130 Nickerson Street, Suite 200, Seattle, WA 98109-1658

206-263-3000 http://dnr.metrokc.gov/wlr/indwaste/

Fact Sheet: Discharging Dental Wastewater

into the King County Sewer System

King County Industrial Waste

Mission Statement

The mission of the Industrial Waste Program is

to protect the environment, public health,

biosolids quality, and King County’s regional

sewerage system. We work cooperatively with

our customers as we regulate industrial discharges, provide technical assistance, and

monitor the regional sewerage system.

Introduction:

In 1995, King County and the Seattle-King

County Dental Society began working with

dentists to achieve voluntary, proper disposal of

wastes. In 2000, King County’s Local Hazardous Waste Management Program in King

County and the King County Industrial Waste

Program (KCIW) began working with the Seattle-King County Dental Society and others to

identify a user-friendly process for all dental

practices in the King County sewer service

area to follow to ensure that they were in compliance with wastewater discharge limits.

By the end of 2003, 97 percent of the dental

practices in the county’s sewer service area

were in compliance with these regulations. The

resulting significant reduction in silver and

mercury concentrations in the county’s

biosolids serves as an ultimate measure of the

effectiveness of these efforts. (See “King

County Biosolids Recycling.”)

How to meet King County regulations for dental wastewater

discharged to county sewers

Department of

Natural Resources and Parks

Industrial Waste Program

Clean Water - A Sound Investment

Topics overview:

Introduction

How to meet local dental wastewater

discharge limits

 The routes to compliance

King County Biosolids Recycling

Regulatory information

Best Management Practices

What can dental practices expect during

an inspection?

A sample equipment and waste

management log

Additional resources

Contact information

1
How to meet local dental wastewater

discharge limits - the routes to compliance:

Route 2:

Dental practices in compliance

with local dental wastewater

discharge limits may apply for

dental wastewater discharge

permits and follow BMPs.

A smaller number of practices may be able to

demonstrate compliance without installing an

approved amalgam separator and can choose to

apply for a King County Dental Wastewater

Discharge Permit in lieu of installing an

approved amalgam separator. A discharge

permit is needed to ensure that a dental practice

meets local dental wastewater discharge limits

on a consistent basis.

KCIW may require a practice with a dental

wastewater discharge permit to regularly collect

and analyze wastewater samples. KCIW may

also require annual reporting.

The permitting route to compliance may apply to

dental practices that do not regularly place or

remove amalgams but may be able to meet the

limits using BMPs only (e.g. pediatric dentists).

Practices that have installed an amalgam

separator that is not on the approved amalgam

separator list maintained by King County, or that

are utilizing another method of metals

pretreatment must also obtain a permit.

Costs for a dental wastewater discharge permit:

The King County Dental Wastewater Discharge

Authorization ranges from $705 - $1545,

renewable every five years. (Per 2005 fee

schedule.)

2

Route 1:

Use an approved amalgam

separator and follow Best

Management Practices (BMPs)

To meet local wastewater discharge limits, the

majority of King County general dentistry practices that place or remove dental amalgam will

need to install a King County approved amalgam separator to remove metals including

mercury and silver from their wastewater.

Selecting amalgam separators:

 Separators must be approved by King

County, which publishes a list of approved

amalgam separators.

 Practices wishing to install amalgam

separators that are not approved by King

County must apply for dental wastewater

discharge permits.

Installing amalgam separators:

 Separators should either be installed at

each chair or in a central location that

receives wastewater from all chairs

(usually closer to the vacuum pump)

where amalgam is removed or placed.

 Separators must be maintained and

wastes disposed of according to

manufacturer’s recommendations.

 Dental practices must keep installation,

maintenance, and disposal records on

site for three years. (See pages 7-8.)

Estimated costs for approved amalgam separators:

Costs include those of purchasing, installing, maintaining and removing amalgam wastes. Approved amalgam

separators may range from $150 - 2000 purchase price;

$200 - 500 for installation, and $200 - 700 annual

maintenance including waste disposal.

Disclaimer: Costs cited here are only estimates, with

information subject to change.
3

Route 3:

Follow BMPs and be inspection

ready:

Certain specialties and practices will not be

required to install an amalgam separator or

apply for a permit if they place or remove

amalgam no more than three days each

year or they limit their practice to one of the

following specialties:

 orthodontics

 periodontics

 oral and maxillofacial surgery

 radiology

 oral pathology or oral medicine

 endodontic and prosthodontic practices

that do not remove or place amalgam

fillings as a service to their clients more

than three days each year

A small number of King County dental

practices that place or remove little or no

dental amalgam will not need to install a

separator or apply for a permit to

demonstrate compliance with the local dental

wastewater discharge limits. In addition to

following BMPs for amalgam wastes and

used silver fixer, each practice that

determines that it places or removes

amalgam three days or less each year

should be able to demonstrate this during an

inspection. Practices should keep a record,

including dates, of each procedure performed

that involves placing or removing dental

amalgam.

