Hopkins Assisted Living - Stormwater and EC Sediment Report

BMP:
Project:Hopkins Assisted Living Community BMP-1804
Date:11/8/2018
Pond Runoff Volume Calculations
Simple Method - V = 3630*Rv*Rd*A
Rd - Rainfall Depth (inches)= 1
Rv = 0.05+0.9*Ia
Rv = Runoff Coefficient
Ia = Impervious fraction = Impervious drainage area/ Total drainage area
A = Drainage area (ac. ) =0.3
Impervious portion of drainage area (ac.) = 0.3
Ia = 1.00
Rv = 0.05 +0.9*Ia
Rv = 0.95
CUFT
Required V = 3630 *Rv*Rd*A =1,035
Provided 1,800
Bioretention
844 NC Highway 39 Louisburg, NC
Note: Per NCDEQ requirements only the net increase in impervious is required to be treated.
Permit Number:__________________
(to be provided by DWQ)
Form SW401-Bioretention-Rev.8
June 25, 2010 Parts I and II. Design Summary, Page 1 of 2
I. PROJECT INFORMATION
Project name
Contact name
Phone number 919-848-6121
Date
Drainage area number
Site Characteristics
Drainage area 13,068 ft2
Impervious area 13,068 ft2
Percent impervious 100.0%%
Design rainfall depth 1.0 inch
Peak Flow Calculations
Is pre/post control of the 1-yr, 24-hr peak flow required? Y (Y or N)
1-yr, 24-hr runoff depth 2.9 in
1-yr, 24-hr intensity 4.9 in/hr
Pre-development 1-yr, 24-hr peak flow 6.890 ft3/sec
Post-development 1-yr, 24-hr peak flow 7.600 ft3/sec
Pre/Post 1-yr, 24-hr peak control 0.710 ft3/sec
Storage Volume: Non-SA Waters
Minimum volume required 1,035.0 ft3
Volume provided 1,800.0 ft3 OK
Storage Volume: SA Waters
1.5" runoff volume N/A ft3
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24-hr runoff ft3
Minimum volume required N/A ft3
Volume provided ft3
Cell Dimensions
Ponding depth of water 12 inches OK
Ponding depth of water 1.00 ft
Surface area of the top of the bioretention cell 1,800.0 ft2 OK
Length:60 ft OK
Width:30 ft OK
-or- Radius ft
Media and Soils Summary
Drawdown time, ponded volume hr
Drawdown time, to 24 inches below surface hr
Drawdown time, total:0 hr
In-situ soil:
Soil permeability in/hr
Planting media soil:
Soil permeability 1.00 in/hr OK
Soil composition
% Sand (by volume)85%OK
% Fines (by volume)10%OK
% Organic (by volume)5%OK
Total:100%
Phosphorus Index (P-Index) of media (unitless)
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
BIORETENTION CELL SUPPLEMENT
1
II. DESIGN INFORMATION
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must be printed, filled out and submitted along with all of the required information.
November 8, 2018
Hopkins Assisted Living Community
John Benton
NOTE: Topographical Survey Infomation provided by Herring-
Sutton and Associates dated October 2017. Address: 2201 Nash Street
NW, Wilson, NC 27896; Phone: [phone]
The proposed site improvements will create 12,036
sf of additional impervious and only the Net
increase of impervious is required to be treated for
stormwater run-off control and treatment.
TBD- Note soils test has been requested.
1 yr - 24 hr storm
1 yr - 5 min
Permit Number:__________________
(to be provided by DWQ)
Form SW401-Bioretention-Rev.8
June 25, 2010 Parts I and II. Design Summary, Page 2 of 2
Basin Elevations
Temporary pool elevation 90.00 fmsl
Type of bioretention cell (answer "Y" to only one of the two
following questions):
Is this a grassed cell?Y (Y or N)OK
Is this a cell with trees/shrubs?N/A (Y or N)
Planting elevation (top of the mulch or grass sod layer)91 fmsl
Depth of mulch N/A inches Insufficient mulch depth, unless installing grassed cell.
Bottom of the planting media soil 85.5 fmsl
Planting media depth 5.5 ft
Depth of washed sand below planting media soil ft
Are underdrains being installed?Y (Y or N)
How many clean out pipes are being installed?1 Insufficient number of clean out pipes provided.
What factor of safety is used for sizing the underdrains? (See
BMP Manual Section 12.3.6)2 OK
Additional distance between the bottom of the planting media and
the bottom of the cell to account for underdrains 1 ft
Bottom of the cell required 84.5 fmsl
SHWT elevation 82.5 fmsl
Distance from bottom to SHWT 2 ft OK
Internal Water Storage Zone (IWS)
Does the design include IWS Y (Y or N)
Elevation of the top of the upturned elbow fmsl
Separation of IWS and Surface 91 ft
Planting Plan
Number of tree species 0
Number of shrub species
Number of herbaceous groundcover species
Additional Information
Does volume in excess of the design volume bypass the
bioretention cell?Y (Y or N)OK
Does volume in excess of the design volume flow evenly
distributed through a vegetated filter?Y (Y or N)OK
What is the length of the vegetated filter?N/A ft
Does the design use a level spreader to evenly distribute flow?N (Y or N)Show how flow is evenly distributed.
Is the BMP located at least 30 feet from surface waters (50 feet if
SA waters)?Y (Y or N)OK
Is the BMP localed at least 100 feet from water supply wells?Y (Y or N)OK
Are the vegetated side slopes equal to or less than 3:1?Y (Y or N)OK
Is the BMP located in a proposed drainage easement with access
to a public Right of Way (ROW)?Y (Y or N)OK
Inlet velocity (from treatment system)1 ft/sec OK
Is the area surrounding the cell likely to undergo development in
the future?N (Y or N)OK
Are the slopes draining to the bioretention cell greater than 20%?N (Y or N)OK
Is the drainage area permanently stabilized?Y (Y or N)OK
Pretreatment Used
(Indicate Type Used with an "X" in the shaded cell)
Gravel and grass
(8+inches gravel followed by 3-5 ft of grass)
Grassed swale
Forebay
Other
N/A
Permit Number:_______________________
(to be provided by DWQ)
Drainage Area Number:_________________
Form SW401-Bioretention O&M-Rev.3 Page 1 of 4
Bioretention Operation and Maintenance Agreement

