The Snyder Industries 3500 Gallon ASTM XLPE Captor Double Wall Tank is a containment vessel built for sites that cannot afford a release. The inner primary tank and the outer secondary shell give you secondary containment in one molded unit, so a primary failure stays inside the outer wall instead of on the ground. Molded in Natural White crosslinked linear polyethylene (XLPE) with a 1.5 specific-gravity rating, this Captor double wall tank holds 3,500 gallons. The 1.5 SG rating is the highest standard XLPE rating, so it covers heavier-than-water chemistries that a 1.0 SG water tank cannot carry.
Will it work for your site?
The tank stands 158 inches tall on a 102 x 102 inch footprint, so confirm your pad and your door or roof clearance before you order a vessel this tall. Filled with water at 1.0 SG the contents weigh 29,190 lb; at the full 1.5 SG rating the contents can reach 43,785 lb, so the pad and foundation under it have to carry that load. With a 102 x 102 inch footprint (about 72 square feet), a full 1.5 SG load works out to roughly 600 lb per square foot of average bearing pressure, so check that against your pad rating before delivery. The molded-in fittings on this unit are a flange, an 18-inch PE threaded/vented fitting, and a manway with 15-inch access. The 18-inch threaded/vented fitting handles fill and venting, and the manway with 15-inch access lets you get inside for inspection and cleaning. See the technical drawing on this page for the exact fitting locations, orientations, and thread/port dimensions, and confirm them against your piping plan before you set the tank. Use the Tank Sizing Calculator and the Tank Sizing Guide to match this 3,500-gallon capacity to your actual draw and required freeboard.
Sizing the freeboard, not just the gallons
A double wall containment tank is not a vessel you fill to the brim. ASTM D1998 and the chemistry of your contents drive how much usable volume you actually have once you account for thermal expansion and density, and the Captor secondary wall changes how you think about overfill. Two guides walk through this for exactly this tank: Snyder Captor double-wall freeboard sizing per ASTM D1998 and, if this XLPE double wall tank is going into an oil or chemical storage role, the Captor SPCC 40 CFR 112 compliance walkthrough. If the tank is part of a private fire-protection or fire-water reservoir setup, the NFPA 22 fire-water reservoir design guide covers sizing discipline and cold-climate freeze protection.
The mistake to avoid
The most common error on a vessel like this is treating the 1.5 SG rating as the only number that matters and ignoring the headspace. Premature failures on polyethylene tanks often start at the vapor-saturated headspace rather than the wetted lower wall, which is why a liquid-side-only inspection can miss them; the HDPE wall-thickness at the vapor-saturated headspace guide explains why and how the ASTM D1998 sizing logic protects against it. Use the manway with 15-inch access to inspect the upper interior, not just the bottom. One more practical point: field piping to the 18-inch threaded port and any bulkhead penetrations should use gaskets and fittings rated to your contents and matched to the molded port size, so pull the exact thread and port dimensions off the drawing before you order hardware.
This XLPE double wall tank ships LTL freight from Snyder's Lincoln, NE plant, quoted live to your ZIP. Get an exact number with our Freight Cost Estimator, or call 866-418-1777 and we will quote it for you. Listed at list price before freight, with freight quoted separately to your delivery ZIP.
