118-22 Correspondence - Jenne Associates.pdf

JENNE ASSOCIATES, LLC Consulting Engineers 35 Gates Avenue, Warren, NJ 07059 Telephone: (908) 698-2890 * Fax: (908) 926-2359 April 11, 2022 Township of West Orange Public Works and Engineering 25 Lakeside Avenue West Orange, NJ .7652 Attn: Leonard Lepore, PE Re: Tributary to Wigwam Brook – Investigation into Frequent Stream Flooding being experienced along Park Drive West and North near the boundary with Llewellyn Park along Tributary to Wigwam Brook FULL ENGINEERING ANALYSIS Proposal #P21021-1 Dear Mr. Lepore: Jenne Associates, LLC (JENNE) is pleased to submit this proposal to provide Civil Engineering Design Services to the Township of West Orange (CLIENT) for the above referenced project. Project Summary – Frequent flooding is being experienced along the Tributary of Wigwam Brook at the point where the open channel watercourse flowing out of Llewellyn Park enters an underground pipe system which carries the flow under Park Drive North to Main Street and its confluence with Wigwam Brook near Ashwood Terrace. Flooding appears to be directly associated with the entrance (inlet) to the underground pipe system becoming blocked by debris carried by floodwaters down the open channel section of the watercourse reducing the ability of floodwater to enter the pipe system. Floodwaters subsequently rise at that location until they overtop the existing ground elevations at Park Drive West and flow down Park Drive North flooding numerous private properties. After each occurrence DPW staff has been mobilized to remove and dispose of the accumulated debris and re-establish a clear unobstructed entrance to the pipe system. The area adjacent to the stream within Llewellyn Park is predominantly undeveloped wooded land that shows little indication of being maintained including removal of fallen or dead trees and branches which contributes to the amount of debris that can make it to the stream channel and flow to the pipe inlet. Scope of Work – Based on our knowledge of Llewellyn Park, experience with past flooding conditions and removal operations at this location and technical experience with stream flow modeling and improvement plan design, JENNE proposes the following scope of work for undertaking an Engineering evaluation of the situation and development of Preliminary Improvement schemes which could be implemented to mitigate the situation in the future: 1. Prepare a

e of work for undertaking an Engineering evaluation of the situation and development of Preliminary Improvement schemes which could be implemented to mitigate the situation in the future: 1. Prepare a base map for use in the engineering evaluations utilizing the West Orange Topographic Maps and other available sources. A delineation of the ground area contributing rainwater to the stream will be shown as well as property lines and current owners.