HomeMy WebLinkAboutWPO200500072 Plan - E&S 2005-09-13 EROSION AND SEDIMENT CONTROL NARRATIVE
FOR
HOLLYMEAD TOWNCENTER, AREA C
REV: January 14, 2004
LOCATION:
Tax Map 32 Parcel 41 D
Rivanna District, Albemarle County, Virginia
OWNER & DEVELOPER
Post Office Land Trust
Charlottesville VA, 22906
PREPARED BY:
Rivanna Engineering & Surveying, PLC
P.O. Box 7603
Charlottesville, VA 22906
434.984.1599
(F) 434.984.8863
_T,v.23, zoo
A. MINIMUM STANDARDS (MS):
All applicable Virginia Erosion and Sediment Control Regulations and Minimum Standards shall be
adhered to during all phases of construction. These include, but are not limited to the following:
1. STABLIZATION OF DENUDED AREAS:
Permanent or temporary soil stabilization shall be applied to bare areas within seven days after final
grade is reached on any portion of the site. Temporary soil stabilization shall be applied within seven
days to denuded areas that may not be at final grade, but will remain dormant or undisturbed for longer
than 30 days. Permanent stabilization shall be applied at areas that are to be left dormant for more than
1 year.
2. STABILIZATION OF SOIL STOCKPILES:
During construction of the project, soil stockpiles shall be stabilized or protected with sediment trapping
measures. The applicant is responsible for temporary protection and permanent stabilization of all soil
stockpiles on site as well as soil intentionally transported from the project site.
3. PERMANENT VEGETATIVE COVER
A permanent vegetative cover shall be established on denuded areas not otherwise permanently
stabilized. Permanent vegetation shall not be considered established until a ground cover is achieve
that, in the opinion of the county Inspector, is uniform and mature enough to survive to inhibit erosion.
4. TIMING & STABILIZATION OF SILT TRAPPING MEASURES:
Sediment basins and traps, perimeter dikes, sediment barriers and other measures intended to trap
sediment shall be constructed as a first step in any land disturbing activity and shall be made functional
before upslope land disturbance takes place.
5. STABILIZATION OF EARTHEN STRUCTURES:
Stabilization measures shall be applied to earthen structures such as dams, dikes and diversions
immediately after installation.
6. SEDIMENT TRAPS AND BASINS:
A sediment basin shall control surface runoff from disturbed areas that is comprised of flow from drainage
areas greater than or equal to three acres. The sediment basin shall be designed and constructed to
accommodate the anticipated sediment loading for the land disturbing activity. The outfall device or
system device shall take into account the total drainage area flowing through the disturbed area to be
served by the basin.
7. CUT AND FILL SLOPES:
Cut and fill slopes shall be designed and constructed in a manner that will minimize erosion. Slopes that
are found to be eroding excessively within one year of permanent stabilization shall be provided with
additional slope stabilizing measures until the problem is corrected.
8. CONCENTRATED RUN -OFF DOWN CUT OR FILL SLOPES:
Concentrated runoff shall not flow down cut or fill slopes unless contained within an adequate temporary
or permanent channel, flume, or slope drain structure.
9. WATER SEEPS FROM A SLOPE FACE:
Whenever water seeps from a slope face, adequate drainage or other protection shall be provided.
10. STORM SEWER INLET PROTECTION:
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All storm sewer inlets that are made operable during construction shall be protected so that sediment -
laden water cannot enter the conveyance system without first being filtered or otherwise treated to
remove sediment.
11. STABILIZATION OF OUTLETS:
Before newly constructed stormwater conveyance channels are made operational, adequate outlet
protection and any required temporary or permanent channel lining shall be installed in both the
conveyance channel and receiving channel.
12. WORK IN LIVE WATERCOURSES:
When work in a live watercourse is performed, precautions shall be taken to minimize encroachment,
control sediment transport and stabilize the work area to the greatest extent possible during construction.
Nonerodible material shall be used for the construction of causeways and cofferdams. Earthen fill may
be used for these structures if armored by nonerodible cover materials.
13. CROSSING A LIVE WATERCOURSE:
When a live watercourse must be crossed by construction vehicles more than twice in any six month
period, a temporary stream crossing constructed of nonerodible materials shall be provided.
14. APPLICABLE REGULATIONS:
All applicable federal, state and local regulations pertaining to working in or crossing live watercourses
shall be met.
15. STABILIZATION OF BED AND BANKS
The bed and banks of a watercourse shall be stabilized immediately after work in the watercourse is
completed.
