In March 2009 we were forwarded a Request for Information from Amy Woods (SSR) from our Vaughan office. The request came from TWD Technologies an engineering firm that we had worked with previously. The project was to install a lining system within a steel containment system for the containment of ethanol. The difficulty with the project was that the 3.20 meter (10.5 foot) high walls were pan profile sheet piles. Sheet piles are typically used when space is at a premium or ground conditions prevent the use of common berm excavation techniques. The method of installing the sheet piles is to drive them in and excavate the inside out which basically leaves a steel reinforced wall system with vertical walls. This works extremely well when constructing an impoundment in constrained space areas, but the profile of the sheet piles make it impossible to install a lining system due to the irregularity of the face of the sheet piles. In the past there have been several methods which have been used to provide a smooth face on the inside of the sheet piles to enable the proper hanging and installation of a geosynthetic lining system. Some contractors have welded flat plate steel to the sheet piles, another method used was to install pressure treated plywood and infill with concrete, both methods are costly and time consuming.
The owner/engineer was also looking for a lining system which would provide the required chemical resistance to ethanol and was proposing a top mounted lining system that meets the ULC requirements for the solvent vapor permeability for ethanol and methanol products.
Layfield explored providing either a ethaform rigid sheet cut to the profile of the sheet piles or a polyurethane (rubinate)spray foam to fill the void spaces caused by the pan sheet pile profiles and to provide a firm, high compressive backing for the geomembrane. Upon review of these two options based on cost and constructability it was decided that the spray foam was the superior option. The foam requirements and specifications were discussed with Polysource Industries (manufacturer) and Canwest Coatings (applicator) to ensure they meet the requirements for adhesion to the steel, compressibility, and resistance to moisture saturation. In addition we had to incorporate a 3” 16 gauge deck profile strip located at the top of the sheet pile walls in order to have a consistent smooth face to attach the galvanized flat bar attachment sealing strip.
We also recommended Hazgard 635 geomembrane complete with LP 10 base liner cushion and protection. Due to site construction delays we were unable to start the spray foam installation until late October and the contractor was unable to sand blast the piles as specified in our quotation due to site specific safety requirements. We were concerned with the adhesion of the spray foam to the untreated sheet piles. Working with our spray on contractor and primer manufacturer we recommended and had approved an adhesive primer in lieu of the sand blasting. We began the adhesive primer installation and spray on foam installation in late October during extremely cold, snowy weather. The cold weather presented another unforeseen issue.
The spray foam expandability is severely restricted at colder temperatures and resulted in twice the amount of product and installation labor initially tendered in to this component of the project. In conversations with the engineer, client, and contractor, Layfield was able to recoup the additional costs caused by the cold weather impact on this component of the project. During the spray on component of the project we were informed that we would not be able to complete all 80 profiles of the sheet piles as the contractor had to leave a portion out for access into the containment cell. We sprayed the uninstalled sheet piles on the ground and the contractor welded them into place after their access requirement had been met and the tanks were placed. Upon the completion of the spray foam component we were able to install 95% of the containment area using Hazgard 635 and attaching to the top of the sheet pile batten strip, using ¼” x 2” galvanized flat bar punched 2” O.C., neoprene gasket, Sika Flex 1A Caulking, and attached on 12” centers with ¼” tech screws.
We returned in March 2010 to complete the lining component after the tanks were installed and the remaining sheets piles were in place.
In December 2010 Layfield was informed that an additional tank containing Hi-tech additive was being placed within the containment area. The engineers approached Layfield to assess the compatibility of the additive with the installed Hazgard 635. Due to the proprietary additive we were unable to obtain the exact composition of the additive, but were fairly confident that it contained BTX’s and could not with 100% of certainty guarantee the suitability of Hazgard 635 for secondary containment of this product. With Rohit Sati’s (Layfield’s Application Specialist) direction and assistance a chemical immersion test kit was provided to TWD and immersion tests were performed with both Hazgard 635 and Hazgard 1000 to determine suitability.
Both materials were tested just in case the Hi-Tech tank would have to be segregated from the main containment area. The materials were immersed at the Suncor Refinery and Rohit performed the thickness, tensile, and elongation tests after 4 days and 7 days of exposure. The results were surprising with the Hazgard 635 exhibiting the least amount of change after immersion when compared to the Hazgard 1000. These results (report attached) were presented to the Owner and Engineer and the Hazgard 635 was approved as an acceptable liner for both the ethanol and Hi-tech additive for secondary containment.
On this project Layfield provided several value added services which allowed the “Owner “to complete this containment project within their estimated budget and within installation time frame allowed to Layfield. The design assistance and solution provided by Layfield to address the sheet pile issues using a spray on foam as opposed to conventional methods saved costs as well as providing the owner and contractor with a lining contractor with the expertise to source out and complete this component of the work. The ability to perform the immersion test and certify the Hazgard 635 as a suitable secondary containment liner within house, saved time, and money, in addition to providing the client with confidence that the lining system will perform as designed.
The exact dollar figure of monies saved by the client is difficult to determine. We know that to face the sheet piles with steel, or plywood and infill with concrete would definitely have been more expensive and time consuming than the spray foam even when including the extra cots for the primer/adhesive and extra spray foam utilized due to the cold weather. The ability to perform in house immersion tests
to satisfy the “due diligence” requirement for the liner performance also saved the client time and money, in addition to proving that the liner meets the performance criteria for secondary containment. Layfield’s ability to address the constructability issues and provides technical, design, and installation expertise illustrates the “team work approach” to solving a clients problems. The contractor, engineering firm, and construction company are very pleased with Layfield’s performance and ultimately the final product which is providing the required secondary containment.