Site 42 Treatment Ponds  

The Shamokin Creek Restoration Alliance in partnership with the Northumberland County Conservation District installed the first treatment system in the Shamokin Creek watershed in the Fall of 1999. Construction was completed and the project was online by the Fall of 2000. In 2006 additional compost was added to the site to facilitate treatment. Site 42 contributes approximately 88% of the iron loading to the Carbon Run subwatershed, located above Site 49. A passive wetland treatment system was installed to remove between 70-90% of the iron loading and add alkalinity to over 2.5 mi of Carbon Run. The subwatershed has two main tributaries that have pH values in the 5-6 range, with relatively minor iron coating problems. The removal of iron in a limestone drain/wetland system at Site 42 should allow macroinvertebrates and vertebrates present in tributaries to begin to repopulate the main branch of Carbon Run.

Site 42 is located on land owned by the Northumberland County Commissioners. It is an overflow (North Mountain Tunnel) from a deep mine that emanated from a culvert installed at the outlet of a mine tunnel.  

Treatment The treatment system consists of three ponds, beginning with a system to add alkalinity, followed by a settling pond (average depth of 1 m). A nearby stripping pit was used as a final settling pond for sludge. The total pond area is approximately 1.2 acres.


The system design was experimental; since its installation a lot has been learned about how to treat AMD. Most passive systems now use more mushroom compost than was originally included here. The chemistry of the water entering and exiting the ponds is tested once a year. Because the site is somewhat difficult to get to more frequent monitoring is not done.



Funding and support

  • Northumberland County Conservation District - project administration
  • SCRA - volunteer work, maintenance, repair
  • Bucknell University Geology - funding, background data, monitoring, data analysis, research, maintenance, repair
  • DEP Bureau of Watershed Management and US Environmental Protection Agency - 319 program funding
  • DEP Bureau of Abandoned Mine Reclamation - repairs
  • US Office of Surface Mining - funding
  • US Natural Resources Conservation Service - mapping
  • US Geological Survey - electrofishing survey
  • Northumberland County Commissioners - land access
  •  Damariscotta - design and consulting