Team behind collecting, disposing Sonoma County’s household hazardous waste are skilled in science

Read more at the Press-Democrat

November 6, 2023

Working hands-on with household hazardous waste — the term covers everything from used motor oil, pool chemicals and old buckets of paint, fluorescent bulbs and lead-acid auto batteries — is definitely a dirty job.

It can also be dangerous.

Working hands-on with household hazardous waste — the term covers everything from used motor oil, pool chemicals and old buckets of paint, fluorescent bulbs and lead-acid auto batteries — is definitely a dirty job.

It can also be dangerous.

"I'm helping to preserve an existence for my kids and beyond. Not to mention the birds and bees, and the flowers and trees," he said.

A complex system of help

Zero Waste Sonoma operates an ambitious, multifaceted, aollection system for household hazardous waste that makes it easy for residents to dispose of leftover household hazardous products. Much of what's collected can be reused or recycled. For example, motor oil is cleaned up, put into barrels or tanks and shipped out for reuse in the petroleum industry.

During fiscal year 2022-2023, the facility collected 1.2 million pounds of household hazardous waste. Of that, 71,457 pounds were reused and 606,812 pounds were recycled, including propane cylinders, motor oil, bulbs, household batteries, paint, fire extinguishers and auto batteries.

This complex system has a vast number of moving parts that include various governmental agencies and private companies. All these parts are coordinated and overseen by Zero Waste Sonoma, a joint powers authority that acts on behalf of the county's nine cities and unincorporated areas to help residents and businesses reduce, reuse, recycle and discard materials in a safe and environmentally responsible way.

The organization's household hazardous waste program is managed by Scott, who has worked in the environmental arena since graduating from Chico State in 2008.

Zero Waste Sonoma contracts with Clean Harbors, a nationwide provider of environmental services that include hazardous material management and disposal, to operate the Sonoma County Household Hazardous Waste Facility.

Holbrook, a Clean Harbors employee, oversees the day-to-day facility operations in Petaluma, doing everything from running a forklift to mixing chemicals to preparing a truckload of hazardous waste for shipment. A former member of United States Army Aviation, Holbrookholds a degree in chemistry from Southern State Community College in Ohio.

Paint is the top item at the facility

In an average week, approximately 339 residents drop off household hazardous waste at the county's facility in the bucolic northwestern hills of Petaluma. The site on Mecham Road is open for the free drop off every Thursday, Friday and Saturday from 7:30 a.m. -2:30 p.m., except on some holidays.

The drive-thru process does not take long and is usually uneventful. The process is meant to be easy as easy as possible for county residents. Drivers never leave their vehicles and waste must be placed in the trunk or truck bed. After a brief check-in, a staff member removes the hazardous material, and the resident drives away.

At that point, the various hazardous materials are placed in designated areas within the facility.

Some items, such as paint, may have a quick turnaround here. If the cans look new enough and are at least half-full, they're brought to the outdoor reuse lockers, where contents are free for Sonoma County residents. When available, the lockers also offer recycled pool chemicals, household cleansers and other items.

"County residents can pick up any item in the reuse lockers for free," Scott said. "Paint is the number one item that we receive at the facility, and it's also the number one item we put out in the reuse area."

When paint doesn't meet reuse locker standards, it's bulked into 55-gallon drums to produce one of four colors: tan, white, gray and light green. The paint is then poured into five-gallon buckets, which are also free to Sonoma County residents.

"We really want jurisdictions like public works departments to take more advantage of that," Scott said. "It's great for graffiti abatement or painting warehouses inside and out."

Safety is always top priority

Materials that present greater hazardous risk are brought to hot zones where only staff members have entry. While working, all staff members — including those unloading waste from cars — are required to wear chemically resistant coveralls, steel-toed boots, impact-resistant safety glasses, and chemical/impact-resistant gloves.

In the main chemical segregation area, walled bays separate hazard classes. Each bay contains large placards that clearly identify its contents and instructions for staff and emergency responders.

"We don't mix materials that could be dangerous together, especially items that could create fumes." Holbrook said.

A 450-gallon tank in the main chemical segregation area contains used motor oil, while used antifreeze is bulked into a neighboring 200-gallon tank. A Safety-Kleen truck arrives periodically to siphon off the contents of both tanks for recycling.

