141 Cranberry Highway
West Wareham, MA 02576

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Covanta Semass

Reducing Landfill Waste

Located in West Wareham, Massachusetts, the Southeastern Massachusetts (SEMASS) Resource Recovery Facility is an award-winning Waste-to-Energy Facility that serves the nearly 40 participating communities in Cape Cod, Southeastern Massachusetts and the Boston metropolitan area with reliable and sustainable waste management. 

In addition to keeping waste out of landfills, we are committed to ensuring safe operations and minimizing environmental impacts. We have been consistently recognized for exceptional operations and community involvement, including the American Society of Mechanical Engineers (ASME) Materials & Energy Recovery Division (MER) Facility Recognition Award, the Solid Waste Association of North America (SWANA) Silver Excellence Award, and the Environmental Business Council of New England (NE-EBC) John A.S. McGlennon Environmental-Energy Award for Corporate Leadership.

Fast Stats: Annual Performance

Every year, our facility processes more than 1,112,000 tons of waste that would otherwise have ended up in landfills.


Less waste in landfills reduce greenhouse gas emissions by 1,041,000 tons of CO2. That’s like taking 203,000 passenger vehicles off the road for one year.


We use waste to produce 78 megawatts of electricity 24/7 - enough to power 51,000 homes for a year.


We also recover 37,600 tons of metal for recycling annually - enough to build 26,000 cars.

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Superior Environmental Performance

We care about our communities and operate well below emissions limits. Over 99.9 percent of what comes out of our plant’s stack is what you’d typically find in air - water vapor, nitrogen, oxygen, and carbon dioxide. The remaining constituents are well below federal and state standards.

The following data is presented in units required by the facility's permit as averaged emissions.

a. Permit Limits are derived from USEPA standards for Large Municipal Waste Combustors (40 CFR 60, Subparts A, Cb and Eb) or state specific limits if more stringent.
b. CO, SO2 and NOx values are the daily (24-hr) block averages for that day.
c. Opacity values are the maximum 6-minute average for that day.
d.  All emission values reported in units consistent with the permit: CO, SO2 and NOx reported as parts per million, dry gas basis, corrected to 12% CO2 for Units 1&2 (ppmdv12) and 7% O2 for Unit 3 (ppmdv7), Opacity as %, SO2 Removal Efficiency as %.
e. SO2 compliance is based on concentration (ppm) or removal efficiency (% reduction between inlet and outlet emissions).
f. The dash symbol (-) indicates that a unit is off-line, has insufficient data for a compliance period or is in an exempted period.

*Results are provided for informational purposes only. Data is posted 24 hours after completion of each day to allow for quality assurance/quality control (QA/QC) review.

Read the Continuous Emission Monitoring  System (CEMS) FAQs to learn more

For more information on facility performance click here.

Process in Action

Waste-to-Energy: How Does It Work?

Waste-to-Energy takes non-hazardous waste - otherwise destined for landfill - and combusts it to generate steam for electricity generation. Ash is processed to recover metal for recycling while all gases are collected, filtered and cleaned before being released safely into the atmosphere.

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