Reconstruction of Veterans Lane and

its Impact on the Floodplain

By: Mark Mayhew, PE1

1. Development – Overview2. Cooks Runs – Veterans Lane3. Raising Roadway – Modeling4. Flood Storage

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1. Development – Overview• 19.2 acre abandoned manufacturing site SFH to north,

apartments to east, shopping & multi-story age- restricted housing to south.

• GPH proposed 117 unit neo-traditional housing with 73,000 sf office/commercial

• One detention basin proposed within commercial section

• Site traversed by twin 24” gas mains.• Cooks Run flows east to west along southern property

line.

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Cooks Run

• The Site was traversed by approximately 800 lf of Cooks Run, a tributary to the Neshaminy Creek.

• It was also transected by two Texas Eastern gas pipelines and existing water and sanitary lines.

• The floodplain of Cooks Run had been significantly impacted by prior site development over the past years.

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FEMA Flood Insurance Rate Map

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• Veterans Lane runs along the banks of Cooks Run with only 20 to 40 feet separating the streamand the roadway curb line.

• The roadway flooded frequently, as much as 1’during the 2-yr storm and over 3’ during the 100-yr storm.

Veterans Lane

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Cooks Run Pre-Construction

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Cooks Run Pre-Construction

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Cooks Run Pre-Construction

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Existing Culvert

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• Granor Price Homes’ Lantern Hill development wasconditioned upon GPH reconstructing and raising a portion of Veterans Lane.

• Raising the roadway would add fill to the floodplain, potentially impacting adjoining properties.

• GPH, TWT, the Borough and adjacent property owners joined together to actually lower upstream flood elevations.

Lantern Hill, Doylestown, PA

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3. Model Roadway

• Analysis of existing relief(area was not over roadway)

• Analysis of proposed roadway(develop stage – discharge)

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Stormwater Calculations

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Veterans Lane Plan View

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Veteran’s Lane Profile

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Floodplain Delineation Plan

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Cooks Run - Construction

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Cooks Run - Construction

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Cooks Run - Construction

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Post-Construction• The roadway was raised approximately 3 feet.• The far bank was excavated to recreate a wetland

flood-fringe.• Five, 24” RCP cross drains were installed under the

raised roadway to allow the floodwaters to move under the roadway.

• The water would eventually drain back into the streamwhen the floodwaters receded.

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Cross drains during construction

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4 Flood Storage Plan

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4 Flood Storage Plan (cont.)

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Cooks Run – Wetland Area

Post- Construction

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Cooks Run – Wetland Area

Post- Construction

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Construction of the wood bridge over Cooks Run

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Detention Basin at Lantern Hill

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