Installing Septic System
With increasing frequency, people are asking how to use NSF-listed home plants for office, restaurant, or other nonresidential applications.
Based on the last several years of experience, we are now of the opinion that at no time should any NSF-listed home plant be used on anything other than residential strength wastewater.
Our recommended solution, therefore, is as follows:
1. Immediately stop using inappropriate treatment products. NSF-listed units are only certified for residential strength wastewater.
a. Use a high-strength treatment product or process to pretreat the wastewater, bringing the wastewater strength down to residential strength. Then, and only then, can you use 30TAC285 for the design of the balance of the OSSF.
2. For all non-residential strength applications, use the design approach presented by TOWA’s high strength wastewater workshop.
a. Quantify Q by determining maximum flow, minimum flow, and average flow – hourly, daily, weekly, monthly, even annually (schools).
b. Quantify influent wastewater strength parameters
i. BOD, CBOD
ii. TSS
iii. pH
iv. FOG
v. Temperature
c. Determine effluent wastewater strength parameter limits.
d. Select a treatment and disposal process appropriate for the above conditions and for the site-specific conditions.
3. The Designer must state in writing the assumed influent Q, BOD/CBOD, TSS, pH, FOG, Temperature, and any other criteria, such as nutrients, if applicable, and must state, in writing, the effluent values that the design is intended to achieve.
4. The Regulatory Agency must condition the permit on achieving the effluent values required by the rules or permit. For restaurants, the renewal of the food license should be conditioned on continual compliance with the OSSF permit.
5. Since the wastewater from this type of project is higher risk than residential strength wastewater, additional management activities should be required in the permit to ensure proper treatment and disposal, thereby protecting the public from this increased health risk.
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