I will keep a maintenance record on this BMP. This maintenance record will be kept in a
log in a known set location. Any deficient BMP elements noted in the inspection will be
corrected, repaired or replaced immediately. These deficiencies can affect the integrity
of structures, safety of the public, and the removal efficiency of the BMP.

Important operation and maintenance procedures:
− Immediately after the bioretention cell is established, the plants will be watered
twice weekly if needed until the plants become established (commonly six
weeks).
− Snow, mulch or any other material will NEVER be piled on the surface of the
bioretention cell.
− Heavy equipment will NEVER be driven over the bioretention cell.
− Special care will be taken to prevent sediment from entering the bioretention cell.
− Once a year, a soil test of the soil media will be conducted.

After the bioretention cell is established, I will inspect it once a month and within 24
hours after every storm event greater than 1.0 inches (or 1.5 inches if in a Coastal
County). Records of operation and maintenance will be kept in a known set location
and will be available upon request.

Inspection activities shall be performed as follows. Any problems that are found shall
be repaired immediately.

BMP element: Potential problems: How I will remediate the problem:
The entire BMP Trash/debris is present. Remove the trash/debris.
The perimeter of the
bioretention cell
Areas of bare soil and/or
erosive gullies have formed.
Regrade the soil if necessary to
remove the gully, and then plant a
ground cover and water until it is
established. Provide lime and a
one-time fertilizer application.
The inlet device: pipe,
stone verge or swale
The pipe is clogged (if
applicable).
Unclog the pipe. Dispose of the
sediment off-site.
The pipe is cracked or
otherwise damaged (if
applicable).
Replace the pipe.
Erosion is occurring in the
swale (if applicable).
Regrade the swale if necessary to
smooth it over and provide erosion
control devices such as reinforced
turf matting or riprap to avoid
future problems with erosion.
Stone verge is clogged or
covered in sediment (if
applicable).
Remove sediment and clogged
stone and replace with clean stone.

