• Taxies Information ~--­

- lUI"'''. lUll Cleaning Up Hazardous Waste' Sites: .. ,a"llil If

E c 0 L 0 'Y Cleanup Standards and Cleanup Actions

Background

Washington's hazardous waste cleanup law, the Model Toxies Control Act, mandates

that site deanups protect the state's citizens and environment. In developing the Act's

cleanup regulation, Ecology established cleanup standards and requirements for cleanup

actions that fulfill this mandate. A major portion of this effort was completed in February,

1991. '

The Department of Ecology has worked with the state Science Advisory Board and

representatives from business, local government and environmental groups to define site

cleanup levels.

Determining Cleanup Requirements

The Model Taxies Control Act cleanup regulation defines a two-step approach for ... establishing cleanup requirements for individualsites: ' '

.• Establishing Oeanup Standam5: The standards provide a uniform, statewide

approach to cleanup that can be applied on a site-by-site basis. The two primary

components of the standards, cleanup levels and points of compliance,must be

established for each site. Oeanup levels determine at what level a particular

hazardoussubstance does notthreaten human health or the environment. Points of

compliance designate the location on the site where the cleanup levels must be met.

• Selecting Oeanup Actions: Thisstep involves evaluating methods that could be

used to clean a site and then deciding which of those methods would best achieve

deanup standards. Aside from meeting the standards, the cleanup actions must also

provide permanent cleanup solutions, a reasonable time frame for cleanup and

indude monitoring to ensure effectiveness. '

STEP 1 - How Cleanup Levels Are Set

Eliminating all risks at a contaminated site often is not possible, even after cleanup. And

since any level of exposure to a hazardous substance is assumed to result in some risk.

Mdean" generally means that a site is cleaned up to the point that contamination no

longer poses an unacceptable threat to human health and the environment.

• For cancer-causing substances, the acceptable risk level is defined as a conservative

estimate of a person's chances of developing cancer during a lifetime of consistent

exposure to a hazardous substance. U more than one contaminant is present on a

site, the total health risk for aUcancer-causing substances must be considered when

setting cleanup levels.

• For non-carcinogenicsubstances, the cleanup level for each substance at a site must be

below that which could cause illness in humans. Hmore than one substance at a site

affects the body in the same way, the effect of aDof those substances combined must

be mnsidered when setting cleanup levels.

April 1991 Pu~inzlil;r< N~!-r(l!·r;
•

STEP 2 - Selecting Cleanup Actions

Step two of the cleanup process involves choosing the method or methods used to clean

up a site.

• Permanent Oeanups: Ecology will require use of permanent cleanup methods

wherever practical. The regulation lists preferred technologies in this order: 1) Reuse

or recycling, 2) Destruction or detoxification, 3) Reduction of the amount of waste, 4)

Containment of waste on-site, 5)On-site or off-site disposal.

• The Role of Cost: While cost cannot justify establishing cleanup levels that may

compromise human health or the environment, it can playa role in determining

points of compliance and cleanup actions. Pennitting less stringent cleanup levels

based on cost would be inconsistent with the intent of the Model Toxies Control Act.

• Public Review: Ecology describes the method ofsite cleanup in a draft "cleanup

action plan", which is circulated (or public review and comment, 11Us plan is then

finalized and used as the basis for any negotiations with potentially liable persons

who will be doing the site cleanup.. ..

Other Factors Mfecting Cleanup Requirements

• Property Use: Factors such as zoning, past site use and how adjacent properties are

used are important considerations when determining appropriate cleanup levels.

For most sites. cleanup levels will be set low enough that uses of the property will

not be restrided in the future. Properties in heavy industrial areas may utilize a

higher risk level. U site use changes after cleanup, the standards will be reviewed to

ensure that deanup levels protect human health and the environment. .

• Applicable Slate and Federal Laws: Cleanup levels and methods used must comply

with existing state or federal laws.

• Environmental Conditions: Washington's diverse environment presents many

variables in soil conditions, water tables, climate, and plant and animaJ .

communities.These variables need to beconsidered because they effect the way

hazardous substances interact on a site and how they impact humans and wildlife.

• Technology: Although cleanup technologies are developing rapidly, many

contaminants are still difficult or impossible to remove from soil and water. For this

reason, some flexibility is provided to consider technological limitations when

setting cleanup levels. Additionally, in some cases, cleanup levels are sefat

concentrations lower than what can bereliably measured using today'ssampling

and analytical procedures. In those situations, the lowest reliable measurement

would initially be used. The availability of improved analytical methods will be

periodicaJIy reviewed.

Protection After.Cleanup

• Confinnational Monitoring: Monitoring must be conducted at each site to verify

that cleanup actions worked and remain effective over time.

• Periodic Review: U hazardous materials remain at a site at levels which exceed ---

Method A or Bdeanup levels, Ecology will review the site every five years to ensure --

continued protection of human health and the environment. Ecology will publish a ".--

notice of all periodic reviews in the site register and provide an opportunity for

public review and comment.