16. UNDERGROUND UTILITIES:
Underground utilities shall be installed in accordance with the following standards in addition to other
criteria:
a. No more than 500 linear feet of trench may be opened at one time.
b. Excavated material shall be placed on the uphill side of trenches
c. Effluent for dewatering operations shall be filtered or passed through approved sediment trapping
device, or both, and discharged in a manner that does not adversely affect flowing streams or offsite
property.
d. Material used for backfilling trenches shall be properly compacted in order to minimize erosion and
promote stabilization.
e. Restabilization shall be accomplished in accordance with these regulations.
f. Applicable safety regulations shall be complied with.
17. CONSTRUCTION ACCESS ROUTES:
Where construction vehicle access routes intersect paved public roads, provisions shall be made to
minimize the transport of sediment by vehicular tracking onto paved surfaces. Where sediment is
transported on to a public road surface, the road shall be cleaned thoroughly at the end of each day.
Sediment shall be removed by shoveling or sweeping and transported to a sediment control disposal
area. Street washing shall be allowed only after sediment is removed in this manner. This provision shall
apply to individual lots as well as to larger land disturbing activities.
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18. TEMPORARY E&S CONTROL MEASURE REMOVAL:
All temporary erosion and sediment control measures shall be removed within 30 days after final site
stabilization or after temporary measures are no longer needed, unless otherwise authorized by the local
program authority. Trapped sediment and the disturbed soil areas resulting from the disposition of
temporary measures shall be permanently stabilized to prevent further erosion and sediment.
19. ADEQUACY OF RECEIVING CHANNELS:
Properties and waterways downstream from the development site shall be protected from sediment
deposition, erosion and damage, due to increases in volume, velocity and peak flow rates of stormwater
runoff for the stated frequency storm of 24 -hour duration.
B1. PROJECT DESCRIPTION:
The purpose of this project is to clear and rough grade the property for a proposed shopping center. The
total area to be disturbed by this project will be 49 acres.
B2. EXISTING SITE CONDITIONS:
The site is primarily wooded with sparse areas of grass and brush. The existing topography is rolling
terrain with slopes of 10 -20 %.
B3. ADJACENT AREAS:
The site is bounded to the north and south by commercial areas, to the east by U.S. Route 29, and to the
west by residential districts.
B4. SOIL DESCRIPTIONS:
According to the Albemarle County Soils Survey conducted by the United States Department of
Agriculture Soil Conservation Service, the primary soil types that may be disturbed during this scope of
work have been identified as the following:
1. Pacolet Sandy loam (65B) — Permeability is moderate, surface runoff is rapid, and the hazard of
erosion is severe. Hydrologic group B, K factor .28
2. Mount Lucas silt loam (57C) — Permeability is slow, surface runoff is medium, and the hazard of
erosion is moderate. Hydrologic group C, K factor .28
3. Elioak Loam (27B) — Permeability is moderate, surface runoff is medium, and the hazard of
erosion is moderate. Hydrologic group C, K factor .28
B5. CRITICAL AREAS:
The Stream to the north of the parcel is a critical area and extra caution will be taken to ensure no
sediment runoff into the stream.
B6. EROSION AND SEDIMENT CONTROL MEASURES:
Unless otherwise indicated, all erosion and sediment control practices will be constructed and maintained
according to the minimum standards and specifications as set forth in the Virginia Erosion and Sediment
Control Handbook, latest edition. The minimum standards of the Virginia Erosion and Sediment Control
Regulations shall be adhered to unless otherwise waived or approved by variance.
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,
TEMPORARY CONSTRUCTION ENTRANCE (CE) — 3.02
A paved construction entrance shall be constructed at the entrance of the project site to provide a means
of removing sediment from the tires of construction vehicles leaving the work site. The Contractor shall
remove any mud from the existing road surface by means of sweeping and shoveling. A daily water
supply shall be provided with a 1" water tap and 1.5" hose.
SILT FENCE (SF) — 3.05
Silt fencing will be installed as a first step in construction activities. Location and details are
shown on the plans.
TEMPORARY DIVERSION DIKE (DD) — 3.09
A temporary diversion dike will be installed before site grading begins, for the purposes of diverting storm
and sediment -laden runoff to the appropriate outlet or trapping facility. Location and details are shown
on the plans.
TEMPORARY SEDIMENT BASIN (SB) — 3.13
A temporary sediment basin will be installed before site grading begins, for the purpose of detaining
sediment -laden runoff from disturbed areas. Location and details of the sediment traps are shown on the
plans.
DUST CONTROL (DC) — 3.39
A variety of methods are available to prevent surface and air movement of dust from exposed soil
surfaces and reduce the presence of airborne substances which may present health hazards, traffic
safety problems or harm animal or plant life.
