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Mar-Jac Feedmill

Spruce Pine, Alabama

Storm Sewer


Mar-Jac Poultry Alabama LLC


CDG Engineers


W.S. Newell


Spring 2016

Technical Description:

  • Product: Smooth Cor™ double wall CSP, 12 GA polymer-coated outer shell w/ 18 GA smooth, polymer-coated liner 
  • Length: 335 LF
  • Diameter: 72-inch and 84-inch

Mar-Jac Poultry Alabama LLC planned a major expansion when it decided to build a new $35 million feedmill in Franklin County. This was initiated as a result of a recent acquisition of Birmingham-based Durbin Farms. One of their capital improvement projects was a new feedmill in Spruce Pine, Franklin County, AL which is strategically located within their Alabama footprint to provide feed efficiently to poultry growers in the region. 

The project engineer, CDG Engineers, looked at a few potential options in the site design and permitting, and what would otherwise prove to be a fairly predictable project had quite a surprising turn once the final site location was determined.

Several sites were evaluated. Those that had rail access and acreage for a 6,000+ L.F. rail loop to accommodate up to 100 rail cars were not readily available, and the Spruce Pine site had one particular challenge.  The proposed loop would need to cross Spring Cliff Branch which offered near 100’ canyon walls and some near vertical faces which constrained the site design options substantially.  Another challenge proved to be that the best feedmill location needed to be lowered approximately 30’ to match the existing Norfolk Southern rail elevation.  

The initial, and most obvious, solution was a bridge to cross the gorge. However, Mar-Jac was wary of this option.  In addition, the earthwork on this project would produce in excess of 200,000 cubic yards of soil to be removed from the mill site.  These points focused the efforts of CDG toward piping and fill for the railroad crossing of Spring Cliff Branch.  The anticipated height of cover over any piping or culvert solution would be in excess of 80', and it seemed inevitable that a cast-in-place, structurally designed culvert would be required which would substantially impact both construction time and overall cost.

Eighty feet of cover exceeded allowable limits on all design charts for typical concrete, corrugated metal, and precast concrete box culverts. The time required for design and construction of this option proved prohibitive to the overall project schedule since soil removal for the mill site needed to begin as soon as possible and that material would be needed to place over the culvert. 

Several meetings were held to determine the best solution. Based on the results of these meetings, CDG Engineers decided to include a requirement in the bid package that the selected bidder utilize the plan, profile, and hydraulic capacity provided by CDG to propose a stormwater conveyance that would meet the project requirements within a short time-frame.  

Ultimately, the bid was awarded to contractor W.S. Newell. Newell, along with the assistance of pipe manufacturer, Contech Engineered Solutions LLC. Together, the team proposed a polymer-coated Smooth Cor™ double wall corrugated steel pipe system with a specialized bedding configuration that would provide the strength and durability needed to withstand the significant loading this piping would receive. 

Smooth Cor™ is unique in that the double wall pipe consists of a standard corrugated steel pipe as its structural exterior shell and a hydraulically smooth steel liner, which provides an excellent alternative to reinforced concrete pipe in weak soils and steep slopes. The liner is continuously attached to the exterior shell along the lock seam. Both the interior liner and exterior shell are coated on both sides with polymer coating. The smooth steel liner provides enhanced hydraulics with a Manning's "n" capable of 0.012.   

Within a few weeks of selecting the Smooth Cor™ option, the crossing was cleared, and the pipe was onsite.  Construction was not delayed, and the project schedule was held intact. Chris Ross of CDG Engineers stated, "Credit is due to W.S. Newell and Contech for a timely, workable solution, as well as Spectrum Environmental for their expertise and support through the USACE permitting process.  Thanks go out to Mar-Jac Poultry for allowing CDG to play a part in this great project."

Technical Description:

  • Product: Smooth Cor™ double wall CSP, 12 GA polymer-coated outer shell w/ 18 GA smooth, polymer-coated liner 
  • Length: 335 LF
  • Diameter: 72-inch and 84-inch

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