,ma QTATE LIBRARY 



M /-. 



. . . Shows the alternatives do work 



What are the alternatives to conventional 

 septic systems? 



Best bets 



— The renovation levee, or mound, system is 

 one of the most promising for very poor conditions 

 because the mound bypasses the local soil com- 

 pletely. Sand and other material are trucked to 

 the site and built into a mound. Sewage is pump- 

 ed to the top of the mound through a pipe. Treat- 

 ment takes place above ground within the mound 

 and by the time the effluent reaches the native 

 soil it is treated. 



Carlile is testing a mound in Plymouth at the 

 Tidewater Research Station and plans to test 

 another in Swan Quarter this spring. 



"We have enough data to say we can treat 

 sewage with this system," Carlile says. "Our sys- 

 tem isn't the optimum one yet; it needs improve- 

 ments. But we think we know enough to do it 

 better than it's being done (conventionally)." 



Wisconsin and Pennsylvania are also experi- 

 menting with the mound system and Pennsyl- 

 vania has actually installed about 2,000 home 

 systems while continuing research. 



> ow pressure pipe system: These one-inch perforated 

 i pipes are on a test site at Holiday Island, N.C. 



Carlile estimates the mound costs from 10 to 

 100 per cent more than a conventional system, 

 depending on shipping costs. The mound cannot 

 be used in some areas. It needs much less space 

 than a conventional septic system, but the space 

 occupied is above ground. Carlile is experimenting 

 with using a 40-foot to 50-foot long and 20-foot 

 wide mound for several, perhaps as many as 10, 

 homes. 



— The low pressure pipe system is a good pos- 

 sibility for marginal sites. It relies on native 

 soils, and is a promising option in areas where 

 local dirt is okay but the water table is high at 

 certain times of the year or there is a bed of clay. 

 Sewage effluent is distributed over a large area 

 through a network of shallow perforated pipes. 

 This system needs a pump to bring the effluent 

 from the tank to the lines. But it is still com- 

 parable in price to a conventional system. Its 

 main advantage is that effluent is not concen- 

 trated in one area as it is in a conventional septic 

 system. When a conventional system fails — even 

 temporarily — pollution occurs in one intensified 

 spot. Failure of a low pressure pipe system would 

 be much less dramatic. 



Six low pressure systems have been installed 

 and are being monitored at Holiday Island, a 

 second home development in Perquimans County. 



Other options 



— A shallow conventional system can work in 

 areas with high water tables. A shallow con- 

 ventional v-system has the added advantage of 

 v-shaped walls which give about 40 per cent more 

 surface area for absorption than the normal square 

 walls. 



Three shallow conventional systems are work- 

 ing now at Holiday Island. 



— The dual field system is another modifica- 

 tion of a conventional system. Two fields are in- 

 stalled and back each other up. If one field begins 

 to fail it can be switched off for a rest while the 

 second field takes over. And vice versa. 



(Please see "We're," page 4) 



The University of North Carolina Sea Grant 

 College Newsletter is published monthly by the 

 University of North Carolina Sea Grant College 

 Program, 1235 Burlington Laboratories, Yarbor- 

 ough Drive, North Carolina State University, 

 Raleigh, North Carolina 27607. Vol. 4, No. 2, Feb- 

 ruary, 1977. Dr. B.J. Copeland, director. Written 

 and edited by Karen Jurgensen and Johanna Seltz. 

 Second-class postage paid at Raleigh, N.C. 

 27611. 



