Haney Road Stream Crossing Replacement-2018
Haney Road in Hamilton Township had been closed for several years due to collapsing pipes at a stream crossing just north of Hamilton Square. The township was concerned about endangered turtles in the vicinity of the project as well as the obvious costs associated with the replacement structure.
The existing condition was two 36” corrugated metal pipes, both super elevated above the stream bottom at the upstream and downstream ends. The upstream pipe entrances had no headwall excepting a few strategically placed rocks. The downstream pipe exits had a retaining wall above the pipes fabricated from some old sections of guiderail. The drop off at the downstream end was just over 1 foot, severely limiting aquatic organism passage (AOP). Road over topping during larger storm events was uncommon; however a significant backwater condition existed onto the southerly upstream property before the road would overtop. In addition to limiting AOP, the water opening was significantly undersized.
Funding was approved by the MCCD Board in 2017 through the Low Volume Road Program. The township engineer, R.K.R. Hess, proposed an 11’ 11” x 3’ 7” aluminum box arch to replace the twin pipes. The elevations of the flat bottomed structure would be depressed below the existing stream bed, matching the stream slope, as required by the DEP permit. A qualified wetland biologist determined there were no endangered species present and the permit was secured. The District requested the assistance of a Trout Unlimited stream restoration specialist to determine the stream restoration specifics through the crossing.
Original Grant Request- $ 133,000
Amendments- $ 12,684
Total Program Funds- $ 145,684
In-kind Funds from Township- $ 91,513
Total Project Costs- $ 237,197
The successful contract bidder was E.F. Possinger and Sons of Stroudsburg. Kyle Possinger was the superintendent for the site work. Dan Lee was the project manager. Work started in late August of 2018, and was substantially completed in October of the same year. Geotechnical testing revealed existing soils needed reinforcement for the proposed culvert placement. The site was over-excavated and geotextile and 2A stone was added to the base. The over-excavated streambed material was saved for later use in rebuilding the streambed through the crossing structure and upstream and downstream restoration.
The structure was assembled in three days and set in place as one unit. End plates extending beneath the structure headwalls had to be infilled with flow-able concrete to seal the voids and anchor the structure. Backfilling and reconstruction of the stream channel could then be conducted. The work within the structure had to be carried out by hand. The clay material was difficult to work with using rakes and shovels. It was a back breaking day for the crew.
Log and cobble grade controls were installed to mimic the pool and riffle pattern of the existing downstream flow regime. This allows for bed stability, transport of sediment through the crossing without scouring, and AOP. By mimicking the streams natural shape and flow pattern through the road crossing, maintenance costs are reduced due to the elimination of gravel bars and aggradation wedges which frequently occur when undersized structures are in place. Additionally, the resulting downstream scour holes and bank erosion from accelerated velocities are eliminated as the transported sediment and cobble will continue to move through the structure and maintain the natural transport of material downstream.
The existing condition was two 36” corrugated metal pipes, both super elevated above the stream bottom at the upstream and downstream ends. The upstream pipe entrances had no headwall excepting a few strategically placed rocks. The downstream pipe exits had a retaining wall above the pipes fabricated from some old sections of guiderail. The drop off at the downstream end was just over 1 foot, severely limiting aquatic organism passage (AOP). Road over topping during larger storm events was uncommon; however a significant backwater condition existed onto the southerly upstream property before the road would overtop. In addition to limiting AOP, the water opening was significantly undersized.
Funding was approved by the MCCD Board in 2017 through the Low Volume Road Program. The township engineer, R.K.R. Hess, proposed an 11’ 11” x 3’ 7” aluminum box arch to replace the twin pipes. The elevations of the flat bottomed structure would be depressed below the existing stream bed, matching the stream slope, as required by the DEP permit. A qualified wetland biologist determined there were no endangered species present and the permit was secured. The District requested the assistance of a Trout Unlimited stream restoration specialist to determine the stream restoration specifics through the crossing.
Original Grant Request- $ 133,000
Amendments- $ 12,684
Total Program Funds- $ 145,684
In-kind Funds from Township- $ 91,513
Total Project Costs- $ 237,197
The successful contract bidder was E.F. Possinger and Sons of Stroudsburg. Kyle Possinger was the superintendent for the site work. Dan Lee was the project manager. Work started in late August of 2018, and was substantially completed in October of the same year. Geotechnical testing revealed existing soils needed reinforcement for the proposed culvert placement. The site was over-excavated and geotextile and 2A stone was added to the base. The over-excavated streambed material was saved for later use in rebuilding the streambed through the crossing structure and upstream and downstream restoration.
The structure was assembled in three days and set in place as one unit. End plates extending beneath the structure headwalls had to be infilled with flow-able concrete to seal the voids and anchor the structure. Backfilling and reconstruction of the stream channel could then be conducted. The work within the structure had to be carried out by hand. The clay material was difficult to work with using rakes and shovels. It was a back breaking day for the crew.
Log and cobble grade controls were installed to mimic the pool and riffle pattern of the existing downstream flow regime. This allows for bed stability, transport of sediment through the crossing without scouring, and AOP. By mimicking the streams natural shape and flow pattern through the road crossing, maintenance costs are reduced due to the elimination of gravel bars and aggradation wedges which frequently occur when undersized structures are in place. Additionally, the resulting downstream scour holes and bank erosion from accelerated velocities are eliminated as the transported sediment and cobble will continue to move through the structure and maintain the natural transport of material downstream.
Before-Upstream End- only the left pipe carried flow during low-flow conditions.
After- Upstream End-flow is centered in the structure, with banks through the entire reach.
Demolition Phase- a better look at the old downstream pipe condition-guide rails removed.
Stone bed placed for structure placement with wing wall excavation-stream pumped around.
End plate cutoff wall prior to backfill.
Looking through the structure following stream reconstruction through the road crossing.
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Before-Downstream End- drop off at pipe outlets.
After-Downstream End- cobble grade control at the outlet again centering stream flow.
During Excavation for the new box arch culvert-material salvaged for stream bed construction.
Structure placed and being backfilled.
Upstream end after stream reconstruction.
Downstream end at high flow event December 2018
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