Borough of Mount Joy, Lancaster County, PA


Mount Joy Borough Authority


Evaluate alternatives for compliance with proposed nutrient loading limits for Authority’s Wastewater Treatment Plant. Study evaluated upgrades to the existing facilities and nutrient trading options.


Nutrient Credit Trading to meet compliance

Mount Joy Borough Authority Nutrient Trading Project

As the first nutrient credit trade in the state, this project serves as a guide for municipalities and municipal authorities in need of an alternative to facility upgrades for compliance with the Chesapeake Bay Tributary Strategy.

Based on the Pennsylvania Department of Environmental Protection’s (PA DEP) nutrient loading criteria of 6-mg/l total nitrogen (TN) and 0.8-mg/l total phosphorus (TP) at the WWTP’s design flow of 1.53 MGD, the TN and TP loading limits for the plant were expected to be 27,945 lbs. and 3,726 lbs., respectively. Upon review of the current TN concentrations in the WWTP’s effluent, it became apparent the existing treatment processes would not be capable of meeting the nitrogen loading limits.

In the study, ARRO concluded that nutrient credit trading was the most cost-effective method for MJBA to meet compliance. Other solutions included:

  • A 76 percent savings to the ratepayer over plant upgrades
  • ARRO assisted MJBA in discussions with Brubaker Farms of Lancaster County to purchase the necessary credits
  • ARRO submitted a Nutrient Credit Trade Proposal to PA DEP on behalf of MJBA

In the case of MJBA, the purchase of nutrient credits saved rate payers a minimum of $12 per lb. of nitrogen from the cost of treatment plant upgrades and allowed for a cost-effective solution for achieving compliance.

“Groups like Mount Joy are learning firsthand how effective nutrient trading can be in meeting environmental goals at less expense than traditional command and control approaches. Mount Joy’s vision is a true showcase for many other local communities.”

John Hines
Executive Director – Water Planning Office
Pennsylvania Department of Environmental Prote


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ARRO Consulting, Inc.
(717) 569-7021    108 W. Airport Road    Lititz, PA 17543