What will be the “permanent impacts” of open trenching? If human impacts and modifications are significant enough, they can have lasting impacts on water and biological quality. Examples are the effects on the Olentangy River of low-head dams and the construction of SR 315.

Short-term impacts are more predictable. The potentially impacted stretch of the Olentangy River is both an “Exceptional Warm-water Habitat” (the highest water and biological quality found in an Ohio stream as classified by Ohio EPA) and part of the State Scenic River portion of the river.  This part of the Olentangy is as ecologically significant as similar stretches of Darby Creek. The likely impacted portion of the river supports populations of State Special Interest Species mussels, including the Round Pigtoe and the Wavy-lined Lampshell, both of which are sensitive to increases in sedimentation and turbidity.  Portions of the river within one mile downstream of the trench site also support populations of the State Endangered Spotted Darter and the State Special Interest Species, the Bluebreast Darter. 

Open trenching involves diverting the river from the construction site, trenching through unconsolidated sediment, soil, and limestone bedrock, and installing and burying the pipeline, followed by some type of backfilling and then allowing for the return of the river. process will lead to destruction of the river channel in the immediate vicinity of the trench; dewatering of the sediments upstream and downstream of the trench; increased sedimentation and turbidity downstream of the trench (including the generation of fine angular rock fragments as sediments); destruction of the river banks by movement of heavy equipment into the stream; of diesel fuel and/or oil from equipment into stream sediments and the stream; and significant disruption of stream hydrology and in-stream habitat downstream of the trench cut due to the diversion of the river.  Aquatic biotas in the vicinity of the trench cut would certainly be extirpated and biotas upstream and downstream of the cut would also be adversely impacted.  More predictable long-term effects of open-trenching include setting a precedent for additional construction projects.

This stretch of the river is ecologically fragile and geologically unsuitable for the types of large subdivisions and commercial developments evidently planned for this part of Delaware County.  River status is given to this portion of the Olentangy because of the numerous steep shale cliffs and narrow ravines of its tributary streams.  These tributaries are typically short, with steep gradients and a rock bottom.  They do not naturally allow for much infiltration and settling of storm-water runoff following a rain. The only reason water quality has remained comparatively good in this area has been the wood lots, meadows, and pastures that make up much of the upland. conversion to subdivisions and commercial developments, these upland areas would become impermeable, allowing runoff to bring sediments and pollutants into the tributaries and the river.

Trenching of the uplands and the ravine walls to install infrastructure to support these developments will disrupt the area’s complex hydrogeology further, leading to degradation of the adjacent ravine areas.  The upshot of all of this development will be the degradation of the river from a State Scenic Exceptional Warm-water Habitat to a suburban sewer. supplies obtained from the river will require significantly more treatment prior to use as a drinking water source, leading to increased costs to ratepayers.  Sport or recreational uses of the river and the attendant tourism dollars will vanish into the muddy muck of what once was a vibrant, high-quality, flowing stream.  These changes in the river in southern Delaware County will also have serious impacts on water and biological quality farther downstream in Franklin County.

The most significant natural resource in Delaware County will be largely destroyed for a few more houses and strip malls. Residents and taxpayers are going to be left holding the bill for a depleted resource and the loss the area’s rural heritage. Open trenching in this area calls into question the ability of ODNR’s Scenic River program to protect the state’s unique natural landscapes. Several decades of work by Ohio EPA’s Division of Surface Water and volunteer watershed groups like FLOW to restore Ohio’s rivers and streams to the standards proposed by the national Clean Water Act will be lost.

Open Cut Trench Public Hearing
Thursday, Nov. 17, 6:30 PM
Olentangy High School

Ohio EPA will hold a public hearing on a request by Delaware County to open cut trench the Olentangy River and install a 42-inch sewer line. It will be in the Commons Area of Olentangy High School, 675 Lewis Center Rd.—east  of US 23, 6 miles north of I-270. We urge concerned citizens to attend.