EXECUTIVE SUMMARY (Without Figures) rev - Town of Falmouth

and distribute the treated water over a greater area so that all the nitrogen TMDLs can be met, to
reduce the area of environmental impact for recharge, and to allow reuse for recharge of ponds,
streams, wetlands, and drinking water supplies. The following two treatment technologies were
evaluated to meet Massachusetts’ highest standards for treated water reuse and recharge into
Zone II areas:
Membrane Bioreactors (MBR) followed by granular activated carbon (GAC) adsorption
treatment (Treatment Scenario B).
MBRs followed by reverse osmosis (RO) water purification and carbon adsorption
treatment (Treatment Scenario C).
In addition to achieving lower total nitrogen concentrations, these process combinations would
be designed to remove endocrine disruptors, personal care products, and pharmaceuticals in the
water. Trace amounts of these components are now being detected in wastewaters and water
supplies due to their increased use and the development of more precise analytical methods.
These components are called “emerging contaminants” because they are being detected at low
levels but no threshold limits for human or environmental health have yet been developed.
MassDEP recently (early 2009) developed a total organic carbon (TOC) limit of 3 mg/L for
recharges into a Zone II area with groundwater flow times of greater than two years. The TOC
parameter is a surrogate for the many emerging contaminants that may be in the water; and
MassDEP research has indicated that treated water with TOC values less than 3 mg/L also have
very low (or non-detectable) levels of the emerging contaminants. MassDEP also developed a
TOC limit of 1 mg/L for recharges into a Zone II area with groundwater flow times of greater
than 2 years that do not have the benefit of treatment in the unsaturated soil zone (i.e, for direct
recharge to the groundwater system). MassDEP does allow some modifications to these limits
for specific circumstances after discussions/negotiations with MassDEP.
This evaluation also included infiltration of the treated water to the groundwater system through
a series of recharge wells located in the Route 151 right-of-way. The recharge wells require little
land disturbance, but must have highly purified water to avoid “soil plugging” at the well screen
and subsequent reduction of infiltration capacity. Treatment Scenario C can produce a treated
water suitable for well recharge as demonstrated at existing municipal installations. Treatment
Scenario B is a lower cost treatment technology that is believed to be suitable for well recharge.
Town of Falmouth, MA ES-12
Draft Comprehensive Wastewater Management Plan and
Draft Environmental Impact Report
7104510.6