"Once motor oil is re-refined," Holbrook said, "it's a better quality than standard motor oils — it's more refined and guaranteed to have less additives. For industrial applications it's like a racing oil for motor cars."

The most dangerous area in the facility is the explosive-proof bulking room, where the most flammable materials, like paint thinner or gasoline, are bulked into drums and then shipped off to be bulked further into large tanker trucks.

This room has special safety features such as ventilation and spark-preventive hookups. While pouring chemicals together, the bulker is required to wear a full-face air purifying respirator. Only Holbrook and one other staff member, both with specialized training, are allowed entry.

Shipping out bulked items occurs once or twice a week, and requires Holbrook to pack a semitrailer with precision. Shipping boxes are lined with chemical-resistant material, placement within the truck must be dispersed evenly so as not to overweight the axles, and certain materials must be located at a mandated distance from other materials.

"It's like putting a giant puzzle together," Holbrook said.

You pay for the service, use it

Occasionally, the facility’s daily routine gets upended by a resident driving up with an item that brings operations to a full stop.

Scott recalls the day someone arrived with a crystallized bottle of picric acid, an organic compound that was commonly used decades ago as a tissue dye or medicine, as well as an explosive. It's rarely used these days outside of labs, but old bottles are still sitting around in residential garages or sheds.

"The problem," she said, "is that when picric acid ages, it crystallizes and becomes highly explosive. When this little glass vial came in we needed to completely stop all operations. It was a miracle that it was brought to our facility without exploding — a bump on the road could have made that happen."

Since the county’s household hazardous waste facility doesn't have the proper equipment to accept explosive materials, the bomb squad was called in to safely dispose of it. The local site cannot accept radioactive material, explosives, or biological waste.

Luckily, such stop-the-operations days are rare and the Sonoma County Household Hazardous Waste Facility encourages residents to drop off their household waste.

“All county residents pay for household hazardous waste through their garbage services,” Scott said. “So they should use it. Come to us. Bring us your unwanted items: paints, pool chemicals, batteries, pesticides, motor oils and all the rest."

Disposing of houshold hazardous waste in Sonoma County

Household hazardous waste is waste that has substantial or potential threats to public health or the environment. These items include aerosol sprays, antifreeze, asbestos, fungicides, paint, photo chemicals, vape pens and more. To see a full list, go to

Sonoma County offers three methods for disposing of household hazardous waste for all residents.

1. Bring your hazardous waste to the Central Disposal Site: Be sure to bring your ID to prove residency and place your household hazardous waste in sealed containers in your trunk, packed to prevent spills. Remain in your car throughout this process.

Maximum limits: 15 gallons of liquid (in maximum 5-gallon containers) and 125 pounds of solid material.

Hours: 7:30 a.m.-2:30 p.m., Thursday, Friday and Saturday

Location: 500 Mecham Road., Petaluma

More information: 707-795-2025,

2. Bring your household hazardous waste to a collection event: Every Tuesday, from 4-8 p.m., there is a household hazardous waste collection event somewhere in Sonoma County. Appointments are required. A full schedule and links to online registration are available at Zero Waste Sonoma.

For more information:

3. Receive Pickup of your household hazardous waste with the Rover Service: Every Wednesday the Rover Service covers a different area of the county, picking up household hazardous waste at homes. A fee is charged for this service (it’s free for seniors over 80 and housebound residents).

More information:

Disposing of houshold solar panels in Sonoma County

Sonoma County residents can dispose of unwanted residential solar panels during three upcoming solar panel recycling events. There is no charge for residents to drop off their panel, but an appointment is required.

No panels from businesses or other counties will be accepted.

1. Santa Rosa Solar Collection Event

Location: Luther Burbank Center for the Arts, 50 Mark West Springs Road, Santa Rosa

Time: Friday, Jan, 12 from 9 a.m.-5 p.m.

Book an appointment:

2. Sonoma Solar Panel Collection Event

Location: Sonoma Community Center, 276 E. Napa St., Sonoma

Time: Friday, April 5 from 9 a.m.-5 p.m.

Book an appointment:

3. Healdsburg Solar Panel Collection Event

Location: Healdsburg Community Center, 1557 Healdsburg Ave., Healdsburg

Book an appointment:

For more information: 707-565-3632,