---
title: Operations, Maintenance and Replacement of Passive Treatment Systems
description: "## Summary Even passive AMD treatment systems require ongoing operations, maintenance, and replacement (OMR) planning. This page provides an overview of common OMR activities organized by treatment system type -- including metals removal, limestone replenishment, and compost replacement -- with…"
url: "https://aml-connect.org/aml-knowledge-base/operations-maintenance-and-replacement-of-passive-treatment-systems/"
updated: "2026-10-16"
category: "AML Reclamation & AMD Treatment / AMD Treatment / Passive Treatment / Operations, Maintenance and Replacement"
---

# Operations, Maintenance and Replacement of Passive Treatment Systems

## Summary

Even passive AMD treatment systems require ongoing operations, maintenance, and replacement (OMR) planning. This page provides an overview of common OMR activities organized by treatment system type -- including metals removal, limestone replenishment, and compost replacement -- with links to detailed guidance for each system.

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For AMD discharges where passive treatment methods are sufficient, the passive systems require much less continuous maintenance than active treatment.  Still, even passive systems require a plan for ongoing operation, maintenance, and replacement (OMR).  Such OMR concerns should be analyzed even before the system is constructed, based on water quality information and flow measurements.

Provisions must be made for even the most basic maintenance activities, including mowing grass around a system and removing leaves that may clog conduits.  Some systems are surrounded by fences to prevent vandalism.  Also, animals may damage a system, especially muskrats, whose tunnels must be blocked with dirt and rocks.

Different types of passive treatment systems require specific OMR activities.  The list below includes some of these requirements and the types of systems to which they apply.  Follow the links for descriptions of each system, including more detailed OMR information.

## Clean & remove accumulated metals

- [Aerobic wetlands](http://amrclearinghouse.org/Sub/AMDtreatment/AnerobicWetland.htm)
- [Settling ponds](http://amrclearinghouse.org/Sub/AMDtreatment/SettlingPonds.htm)
- [SAPS & Vertical flow ponds](http://amrclearinghouse.org/Sub/AMDtreatment/-SAPS-VFP'S.htm) (via flushing)
- [Anoxic limestone drains](http://amrclearinghouse.org/Sub/AMDtreatment/AnoxicLimestoneDrains.htm) (at effluent only)

## Replenish limestone

- [Anoxic limestone drains](http://amrclearinghouse.org/Sub/AMDtreatment/AnoxicLimestoneDrains.htm)
- [Diversion wells](http://amrclearinghouse.org/Sub/AMDtreatment/DiversionWells.htm)
- [Limestone channels](http://amrclearinghouse.org/Sub/AMDtreatment/LimestoneChannels.htm)
- [Limestone sands](http://amrclearinghouse.org/Sub/AMDtreatment/LimestoneSands.htm)

## Replace compost

- [SAPS & Vertical flow ponds](http://amrclearinghouse.org/Sub/AMDtreatment/-SAPS-VFP'S.htm) (via flushing)
- [Sulfate-reducing bioreactors](http://amrclearinghouse.org/Sub/AMDtreatment/SulfateReducingBioreactors.htm)

For why steady funding matters, watch WPCAMR's video [Importance of Operations, Maintenance, and Rehabilitation Funding for AMD Treatment Systems](https://www.youtube.com/watch?v=7Jd867XDFSI).

[Final Recommendations of the Long Term Operation, Maintenance, and Replacement Workgroup](http://amrclearinghouse.org/Sub/AMDtreatment/OMRworkgroup.pdf) PA Department of Environmental Protection

[Operation and Maintenance Manual for Passive Treatment Systems](http://amrclearinghouse.org/Sub/AMDtreatment/OM%20Guidance%20Manual%20Damariscotta.pdf) developed by Damariscotta

[Why do some passive treatment systems fail?](http://www.dartmouth.edu/~cehs/CAGsite/treatment.html) by James J. Gusek, P.E.

[Operation & Maintenance Technical Assistance](http://www.streamrestorationinc.org/omtag.html) for Passive Treatment Systems, a service provided by Stream Restoration, Inc.

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## Related Pages

- [Treatment Strategies](/docs/treatment-strategies-overview) -- Treatment selection framework
- [Anoxic Limestone Drains](/docs/anoxic-limestone-drains)
- [SAPS and Vertical Flow Reactors](/docs/saps-vertical-flow-reactors)
- [Settling Ponds](/docs/settling-ponds)
- [Sulfate Reducing Bioreactors](/docs/sulfate-reducing-bioreactors)
- [Restoration Planning](/docs/restoration-planning) (Watershed Assessment) -- Plan OMR before construction

## Source and Last Reviewed

Source: AMR Clearinghouse (amrclearinghouse.org). Migrated to AML-Connect. Last Reviewed: 2026-03-13.

**Tags:** o-and-m, passive-treatment, practitioner, planning