Stormwater Management Narrative
480 Broadway, Suite 324 | P.O. Box 272 | Saratoga Springs, NY 12866 | 518.832.4005
STORMWATER MANAGMENT NARRATIVE
Project: Leuci Residence
Date: January 15, 2021
Project Background:
The project site is a 34.4 acres parcel located at 277 Chestnut Ridge Road in the Town of
Queensbury (Tax Map ID 290.-1-48). The existing site is composed of an existing gravel driveway
that terminates at a cleared area with a gravel/dirt ground covering surrounded by a mixed
forested/grass area. The cleared area then slopes down at grades near or exceeding 15% to a
stream that traverses from north to south through the west portion of the site, approximately
900 feet from the proposed house location. The site soils consist of Charlton fine sandy loam,
Belgrade silt loam, Fluvaquents-Udifluvents complex, Raynham silt loam, Rhinebeck silt loam, and
Wareham loamy sand. All proposed work will be completed in areas consisting of Charlton fine
sandy loam which is classified as hydrologic soil group B. Details and delineation of site soils are
presented in the USDA soil report provided in Appendix B of this narrative.
Development:
The proposed development includes the construction of a single-family residence, an accessory
garage structure, the extension of an existing gravel driveway to access the residence and
detached structure, an on-site wastewater treatment system, an on-site potable water well and
permanent stormwater control measures. Total disturbance area is approximately 25,436 square
feet (sqft. The proposed work will create approximately 6,325 sqft of impervious area,
encompassing a marginal 0.4% of the total property area. Proposed work will primarily take place
within the existing clearing, located on the ridge traversing through the property. No work will
take place within proximity of the stream or the delineated flood zones.
Stormwater Management:
Proposed stormwater control measures include a 10-foot-wide grass lined swale and an
detention basin. In addition to the permanent control measures, temporary erosion and
sediment control measures will be installed and maintained throughout the duration of
construction in accordance with the New York State Stormwater Management Design Manual,
January 2015 and the New York Standards and Specifications for Erosion and Sediment Control.
Refer to the construction drawings for the locations and details of the proposed stormwater
features.
The site was broken up into three subcatchment areas. Subcatchment 1S consists of the majority
of the proposed residence roof, lawn area surrounding the residence and undisturbed woods
near the perimeter of the property. Stormwater runoff from the new residence roof will be
conveyed via sheet flow to the lawn area surrounding the base of the residence. This area will
serve as a vegetated buffer for infiltration of runoff generated from the roof. Subcatchment 2S
consists of the new gravel driveway, the accessory structure roof, and lawn area adjacent to the
gravel driveway. Runoff from the roofs and proposed gravel driveway will be conveyed via sheet
flow to a grass lined swale that discharges to an detention basin. Excess runoff will then outlet
the basin via a stone-lined broad crested weir to an undisturbed woods/grass mixed area.
Subcatchment 3S consist of existing gravel/grass areas that will be re-graded and vegetated, the
existing gravel driveway, and woods/grass mix areas along the perimeter of the property. Runoff
within this subcatchment will follow existing drainage patterns. The Subcatchment Plans and
HydroCAD Diagrams are included in Appendices C and D of this narrative. Detailed stormwater
runoff calculations are included in Appendix D.
The design storm event was assumed to be customized storm curves based upon Extreme
Precipitation Data in New York & New England available through a joint collaboration between
the Northeast Regional Climate Center and Natural Resources Conservation Service for Type II
storm events. The rainfall magnitude for the 25-year storm events was determined to be 4.41
inches. The runoff rates were modeled using HydroCAD version 10.0 software which calculates
runoff based on the modified SCS TR-20 method. The peak runoff discharge passing through the
proposed stormwater management system will be attenuated to be less than or equal to the pre-
development flow rates for the 25-year 24-hour storm at established discharge design points.
The peak off-site discharge rate for the 24-hour 25 year is as follows:
Pre-Construction Post-Construction
Design Point #1 1.89 cfs 1.26 cfs
Design Point #2 3.67 cfs 2.36 cfs
The peak off-site discharge rate at Design Point #1 was reduced from existing conditions to post
conditions through the reduction of the overall contributing subcatchment area. Runoff
generated within a portion of the existing subcatchment area, where the proposed residence will
be constructed, will be controlled by the detention basin in Subcatchment 2S and is consequently
tributary to Design Point #2, rather than #1. Areas surrounding the base of the residence will be
vegetated and maintained to facilitate runoff generated from the roof. No additional permanent
stormwater practices are required to attenuate runoff within this subcatchment.