Form SW401-Bioretention O&M-Rev.3 Page 2 of 4

BMP element: Potential problems: How I will remediate the problem:
The pretreatment area Flow is bypassing
pretreatment area and/or
gullies have formed.
Regrade if necessary to route all
flow to the pretreatment area.
Restabilize the area after grading.
Sediment has accumulated to
a depth greater than three
inches.
Search for the source of the
sediment and remedy the problem if
possible. Remove the sediment and
restabilize the pretreatment area.
Erosion has occurred. Provide additional erosion
protection such as reinforced turf
matting or riprap if needed to
prevent future erosion problems.
Weeds are present. Remove the weeds, preferably by
hand.
The bioretention cell:
vegetation
Best professional practices
show that pruning is needed
to maintain optimal plant
health.
Prune according to best professional
practices.
Plants are dead, diseased or
dying.
Determine the source of the
problem: soils, hydrology, disease,
etc. Remedy the problem and
replace plants. Provide a one-time
fertilizer application to establish the
ground cover if a soil test indicates
it is necessary.
Tree stakes/wires are present
six months after planting.
Remove tree stake/wires (which
can kill the tree if not removed).
The bioretention cell:
soils and mulch
Mulch is breaking down or
has floated away.
Spot mulch if there are only random
void areas. Replace whole mulch
layer if necessary. Remove the
remaining much and replace with
triple shredded hard wood mulch at
a maximum depth of three inches.
Soils and/or mulch are
clogged with sediment.
Determine the extent of the clogging
- remove and replace either just the
top layers or the entire media as
needed. Dispose of the spoil in an
appropriate off-site location. Use
triple shredded hard wood mulch at
a maximum depth of three inches.
Search for the source of the
sediment and remedy the problem if
possible.
An annual soil test shows that
pH has dropped or heavy
metals have accumulated in
the soil media.
Dolomitic lime shall be applied as
recommended per the soil test and
toxic soils shall be removed,
disposed of properly and replaced
with new planting media.

Form SW401-Bioretention O&M-Rev.3 Page 3 of 4

BMP element: Potential problems: How I will remediate the problem:
The underdrain system
(if applicable)
Clogging has occurred. Wash out the underdrain system.
The drop inlet Clogging has occurred. Clean out the drop inlet. Dispose of
the sediment off-site.
The drop inlet is damaged Repair or replace the drop inlet.
The receiving water Erosion or other signs of
damage have occurred at the
outlet.
Contact the NC Division of Water
Quality 401 Oversight Unit at 919-
733-1786.

Permit Number:_______________________
(to be provided by DWQ)
Form SW401-Bioretention I&M-Rev. 2 Page 4 of 4

I acknowledge and agree by my signature below that I am responsible for the
performance of the maintenance procedures listed above. I agree to notify DWQ of any
problems with the system or prior to any changes to the system or responsible party.

Project name:Hopkins Assisted Living Community
BMP drainage area number:1

Print name:John Hopkins
Title:Property Owner
Address:844 Highway 39 Louisburg, NC
Phone:
Signature:
Date:

Note: The legally responsible party should not be a homeowners association unless more than 50% of
the lots have been sold and a resident of the subdivision has been named the president.

I, _____________________________________, a Notary Public for the State of
____________________, County of ____________________, do hereby certify that
______________________________________ personally appeared before me this
day of _________________, _______, and acknowledge the due execution of the
forgoing bioretention maintenance requirements. Witness my hand and official seal,

SEAL

My commission expires