Double Wall

Underground Double Wall Wanks

FRP/Mocoat is a leading manufacturer of double wall tanks – both above ground and below ground throughout North America. Our projects start with proper engineering design in conjunction with customer specific requirements. An in-house autocad drawing will be generated for approval and involves a sign off from a professional engineer registered in the province or state that the tank will be put into service.

The interstitial space is composed of a 3D fabric providing for continuous monitoring of the interstitial space while also providing continual laminating support to maximize strength. Each primary tank is tested and the interstitial space is also tested using either a pressure or a vacuum test.

Benefits include:

  • Secondary Containment -The outer wall captures leaks from the inner tank, helping prevent spills from reaching the environment.
  • Leak Detection – The space between the two walls can be monitored for leaks, allowing problems to be identified before product escapes.
  • Environmental Protection – Reduces the risk of soil and groundwater contamination, which is especially important for underground installations.
  • Regulatory Compliance – Helps meet many environmental and storage regulations that require secondary containment or leak monitoring.
  • Corrosion Resistance – FRP is highly resistant to corrosion from moisture, soil conditions, and many chemicals, unlike unprotected steel.
  • Long Service Life – Properly manufactured and installed FRP tanks can provide decades of reliable service with minimal corrosion-related maintenance.
  • Lower Maintenance Costs – Corrosion resistance and integrated leak monitoring can reduce inspection, repair, and replacement costs over time.
  • Chemical Compatibility – FRP can be engineered with different resin systems to suit a wide range of chemicals and petroleum products.
  • Lightweight Construction – FRP tanks are lighter than comparable steel tanks, making transportation and installation easier.

 

Click on the link below to watch a video on our double-wall tanks!

Videos – FRP Mocoat Fiberglass Ltd. (frpmfg.com)

Frequently Asked Questions

Are FRP septic tanks approved for use in Washington State?
Yes. Every FRP septic tank we manufacture meets or exceeds CSA Standard B66, a key compliance benchmark for wastewater containment. These tanks are suitable for use across Washington in residential, industrial, and remote applications, where code-compliant, environmentally safe septic solutions are required.
We offer a variety of sizes to accommodate different needs – from small-capacity tanks for cabins and tiny homes, to larger systems for full-time residences, work camps, and commercial setups. Our team can help you select the right size based on your expected usage and site conditions.
With proper installation and maintenance, fiberglass septic tanks can last 40 years or more. Their corrosion resistance and seamless construction help prevent leaks and structural failures, even when buried underground for decades. That’s why many Washington property owners choose fiberglass over concrete or steel.
Washington’s coastal zones, like those around Seattle or Bellingham, deal with high groundwater and fluctuating soil conditions. Fiberglass septic tanks are non-corrosive and watertight, making them a great fit for these environments. Their lightweight nature also allows for easier placement without the need for heavy equipment, even in challenging terrain.

Related Products