Patent ID: 8070005

Claim:
A molded plastic tank for receiving and treating wastewater, having a generally oblong body comprised of a plastic wall and opposing end caps spaced apart along the tank length, the body having a generally rectangular or circular cross section; the tank having at least two spaced apart access ports at the top of the tank, disposed on either side of the midpoint of tank length, for providing access to the interior of the tank during use; the body wall having a plurality of corrugations running transverse to the tank length on the sides of the tank and on at least a portion of the top of the tank; said wall at the top of the tank shaped as a molded-in beam structure comprised of (a) at least one peak corrugation running lengthwise along the tank top from proximity of one access port to proximity of the other access port and (b) a lengthwise valley corrugation on each side of said at least one lengthwise peak corrugation, to space apart the lengthwise corrugation from the ends of at least some of said transverse corrugations at the top of the tank.