Albarrie Geocomposites Ltd. had the privilege to install our SorbWebTM Plus secondary oil containment system for TransCanada Pipelines. This is the first of many pump stations in the 12 billion dollar Keystone Project Pipeline being installed from Canada to the Gulf of Mexico. The site was located in a farmer’s field and would be isolated from urban contact so SorbWebTM Plus was therefore the best solution, as it is a maintenance free secondary oil containment system. The transformer at this site contained a considerable amount of oil at 9,570gals or 36,226 liters. The site also required drainage due to the soils being impermeable.
We start with the excavation and also build side slopes around the transformer at a 1:1 slope. This is done when the transformer pads are not as deep as the containment and we don’t want undercutting or erosion under the pad to occur.
We strap all the transformer pads with the impermeable liner by drilling through the plastic straps and hammering in a concrete anchor.
A 2”(50mm) base sand layer is placed on the floor of the containment and the drainage(wick drains) are laid out. The sand will aide in the drainage process.
The wick drains are typically arranged in central areas with equal distances from the side slopes.
Several types of connections are used with the wick drains, here we see a versatile connector that can be used as a ‘Y’ or a 90. The unused openings are taped over.
The lines are connected together and brought to an area where it exits the containment site. A minimum slope of 0.5% must be maintained for the system to properly drain.
The wick drains are then backfilled with the sand.
We excavated through the bank to an existing gravel swale where the wick drains will drain. A minimum width of 18” (0.45m) is required.
A non woven geotextile is placed in the trench to prevent backfill from migrating into the system and the wick drain is laid in.
A washed crush stone is placed over the wickdrains. A minimum depth of 12”(0.30m) of stone is required.
The entire trench is filled with the washed stone.
The non woven geotextile is then folded over and the area can be backfilled with native material.
The end portion of the wick drain is cleared of any stone that would inhibit the water flow.
Here is the completed drainage trench.
We can now start with the containment by laying down non woven geotextile on the banks.
This is followed by the impermeable liner.
The transformer pads are strapped with the impermeable liner.
Non woven geotextile is also placed on the interior slopes around the transformer pad.
The Oilmat is then glued down with 2 beads of silicone sealant.
The Oilmat edge is also silicone sealed.
The Oilmat edge is then sprinkled with loose copolymer(white powder) and is double beaded on the top side with the silicone sealant.
The top layer of impermeable liner is then folded down and glued to the Oilmat. An extra bead of silicone sealant is placed along the edge and then covered with the loose copolymer again.
Once all the Oilmat is glued in place the adsorbent layer is placed.
Here we see the interior slope of the transformer pad wrapped with the impermeable liner.
The adsorbent layer is followed by a woven geotextile fabric.
Then a 2” (50mm) layer of sand is placed.
Another woven geotextile fabric is placed over the sand layer. (picture from another site)
In the case of conduits adjacent to the transformer pads we followed these steps. Strap up tight on either side of the conduits. Fill the hole with sand just below the level of the strapping.
Fill the area with loose copolymer.
Neatly cut a piece of Oilmat to fit around the conduits
Silicone seal around the contact points with the wall, conduits, impermeable liner and the Oilmat.
Neatly cut a piece of impermeable liner to fit around the conduits and overtop of the liner that is already in place.
Finally silicone seal and tape all edges and open areas.
The containment is then filled with the designed required stone, in this case a minimum ¾” washed crush.
The containment is only filled up to a point below the strapping. We want to see if there is any pulling of the strapping off the walls. We then can do a final silicone bead along the impermeable liner attachment.
We can also seal any remaining small conduits.
The containment is then filled to the design height with the rest of the stone and leveled off. As you can see it will stand up to a considerable amount of weight.
Here is the finished completed graded site and the entire containment system is non intrusive or even visible. It will protect the environment in the event of a catastrophic transformer failure for many years with no maintenance whatsoever.
Prepared by: Michael J Dowds
Prepared by:
Michael J Dowds
of Albarrie Geocomposites Ltd.
Civil Engineering Technologist
T- (705) 737-0551
F- (705) 733-5053
www.sorbwebplus.com
www.albarrie.com