MAINTENANCE OF STORMWATER MANAGEMENT SYSTEM
The grass-lined swale shall maintain a grass height of 4 to 6 inches and shall be monitored for
excessive sediment build-up within the bottom of the channel. The broad crested overflow weirs
should be checked for the accumulation of debris that may constrict runoff from flowing freely at
the outlet invert elevations. In addition to the maintenance of the stormwater practices
described, the lawns and landscaped areas shall be maintained in good condition to prevent
erosion. Any deteriorated areas of lawn shall be re-seeded, and a stable turf reestablished.
Additionally, the property owner shall provide arrangements for the future maintenance of the
post-construction stormwater control measures in accordance with the Sample Stormwater
Control Facility Maintenance Agreement (see Appendix A ) to be recorded in the office of the
County Clerk or its terms shall be incorporated into covenants appearing in the deed,
declarations of covenants and restrictions or other such documents to ensure that record notice
of its terms is provided to future owners of the site.
If you have any questions, please contact the undersigned at (518) 832-4005.
Sincerely,
Matthew E. Huntington, PE
Principal
For
Studio A | Landscape Architecture + Engineering
STORMWATER MANAGEMENT
147 Attachment 5
SCHEDULE E
Sample Stormwater Control Facility Maintenance Agreement
Whereas, the Town of Queensbury ('municipality') and (the "facility owner") want to
enter into an agreement to provide for the long term maintenance and continuation of
stormwater control measures approved by the municipality for the below named project, and
Whereas, the municipality and the facility owner desire that the stormwater control
measures be built in accordance with the approved project plans and thereafter be maintained,
cleaned, repaired, replaced and continued in perpetuity in order to ensure optimum performance
of the components. Therefore, the municipality and the facility owner agree as follows:
1.This agreement binds the municipality and the facility owner, its successors and
assigns, to the maintenance provisions depicted in the approved project plans which are
attached as Schedule A of this agreement.
2.The facility owner shall maintain, clean, repair, replace and continue the stormwater
control measures depicted in Schedule A as necessary to ensure optimum performance of the
measures to design specifications. The stormwater control measures shall include, but shall not
be limited to, the following: drainage ditches, swales, dry wells, infiltrators, drop inlets, pipes,
culverts, soil absorption devices and retention ponds.
3.The facility owner shall be responsible for all expenses related to the maintenance of
the stormwater control measures and shall establish a means for the collection and distribution
of expenses among parties for any commonly owned facilities.
4.The facility owner shall provide for the periodic inspection of the stormwater control
measures, not less than once in every five year period, to determine the condition and integrity
of the measures. Such inspection shall be performed by a Professional Engineer licensed by the
State of New York. The inspecting engineer shall prepare and submit to the municipality within
30 days of the inspection, a written report of the findings including recommendations for those
actions necessary for the continuation of the stormwater control measures.
5.The facility owner shall not authorize, undertake or permit alteration, abandonment,
modification or discontinuation of the stormwater control measures except in accordance with
written approval of the municipality.
6.The facility owner shall undertake necessary repairs and replacement of the
stormwater control measures at the direction of the municipality or in accordance with the
recommendations of the inspecting engineer.
7.The facility owner shall provide to the municipality within 30 days of the date of this
agreement, a security for the maintenance and continuation of the stormwater control measures
in the form of a (Bond, letter of credit or escrow account).
147 Attachment 5:1 04 - 15 - 2009
QUEENSBURY CODE
8.This agreement shall be recorded in the Office of the County Clerk, County of
Warren, together with the deed for the common property and shall be included in the offering
plan and/or prospectus approved pursuant to _________________.
9.If ever the municipality determines that the facility owner has failed to construct or
maintain the stormwater control measures in accordance with the project plan or has failed to
undertake corrective action specified by the municipality or by the inspecting engineer, the
municipality is authorized to undertake such steps as reasonably necessary for the preservation,
continuation or maintenance of the stormwater control measures and to affix the expenses
thereof as a lien against the property.
10.This agreement is effective beginning on: _________________.
147 Attachment 5:2 04 - 15 - 2009