Nearly 90 Chester County municipal officials, managers, engineers, planners, and others interested in addressing stormwater issues recently attended the Chester County 2019 Municipal Stormwater Summit, “Adapting to Changing Trends in Chester County – Growth, Rainfall Patterns, and Stormwater.” The summit was hosted by the Chester County Water Resources Authority (CCWRA) on Sept. 20.
CCWRA Executive Director Jan Bowers kicked off the meeting with an overview of countywide water conditions, including recent precipitation levels, rising chloride levels in local streams, and nitrogen levels in both streams and groundwater in the Octoraro Creek Watershed. She noted that the county experienced significantly above average precipitation throughout 2018 and the first half of 2019; however, the recent dry spell over the past two months has allowed both stream and groundwater levels to approach normal seasonal levels.
CCWRA’s Water Resources Planner Cory Trego covered the upcoming review and update of the Chester County water plans and model stormwater ordinance for the county. These plans include Watersheds – An Integrated Water Resources Plan for Chester County and the Countywide Act 167 Stormwater Management Plan for Chester County. Public outreach events will be held at locations throughout the county beginning at the end of October. The final plan drafts are expected to be completed in the fall of 2021 to allow municipalities to update their stormwater ordinances prior to DEP’s MS4 Sept. 30, 2022 deadline. Municipal officials, residents, and stakeholders will have opportunities to review and comment on the plans throughout the update process. Other highlights focused on the county’s Hazard Mitigation Plan, Resilient Chester County, and Conservation District programs.
The Summit included three featured presentations focused on changing trends in growth, precipitation, and stormwater. Chester County Planning Commission Executive Director Brian O’Leary presented an overview of anticipated growth in population and increases in impervious surface coverage in the county, a major factor impacting stormwater runoff. O’Leary noted that impervious surface coverage is expected to increase from 10 percent in 2015 to 11.5 percent in 2045. This increase is based on projected population and job growth during that time period.
CDM Smith Senior Vice President and Water Resources Engineer Mark Maimone discussed projecting rainfall intensity and storm event frequency in Southeastern Pennsylvania. According to Maimone, recent climate data suggest that this region can expect an increase in both extreme rainfall events and bigger storms in the coming years due to the warming climate. He noted that what was once considered a 100-year storm event has become a 30-year storm event.
Stroud Water Research Center Director of Information Services Charles Dow wrapped up the summit with a discussion about the methods used to analyze the avoided impacts and costs of stormwater that are realized through the preservation of open space. This analysis was used in the 2019 Return on Environment: The Economic Value of Protected Open Space in Chester County, which indicated that, among many other benefits, the protected open space in the Brandywine Creek watershed alone provides $107 million of avoided annual stormwater pollutant removal costs. View the report.