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LEXINGTON-FAYETTE URBAN COUNTY GOVERNMENT
DIVISION OF ENGINEERING
EXECUTIVE SUMMARY
STORMWATER MANAGEMENT PLAN
FOR
Name and Address of Redevelopment Project
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EXECUTIVE SUMMARY
STORMWATER MANAGEMENT PLAN
FOR
Name of Redevelopment Project
Table of Contents
Page 1 Cover Page
Page 2 Table of Contents and Certification Statement
Page 3 General Information
Page 4 Detention Requirements
Page 5 Detention Basin Data Form
Page 6 Summary of Peak Outflows
Page 7 Water Quality Requirements
Page 8 Water Quality Data Form
Page 9 Submittal Checklist
Page 10 List of Supplemental Information Provided in the Appendix
Certification:
I certify that this executive summary was prepared by me or others under my supervision, and
that a copy is being provided to the New Development Section in the Division of Engineering
and the MS4 / Water Quality Manager in the Division of Water Quality.
Date
Engineer’s Signature and Kentucky License No.
Printed Name
Name of Engineering Firm
click to sign
signature
click to edit
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GENERAL INFORMATION
Project Name:
Site Address:
Owner/Developer (Name, email address, phone number):
Engineer (Name, email address, phone number):
Watershed:
Boone Creek Cane Run East Hickman KY River
North Elkhorn South Elkhorn Town Branch West Hickman
Wolf Run
Royal Spring Wellhead Protection Area
U. S. Army Corps of Engineers Jurisdictional Streams and Wetlands
Stream Length (feet): __________________________
Wetland Area (square feet): _____________________
Type of Redevelopment: Residential Commercial
Limits of Disturbance (LOD) in acres: _______________________
(Land disturbance includes demolition, removal of pavements, and other activities that temporarily expose soil. It
does not include repaving or remodeling)
Baseline (before demolition) impervious area within the LOD (acres): _________________________
Proposed impervious area within the LOD after redevelopment (acres): ________________
No. of Outfalls (pipe or open channel at the property line):_______________________
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DETENTION REQUIREMENTS
Complete the applicable box below
Box 1
The net impervious area will be increased above baseline conditions, and detention facilities (new facilities
or modifications to existing facilities) are proposed to reduce the peak flows to baseline conditions for the
design storms in Chapter 5 of the Stormwater Manual (Section 1.8.2 of the Stormwater Manual). In areas
where downstream flooding is known to be a problem, LFUCG may require that peak flows be less than
baseline conditions (1.8.2).
Complete the Detention Basin Data Form for each basin.
Complete the Summary of Peak Flows for each outfall (pipe or open channel at the property line).
Article 16-2(g) of the Zoning Ordinance (check one box below):
Stormwater management facilities are provided for off-street parking areas containing five (5) or more parking
spaces and/or more than 1,800 square feet.
Off-street parking area is 1,800 square feet or less, or less than 5 parking spaces.
Box 2
On-site detention is not required (at least one box below must be checked for the project to be exempt,
Section 1.8.2 of the Stormwater Manual). In areas where downstream flooding is known to be a problem,
LFUCG may require that peak flows be less than baseline conditions (1.8.2)).
The impervious area will not be increased.
The Engineer has conducted a Downstream Study and all of the following apply within the study area.
there will be no increase in downstream water levels within the DSA for the design storms for
flood control structures in Chapter 5, and the 25yr-24hr storm
the downstream drainage system within the DSA has sufficient capacity as defined in Table 1-5
Note: The Downstream Study Area (DSA) means the area beginning at the property line and
extending downstream to a point equal to 10 times the area of the proposed limits of disturbance.
Detention is provided in existing facilities as part of a regional stormwater quantity master plan
Expansion Area 2 Beaumont Centre Coldstream
Hamburg Reynolds Road Masterson Station
Other _________________________________________________________
Detention is provided offsite in existing facilities (explain in the Appendix):
Supporting documentation attached, including map of offsite detention basin
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DETENTION BASIN DATA FORM
Detention Basin No. __________ (Complete for each Basin)
Type of Detention Facility:
Detention Basin Underground Detention Retention Pond Extended Detention
Green Infrastructure w/detention volume: Infiltration Trench Bio-retention Bio-infiltration Swale
Permeable Pavement
Proposed Total Detention Volume: cubic feet (top of embankment to bottom of basin)
Peak Flow Attenuation Design
Design Storm
Peak Flows
Baseline
Basin Inflow
10yr-6hr
100yr-6hr
2006 actual storm
1995 actual storm
100yr-24hr storm:
Peak Stage __________________ (assuming no flow through the principal spillway)
Emergency Spillway Elevation _________________
Elevation of Normal Pool of Wet (Retention) Ponds _________________________
Wet Ponds are designed with anti-seep collars
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SUMMARY OF PEAK FLOWS
Outfall No.
Peak Flow (cfs)
10yr-6hr
100yr-6hr
2006
1995
1
Baseline
After Redevelopment
2
Baseline
After Redevelopment
3
Baseline
After Redevelopment
4
Baseline
After Redevelopment
5
Baseline
After Redevelopment
6
Baseline
After Redevelopment
7
Baseline
After Redevelopment
8
Baseline
After Redevelopment
9
Baseline
After Redevelopment
10
Baseline
After Redevelopment
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WATER QUALITY REQUIREMENTS
Complete the applicable box below
Box 1
Water Quality is addressed as follows (Section 1.8 of the Stormwater Manual):
Option A: The baseline impervious area within the LOD will be reduced by at least 20%.
