Multilevel Environmental Impact Analysis - Environmental Impact Analysis: Process and Methods - page 238

the recent history of close cooperation between the federal agencies and
MWRA, the proven success of MEPA, and the level of trust developed, the
U.S. EPA deferred to the MWRA and MEPA, and no federal EIS or other
NEPA analysis was performed for the CSO program.

6.3 Multilevel Environmental Impact Case Studies

6.3.1 Boston Harbor Cleanup

The Boston Harbor Cleanup program is an actual example of a multilevel
environmental impact evaluation and EIS that developed sufficient informa-
tion at each level to keep the cleanup moving forward (see Section 10.1 for an
overview of the Boston Harbor Program). At issue was the wastewater gener-
ated from the Boston metropolitan area, which was almost 3.8 million cubic
meters of total wastewater a day from approximately 2.5 million people,
which received little or inadequate treatment prior to discharge to Boston
Harbor. The wastewater was conveyed to two primary wastewater treatment
plants, Nut Island for the southern portion of the system and Deer Island for
the northern portion. Both plants were designed to provide primary waste-
water treatment (i.e., short detention and settling of approximately 50% of
suspended solids), but age, lack of maintenance, inconsistent operation, and
flows in excess of capacity prevented the plants from even meeting accept-
able primary treatment standards.
The problem was exacerbated by the handling of wastewater residuals (also
known as sewage sludge). Following stabilization, the wastewater residu-
als, consisting primarily of the suspended solids that were removed during
primary treatment, were also discharged to Boston Harbor. The prescribed
operating procedure was to discharge the residuals only on the outgoing tide
so that they would be flushed from the harbor. However, the solids washed
back into the harbor when the tide reversed. Also, the operation was less
than perfect and discharge of residuals often occurred on the incoming tide,
leading to accumulation of solids in the harbor. This accumulation of solids
had a devastating impact on Boston Harbor caused by the concentration of
toxic compounds associated with the suspended solids, the depletion of dis-
solved oxygen as the solids decayed, and introduction of nutrients stimulat-
ing excessive algal growth.
The wastewater collection system was another contributing factor to the
degraded condition of Boston Harbor. The collection system was designed
early in the 20th century (and parts of the system a century before that) to
accept storm water runoff from all but the largest storms and convey it to
the wastewater plant for treatment prior to discharge. As the population
grew, this combined collection system (i.e., conveying the combined sanitary