Continental Lime Ltd. Storm Water Runoff Collection Pond Project
Geosynthetics used in a Water Containment Application
Continental Lime Ltd, a company that produces a diverse range of lime and calcium based products was required by the Alberta Environmental Protection Agency (AEP) to provide a storm water runoff pond for their Exshaw, Alberta plant facility. The AEP regulations require proper collection and containment of all storm water runoff over disturbed soils on their plant site. This project review focuses on how geosynthetic materials can effectively and economically enhance the construction and completion of this storm runoff pond, as well as comply with the Alberta Environmental Protection regulations.
The project site is located at the Continental Lime Ltd. Exshaw, Alberta plant facility approximately 90 kilometers west of Calgary, Alberta. Throughout the spring and summer of 1999 Continental Lime and Layfield Plastics worked together adapting and revising the pond design, as well as, providing suitable geomembrane pond liner material options. Layfield Plastics’ extensive technical expertise and industry leading installation experience with geosynthetic lining materials contributed to the pond design adopted by Continental lime for this project.
In October of 1999 Continental Lime provided final detailed pond design drawings and project requirements to Layfield Plastics. (See Figures P1-P3). Specific site conditions created a number of factors that had to be addressed in providing the most effective geomembrane liner material to line this particular pond. One factor was that the storm water runoff pond area was to be constructed on an old, onsite soils landfill area and there was concern regarding potential differential sub grade soils settlement. Another factor to be considered was the late in the year construction start up for this project. The potential onset of winter weather conditions would be an influential factor in choosing the appropriate geosynthetic material to complete this job.
Layfield Plastics was awarded the contract to supply and install the geomembrane liner materials for this storm water runoff pond. After considering a number of geomembrane lining options, Continental Lime selected Layfield Plastics’ Polyvinyl Chloride (PVC ) 40 mil material to line this pond. PVC liner is a pliable, extremely flexible material to line that can be shop welded or fabricated into large custom sized panels, which may be folded, rolled and packaged for shipment to site. These custom panels may then be quickly unfolded and deployed on site. Shop fabricated liner panels are easily welded under ideal conditions and can drastically minimize the amount of field welding required on site.
Based on the provided pond dimensions, Layfield Plastics was able to provide a customized geomembrane panel layout (See figure P4) best suited to line the required surface area of the pond. Layfield was able to effectively line the pond using only four (4) custom sized fabricated PVC 40 mil panels, panel size as follows:
PVC 40 mil Panel Dimensions:
4 Panels total
2 Panels – 181 feet by 76.1 feet
2 Panels – 181 feet by 83 feet
All Layfield Plastic shop fabricated liner panels are subject to intensive quality control shop testing for welded seams. Every fabricated panel is tested at a frequency of a destructive test every 1000 lineal feet or every fifth welded seam to ensure the highest integrity. All shop test results are documented and provided to the client for their records.
Continental Lime required completion of this project prior to the end of 1999. Due to the late construction start only a limited amount of time was available to complete the project prior to the onset of winter. The ability to fabricate large custom sized, flexible PVC 40 mil panels in Layfields controlled shop environment allowed for a reduced amount of field welding on site. In turn this allowed for a shorter construction time required to complete the project. The PVC 40 mil panels were shipped to site to await a suitable fair weather installation time period to occur.
Another advantage of the fabricated PVC liner material is PVC’s inherent high elongation properties (greater that 350% elongation at break). This high elongation enable PVC to adapt and conform to rough sub grades better than most other geomembrane liner materials. Variations in sub grade soil characteristics may lead to differing levels of soil compaction, subsequently increasing the potential for differential settlement in the constructed pond area. The flexibility of the PVC liner material enhances its ability to conform to these possible localized settlements in the sub grade soils. This project required a soil backfill overtop of the PVC liner. The soil backfill material available contained significant quantities of large, angular gravel components that could potentially damage the liner during installation and ongoing pond operations. Layfield Plastics provided a layer of Non-Woven Geotextile material (LP8) to act as a cushioning overlay, protecting the liner form any damage due to the placement of these poor backfill soils.
The storm water runoff pond project for Continental Lime was a time sensitive project. Layfield Plastics’ ability to fabricate large, custom PVC 40 mil panels and vast installation experience allowed this project to be completed on schedule, prior to the onset of winter weather conditions. The use of PVC 40 mil geomembrane liner materials to line this pond was a cost effective, efficient solution to the specific site and design requirements. The Continental Lime storm water runoff pond project is another successful example of Layfield Plastics industry leading ability to provide geosynthetic solutions for a diverse range of liquid containment applications.
*Thanks to Eric Roy from Continental Lime Ltd. for his assistance with this project review.