Highway comfort stations and recreational areas frequently use septic tanks for waste water disposal. With the advent of large numbers of recreational vehicles (RVs) equipped with holding tanks for wastewater, holding tank dump stations have been pro vided at highway comfort stations and recre ational areas. These RV wastes appear to impair the operation of, and cause premature failure of, septic tank-percolation field sys tems, particularly in California where RV traffic is intensive. Two causes of the problem are evident. First, organic and hydraulic overloading of waste disposal facilities may occur because of the extraordinarily high rates at which high strength RV wastes are discharged to the facilities. In summer, RVs may sometimes be seen lined up waiting to use a dump station ; in such cases, the hydraulic detention of septic tanks provided for RV waste treatment may be less than 1 hour. Second, preservative chemicals added to the RV waste holding tanks for odor control are toxic and inhibit bio degradation of organic wastes in the septic tanks. If organic solids do not degrade in the septic tank, they accumulate to fill the septic tank prematurely, and pass to and clog the percolation field. The objectives of this research were twofold : first, to characterize wastewater discharged to highway comfort stations and RV dump sta tions, and second, to evaluate experimentally the degree of inhibition of anaerobic bio degradation caused by toxicants in RV waste. This information then could be used in the development of methodology and design criteria for anaerobic treatment of RV wastes containing preservatives.

Toxic inhibition of anaerobic biod?gradation

Water and wastewater systems at highway rest areas

Design guidelines for rest-area wastewater treatment systems that are capable of complying with the requirements of PL 92-500 are presented. Also presented is guidance for determining wastewater flow and constituent concentration. Each wastewater treatment system presented (septic tanks, lagoons, extended aeration package plants, trickling filters, rotating biological filters, land treatment systems, intermittent sand filter systems, and disinfection) includes a process description, a discussion of the performance, flexibility, reliability, and operational procedures, preliminary design formulations, and references and selected bibliography. Also included is a flow chart showing a general design proceudre for new and existing rest areas with emphasis on water supply needs and wastewater treatment systems. /FHWA/

N R Francingues Jr

Papers

Wastewater treatment systems for safety rest areas