Three's company.

Jackson Township on Thursday became the third municipality to recommend that Butler County adopt a report detailing the Lower Connoquenessing Watershed and projects that could stem the tide of flooding.

The report, which was prepared by the Herbert, Rowland & Grubic engineering firm for 10 participating municipalities and the county, addresses whether changing release rates for future developments can mitigate historic and future impacts on flooding and suggests potential projects in 33 “problem areas” identified by the municipalities.

Adams, Cranberry, Forward, Lancaster and Penn townships as well as Evans City, Harmony, Seven Fields and Zelienople participated in the study alongside Jackson Township.

According to the HRG report, changing the release rates from new developments will not be a silver bullet to stem the tide of flooding along the Breakneck or Connoquenessing watersheds. But there's still reason to do it, the report states.“Adopting release rates will generally provide benefits to storm sewer systems and small streams as a result of reduced peak flows,” the report states.In other words, slowing how quickly stormwater enters Connoquenessing tributaries can, along with other work, slow some form of flooding.Chris Rearick, Jackson Township manager, said developers are required to hold back — using tools such as retention ponds — the difference between the amount of water flowing off a property before and after development.“Obviously, if it were open fields, it would be one release rate; if it were wetlands, it would be another,” he said.Reducing release rates as suggested by the HRG report would add another tool to the township's arsenal in battling flooding.“Additional developments, we are expecting, would hold back more water and, to an extent, reduce some existing issues,” Rearick said. “That's not to say it's going to solve all flooding.”Rearick noted that requiring reduced release rates in new construction opens the door to another tool: making suggestions to developments that have been or are being built. “It gives us the basis to work with existing (homeowners' associations) and plans, on potentially enlarging basins,” Rearick said.

In fact, enlarging basins is one of four projects recommended to the township by HRG's report. Jackson agreed to look at an additional problem area such that Harmony could study two potential projects, given the latter's smaller landmass, population and budget.Along the Tollgate School Road corridor, HRG recommends working with multiple homeowners' associations to improve, rehabilitate or even fully retrofit existing stormwater detention basins. That would occur, the report states, in the Brookview Farms, Dutch Creek, Jackson Crossings, Old Hickory Highlands and Spring Valley developments.The report estimates it could cost between “a few hundred dollars” for outlet structure modifications to upward of $100,000 per basin for a “full basin retrofit.”HRG's report also looked along the Evergreen Mill Road corridor, on German Street and along the Textor School Road corridor.With Evergreen Mill, HRG stated several properties — including manufacturing business, residences and The Grove at Harmony — are stranded because of high water during flood events. In its estimation, one potential option would be to provide access across the Little Connoquenessing Creek from Evergreen to the Seneca Valley campus; another option could be finding access through properties to Precision Drive and Meadow Brook Lane.One way to do that, HRG reported, would be to build a pedestrian bridge into the township's pedestrian trail, which the engineering firm suggested could cost $900,000 to $1.2 million, excluding property costs.

Along German Street, across Route 68 from Swampoodle, HRG suggested a low-cost project, between $25,000 and $45,000, of removing an undersized pipe obstruction between Route 68 and German Street and replacing it with a stabilized vegetation channel. HRG also stated the basin at the industrial park along Whitney Drive could be retrofitted “at a relatively low investment” to provide additional stormwater detention.Finally, HRG recommended another low-cost project along the Textor School Road corridor. The engineering firm suggested the township install “proper stormwater facilities” along the steep hill, installing roadside swales, piping and inlets to capture and convey runoff. Estimated cost is between $65,000 and $90,000.Rearick said the report's suggestions were reasonable, and noted the low costs of two or three suggested projects were exactly what the township sought.“One of the goals of the study was to find pragmatic ways to help reduce localized flooding instances within the municipalities,” Rearick said. “Fortunately, there are products per the determination of the engineers that will have a significant impact and a cost that is reachable.”