Amanda Wilson
Dewatering removes surface water or groundwater from a site before construction commences. It’s one of the most vital steps in constructing structures with high water tables, inadequate slopes for water run-off, or excavations and trenches where water can accumulate. Rising environmental awareness, coupled with the stringent regulations for sludge disposal, drives the global dewatering equipment market, estimated to reach around $5.4 billion by 2025 at a CAGR of 4.4% from 2020 to 2025.
Why Dewatering is Important for Your Construction Site
Dewatering is crucial in construction as it offers stable and dry conditions for excavations by increasing soil stability and ensuring worker and equipment safety. Here are some reasons why dewatering construction sites is more significant than it appears.
- Providing a Safe Working Environment: Groundwater and surface water pose unsafe working conditions. Water can impede or damage the working of construction equipment. The wet or muddy ground can result in a tripping hazard for workers and also obstruct specific tasks.
- Firm Up the Soil: Dewatering of underground and surface water dries up the soil. Dry soil stabilizes the landscape by reducing the risk of sediment being carried off by the water and making it suitable for construction. It prevents incidents like groundwater or soil leakage, sand soiling, basement floatation, and upheaval failure.
- Environmental Protection: Standing water can attract mosquitoes and other pests and, therefore, pose a risk of diseases. Further, water can accumulate waste and toxins. Dewatering helps remove contaminated water and toxins and reduces the health hazards caused by pests and mosquitoes, besides helping comply with environmental regulations.
How Improper Dewatering and Disposal Affects Construction Sites and The Environment
Dewatering and water disposal, done right, are essential not only for construction but also for the surrounding ecology. As the water can contain harmful pollutants, improper collection and water disposal can lead to undesirable effects on the environment, besides causing erosion and related problems. It can result in significant hazards during construction site preparation and also during the building’s life cycle. It can lead to increased costs, safety risks, and undesirable delays.
Some of the associated impacts of improper management and discharge of water can be.
- Potential surface flooding.
- Adverse effects on building structure due to variations caused by soil conditions.
- Risk of erosion and related issues.
- Damage to adjacent properties due to flooding.
- Dampness and associated unhealthy conditions, including termite infestation.
Steps in Dewatering Process
- Water Assessment: Examine water’s nature and determine which contaminants it can contain and sediments you may need to separate.
- Get the required permits:Determine and obtain the permits mandated by federal, state, and local governments.
- Treat the water:Conduct preliminary treatment on-site based on the dewatering method and nature of pollutants, including filtering, removing silt, impurities, and sediments, and discharge it at the proper location.
The Need for Water Disposal for Dewatering Systems
Any dewatering system needs a robust and reliable water disposal route with adequate capacity for three primary reasons, which is often overlooked until pumping is about to begin.
- Continuity of Water Discharge: As the groundwater element of the water discharge is produced 24×7, it’s practically impossible to store water on-site; you need to transport it away from the construction site. Further, in large construction projects, the pumping could last several years.
- Pumping Tests Also Needs Reliable Water Disposal:Before starting the actual dewatering process, water from pumping tests also needs proper disposal. Also, water from well development requires careful disposal before the dewatering begins.
- The Weather Plays a Major Role:Some dewatering systems, like large excavations, pump a significant portion of surface water. Certain climate conditions such as tropical storms or snowmelt during spring add extra stress on this water disposal infrastructure.
Possible Water Disposal Methods
There is a range of water disposal methods, and they mandate obtaining relevant permits.
- Onsite Dewatering:If the water is pollutant-free, you can store the water in a secure location on-site and repurpose it for construction needs and let the rest evaporate. Sometimes, it’s also piped to nearby users for farmland irrigation or other purposes.
- Sewer System Discharge:Water with permissible pollutant levels can be discharged through the sewer systems after mandatory testing and treatment.
- Discharge to Adjacent Land: Water can be discharged to unoccupied land adjacent to the construction site with a detailed agreement with the owner.
- Disposal to Surface Water:Water can be discharged to an existing water body such as a lake, river, or sea after obtaining permission from an Environmental Regulator.
- Discharge Offsite:Water is collected and transported to an off-site facility for discharge using dewatering roll-off containers. Based on the water quality, it can be repurposed for uses like irrigation.
- Offsite Treatment:If the water consists of hazardous toxins or sediments, the safest and probably the only dewatering option is to transport it off-site for treatment to avoid adverse environmental impact.
Choosing the Right Discharge Area for Your Construction Dewatering
The right discharge area for construction dewatering is critical for a successful and on-schedule construction project. Here are some things to keep in mind while selecting a discharge area.
- Avoid Natural Slopes: The discharged water moves faster than naturally occurring stormwater, limiting the soil’s absorption rate and causing potential erosion. Discharging water on natural slopes can further increase the speed of water flow and lead to severe erosion. It can cause permanent alteration in the landscape. Thus, it’s recommended to avoid natural slopes and select a relatively leveled discharge area to avoid run-off problems and erosion.
- Find a Wooded Buffer: As shrubs and trees help reduce water travel speed to watersheds and streams, the discharge area should be in the vicinity of a wooded buffer. This way, the shrubs, and trees will absorb some of the water and help reduce erosion. It’s also helpful in limiting the loss of fish habitat and stream bank erosion, especially when a large water volume is discharged.
- Check the Water Table: In areas with a high-water table, the soil is saturated with groundwater, and hence, establishing a discharge area is almost impossible. In such cases, you can use a well with a pump to remove groundwater from the site and collect it in frack tanks or temporary storage ponds before loading it onto tankers for permanent disposal elsewhere.
Reliable disposal of the water from dewatering systems is often the last point on most contractors’ checklists; however, it’s important to avoid unnecessary fines, costs, and project delays. Dewatering tank solutions and frac tanks offer reliable, robust, and quick ways to store and transport the waste water from your construction site before it can be reused, recycled, or discharged.