Engineer: Chris Sharp, – Urban Engineering
Geotechnical Engineer: Mathew Alt – Sheild Engineering
We had two real hurdles to jump with this project. The first hurdle was the budget. As with any project, the budget was becoming a real concern for the church. The engineer had originally designed two 6′ x 8′ reinforced box culverts to carry the water from the creek under the two different entrances of the church. To construct the box culverts, the contractor was going to have to create a temporary diversion channel to allow the normal flow of the creek to be re-routed around construction in the creek bottom. The diversion channel, along with the cost of materials of the box culverts, were going to cause the box culverts to be very time consuming and expensive to construct.
The second hurdle was environmental. Since the box culverts are being constructed in the stream, the natural bottom and the sides of the creek were going to be destroyed. Due to the construction in the stream, the owner and engineer were required to get another permit from TDEC.
After a few meetings, Chris Sharp (engineer) and I came up with an alternate design to clear the hurdles of cost and environmental. We worked together to agree to build a Multi-Plate Arch over the creek. The single span Arch handles as much flow as two 6′ x 8′ box culverts and eliminates the concern of debris clogging the upstream entrance of the culvert. The Arch design also has a beveled end to match the slope coming off the roadway, so the massive head walls and wing walls of the concrete structure were eliminated. The Arch sits on footers outside the top of bank of the creek and span the entire creek. This allows the Arch to keep the natural bottom and sides of the creek and eliminated the need for an extra TDEC ARAP permit.
Once we decided on the structure, the contractor built footers and Superior Drainage Products supplied and assembled the Multi-Plate Arch in the field. The contractor then backfilled the structure and the roadway is now taking shape.
Below are pictures of the structure being assembled and backfill being placed over top of the structure: