The Snyder Industries 4000 Gallon ASTM Black Double Wall Tank (SKU 5610000N49) is a self-contained secondary-containment vessel: a 4000-gallon primary tank nested inside an integral outer wall, so a leak in the primary is caught by the outer shell without a separate dike or berm. It stands 178 inches tall on a 102 x 102 inch square footprint and is molded from high density linear polyethylene rated to 1.5 specific gravity. The black resin blocks UV and light, which discourages algae growth in stored water and holds up outdoors year after year.
Will this double wall tank work for your site?
At full water the primary holds roughly 33,360 pounds of contents, and the 1.5 specific gravity rating carries the tank up to about 50,040 pounds of rated contents. Plan your pad around that: the 102 x 102 inch footprint concentrates the load, so a level, engineered slab sized for the loaded weight is not optional. This is a tall, narrow tank — 178 inches of height on a 102-inch square base — so factor in anchoring for wind and seismic exposure at open sites. The tank is fitted per the technical drawing on this page with a flange, an 18-inch PE threaded and vented fitting, and a manway with 15-inch access for entry, cleaning, and inspection of both the primary and the interstitial space. Confirm the fitting locations against the drawing before you plumb, and match each flange and threaded connection with the correct gasket or EPDM seal rated for your stored liquid — the sealing element, not just the fitting, is what keeps a bulkhead connection tight over time. If you are still deciding on capacity, our Tank Sizing Calculator and Tank Sizing Guide help you match usable volume to demand.
Freeboard and the volume you can actually use
Double wall polyethylene tanks are sized under ASTM D1998, and the rated 4000 gallons assumes proper freeboard above the working liquid level. Thermal expansion, contents density, and the vapor-saturated headspace all affect how much of that nominal volume is truly usable and where the wall works hardest over time. Two guides go deep on this exact class of tank: Snyder Captor double-wall freeboard sizing per ASTM D1998 and HDPE wall thickness at the vapor-saturated headspace. For rural fire-water and reservoir duty, the fire-water reservoir design guide covers NFPA 22 sizing and freeze protection.
The mistake to avoid
The interstitial space between the primary and the polyethylene outer wall is the whole point of this design, so keep it clear. Do not drill through the outer wall for a convenient fitting, and do not let the annular space fill with rainwater or debris, which defeats leak detection and adds unaccounted load. Use only the molded-in fittings shown on the drawing, and inspect the interstitial space through the 15-inch manway access on a regular schedule.
This 4000-gallon Snyder double wall black tank ships LTL freight from the Snyder plant in Lincoln, NE, quoted live to your ZIP; Snyder also molds this line in West Virginia, so we confirm the final shipping origin at order. Get a freight quote to your ZIP in seconds with our Freight Cost Estimator, or call 866-418-1777 to talk through fittings, footprint, and scheduling. Listed before freight.