B7. PERMANENT AND TEMPORARY STABILIZATION:
SURFACE ROUGHENING — 3.29
Disturbed areas to be seeded and mulched shall be left in a roughened condition to help decrease runoff
velocities and aid in the establishment of vegetation.
TOPSOILING — 3.30
Topsoil may be stripped from the area to be graded and stockpiles for later use. All stockpiles which will
be left dormant for more than 30 days shall be temporarily seeded. A topsoil stockpile may be selected
onsite by the developer and shall be temporarily protected with surrounding silt fencing.
TEMPORARY SEEDING — 3.31
Temporary soil stabilization shall be applied within 7 days to denuded areas that may not be at final
grade, but will remain dormant (undisturbed) for longer than 30 days and less than 1 year. This includes,
but is not limited to areas such as soil stockpiles. Seeded areas shall be limed when necessary at a rate
of 2 tons per acre, and fertilized at a rate of 450 lbs. per acre of 10 -20 -20 (10 lbs. per 1,000 square feet)
or equivalent. A Temporary Seeding Schedule is attached for proper seed selection.
PERMANENT SEEDING — 3.32
A perennial vegetative covering shall be established on disturbed areas within 7 days of being brought to
final grade on areas not otherwise protected. Selection of the seed mixture shall depend on the time of
year it is to be applied according to the Permanent Seed Schedule as shown on the drawing. Seeded
areas shall be limed when necessary at a rate of 2 tons per acres, and fertilized at a rate of 1,000 lbs. per
acre of 10 -20 -10 (10 lbs. per 1,000 square feet) or equivalent.
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MULCHING — 3.35
All seeded areas shall be mulched with straw immediately following seeding operations. Straw mulch
shall be applied at a rate of two tons per acre.
SOIL STABILIZATION BLANKETS AND MATTING — 3.36
Soil stabilization matting shall be applied in the conveyance areas of the designed diversions to help
reduce velocities and aid in the establishment of vegetation. A detail showing the proper materials and
installation is shown on the plan.
B8. SOIL STOCKPILES AND BORROW AREAS
Excess soil from this site shall be stockpiled onsite or transported to other construction sites with
approved erosion control plans.
B9. STORM WATER MANAGEMENT:
Any increase in stormwater runoff as a result of land disturbing activity will be minimal. The sediment
basin's will provide temporary stormwater detention.
B10. MAINTENANCE SCHEDULE:
A program of maintenance for the erosion and sediment controls specified in this narrative and shown on
the plans are recommended as follows:
1. The Site Superintendent or his representative shall make a visual inspection of all erosion and
sediment controls on a daily basis until the site is stabilized and especially after a heavy rainfall to
assure that all controls are in place and that none have been damaged. Any damaged control shall
be repaired prior to the end of each workday to include re- seeding if necessary.
2. All silt trapping devices shall be cleaned out at 50 percent capacity and sediment shall be disposed of
by spreading on site or hauling away if not suitable for fill.
3. Gravel outlets shall be checked regularly for sediment buildup that may prevent drainage. Controls
shall be inspected and repaired after each rainfall and cleaned if sediment has accumulated to half of
the device's original height.
4. All earthen structures such as diversion dikes and berms shall be checked daily during construction
for breaching by equipment. Repairs shall be made immediately.
5. Silt fences shall be checked after each rainstorm to assure they have not fallen or become clogged
with silt. All repairs shall be made immediately.
6. All seeded areas shall be inspected regularly to see that good stand is maintained. Areas will be re-
fertilized and re- seeded as necessary.
7. After construction operations have ended and disturbed areas have been stabilized, all berms and
sediment - trapping devices may be removed after removal, the ground shall be restored to its natural
or proposed condition to include establishment of permanent vegetation. Removal of any control is
contingent upon approval of the County Inspector.
