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About Us
I. Site Description
II. SEMASS Resource Recovery Facility
III. Associated Satellite Facilities
IV. Links
The SEMASS Resource Recovery Facility (SEMASS RRF) is located on a 95-acre area in the northeastern part of the Town of Rochester, Massachusetts. The site is bordered by state Route 28 (Cranberry Highway) to the north along with light industrial/ commercial properties and woodlands, a mixture of wooded, commercial, and residential areas to the west, and cranberry bogs and associated wetlands areas to the east and south. The facility is located a short distance from Exit #2 on U.S. Interstate Route 495 for convenient truck access. Rail receipt of solid waste (MSW) at the SEMASS RRF is accomplished via several rail spurs on the southern boundary of the facility that connect with two southeastern Massachusetts freight rail lines managed by the Commonwealth’s Executive Office of Transportation and Public Works.
The SEMASS Resource Recovery Facility (SEMASS RRF) is operated and managed by Covanta SEMASS, L.P. on behalf of the owner, the SEMASS Partnership. Covanta Energy, Inc has a 90% ownership interest in the SEMASS Partnership. The SEMASS RRF began full-scale operations in August 1988. The site presently includes the Energy from Waste Municipal Waste Combustor facility (MWC) which is divided into Fuel and Power sides connected by a number of enclosed waste conveyors. The site also includes an administration building, a scale house with entrance and exit scales, a parts warehouse, a water treatment facility, a Maintenance Garage, an equipment laydown yard, and three stormwater detention basins.
II. SEMASS Resource Recovery Facility
The SEMASS Resource Recovery Facility (SEMASS) converts municipal solid waste (MSW) to steam and electricity, and offers MSW disposal for approximately sixty (60) participating communities in Cape Cod, southeastern Massachusetts, and the Boston metropolitan area. The facility is located on a 95-acre site on Route 28 in Rochester, Massachusetts. It is designed to receive MSW, magnetically separate and shred it to produce processed refuse fuel (PRF), which is fired in specially designed waterwall boilers.
The original plant, referred to as the “Base Plant” included Emission Units No. 1 and 2, a condensing turbine generator, air-cooled condenser, water-cooled auxiliary condenser, air pollution control equipment, a switchyard, and auxiliary support systems. Emission Unit No. 3 was constructed at a later date and is termed the “SEMASS Expansion” plant. Emission Unit No. 3 also includes a condensing turbine generator, air-cooled condenser, air pollution control equipment, a switchyard, and auxiliary support systems.
SEMASS consists of three boilers, each rated at a design heat rate input of 375 million Btu per hour (MMBtu/hr). The design PRF feed rate to each boiler is 41.67 tons per hour based on the lowest anticipated PRF heating value of 4,500 Btu per pound (Btu/lb). Combustion temperatures in the boilers and the furnace design ensure exposure of gases to a minimum temperature of 1,800ºF for one second after secondary air injection.
MSW is delivered by truck and rail to an enclosed solid waste receiving building where it is unloaded onto a tipping floor. The MSW is loaded onto conveyors, inspected at picking platform stations, and then sent for shredding and processing by four horizontal-shaft hammermills which create the PRF.
From the combustion of PRF, each boiler can produce up to 320,000 pounds of steam per hour. The steam generated from the boilers is supplied to two (2) steam turbines each with electric generators capable of producing a total of 80 Megawatts of renewable electricity. The SEMASS RRF uses approximately 10-12 Megawatts for its own parasitic power needs with the remainder provided to the New England power grid system via NSTAR.
Air Pollution Controls
The SEMASS RRF boilers are equipped with state of the art pollution control equipment as detailed below.
Ash System
Bottom Ash and Processed Bottom Ash (PBA).
Bottom ash from each boiler is processed through two submerged drag chain conveyors, one for coarse ash and one for fine ash. These conveyors convey the cooled ash to a vibrating shuttling conveyor which transfers the material onto either the vibrating slip stick conveyor or the ash belt for transport to the Ash Plant. Prior to discharging into the Ash bunker, the bottom ash passes under redundant drum magnets that provide primary ferrous removal.
A front end loader is used to transport bottom ash from the storage pit to a storage hopper. A vibrating pan conveyor then conveys the material at a controlled feed rate onto a primary belt conveyor. A permanent secondary magnet system is provided to collect any additional ferrous metals from the ash stream. The ferrous product is then routed to small hoppers via a discharge chute.
