The owner of an RV storage facility located within the popular Imperial Sand Dunes Recreation Area east of farmland in the Imperial Valley has admitted in a San Diego courthouse to dumping "potentially millions of gallons of untreated human waste and sewage" illegally on federal recreation lands.

Michael J. Mamelli Sr. obtained a permit from Imperial County and the Bureau of Land Management in the mid-2000s to open Glamis Dunes Storage, a facility allowing frequent visitors to the dunes to store their campers and off-road vehicles near camping areas.

With the permit, Mamelli was allowed to construct a 20,000 gallon holding tank, allowing RV users to dump their black (toilet) and gray (sink and shower) water tanks before storing vehicles. He then promised to haul the waste to an offsite facility for treatment and disposal.

Instead, according to a Courthouse News Service report, in 2010 Mamelli hired a contractor to build a septic leach field and install a pump to disperse the waste onsite, with the lines concealed under gravel. Installation of a septic system was specifically prohibited in the permit he had obtained, however.

Mamelli has already agreed to forfeit $50,000 and pay restitution costs for cleanup of the site to Bureau of Land Management and the Imperial County Department of Environmental Health. He faces up to three years in prison and $750,000 in additional fines at his sentencing, scheduled for February 2015.