King County Biosolids Recycling

For more than 30 years, King County has

been turning wastewater solids into a product

called biosolids. All of King County’s biosolids

are used beneficially in agriculture and forestry or as an ingredient in compost for

landscaping and gardening. Biosolids contain

organic matter, as well as nitrogen, phosphorus, potassium and other nutrients necessary

for plant growth. This valuable soil amendment can be used to build soils, revegetate

barren areas and fertilize crops.

In order to be safely recycled, biosolids must

meet stringent quality standards set by the

U. S. Environmental Protection Agency. King

County’s Industrial Waste Program (KCIW)

and the Local Hazardous Waste Management Program in King County work with

industries, businesses and citizens to limit the

amount of metals and organic contaminants

entering the sewer system. Thanks to continued efforts by local industries and businesses

to meet source control requirements set by

the county, biosolids contain only small

amounts of metals and organic pollutants.

For contact information see page 8.
4

What are the requirements for

dental practices in King County?

Dental practices that remove and or place

amalgam must use approved amalgam management practices and must install an amalgam separator. (A small number of practices

may choose to apply for a King County Dental

Wastewater Discharge Permit.)

Why do dental practices need to

meet the dental wastewater

discharge limits?

Protecting water quality is a sound business

investment. The region is committed to improving its natural resources, including water. This

means that businesses and regulators must

work together to find better ways to manage

waste.

Regulations are designed to prevent businesses from discharging substances that can

degrade the wastewater treatment process,

harm workers or facilities, or impact surfacewater quality. All wastewater discharged by any

business, located in the King County sewer

service area, including dental practices, must

adhere to regulations as described in King

County Code—Title 28 (KCC) and Public Rule

PUT 8-13 (PR).

Most commonly, dental practices need to

address the amounts of mercury and silver

they discharge to the sewer system. While this

is only a portion of the mercury and other

pollutants going into the environment, dental

amalgam nonetheless is identifiable and controllable in the waste stream.

What are the rules defining the

wastewater discharge limits?

King County limits for metals and their applicability to businesses in the sewer service area

are cited in King County Code—Title 28 (http://

www.metrokc.gov/mkcc/CODE/index.htm#28)

and in King County Industrial Waste Local Discharge Limits at

http://www.metrokc.gov/recelec/archives/

policies/put813pr.htm on the internet.

If an industrial user discharges less than 5,000

gallons of wastewater per day, the industrial user

must comply with local discharge limits for mercury of 0.2 parts per million (ppm) and for silver

3.0 ppm.

For more details about our rules and regulations

go to http://dnr.metrokc.gov/wlr/indwaste.htm

or call KCIW at 206-263-3000 to have a copy of

the regulations mailed. (See end of document for

additional contact information.)

County Code provides that businesses or individuals who illegally discharge substances to the

sewer system must pay for damages and may be

fined. Names of businesses that are fined are

published in a Seattle Times display ad titled

“Companies Violate Pretreatment Standards.”

King County dentist and KICW inspector view

the practice’s amalgam separator.

Regulatory information
5

Whichever route to compliance is applicable to

a particular dental practice, it is crucial that all

practices follow BMPs for amalgam wastes and

spent fixer used in X-ray processing.

KCIW requires that all dental practices use

BMPs as a means of limiting metal discharges

into the sewerage system.

1. BMPs for amalgam wastes:

 Keep amalgam out of sinks and never

rinse amalgam waste down the drain.

 Clean or replace chair-side traps on a

regular schedule and properly dispose of

amalgam waste.

 Clean vacuum pump filters regularly,

according to the manufacturer’s recommendations, and properly dispose of

amalgam waste.

 Send amalgam wastes to a licensed

TSDR (treatment, storage, disposal, or

recycling facility.

 Maintain all disposal records on site for

three years.

 King County expects all dental practices

to apply BMPs for amalgam wastes on

an ongoing basis.

2. BMPs for properly handling spent

 fixer used in X-ray processing:

 Collect spent fixer and have it disposed

of by a vendor who will recover the silver

in it.

 (OR)

 If practices prefer to treat the fixer on

site and dispose of it down the drain, they

must remove the silver by installing two

chemical recovery cartridges (CRCs) in

a series. Cartridges must be sized and

maintained according to the

manufacturer’s recommendations.

 Maintain all disposal or maintenance

records on site for three years.

 King County expects all dental practices

to apply BMPs to spent fixer on an on

going basis.

3. BMPs for use of cuspidors:

 Practices may discharge wastewater

from cuspidors directly to the sanitary

sewer without having to route then

through the amalgam separator

provided that:

During placement or removal of

amalgam, use suction device to

evacuate waste and use cuspidor

primarily as receptacle for patients

when they rinse their mouths for

refreshment.

Maintain in-line filters in cuspidor and

handle all dental wastes, including

waste amalgam particles, according

to current BMPs for Dental Office

Wastewater.

Best management practices (BMPs) for dental

practices in King County sewer service area.
The compliance inspection process:

Compliance inspections of all dental practices

that discharge mercury into the King County

sewerage system occur on an ongoing basis.

Each year the county inspects a portion of

dental practices in the sewer service area for

compliance with its regulations and general

compliance with federal, state and local hazardous waste regulations.

