Quality of Runoff Leachate Collected from Biosolids and Dairy-Manure Compost-Amended Topsoils

Abstract

Compost amendment of pavement shoulder subgrades was attempted to mitigate shrinkage cracking, which otherwise would result in severe distress to adjacent pavement infrastructure systems. Two types of composts, biosolids and dairy-manure composts, were evaluated. As a part of this application, the runoff leachate emanating from the compost soils needs to be environmentally assessed as this leachate potentially ends up in storm sewer collection systems. As a part of the research, runoff collection systems were placed in both dairy-manure and biosolids compost-amended soil sections and a control untreated soil section. The collected water samples at various time intervals were then subjected to various chemical and environmental tests, including total suspended and dissolved solids, biochemical and chemical oxygen demand, total Kjeldahl nitrogen (TKN), and phosphorous measurements. This paper presents a summary of these test results from both sections and their comparisons with similar results from another leachate collected from a control or untreated section. These test results are also compared with a few local studies conducted on highway runoff samples and EPA benchmark values. Possible causes for chemical contaminant concentration differences in the leachate samples from both composts are also explained.