"People now are more aware of the 

 restraints on where they can build," 

 adds O'Neal. "They don't just go out 

 and buy a piece of land and then worry 

 about getting a permit for a septic 

 tank." 



Throughout North Carolina the 

 news of Carlile's work is spreading fast. 

 In the last three years more than 100 

 low pressure distribution and 10 

 mound systems have been installed un- 

 der his supervision in 11 coastal coun- 

 ties. Dozens more have been installed 

 by contractors and individual home- 

 owners who have found out about the 

 systems at workshops led by Carlile. 



"We've been able to use so-called 

 marginal lands that otherwise we'd 

 have no choice but to turn down," ob- 

 serves Craven County Sanitarian Al 

 Harris. "The alternative systems 

 allow us to have economic growth and 

 yet we're still protecting the environ- 

 ment." 



The density threat 



In recent months Carlile has focused 

 his attention on the southern section of 

 the coast where dense populations pose 

 the most serious problem. 



"We're projected to be a major 

 growth area in North Carolina," ex- 

 plains New Hanover County 

 Sanitarian Frank Olive. "More growth 

 means more homes and more homes 

 mean more septic tanks and increased 

 potential for pollution. You get the 

 domino effect." 



Although the city of Wilmington has 

 a centralized sewage system, outlying 

 unincorporated areas in New Hanover 

 and Brunswick Counties currently rely 

 on on-site disposal methods. As in 

 many coastal areas, sites suitable for 

 conventional septic systems are few 

 and far between. 



"Most of our lots are requiring some 

 sort of modification," says Olive. 

 Typically this involves such remedial 

 measures as drainage, back filling and 

 modified trenching. But on some sites 

 this isn't enough. It is in these areas 

 that Olive thinks Carlile's work could 

 have the greatest impact. 



So far two low pressure and one 

 mound system have been installed in 

 the county. While it is still too early to 

 tell if the systems will work there, 

 Carlile, Olive and many local contrac- 

 tors and developers are keeping a 

 watchful eye on their performance. 



Despite the success of his work in 

 coastal North Carolina, Carlile is the 



first to emphasize that the systems are 

 not a panacea to septic waste disposal 

 problems in all rural areas. "Some peo- 

 ple get the idea that with alternative 

 systems you can build in the marsh," 

 he jokes. "The fact is that we're still 

 looking at sites that are unsuitable and 

 can't be developed." 



Maintenance needs 



One of Carlile's chief concerns is the 

 fact that modified systems require 

 more maintenance than conventional 

 ones. "The old conventional system, 



when it's working right, is the most 

 maintenance-free system available," 

 he says. 



With modified systems pumps must 

 be inspected regularly, distribution 

 lines checked and tanks pumped out 

 before they fill with solids. "A home- 

 owner has to be aware of what the 

 system is, how it works and what 

 routine maintenance is required," he 

 stresses. How well an alternative 

 system works, Carlile warns, ul- 

 timately depends on how mindful a 

 property owner is of routine main- 

 tenance needs. 



New twists to an old design 



There's nothing new about the septic 

 tank. In fact it's one of the oldest 

 systems of waste treatment. It was 

 first introduced to this country nearly 

 a century ago and, for the most part, 

 has remained relatively unchanged. 

 Today in North Carolina there are 

 more than two million septic tanks in 

 operation with an estimated 50,000 

 more being added yearly. Nationally, 

 85 percent of the individual, on-site 

 waste disposal systems rely on septic 

 tanks and cesspools. 



In a nutshell, the septic system takes 

 advantage of the soil's natural 

 filtering properties. Wastes are chan- 

 neled from the house into a holding 

 tank where solid portions settle out at 

 the bottom of the tank as sludge. 

 Although anaerobic bacteria in the 

 tank digest or breakdown much of the 

 sludge, residual solids accumulate and, 

 from time to time, must be pumped out 

 and disposed of — either at a treatment 

 plant or land application site. 



The liquid portion of the waste or ef- 

 fluent flows out of the tank and travels 

 along a series of pipes into a specially 

 designed absorption field. In the ab- 

 sorption field the effluent slowly seeps 

 through the soil. The soil acts like a 

 huge filter, trapping solids and absorb- 

 ing dissolved contaminants in the ef- 

 fluent. These trapped materials, in 

 turn, are nourishment for tiny 

 organisms growing in the soil. By the 

 time the effluent has traveled through 

 the various soil layers and reaches 

 ground water it has been thoroughly 

 treated. 



At least in theory that's how a septic 

 system operates. But not all soils act 

 the same way in filtering effluents. 

 Sandy soils, for example, have such 

 large pore spaces between the soil par- 

 ticles that the effluent may rush 

 through the absorption field without 

 being filtered. 



By contrast, tight soils with high 

 clay content can be so dense that they 

 are impermeable. The result — 

 untreated wastewater collects or ponds 

 on top of the impermeable layer and 

 can surface. 



When theory breaks down 



