Drainage Report and Supplement 82625

INTRODUCTION This report is submitted in support of an application to the Board of Adjustment of The Township of West Orange for site plan and variance approval. The Applicant, Montclair Stables LLC, has purchased the existing equine facility on Woodland Avenue and proposes to make improvements to the site. The primary improvements are the re-orientation and reconstruction of the existing outdoor sand riding arena and the re-location of the paved parking lot and driveways. The Applicant also proposes to make improvements to Nicholas Avenue; a paper street located at the rear of the property. This facility has used part of Nicholas Avenue as a driveway for decades. The proposed improvements include extending the driveway to connect to the paved portion of Nicholas Avenue near its intersection with Cannon Street. The driveway would function as a one-way driveway which would exit near the Cannon Street intersection and there would be new security gates at both ends. There are presently two buildings on the site, a barn and an indoor riding arena which are connected by a one-story concourse. There are no changes proposed to the configuration of these buildings. The Existing Drainage Area Plan, as well as the Existing Conditions Plan in the application set, depict a dwelling and related improvements which existed on Lot 176 until recently. The dwelling was removed under a demolition permit issued by the West Orange Construction Code Office. The trees that are scheduled for removal are indicated on Sheet SE-2 of the application set as well as on the Landscape Architect’s drawings. Due to the total surface area that will be disturbed under the present definition of disturbance in the Stormwater Management Regulations, this project is considered a major project. Over one acre of land area will be disturbed. Since less than one quarter of an acre of new “vehicular surface”, the required water quality standards are satisfied by the proposed project. The project is located in the Metropolitan Planning Area PA-1 on the State Plan Policy Map, therefore, the project is exempt from complying with the groundwater recharge provisions of the local stormwater management ordinance. The drainage analysis and calculations presented herein are intended to document compliance with the stormwater runoff quantity standards found in section 25-29.4r of the West Orange Land

t ordinance. The drainage analysis and calculations presented herein are intended to document compliance with the stormwater runoff quantity standards found in section 25-29.4r of the West Orange Land Use Regulations: Section 25-29 Stormwater Control. EXISTING DRAINAGE The existing drainage patterns are indicated on the attached Existing Drainage Areas Plan. The area considered includes the site, a portion of Nicholas Avenue, a small portion of adjacent Lot 132 and an existing bridle path on Lots 1 and 2 in Block 152.26. An easement for the bridle path appears on the Tax Map. The total study area includes 175,847 square feet, or 4.037 acres. Under present conditions, two primary drainage areas were delineated and are shown on the Existing Drainage Areas Plan along with the surface coverage summary for each drainage area. This plan also indicates the time of concentration travel paths with the land slope and flow type for each reach. Page 1