Converting bottom ash to PBA involves a series of conveyors, screens and pans to grade the material to a size of >3/8” but less than 4-inch (typically). Non ferrous metals are reclaimed from material during this process by exposure of the material to an eddy current separator (ECS ). PBA is transported to the PBA Storage Silo for temporary storage prior to off-site transport.SEMASS Resource Recovery Facility schematic process diagram
III. Associated Satellite Facilities
The network of supporting satellite facilities form the unique system that Covanta SEMASS uses to manage and control the daily load of incoming solid waste, process this waste, and dispose of by-product combustion ash in a safe, environmentally compliant, and cost-effective manner. The network of these supporting satellite facilities provides significant operational flexibility to the SEMASS RRF. Refer to their descriptions below.
CMW Landfill.
The CMW Landfill is located on a site approximately 95 acres in size in the southeastern section of Carver, MA. Ash from the SEMASS Resource Recovery Facility (RRF) and by-pass solid waste (MSW) is disposed at the landfill. Refer to the facility layout in Attachment A. Site access is from Federal Road. Landfill North, an older unlined landfill from the 1970’s occupies the north end of the site and was closed and capped in 1995. Landfill South occupies the southern end of the site and is a modern, double-lined landfill. Landfill South started operating in 1988 at the same time as the SEMASS RRF and is comprised of five Phases (I through V) split into fifteen (15) cells. The “valley” area between Landfill North and Landfill South, known as the Final Development Phase, consists of two, double-lined Phases (VI and VII) split into 3 cells. Construction of the first portions (Phase VI, Cell A and Phase VI, Cell B) of the Final Development Phase has been completed and are operational. Construction of Phase VII is currently underway at the date of this application.
The CMW Landfill is dedicated to the SEMASS RRF and is not open to the public. CMW Landfill is a critical component for ash and bypass solid waste disposal for SEMASS. Construction, operation, and maintenance of CMW Landfill is a cooperative three-way arrangement between the landowner (Wankinco River, Inc.), the permittee (CMW Regional Refuse Disposal District – the local Solid Waste Authority) and Covanta SEMASS (the Operator).Braintree Transfer Station.
The Facility is located on Ivory Street in Braintree, Massachusetts, occupying the former Town of Braintree solid waste incinerator building adjacent to the former Town landfill. SEMASS modified and expanded the old incinerator building in 1988 into a solid waste transfer station to enable it to accept solid waste from Braintree and other communities in the immediate Boston metropolitan area.
The Braintree TS is comprised of a tipping floor of approximately 10,000 square feet opening directly to two loading pits, each of which can accommodate a waste transfer trailer. There are two truck scales; one is used for incoming waste collection vehicles, and the other for outgoing transfer trailers. Ample maneuvering room exists in front of the tipping floor for waste collection vehicles pulling into or out of the facility. There is a separate waste drop-off area for Braintree residents on the south side of the building operated by SEMASS, and a household recyclables collection area, owned and operated by the Town of Braintree, just to the north of the Facility.
CMW-Rochester Convenience Center.
The Center is located at the intersection of Route 28 and King’s Highway in Rochester, MA very close to the SEMASS RRF. The site is over 10.5 acres with approximately 2 acres of waste handling area. The Center is accessed by a paved entrance road off Route 28. The Center has locations for the receipt of residential drop-off solid waste materials, recyclables, and yard waste for the residents of the SEMASS Host Communities: Carver, Marion, Rochester, and Wareham. The center operates with two (2) 4-cubic yard waste compactors plus several roll-off containers for recyclables (bottles, cans, paper, plastic, etc.). A SEMASS attendant operates the compactors and ensures smooth operations of the facility. Compactor roll-off containers, when full, are brought to the SEMASS RRF for emptying.Construction, operation, and maintenance of the CMW-Rochester Convenience Center is a cooperative arrangement between the CMW Regional Refuse Disposal District (Owner & Permittee) and Covanta SEMASS (the Operator).
For more information on Covanta Energy visit the corporate website: www.covantaholding.com
For more information on Municipal Waste Combustors in Massachusetts, facility and trend information, and their regulations, visit the MADEP’s website at: www.mass.gov/dep/recycle/solid/mwc.htm