evaluation of gravelless pipe systems for onsite wastewater

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Soil Classification Results of Effluent Analyses Table 1. Soil Classification by System # of systems with problems # of systems with no problems Sand 3 1 Fine sand 5 2 Loam 1 >NA Sandy clay loam 1 NA Loamy sand 1 NA The results from the septic tanks and gravelless pipe for BOD, TSS and DO were all within normal levels to be expected in a septic tank effluent. The BOD values were all below 220 mg/1 and the TSS values were below 65 mg/1. Many of these were skewed because the first thing many homeowners do when there is a problem is to pump the septic tank. This pumping affects these results and the typical operation of these tanks may have been different. Visual inspection indicates that there is reason for concern that some of these tanks may not be watertight. This was not apparent during the site evaluations but these were not done during the spring when such high water table conditions may exist, in the vicinity of the tanks. Flow Results Five of the eleven homeowners installed flow meters to monitor the flow. Flows were monitored for periods of seven to fourteen days. Three of the homes had flows well below the design levels. Two were close to or above their design flow rates. It is not possible to make a definitive conclusion based on such limited time periods. However, consistent flows at or above design values will shorten the life and reduce performance in any onsite system. The other homes refused or could not install a flow meter. In these instances we do not know if the system is being hydraulically overloaded. Based on the number of people living in these homes and the number of water using devices, none of them appear to be exceeding the daily estimated sewage flow rates.
Homeowner Usage Results The table below summarizes some of the homeowner water use patterns. House Age Garage Disposal Table 2. Homeowner Data Summary Water Softener Dish washer Anti-bacterial Soap Long Term Prescription Drug(s) Date of Last Pumping 1 10 x x x x Summer 1999 2* 2 Spring 1999 3 4 na na na na na na 4 9 x x Summer 2000 5 4 x x x x Winter 1999 6 5 x x Summer 2000 7 7 x x x Fall 98 8 6 na na na na na 9 5 x x Summer 2000 10 5 x x Summer 2000 11 10 na na na na na na 12 5 x x Summer 2000 13* 3 x x x Spring 2000 14* 7 x x x Fall 1999 * Systems with no apparent problems Reasons for Failure The average age of the gravelless system evaluated was six years with a minimum age of two and the maximum of ten years. Age is important because Chapter 7080 became mandatory in 1996. Previously using 7080 was voluntary, so a person could choose to downsize gravelless systems by 20-50%, which was a manufacturers recommendation. This evaluation looked at systems using various ‘brands’ of gravelless pipe. There are four main
Page 1 and 2: EVALUATION OF GRAVELLESS PIPE SYSTE
Page 3: RESULTS AND DISCUSSION System locat
Page 7 and 8: 4. All systems evaluated had biomat
Page 9: RECOMMENDATIONS 1. More systems sho

evaluation of gravelless pipe systems for onsite wastewater

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