What is prohibited in the context of perc test rates?

Averaging of perc test rates across a site is prohibited because it can lead to inaccurate assessments regarding soil permeability. Each perc test measures the infiltration rate of water specific to the area surrounding the test site. Soil properties can vary significantly within a given site due to factors like composition, compactness, and depth. Averaging results from different areas disregards these variations and may result in a design that does not account for the worst-case scenario, potentially leading to drainage issues and system failures.

On the other hand, using the highest rate for design is often recommended to ensure systems can handle the maximum expected flow. Testing in wet conditions may provide misleading results, but it is not generally prohibited unless specific regulations dictate otherwise. Performing tests on sloped areas may also be acceptable depending on local guidelines and conditions. Therefore, the prohibition against averaging highlights the necessity for precise and localized assessments to ensure effective wastewater management.