Install Permeable Reactive Barriers
Permeable reactive barriers (PRBs) can treat groundwater with high levels of nitrogen. They can be installed near the shoreline to intercept groundwater flow before it reaches a bay or cove, or at the edge of a septic system drain field to intercept and treat nitrogen-enriched septic effluent. In each instance, a trench is dug with a mixture of course sand, wood chips, compost and/or other material, and the carbon source fuels the uptake of nitrogen by microbes in the groundwater.
Nitrogen Removal
- 70-75%
Cost Efficiency
- $140 per pound of nitrogen removed
Project Costs
- Overall Cost Range: $2,500 to $3,000
- Operations and Maintenance: $220 per year
Strengths
- PRBs are less expensive than a full septic upgrade
- They treat septic effluent or nitrogen-enriched groundwater directly before it enters water body
- Treats the remaining nitrogen in groundwater from older septic systems
- PRBS have highly effective (70-75%) nitrogen removal
- Require little maintenance
Weaknesses
- PRBs are not necessarily under warranty
- Lifespan of treatment material is still unknown
- Requires specific lot size and space for construction
- Correct placement of PRB requires understanding of groundwater flow in the area, etc.
- Technologies are still in development
- Unclear requirements for permitting
