St. John’s Park

Overview

The PWSA St. John’s project aimed to develop an intensive Green Stormwater Infrastructure (GSI) urban designs for cost effective and efficient capture, detention, and/or infiltration/slow-release of the first 1.5-inches of total stormwater runoff from the project contributing drainage area. The goal of the project was to effectively managing the runoff generated from a tributary area containing approx. twelve (12) impervious acres while achieving a competitive final construction cost per impervious acre of runoff captured. GSI practices were designed to manage tributary runoff while providing a pathway for connection back into the combined sewer system to avoid flooding of neighboring properties.

The selected design option implemented local GSI source controls within the upland portions of the delineated sewershed to manage stormwater, with the remaining downslope areas conveyed to the rain gardens within the St. John’s site. Existing catch basin bypass and curb gutter enhancement were designed to safely manage the 25-year 5-minute intensity design storm while bypassing runoff from the 1.5-inch event with capture downstream.

As Project Manager and Contract Prime, Ethos was responsible for coordinating the efforts of numerous subconsultants, and led the overall design, stormwater modeling, plan production, permitting, and community engagement efforts. Although it was anticipated to meet performance and cost targets, the project was placed on hold by PWSA at approx. 60% design, due to shifting budget priorities.