A Goldilocks Design For Secondary Oil Containment: Walls, Floor, Drainage



transformer-oil-containment

Anyone with children is familiar with the story of “Goldilocks and The Three Bears,” in which a young girl named Goldilocks stumbles into a house owned by three bears. She brazenly attempts to make herself comfortable by sitting in their chairs, laying in their beds, and even eating their food. In her quest, she finds the first and second choices are always too much in opposite extremes, but the third is always “just right.”

 
 

While a relatively weak story line, even for a children’s tale, it is the source of the Goldilocks Principle, a concept that states that something must fall into certain margins, as opposed to reaching extremes. This principle is applied across a number of disciplines, most notably in astrobiology (for instance, the Earth is referred to as a Goldilocks Planet, because it’s neither too hot nor too cold, or too wet or too dry – it is the ideal climate to support life as we know it). However, it is also applicable in developmental psychology, biology, economics and engineering.

With so many options to choose from for your transformer containment in the marketplace today, it can be a challenge to decide which solution is the best fit to protect your electrical substations and transformers. Though there are a number of variables that can affect your decision, discovering the solution that is “just right” is simpler than you’d expect, as long as it provides walls, a floor, and drainage for rainwater.

The main purpose of a substation is to step-up or step-down power so it can be consumed as part of the electrical generation, transmission and distribution system. Most substations include transformers to change the voltage levels between high transmission voltages and low distribution voltages. They are designed and built based on reliability and cost, in which the engineering team is focused more often on functionality than aesthetics. It is also the responsibility of the utility companies to protect the environment and the public from a potential oil spill. Facilities that have an aboveground oil storage capacity of 1,320 gallons or more, such as large electrical transformers that utilize oil for cooling, are subject to SPCC regulations (40 CFR Part 112), meaning they require transformer containment.

Fiberglass Walls by Strongwell® Coporation for transformer containment
Fiberglass Walls by Strongwell® Coporation

When challenged to create a transformer containment system that offers both aesthetic appeal as well as durability and efficiency, we partnered with Strongwell® Corporation to develop a Goldilocks solution that provides walls, floor and drainage that are all “just right.” Strongwell’s COMPOSOLITE® fiberglass walls offer a sleek and affordable alternative to concrete. Strong and corrosion-resistant, they are easily installed and require little on-going maintenance. Standard COMPOSOLITE® panels are manufactured using a fire retardant polyester resin system in a slate gray color.

Transformer Containment In Place
Transformer Containment In Place

Combined with a C.I.Agent® Geomembrane Liner floor, which simultaneously serves as a lining and transformer containment solution for non-impervious soils, the chance of oil escaping the containment structure decreases dramatically. The liner should be covered with at least six inches of cleaned washed stone, to protect the liner from UV rays and punctures when walking over the area. The stone provides some fire protection as well.

Transformer Containment Drawing with Separate Vault Housing C.I.Agent HFF Oil Stop Valve
Transformer Containment Drawing with Separate Vault Housing C.I.Agent HFF Oil Stop Valve

Finally, for the system to function effectively, there must be a method to evacuate water from the transformer containment area. A drain should be installed in the lowest point of the containment area, to pipe rain and storm water to a vault approximately three to four feet outside of the walls. The vault houses a C.I.Agent® HFF Oil Stop Valve, which filters and processes waste water at a steady flow rate, and in the event of a significant oil discharge, will automatically shut off flow.

Secondary Containment with C.I.Agent® HFF Oil Stop Valve
Secondary Containment with C.I.Agent® HFF Oil Stop Valve

As you can see, this system is just right for utilities. Not only does it put them in compliance with EPA’s Spill Prevention Control and Countermeasure Rule 112.7 and meets IEEE 980 Standards, they also reap the benefits of a low-cost, highly-effective, redundant system that provides both containment and drainage capabilities. Another bonus: Companies get to utilize the vast knowledge, extensive experience, and quality products of C.I.Agent Solutions® and Strongwell®.

