Boston Sand & Gravel’s Charlestown facility not only operates with an active environmental management system to ensure regulatory compliance but it is also on a journey toward environmental sustainability, which began a decade ago. Our measurable accomplishments in sustainability include water recycling and conservation, commissioning a 109 kW solar energy array and steadily diminishing our greenhouse gas emissions and carbon footprint. Within the past 5 years we have succeeded in reducing facility demand for electricity and natural gas by 50% per unit of production and we are planning to further improve on that achievement.
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Protecting the Environment
Air Quality management: The plant’s program for air quality management complies with MA DEP regulations and management best practice procedures for the ready mix concrete industry. Fugitive emissions (dust) from material stock piles, yard and surface roads are controlled daily by water spray. Source emissions for cement, slag and fly ash off loading and for batching are controlled though dust collectors and bag houses, which are inspected and serviced by trained personnel and audited by environmental staff, in accordance with our state air permit. Combustion emissions are minimized with rigorous inspection and maintenance to ensure optimal operating efficiency.
Water Management: The facility is located in an area of increasing urban density with mounting competition for the municipal water supply. The plant yard has been reconstructed to collect all process and stormwater and reuse it for truck wash out and for batching a flowable fill product. The co-mingled stormwater and process water (‘gray water”) is treated at the waste water treatment plant and discharged under a NPDES permit to a local river. The process water recycling system implemented in 2003 not only enabled the use of gray water in batching flowable fill but also reduced the waste water loading to the treatment plant, lowered energy consumption and reduced the following: potable city water usage, the volume of waste water treatment chemicals and discharge of treated process water to the local river.
Concrete – Excess concrete returning from jobsites is recycled by forming blocks or crushing the hardened concrete for sale as road base or other fill.
Renewable Energy – Solar: Our commitment to reducing petroleum based energy sources extended to installing and commissioning a 109 kW (dc) photovoltaic solar energy system at the BS&G Maintenance Facility in December 2008. The system was designed to provide 75% of the annual energy demand of the facility, freeing up 120,000 kWh of power to other grid users and eliminating 94 tons/yr of carbon dioxide associated with greenhouse gas emissions. Consistent solar energy production coupled with on-going energy efficiency measures have resulted in the solar array providing nearly 110% of the facility’s power needs allowing us to sell excess electricity back to the grid.
Greenhouse Gas Reduction: In a 5 year period our initiatives in energy demand reduction and renewable solar energy allowed the facility to produce an equivalent production volume using 52% less energy with a similar reduction in carbon dioxide (greenhouse gas) emitted to the atmosphere.