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Washington State Department of Ecology

Best Management Practices (BMPs)
For Management and Disposal of Street Wastes

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July 1995

Table of Contents

Summary Street Waste Management Site Inspection Solids Liquids Appendices


Many local governmental units and private vendors do not currently have a safe location for the disposal of street waste. Unanswered handling and disposal questions have discouraged public and private entities from routinely cleaning streets and stormwater facilities. Furthermore, ordinances, laws, and guidelines governing solid waste handling and disposal often do not address street waste handling and disposal. This ambiguity makes compliance confusing and difficult for the public and private operators alike (King County 1994).

These Street Waste Guidelines were developed to help local governments, stormwater managers and equipment operators develop and improve their stormwater maintenance and waste disposal programs. The reader is cautioned that these guidelines are based on current knowledge and rules and will become outdated as rules change and more data on the character of street waste becomes available. This July 1995 Draft is to elicit comments and suggestions from readers and should not be used as approved Department of Ecology Guidance.

This document outlines recommendations for testing, use, and disposal of solids and liquids collected during the maintenance of stormwater detention, treatment, and conveyance systems. These materials, plus solids collected during street and parking lot sweeping, are included in the general grouping of Street Waste.

Street waste can be extremely variable in types and amounts of contaminants. These contaminants vary depending on land use, illicit discharges, accidental spills, and the frequency of cleaning. Street waste can cause high turbidity, or contain oil and petroleum products, pesticides, fertilizers, fecal material, metals, and other substances that present a threat to human health and the environment. If these substances accumulate in the storm drainage systems, they can pollute water and cause damage to fish, wildlife, and water supplies.

Sampling studies have shown that, unless obviously contaminated, street waste usually classifies and should be handled as solid waste. Disposal, reuse, and recycling options are complicated by variations in physical and chemical characteristics. In many cases, testing requirements and liability considerations can make reuse more expensive than disposal at a landfill.

Street Waste Handling Strategy

The following strategy is a simplification of this guidance's recommendations for use or disposal of street wastes in an economic manner that still protects the environment:

"Street Wastes" include liquid and solid wastes collected during maintenance of stormwater catch basins, detention/retention ponds and ditches and similar storm water treatment and conveyance structures, and solid wastes collected during street and parking lot sweeping. Solids and liquids from cleaning of electrical vaults, vehicle wash sediment traps, restaurant grease traps, similar non- storm sewer facilities, and sanitary sewers are not included in this guidance. For the purpose of this guidance, street waste shall not include waste material from these facilities.

All street waste shall be given a visual and site evaluation for obvious contaminants and an historical review for spills back to the date of the most recent cleaning. The waste site should be sampled and tested for likely hazardous waste constituents or toxicity if contamination is suspected or has been found at this site in the past. Disposal and use options of tested waste will be determined by the test results and dangerous waste rules.

All street wastes must be sampled and tested for contaminants on a regular basis by time or volume. This will help reevaluate this guidance in the future and provide certainty to those receiving the wastes.

All street wastes may not reused or disposed of without the knowledge and permission of the final receiver.

The street waste solids constituents most commonly of environmental concern are Petroleum Hydrocarbons, Polycylic Aromatic Hydrocarbons (PAHs), and lead. Street waste solids that are not visually contaminated and pass an historical and site evaluation usually do not test as dangerous (hazardous) waste. and should be classified and treated as solid waste. The jurisdictional health district has authority for management of street waste solids classified as solid waste.

There are no appropriate regulatory methods to classify solid waste solids as 'clean'. The Model Toxics Control Act (MTCA) Method A cleanup levels have been used as an approximation of 'clean' for hydrocarbon contaminated soils, but street waste usually contains too high of levels of Petroleum Hydrocarbons and PAHs to meet the Method A cleanup levels. We hope to develop an affordable chemical test for 'clean' street waste.

The following disposal options are only for street waste solids that have passed a visual and historical inspection. Disposal options and testing requirements for street waste solids depend on the needs and physical requirements of the final receiver of the waste. Street waste solids classified as solid waste may be disposed of at a permitted landfill, used in asphalt and portland concrete manufacture, or used as subgrade in road and parking lot construction. Additional disposal/treatment methods are being studied, but may require analytical testing that costs more than current disposal costs. Disposal at a permitted landfill is often the simplest, least expensive, and most environmental protective method for disposal of street waste. Small quantities (less than 200 lb.) of street waste solids may be disposed of with solid waste.

High organic material from swale mowing (grass) and street sweeping (leaves) may be used as feed stock in a compost facility if they pass the inspection. This material is not to be made into Grade AA compost. Topsoil made from high organic street waste may only be used in low contact areas such highway medians and industrial parks.

Coarse sand screened from street sweepings may be reused for street sanding if it passes the inspection and it contains greater than 50% coarse sand (1-4mm) which is indicative of low traffic impact. The fines from the street sweeping should be considered as solid waste.

The following disposal options are only for street waste liquids from sites that have passed a visual and historical inspection. Liquids from eductor (vactor type) cleaning of storm sewer catch basins and detention facilities should be disposed of at a solids/liquids decant station or liquids only decant treatment facility discharging to a permitted wastewater treatment plant. The liquid shall be treated using All Known And Reasonable Technology (AKART) to settle solids and remove other contaminants to meet treatment plant local limits.

Decanting of liquids back into the storm sewer catch basin or detention facilities that they were taken from is allowed only if no other practical means are available, the facility is remote from surface waters, the liquids will not leave the site in 24 hours, and All Known And Reasonable Technology (AKART) is used before discharge.

Discharge of street waste liquids to surface water or ground water may be possible if water quality discharge limits can be met and a discharge permit is obtained. Presently used technology is not adequate to meet discharge limits for this type of discharge. Decanting of liquids and solids at specially constructed wet ponds or evaporation basins is also possible, but has not been done in Washington and will likely require permitting.

Disposal facilities for liquids and solid should be made available to all private and public operators that meet disposal facility licensing and site evaluation requirements.

Street Waste Management Site Inspection Solids Liquids Appendices
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