Waste: Use of ‘Integrated Constructed Wetlands’ (ICW)

Glaslough, Castle Leslie, County Monaghan

Integrated Constructed Wetlands (ICW)

ICW site in Castle Leslie

Courtesy of Dan Doody

Integrated Constructed Wetlands (ICW)
Courtesy of Dan Doody

Integrated Constructed Wetlands (ICW)

ICW site in Castle Leslie

Courtesy of Dan Doody

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Glaslough is a historic village located some 10 km NE of Monaghan town and was developed around the renowned Castle Leslie and the picturesque Glaslough Lake.

The sewerage collection system serving the village of Glaslough became overloaded resulting in non compliance. Integrated Constructed Wetlands (ICW) were identified as a potential solution to the problem.

Natural wetland systems provide a range of environmental services including the treatment of polluted water.

Integrated Constructed wetlands (ICW) mimic shallow emergent-vegetated type wetlands and have the added objectives of landscape-fit and enhancing biodiversity. They have been shown to excel in the sustainable treatment of polluted water of various types. ICW systems with their relatively larger surface-water areas, optimal configurations and biological diversity facilitate treating, recycling and assimilating intercepted materials from the natural catchments which flow into the wetlands allowing us to deal with man-made pollution.

A constructed pond

A constructed pond

Courtesy of Dan Doody

A constructed pond
Courtesy of Dan Doody

A constructed pond

A constructed pond

Courtesy of Dan Doody

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Constructed wetlands have been used for dealing with sewage and industrial water-based waste since the 1960s. ICW allow liquid waste streams (from a variety of sources) to flow sequentially through a number of vegetated ponds, which, through a combination of physical, chemical and biological processes, have the capacity to produce a high quality effluent.

In Castle Leslie, five ponds stretching over some 6.74 ha were created and a wide variety of wetland species were planted. No pre-treatment needs to be carried out. The influent is pumped directly to a receiving (sludge) pond. From there the liquid flows by gravity through five sequential vegetated ponds and the effluent discharges directly to the Mountain Water River.

The Water Framework Directive was adopted into Irish law in December 2003. It provides a comprehensive framework for water quality management across the EU. ICWs could play a significant role in helping us to achieve the “good status” in all water bodies. Due to the slow movement of water through the ponds suspended matter is deposited, and there is adequate time for both aerobic and anaerobic digestion of organic matter. There is good reduction of nitrates and phosphates which can be greater than 95%. Reduction of fecal indicators is of the order of 99% due to the long retention times and the complex ecology of the aquatic system. ICWs may also remove endocrine disrupters such as estrogen and testosterone which are poorly removed with conventional wastewater treatment systems.

Mutli-functional space for recreation, biodiversity and ecologically sound sewage treatment

The area is used for recreation and riding trails have been provided. This is good example of a multi-functional project providing space for recreation, biodiversity and ecologically sound sewage treatment.

Courtesy of Dan Doody

Mutli-functional space for recreation, biodiversity and ecologically sound sewage treatment
Courtesy of Dan Doody

Mutli-functional space for recreation, biodiversity and ecologically sound sewage treatment

The area is used for recreation and riding trails have been provided. This is good example of a multi-functional project providing space for recreation, biodiversity and ecologically sound sewage treatment.

Courtesy of Dan Doody

Enlarge image

The Glaslough ICW has a design capacity of 1750 population equivalent (pe). (The current load is approximately 700pe). The total Capital Cost of providing and constructing the ICW (including land lease and monitoring equipment) is €770,000 including VAT. The estimated cost of a traditional treatment facility of 650pe capacity for Glaslough was €1,530,000 at 2008 prices. Including the monitoring equipment costs and the cost of additional amenities including surfacing horse riding trails, the ICW provides approximately 3 times the pe capacity at half the price.

Early results for Glaslough ICW are very encouraging with effluent quality, during the first year of operation, consistently matching the quality of the receiving Mountain Water River.