 

 

Installation Steps for the Strongwell® / C.I.Agent Solutions® “Goldilocks” Secondary Containment System

Note: Substation must be excavated prior to installation of transformer containment system



Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Step 7
Step 8

1. Install Strongwell® COMPOSOLITE® walls around the transformer containment area. Each containment system is shipped as a kit, which includes the following materials:

Fiberglass walls Containment System
Fiberglass walls Containment System
  • COMPOSOLITE® panels – maximum length 24′; weight approximately 7.5 lbs/ft
  • Square tubes for post with pre-drilled holes
  • Splice plates with pre-drilled holes (if required)
  • Corner angles with pre-drilled holes
  • 316 stainless steel bolts
  • Cap channel with nylon rivets – furnished in 20′ lengths for field cutting
  • Drill bits for bolts and rivets
  • Tubes of Pilogrip® adhesive
  • Adhesive applicator
  • Flat strips and self-tapping screws for liner (if required)

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2. Once the walls are installed for your transformer containment, lay 2 to 6 inches of pea gravel as a base for the C.I.Agent Geomembrane Liner to lay over.

Transformer Containment Filled in with Pea Gravel
Transformer Containment Filled in with Pea Gravel

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3. Lay the Geomembrane Liner over the gravel and attach to the walls via aluminum flat bars (similar to how the polyvinyl liners are attached to concrete pads or piers)

Left Image: Geotextile fabric for extra protectionRight Image: Transformer Containment with added protection of Fiberglass Walls
Left Image: Geotextile fabric for extra protection
Right Image: Transformer Containment with added protection of Fiberglass Walls

Note: Multiple options available for types of geomembrane liners available, including polyvinyl liners – contact C.I.Agent Solutions for details

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4. Install a drain in the liner floor at the lowest point of elevation within the containment area. Install a pipe to drain water outflow to a concrete vault positioned 3 to 4 feet outside of the transformer containment area, through an outlet in the wall. The pipe needs to allow for one foot of head pressure.

Left: Drain for transformer containment leading to vault with C.I.Agent® HFF Oil Stop valveRight: Transformer containment with walls, floor and drainage for rainwater
Left: Drain for transformer containment leading to vault with C.I.Agent® HFF Oil Stop valve
Right: Transformer containment with walls, floor and drainage for rainwater

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5. Install a vault in the ground approximately 3 to 4 feet outside of the transformer containment area.

Transformer containment vault for C.I.Agent® HFF Oil Stop Valve
Transformer containment vault for C.I.Agent® HFF Oil Stop Valve

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6. Install a C.I.Agent HFF Oil Stop Valve within the vault at an elevation lower than the drain (preferably by at least 1 foot) to provide head pressure necessary for steady flow rates. A pre-filter must be added at the floor drain and on the HFF unit.

For unexpected hydrocarbon release, C.I.Agent® HFF Oil Stop Valve in vault.
For unexpected hydrocarbon release, C.I.Agent® HFF Oil Stop Valve in vault.

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7. Cover liner floor with at least 6 inches of clean, washed stone free of fines for added fire protection. Additional stone will also help slow the flow of water during historical rain events.

Transformer Containment for Secondary containment with C.I.Agent® HFF Oil Stop Valve
Transformer Containment for Secondary containment with C.I.Agent® HFF Oil Stop Valve

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8. Cover vault with grate or other cover (such as Strongwell’s UTILICOVER trench cover system)

Protected C.I.Agent® HFF Oil Stop Valve
Protected C.I.Agent® HFF Oil Stop Valve

Note: If not covered completely from exposure to sunlight, it is recommended to place ADS Pipe around HFF filter to protect it from damaging UV rays

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Related Links:

T&D article on AEP using Strongwell for Secondary Containment

COMPOSOLITE Flyer

Strongwell Containment Systems

 

 

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