High strength waste (HSW) presents a challenge for any type of onsite wastewater treatment system. This is apparent in restaurant facilities, where the design life of the system is significantly less than a typical residential system. This can also be a factor in other types of businesses that generate HSW. Each facility type will have unique wastewater characteristics as well as unique site and soil conditions for the designer to consider. Therefore, the more information the designer can obtain, the better the proposed design will accommodate certain distinct, potentially problematic conditions. Initial information gathering may include effluent sampling, water meter records, and/or usage patterns. This document provides recommendations on how to address HSW.
Please note that many of the recommendations are in excess of code required minimums. Due to the variability in the creation of HSW, even among similar establishments, many health codes fail to address HSW or address it too broadly. The designer should review the costs and benefits of any additional, recommended design features with the owner. Whereupon the decision for incorporating potentially significant costs initially, to increase reliability and longevity of the wastewater system, will reside with the owner.
HSW has been defined by many agencies and publications and varies accordingly. The State of Georgia regulations define HSW as greater than 200 mg/l Biochemical Oxygen Demand (BOD) or Total Suspended Solids (TSS). However, there may be constituents other than BOD/TSS that would make the waste stream “high strength” including but not limited to pH (too high or too low), fats, oils & grease (FOG), or nitrogen (N). HSW has been loosely defined within the industry as anything greater than residential waste strength.