Diehl Park

It is normal for major construction to spark curiosity! The endeavor at Diehl Park has been no different – and for good reasons, this type of work has not been done anywhere locally at this scale. While the City does have some rain gardens, this is a much larger version and comes with numerous benefits.

Our main objective for this project is to reduce Combined Sewer Overflow (CSO) occurrences using a series of green infrastructure practices. This work is supported with funding from the Ohio EPA Surface Water Improvement Fund (SWIF). By removing stormwater from the combined sewer system and letting it filter naturally by percolating into the native soils, we recharge our groundwater, improve the health of our streams and rivers, and protect our drinking water supply.

Rainwater from the parking lot will flow into two designated areas where the structural plastic frames called Silva Cells form a system of suspended pavement allowing for large trees to be planted without compaction of soil around their roots. These frames create storage for soil and water beneath the pavement, allowing additional time for the tree to absorb water and also for infiltration of rainwater into the soils. From there, any excess stormwater will be conveyed through a traditional storm sewer into a Bioretention Basin. Functioning like a large-scale rain garden, the stormwater will slow down, spread out, and soak into the soils in the basin, with the assistance of native deep-rooted plants selected for their water tolerance. Any additional stormwater – typically, only during a heavy rain, will then be carried into an existing storm sewer conveying water directly into the Tiffin River.


A large oak tree can transpire 40,000
gallons of water annually. (USGS)

Diehl Park Project Fact Sheet

Preservation of Trees was another important aspect of this project. Numerous design options were considered, one that would have used a Bioswale to convey stormwater rather than the traditional storm sewer. Ultimately this green option was rejected as not feasible because it would have required the removal of several large, beautiful trees. Mature trees are the absolute best possible solution for stormwater management due to the large volumes of water they can capture, store, filter, consume, absorb, and transpire.

In addition to the demonstration of various stormwater best management practices, the “east” parking lot will be resurfaced and also increase in size. The adjacent area has also benefitted from Natureworks grant funds, used for the installation of new sidewalks and playground equipment.


Please come and see for yourself what’s going on at Diehl Park!





This project was financed in part through a grant from the Ohio Environmental Protection Agency under the provisions of the Surface Water Improvement Fund.

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