Septic Tank Treatment
(1) NSF-listed treatment units are only certified, and can only handle, residential strength wastewater at their rated flows. The same is true for current published designs for media filters.
(2) Commercial and Institutional facilities must utilize "pretreatment" processes (ATU's and most media filters do not function as pretreatment processes) to first bring the BOD, TSS, FOG, and any other aspect of the wastewater down to a residential strength before one can employ ANY portion of 30TAC285.
(3) When the greywater is removed from the wastewater flow, the remaining blackwater is no longer residential strength, and must therefore be pretreated as discussed above.
(4) Drip systems designed to minimum sizes allowed by 30TAC285 must be time dosed, or at some point they will surface effluent. At some point, there will be an excessive flow sent to the drip field, and if not controlled by time dosing, there will be surfacing.
(5) There is virtually no storage room in the disposal field of a drip system, so the storage room must exist by creating additional reserve in the pump tank. Even a high water alarm is better than surfacing effluent.
(6) Sewage-contaminated sand, gravel, filters, and the like, must either remain on site or be transported offsite by DOT/TCEQ/EPA approved method(s).
(7) Drip fields on a slope must be designed and installed to prevent drain-back. Otherwise, the lowest part of the field gets overloaded.
(8) Drip lines MUST be laid parallel to the contour lines - NO EXCEPTIONS.
(9) Screen filters are not the best choice for drip irrigation filtration. Some form of three dimensional filter is much better at capturing organics.
(10) Manual flushing of drip fields every 3 to 4 months is generally insufficient. Flushing frequency is a factor of effluent quality, field design, dosing and resting times, and volume of flow, among other considerations. The better the design of the field, the better the quality of effluent (remember filtration!), the lower the flow, the lower the dosing frequencies, the less frequently one needs to flush the field tubing.
(11) Tablet chlorinators using calcium hypochlorite, like the ones commonly used in the on-site industry, are not capable of delivering 3 to 4 month's disinfection unattended. For that matter, liquid chlorine loses strength rapidly, which reduces the efficacy of the disinfection process.
(12) Media filters (sand filters, gravel filters, etc.) are not maintenance free.
(13) No treatment product or process can guaranty absolute end results when we leave the input values completely uncontrolled.
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