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RESERVOIR REPORT
Reservoir Number: 1
Name: Front Basin /SWM Facility
[RATING CURVE LIMIT]
Minimum Elevation = 512.0000 (ft)
Maximum Elevation = 525.0000 (ft)
Elevation Increment = 0.5000 (ft)
[STAGE STORAGE INFORMATION]
Storage Method: User - Defined Storage
Input Method: Area
Number Elevation Area Ave Area Volume Cumulative Volume
(ft) (sq ft) (sq ft) (cu ft) (cu ft)
1 511.9000 0.0000 0.0000 0.0000 0.0000
2 512.0000 22675.0000 11337.5000 1133.7500 1133.7500
3 515.0000 26892.0000 24783.5000 74350.5000 75484.2500
4 520.0000 34548.0000 30720.0000 153600.0000 229084.2500
5 525.0000 42990.0000 38769.0000 193845.0000 422929.2500
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[RESERVOIR STAGE STORAGE /DISCHARGE]
Elevation Stage Area Storage Discharge
(ft) (ft) (sq ft) (cu ft) (cfs)
512.0000 0.0000 0.0000 0.0000 0.00
512.5000 0.5000 23377.8333 5844.4583 0.00
513.0000 1.0000 24080.6667 17709.0833 0.00
513.5000 1.5000 24783.5000 29925.1250 0.00
514.0000 2.0000 25486.3333 42492.5833 0.00
514.5000 2.5000 26189.1667 55411.4583 0.00
515.0000 3.0000 26892.0000 68681.7500 0.00
515.5000 3.5000 27657.6000 82319.1500 0.00
516.0000 4.0000 28423.2000 96339.3500 0.00
516.5000 4.5000 29188.8000 110742.3500 0.00
517.0000 5.0000 29954.4000 125528.1500 0.00
517.5000 5.5000 30720.0000 140696.7500 0.00
518.0000 6.0000 31485.6000 156248.1500 0.00
518.5000 6.5000 32251.2000 172182.3500 0.00
519.0000 7.0000 33016.8000 188499.3500 0.00
519.5000 7.5000 33782.4000 205199.1500 0.00
520.0000 8.0000 34548.0000 222281.7500 0.00
520.5000 8.5000 35392.2000 239766.8000 0.00
521.0000 9.0000 36236.4000 257673.9500 0.00
521.5000 9.5000 37080.6000 276003.2000 0.00
522.0000 10.0000 37924.8000 294754.5500 0.00
522.5000 10.5000 38769.0000 313928.0000 0.00
523.0000 11.0000 39613.2000 333523.5500 0.00
523.5000 11.5000 40457.4000 353541.2000 22.19
524.0000 12.0000 41301.6000 373980.9500 51.46
524.5000 12.5000 42145.8000 394842.8000 52.65
525.0000 13.0000 42990.0000 416126.7500 53.82
Maximum Storage = 416126.7500 (cu ft)
Maximum Discharge = 53.82 (cfs)
RESERVOIR REPORT
Reservoir Number: 1
Name: Rear Basin
[RATING CURVE LIMIT]
Minimum Elevation = 557.0000 (ft)
Maximum Elevation = 567.0000 (ft)
Elevation Increment = 0.5000 (ft)
[STAGE STORAGE INFORMATION]
Storage Method: User - Defined Storage
Input Method: Area
Number Elevation Area Ave Area Volume
(ft) Cumulative Volume
(sq ft) (sq ft) (cu ft) (cu ft)
1 557.9000 0.0000 0.0000
2 558.0000 5863.0000 2931.5000 293.1500 293.1500
3 560.0000 6656.0000 6259.5000 12519.0000 12812.1500
4 565.0000 10450.0000 8553.0000 42765.0000 55577.1500
5 567.0000 12263.0000 11356.5000 22713.0000 78290.1500
[DISCHARGE INFORMATION]
Structure Number: 1
Type:
Name: Rear Basin Stand Pipe
[RESERVOIR STAGE STORAGE /DISCHARGE]
Elevation Stage Area
(ft) (ft) (sq ft) Storage Discharge
(cu ft) (cfs)
557.0000 0.0000 0.0000 0.0000
557.5000 0.5000 0.00
0.0000 0.0000 0.00
558.0000 1.0000 5863.0000 1465.7500 0.00
558.5000 1.5000 6061.2500 4446.8125
559.0000 2.0000 0.00
6259.5000 7527.0000 0.00
559.5000 2.5000 6457.7500
560.0000 10706.3125 0.00
60.0000
3.0000 6656.0000 13984.7500 0.00
560.5000 3.5000 . 7035.4000 17407.6000
561.0000 4.0000 0.00
7414.8000 21020.1500 0.00
561.5000 4.5000 7794.2000 24822.4000
562.0000 5.0000 0.00
8173.6000 28814.3500 0.00
562.5000 5.5000 8553.0000 32996.0000
563.0000 6.0000 0.00
8932.4000 37367.3500 0.00
563.5000 6.5000 9311.8000 41928.4000
564.0000 7.0000 9691.2000 0.00
564.5000 7.5000 46679.1500 0.00
10070.6000 51619.6000 9.25
565.0000 8.0000 10450.0000 56749.7500
565.5000 8.5000 10903.2500 62088.0625 28.94
566.0000 9.0000 11356.5000 67653.0000 33.41
566.5000 9.5000 11809.7500 73444.5625 37.36
567.0000 10.0000 12263.0000 79462.7500
40.92
Maximum Storage = 79462.7500
Maximum Discharge = (cu ft)
40.92 (cfs)
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