Legionella – Construction and Water Quality Management
Construction projects create unique water quality issues that need to be addressed to ensure minimizing the risk of Legionella and waterborne diseases. Risks of diseases can be minimized if requirements are followed during the design, construction, commissioning, replacement and expansion of new and existing buildings or structures. All water systems and components should be included in a comprehensive, water management plan. This management practice can not only minimize the risk of waterborne disease, including Legionella, but also reduce the liability risk for the building owner while increasing defensibility.
Best Practices for construction projects may include:
- Erosion and Sediment Controls
- Stormwater Management Controls
Erosion and Sediment Controls
Erosion and sediment controls may include both stabilization and structural control measures that are generally used during construction. These measures are designed to prevent or reduce erosion while redirecting stormwater flow during construction activities.
Examples of construction stabilization initiatives to prevent or reduce erosion include temporary seeding, permanent seeding and mulching. Temporary seeding is the use of vegetation such as grass, which grows quickly, to hold soil in place to prevent erosion due to wind current or stormwater. Permanent seeding is the use of vegetation to prevent soil erosion, then remain as part of the final landscaping. Mulching is the use of a material such as hay, grass, wood ships, gravel or straw on top of the soil to prevent erosion.
Structural control measures prevent pollutants from leaving the construction site and limit the amount of water flow or change the direction of the water flow. Examples include earth dikes, silt fences, sediment traps and sediment basins. Earth dikes use soil to divert uncontaminated water from contaminated areas. They also allow contaminated water flow to deposit in sediment traps. Silt fences trap sediment on one side of the fence while allowing water to flow through. Sediment traps allow sediment to settle in a specified area, such as an empty pond. And sediment basins allow sediment to settle in a specified area while controlling the release of water flow.
Stormwater Management Controls
Stormwater management controls are generally used after completed construction to prevent pollution due to stormwater runoff. Examples include retention ponds, detention ponds, infiltration and vegetated swells/natural depressions. Retention ponds are formed when stormwater runoff is retained in a pond. The stormwater may then be removed through evaporation, infiltration or emergency bypass. A detention pond holds water while sediments settle. The water is then slowly released. Infiltration measures may include trenches, basins and dry wells that allow water to move from the surface into the soil below. Last, vegetated swells and natural depressions are vegetation, usually grass, that lines the swell and removes sediments from the runoff. The water then infiltrates into the surface soil.
Benefits of using a comprehensive water management plan designed and implemented by Nancrede Engineering during construction include minimizing the risk of waterborne disease, such as Legionella. Legionella can travel up to 6 km or 3.78 miles. That’s a large radius that could potentially encompass a dense population. Minimizing the risk of Legionella or another waterborne pathogens will reduce the risk of liability while increasing building owner defensibility. Implementation of a comprehensive water management plan may also increase the real estate/asset value for the building owner. The use of a documentation process to track verification and validation may prove to be priceless.
From an environmental standpoint, implementing a comprehensive water management plan during construction can reduce the impact of soil/sediment invasion into water systems thus reducing pollution. Best Management Practices include structural, vegetative and managerial practices that treat, prevent or reduce water pollution.
Finally, decorative or display settings used as part of the aesthetics in a finished building/structure such as fountains and waterfalls, create potential hazards that should be addressed in a comprehensive water quality management plan. This plan should integrate risk management, facility management and construction management with the water management team for defined processes and defensible consistency.