Inspectors from KCIW, the Local Hazardous

Waste Management Program in King County

(LHWMP) and Public Health – Seattle & King

County may inspect dental practices. Inspectors may schedule inspections with dental

practices or may visit without prior notice.

While KCIW and LHWMP each have their own

criteria, the two agencies are combining their

inspections into one session for ease of the

dental practices.

Since dental practices that are certified by the

EnviroStars program have already demonstrated compliance with these regulations, they

will not receive additional inspections. (See

page 8 for additional EnviroStars information.)

What can dental practices expect

during an inspection?

During inspections, which will normally last

less than one half hour, the inspector:

 Will look to see if the dental practice has

ONE of the following:

• an approved amalgam separator unit

(ASU) properly installed (see Compliance

Route 1, page 2), or

• a valid wastewater discharge permit,

(see Compliance Route 2, page 2), or

• an exemption from the above requirements (see Compliance Route 3, page 3).

 Will check to see that X-ray fixer is properly

managed.

 Will check to see that other hazardous

wastes such as scrap amalgam, lead foils,

and certain disinfectants are being disposed

of properly.

 Will check records such as:

• receipts or other documentation for

equipment maintenance, and,

• solid and liquid hazardous waste removal

records.

 Will also answer any questions practices may

have about maintaining compliance.

Inspection follow-up:

A typical follow-up to an inspection would include

the inspector completing an inspection report

and evaluating the dental practice for compliance. If the practice is in compliance there will be

no further action.

Minor Problems:

If minor problems are noted during the inspection, King County will follow-up to see if they

have been corrected promptly. If so, there will be

no further action.

Major Problems:

If the inspector noted major problems (e.g. no

separator or permit in place when required) he

or she will set up a compliance schedule for that

dental practice. If the practice does not correct

the problem within 30 days, King County will

proceed using its Enforcement Response Plan.

The goals of this plan are to:

 Correct violations as soon as possible.

 Treat all industrial dischargers equitably.

 Eliminate any economic advantage to a

 business for not complying.

 Recover costs caused by violations.

More information about the Enforcement Response Plan is contained on the KCIW Web

pages. See “Enforcement” or “Dental Office

Waste.”

For additional information regarding compliance

inspections, see contact information page eight.

What can dental practices expect during an inspection?

6
7

Suggested equipment and waste management log

See example provided by the King County Industrial Waste program as a resource for dental

practices on next page. Records should be kept three years, including receipts and manifests.

Date Event or Number or Vendor name Signature and title of

waste type amount dental practice employee

and units
Printed on recycled paper INTERNATIONAL UNION

GRAPHIC COMMUNICATIONS

UNION GCIU LABEL GCIU 1202M 5053dh.p65

Department of

Natural Resources and Parks

Industrial Waste Program

130 Nickerson Street, Suite 200

Seattle, Washington 98109-1658

206-263-3000

206-263-3001 FAX

King County’s Wastewater Treatment Division protects

public health and water quality by serving 18 cities, 16

sewer districts and more than 1.4 million residents in

King, Snohomish and Pierce counties. Formerly called

Metro, the regional utility now operated by King County

has been preventing water pollution for nearly 40 years.

Additional resources for meeting the local dental

practice wastewater discharge limits:

8

KCIW’s Dental Office Waste Web pages, http://dnr.metrokc.gov/wlr/indwaste/dentists.htm include:

 a downloadable version of this fact sheet;

 a downloadable Dental Practice Wastewater Discharge Permit Application and Guidelines

and Instructions;

 the list “Amalgam Separators Approved by King County”; a comparison chart for King County

approved amalgam separators, and links to information about companies that transport dental office

waste to licensed TSDRs (treatment, storage, disposal, or recycling facilities); and,

 information about the EnviroStars program, a service of the Local Hazardous Waste

Management Program of King County that certifies businesses for their efforts in

preventing pollution and reducing hazardous waste.

To request mailed copies of this information, see contact information below.

King County Biosolids Recycling: For more information see the program’s Web pages at

http://dnr.metrokc.gov/WTD/biosolids/ or contact Technology Assessment and Resource

Recovery by calling 206-684-1255 or emailing roberta.king@metrokc.gov.

This information is available in

accessible formats for persons with

disabilities upon request. Please call

206-263-3000 or TTY relay service at

1-800-833-6388.

Date Event or Number or Vendor name Signature and title of

waste type amount and units dental practice employee

Example

3/8/95 silver fixer 5 Gallons Safety Kleen Helen Delecroix/ Dental Assistant

3/8/95 Harvey’s 2 Gallons Safety Kleen Helen Delecroix/ Dental Assistant

1/1/04 replace filter 1 ABC Dental Helen Delecroix/ Dental Assistant

on ASU filter Supply

5/5/05 scrap 5 gallon bucket Enviroclean Dr. Young / Dentist

amalgam/

lead foils

Sample equipment and waste management log

Example provided by the King County Industrial Waste program as a resource for dental practices. Records should

be kept three years, including receipts and manifests.

March 2005