Natural restoration, also called natural attenuation, is the cleanup of groundwater contamination by natural physical, chemical, and microbiological processes. The rate and effectiveness of natural restoration of groundwater quality is affected by many factors, including the type and amount of contamination, and the physical and geochemical nature of the aquifer. Prediction of the rate and effectiveness of cleanup requires a sound scientific understanding of the complex interactions of these processes and factors. The USGS is adding to this understanding through a detailed study of a treated-wastewater plume at the Massachusetts Military Reservation on Cape Cod. The plume has been undergoing natural restoration for 10 years since 60 years of land disposal of treated sewage ended in 1995. The study includes monitoring of groundwater quality, tracer tests and laboratory experiments to identify and characterize the cleanup processes, and numerical modeling to integrate the understanding of these processes.

Environmental Science and Technology - January 2006
Long-term natural attenuation of carbon and nitrogen within a groundwater plume after removal of the treated wastewater source
Abstract

USGS Water-Resources Investigations Report 03-4017
Reactive-transport simulation of phosphorus in the sewage plume at the Massachusetts Military Reservation, Cape Cod, Massachusetts
Abstract

USGS Water-Resources Investigations Report 99-4018C
Natural restoration of a sewage plume in a sand and gravel aquifer, Cape Cod, Massachusetts
Abstract

USGS Water-Resources Investigations Report 99-4018C
Evolution of a groundwater sewage plume after removal of the 60-year-long source, Cape Cod, Massachusetts--pH and the fate of phosphate and metals
Abstract

USGS Water-Resources Investigations Report 99-4018C
Evolution of a groundwater sewage plume after removal of the 60-year-long source, Cape Cod, Massachusetts -- Changes in the distribution of dissolved oxygen, boron, and organic carbon
Abstract

USGS Water-Resources Investigations Report 99-4018C
Modeling the evolution and natural remediation of a groundwater sewage plume
Abstract

Map showing the locations of monitoring wells and multilevel samplers used to investigate the natural restoration of the contaminated aquifer following the cessation of disposal of treated wastewater onto infiltration beds at the Massachusetts Military Reservation. See LeBlanc and others (1999) for more information about the investigation.

View southeast of area that is focus of natural-restoration study. Treated wastewater was applied to sand-infiltration beds (in foreground) from about 1936 to 1995. Ashumet Pond is about 1,700 feet southeast of the infiltration beds.

Longitudinal vertical sections showing specific conductance (µS/cm), dissolved oxygen (µM), and boron (µM) in groundwater along transect A-A' (see map above) in 1996 (0.5 yrs), 1998 (2.5 yrs), 2000 (4.5 yrs), 2002 (6.5 yrs), and 2004 (8.5 yrs post-cessation). Dots show positions of well screens and multilevel sampler ports (Modified from figure 3 in Repert and others, 2006)

Longitudinal vertical sections showing DOC, nitrate, and ammonium (µM) in groundwater along transect A-A' (see map above) in 1996 (0.5 yrs), 1998 (2.5 yrs), 2000 (4.5 yrs), 2002 (6.5 yrs), and 2004 (8.5 yrs post-cessation) (Modified from figure 4 in Repert and others, 2006)