Albarrie Geocomposites Ltd. had the privilege to install our SorbWebTM Plus secondary oil containment system for PECO – (Philadelphia Electric Company).This site was a new substation that included three 500 – 230 Kv transformers plus one spare. They each contained 16,700 gals of oil and they were all individually surrounded by concrete walls that would eventually tower 34’ in the air.
Center Point Substation - Lansdale, Pennsylvania
Center Point Substation - Lansdale, Pennsylvania
This is the spare transformer that didn’t have any containment walls and therefore was not ready for our installation yet.
Here the grounding grid is being installed before the SorbWeb system is installed.
The base 2” layer of sand is placed over the grounding grid. As you can see the front wall was not installed for ease of entering all 3 containments. The plan was to install the SorbWeb system up as close to the proposed wall then build the wall and return to tie everything together.
We started with the installation of the impermeable liner along the perimeter walls.
Next came strapping the impermeable liner to the transformer pad.
All grounding wires were secured to the pads with brackets which will prevent any movement that would disturb or damage the impermeable liner.
The strapping is anchored to the pad as close to the grounding wire as possible.
The first piece of Oilmat is lifted into place and rolled out.
The Oilmat is rolled back one edge at a time and the impermeable liner is swept.
The impermeable liner is prepared with 2 silicone beads.
A bead of silicone is placed along the edge of the Oilmat and the impermeable liner and blended to form a good seal. Then 2 more beads are placed on top of the Oilmat.
The impermeable liner is folded down and laid on top of the silicone beads then a final bead of silicone is run down the edge with the Oilmat. The Oilmat is now completed in this area.
We sprinkle loose copolymer along the edge as an added protection.
When we have 2 layers of Oilmat coming together we make sure we have at least an overlap of 6” and glue it together with the standard 2 silicone beads as well as the bead along the edge and finally the loose copolymer sprinkled over the joint.
In front of all 3 transformers were 3 – 5” conduits.The procedure for sealing them are as follows: 1) Sprinkle loose copolymer on the ground around the conduits.
2) Neatly cut and fit the Oilmat around the conduits. You must be patient and take your time. Glue the Oilmat to the impermeable liner in behind the conduit.
3) Silicone all joints and areas around the conduits.
4) Place 2 beads of silicone on the Oilmat along the back of the conduits and then fold the upper layer of impermeable liner down and finish with the final bead along the edge.
5) Then, do it all over again with a scrap piece of Oilmat. Neatly cut and fit this time with the open cuts facing out. Glue the Oilmat down to the other Oilmat.
6) Silicone all joints and areas around the conduits.
7) Sprinkle loose copolymer over the entire area.
We can now go ahead with the rest of the SorbWebTM Plus System starting with the adsorbent layer.
The woven geotextile is laid out over the adsorbent layer with shovels full of sand to hold it in place.
The 2” sand layer is placed over the woven geotextile.
Another layer of woven geotextile then covers the layer of sand. This process was repeated until all 3 containments were at this stage. Unfortunately the fire quenching stone was not available to be placed at this time.
Typically when applying the final bead along the concrete walls and transformer pads we like to wait until the stone is placed at least a certain amount up the wall to ensure there is no pulling or separation of the strapping. But in this case the height was only 16” and we had lots of slack in the impermeable liner. Nonetheless the foreman was advised to keep watch as the stone was placed.
Here we have how the grounding wires look when completed and all sealed.
And here is a single conduit that was easily sealed with silicone because we get the strapping in tight behind the conduit.
This ends this portion of the installment, I will be requested to return in the future to tie the open ends together and complete the spare transformer containment .
Stay tuned…..
Prepared by: Michael J Dowds
Albarrie Geocomposites Ltd.
Civil Engineering Technologist
