Section 1. COAL, COKE AND POWER PLANT WASTES
DESIGN AND OPERATION OF A WASTEWATER TREATMENT FACILITY
AT AN EXISTING FOSSIL POWER PLANT
Daniel A. Carvalho, Chemical/Environmental Engineer
Stone and Webster Engineering Corporation
Boston, Massachusetts 02107
Dinesh K. Patel, Project Engineer
Boston Edison Company
Boston, Massachusetts 02110
INTRODUCTION
The New Boston/L Street Station is located in Boston, Massachusetts, within two miles
of downtown Boston.   Consisting of two 380-MW oil-fired steam electric generating units
and three oil-fired steam generating units, the station is also part of Boston's district steam
heating supply system.   The problem of limited space was solved by constructing the entire
waste treatment facility indoors within Turbine Room No. 3, which is no longer in use.   For
example, an existing reinforced concrete turbine pedestal was utilized as the foundation for
the clarifier/thickener.   In addition, the associated condenser pit areas and environs were
utilized or sectionalized, where possible, to locate the various chemical treatment unit operations and required treatment equipment systems.
This paper outlines the basic design considerations developed by S & W in the engineering
and design of this waste treatment facility.   In addition, this paper presents Boston Edison
Company's (BECO) evaluation of the operation and performance of the waste treatment
system based on operating experience gained by BECO from the July 1977 commercial
operation date to the present. This waste treatment facility was designed to meet the
July 1, 1977, Environmental Protection Agency (EPA) National Pollutant Discharge
Elimination System (NPDES) permit limits (Table I) for the New Boston/L Street
Station.
Table I.
1977 EPA NPDES Effluent Limits
(mg/1)
(mgd)
pH Units
Daily Ave                  Daily Max
Daily Ave           Daily Max
Flow
PH
Total Suspended
Solids
Total Oil and Grease
Total Copper
Total Iron
6.5-8.5
30.0
100.0
10.0
15.0
1.0
1.0
1.0
1.0
1.0
2.0
DESIGN CONSIDERATIONS
Waste Characterization and Fundamental System Design
The proper design of a continuous waste treatment system depends on obtaining accurate
information on the frequency and types of wastes to be treated, the variation in both waste
flow and waste constituents (i.e., waste characterization), and, finally, the treatability of
these wastes to meet the EPA NPDES permit limits.   Extensive waste surveys were undertaken to determine the above information and to design the most economical waste collection
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