and around the spillway or pond
outlet pipe. Indications of significant seepage include areas where the soil is saturated or where there
is a flowing "spring" or leak. If "sinkholes" in the dam embankment are notice, or if constant flowing
water is noticed on the downstream side of the dam, then seepage has become excessive and
professional engineering advice should be sought immediately to avert a major structural problem or
a failure of the dam.
PAGE 3

The entire embankment should be inspected for cracks. Pronounced cracks on the embankment
surface indicate the first stages of potential dam failure Short isolated cracks are usually not
significant. but larger, and well-defined cracks indicate a serious problem that may eventually lead to
slope failure such as sliding or sloughing. There are two types of potential cracks:
Transverse cracks appear crossing the embankment and indicate the differential settlement
within the embankment. Any area experience excessive settlement (greater than six (b)
inches) should be restored to the original elevation. A large amount of settlement .within a
small area could indicate serious problems in the foundation or the lower part of the
embankment. Settlement accompanied by cracking often proceeds failure.
Longitudinal cracks run parallel to the embankment and may signal the early stages of a slide
Slides are serious threats to the safety of an embankment. Arch shape cracks are indications
that slides are slipping or beginning to slip. These cracks soon develop into large scraps in
the slope at the top of the slide.
If excessive seepage of significant cracks is detected, the embankment could experience failure. A
geotechnical or civil engineer should be immediately consulted regarding the origin of these problems
and to ascertain the appropriate solution for correcting the situation.
SEDIMENT ACCUMULATION:
To preserve the pond's pollutant removal capability, sediment must be removed in areas where the
capacity of the design sediment storage volume has been exceeded.
The forebay helps to improve the removal efficiency of the pond system by trapping the majority of
coarser suspended solids behind the submerged weir. When sediment deposition in the forebay
exceeds the designed sediment storage capacity, the forebay must be dredged. An indication of when
the forebay sediment capacity is exceeded is when sediment bars are visible near the inlet discharge
or when the sediment level at the inlet to the pond is less than one foot below the normal pool water
surface. Typically, forebays will need to be dredged every 5 to 10 years.
Depth measurements relative to the normal pool water surface elevation (bottom of the low flow
orifice) should be taken at several locations around the pond. This pond is designed with a normal
depth of 3- feet, The sediment is to be removed when the measured depth is less than the design
permanent pool depth. If the forebay is regularly dredged, the frequency of dredging the entire pond
could be greatly reduced
BLOCKAGE OF OUTLETS:
Wet extended detention ponds are designed for the water to exit the pond through the low flow
orifice, the principal spillway, and the emergency spillway. It is important to check all three outlets
for blockage that would impair the pond's water quality and hydraulic functionality.
Low Flow Orifice: The low flow orifice utilizes an inverted orifice to prevent clogging. When the
orifice becomes clogged the water level rises to the principal spillway elevation and the benefits
associated with temporary storage and its gradual release are lost. To preserve "extended detention"
the low flow orifice should be inspected for blockage twice a month and after large storms.
PAGE 4

Principal and Emergency Spillways: Principal and emergency spillways are designed to safely
convey larger than one -inch storms that produce runoff, which exceed the water quality volume of the
pond. if these spillways are blocked so they do not operate at full capacity, the risk of dam
overtopping or other uncontrolled releases may result. To ensure the hydraulic capacity of the
spillways. the spillways should be inspected for blockage twice a month and after large storms.
Vegetative growth in the riser should be removed promptly so that the design capacity of the spillway
is maintained. The outlet area where the barrel projects from the fill should be clear of tree limbs,
sediment accumulation, etc.
The pond also has an emergency drain with a valve located within the principal spillway riser
structure. The operation of this valve should be checked on a bi-annual basis by simply opening and
shutting the valve.
MAINTENANCE CHECKLIST
Perform inspections and maintenance of the pond on a regular basis and after large storm events
Record and file inspections and maintenance activities. An Inspection and Maintenance Report is
aitached for use in documentation.
PAGE �J

DETENTION POND INSPECTION & MAINTENANCE REPORT
,1 X1 1 J1�5 INSPECTED BY.
ALLJg(kDATE OF INSPECTION:
INSPECTION ITEM MAINT.
NEEDED?
(yCSJ lo}
ENTIRE DRAINAGE AREA OF POND
CORRECTIVE ACTIVITIES I COMMENTS
Am�as where bare earth is
Re -seed areas; take temporary measures
a exposed or scarce grass cover?
to prevent erosion until vegetation is
reestablished.
htlets to storm drainage clear
Clear debris to preserve capacity.
of debris?
r
I VEGETATIVE GROWTH
Check vegetative growth on
Mow grass when higher that 8-in.
embankment and adjacent
Fertilize at least bi-annually, Remove
slopes.
clippings, leaves, etc. from pond area.
Check for unwanted vegetative
Remove brush, trees and other woody
growth and animal burrows.
vegetation from embankment. Fill
burrows, eliminate animals.
}
EROSION
Check pond embankments for
Re -vegetate bare earth with strong rooted
bare earth and eroded areas.
grasses; repair eroded areas.
ai
Check for pipe undercut at
Fill eroded areas with good compactable
inlet and outlet discharge
soil, overlay with filter fabric and rip rap
areas.
Cneck for erosion downstream
Seed eroded areas and protect with temp.
I of pipe discharge areas
erosion protection (e.g. matting); if
i
erosion persists may need rip rap lining.
SEEPAGE
l Check the toe of the
The dam may have seepage problems.
downstream dam embankment
Contact the City and a dam engineer
for "springs" or wet spots.
immediately to inspect.
Check embankments and crest
Contact the City and a dam engineer
for pronounced cracking or
immediately to inspect.
slope failures.
SEDIMENT ACCUMULATION
Check sediment in forebay
area.
Check sediment in the main
portion of the pond (once
eves. 5 years)
FUNCTIONALITY OF POND OLITLETS
Sediment should be removed from the
forebay when level is less than I -ft below
normal water surface elevation.
Remove sediment when sediment exceeds
design storage volume.
I Check for blockage in low
Remove blockage; if blockage persists,
no", orifice, principal and
consider modifying trash guard
j emergency spillways.
Check pond drain operation.
Periodically open and close the pond
drain to keep operational
i
PAGE 6