This report consists of three phases. Phase one is a review of existing information on all aspects of highway maintenance waste management. A survey was conducted with the state transportation-highway departments in the U.S. and its territories and Canada. The information obtained in response to the questionnaire, such as quantity of specific waste material and their concentration of specific hazardous material and the method of treatment of disposal was placed in a computer software database for easy accessibility.
Phase two is the characterization of the highway maintenance waste. The waste consisting of road sweepings, vactor sludges, and ditch diggings were found to be contaminated with hazardous substances. Three pollution indicators, total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbons (PAH), and the Microtox solid-phase bioassay toxicity test (MSPT) were used to define the waste. The geometric mean and range for all three parameters were determined for each waste category. Road sweepings were categorized into three age groups: recently collected, recently stored, and aged material. The recently collected material had the highest level of pollutional parameters. Road sweepings were sieved into three fractions. The smallest particle size fraction was found to have the largest concentration of the pollutional parameters.
Based on the waste characterization, the following full scale treatment technologies are suggested to render the highway maintenance waste non-toxic: land farming or bioenvelope, solids washing and rotary kiln incineration. As a pretreatment, rotary screening is recommended. The treated solids can be disposed of in sanitary landfills or used as road fill.