Baseline Impervious Area (before demolition) = ______________ square feet
Impervious Area After Redevelopment = _____________ square feet
Percent Reduction = _______________
OR
Option B: Stormwater Controls (SWCs), Green Infrastructure, or Manufactured Treatment Devices are
proposed to manage at least 20% of the baseline impervious area plus 100% of the net increase in impervious
area. Runoff Reduction is required only for the net increase in impervious area. Modifications to existing
SWCs/Devices may be sufficient.
The Required Water Quality Volume (WQV) is determined as follows:
If B > A: WQV = A x 0.2 x 1.2/12 + (B-A) x 1.2/12 = ________________ cubic feet
If B = A: WQV = A x 0.2 x 1.2/12 = ____________________ cubic feet
where,
A = Baseline impervious area = ___________ square feet
B = Impervious area after redevelopment = __________ square feet
If B < A: Go to Option C
The Required Runoff Reduction Volume (RRV) is determined as follows (only when B>A):
RRV = (B-A) x 0.8″/12 = ________________ cubic feet (enter 0.0 if RRV is not feasible)
Check this box if Runoff Reduction is not feasible because all of the following conditions are
present
the soil infiltration rate is less than 0.5 inches per hour (ASTM D3385)
o infiltration rate of the on-site soils = __________inches/hour
subdrains are not feasible for applicable Green Infrastructure practices
no other Green Infrastructure practices are feasible
Complete the Water Quality Data Form for each outfall (pipe or open channel at the property line).
Describe Existing Stormwater Quality Controls prior to demolition of the site, if any:
OR
Option C: A combination of the above (described in the attachment)
Box 2
Site is Exempt - The amount of land to be disturbed is less than one acre (Section 1.7.2 of the Stormwater
Manual)
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WATER QUALITY DATA FORM
Outfall No. (Complete for each Outfall)
Required WQV (from previous page) = _______________________
Required RRV (from previous page) = ________________________
RRV Provided by Green Infrastructure
Description
RRV (cf)
Impervious Area Disconnection to Developed Green Space
Impervious Area Disconnection to Protected Natural Areas (including floodplains)
Bio-retention and Rain Gardens
Permeable Pavement
Bio-infiltration Swales
Infiltration Basins and Trenches
Groundcover for Vehicular Parking
Tree Trenches and Planter Boxes
Rainwater Harvesting
Vegetated Roofs
Riparian Buffer Restoration
Total
WQV Provided by Other Stormwater Controls
Description
WQV (cf)
Extended Detention Basins
Wet Ponds
Underground Detention
Wetlands
Total
Manufactured Treatment Devices
Description
Impervious Drainage
Area (sf)
WQV Provided (cf)
(Imp. Area x 1.2″/12)
Total
Summary Table of Stormwater Controls
RRV provided by Green Infrastructure (cf)
WQV Provided by Extended Detention, Wet Ponds,
Underground Detention, or Wetlands (cf)
WQV Provided by MTDs (cf)
Total (cf)
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SUBMITTAL CHECKLIST
Engineer’s Drainage Report/Plans (Stormwater Manual Chapter 4 design documentation)
Watershed map with subwatersheds delineated and labeled (4.3.1)
Location map of the stormwater controls and outfalls (4.3.1)
Baseline and After Redevelopment drainage map (4.3.1)
Streams, wetlands, and other environmentally sensitive areas are shown on the plan (4.3.1)
Detention basin design calculations and schematics (4.3.2)
Detention/retention basins are on a single lot (1.5.6)
Baseline and After Redevelopment runoff hydrographs with supporting data and analysis (4.3.2)
Hydraulic analysis of the proposed storm sewers, inlets, culverts, and channels (4.3.2, 1.6.5)
Water quality volume and BMP design calculations and schematics (4.3.2)
Detailed design of control structures and embankments (4.3.2)
Erosion prevention measures are provided at pipe outfalls (Section 1.7.6)
Channel protection measures are provided to prevent bank erosion (1.7.7)
Manufacturer’s design and maintenance standards for stormwater manufactured treatment devices (4.3.2)
If detention is not proposed, a hydraulic analysis is provided of the downstream drainage system that
demonstrates sufficient capacity (1.6.2)
Projects In or Along a Stream/Floodplain
LFUCG's FEMA Floodplain Administrator has reviewed the plans
FEMA Effective Special Flood Hazard Area is shown on the plan (1.5.12)
For areas w/o SFHA, an H&H study has established the BFEs for projects > 5 acres or > 50 lots (1.4.3)
Flood Protection Elevations are shown for structures (1.6.6)
Structures are at least 25 feet from the floodplain (1.6.7)
Plans conform to Table 1-3 regarding allowable uses in the floodplain (1.10)
Mitigation plans proposed for construction in the waters of Fayette County (1.5.5)
Vegetative buffers are shown on the plan (1.10)
Greenways are shown on the plan (4.3.1)
Federal, State, and Local Permits related to proposed construction in a stream or floodplain
LFUCG Division of Engineering Stormwater Permitting Checklist
USACE 404 Permit
KYDOW 401 Water Quality Certification
KY Stream Construction Permit
FEMA LOMR or CLOMR
Special Permit from LFUCG for construction in the floodplain
General
Adequate vehicle access provided to maintain BMPs (driving surface within 10 feet of the BMP)
Maintenance agreement for commercial projects
Appendix
Related drainage studies that affect the stormwater management plan of this project
Narrative of known downstream flooding problems from LFUCG studies or Engineer’s downstream study
Copies of Waivers or Variances from LFUCG
Note: If a box is not checked, provide explanation in the Appendix
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List of Supplemental Information Provided in the Appendix