Construction Dewatering

Most water takings above 50,000 litres on any day require an Ontario environmental permission. Eligible construction dewatering from more than 50,000 through 400,000 litres per day uses EASR registration with required technical reports and operating measures. Takings above the applicable 400,000-litre threshold require a Permit to Take Water under the current regulation.

Not without the required City approval and compliance. Toronto requires a sewer discharge permit or agreement before private water, including groundwater and construction dewatering, enters a storm, sanitary, or combined sewer. Water must meet the specified limits and monitoring conditions. Sediment-laden water is treated, and no construction slurry or debris is allowed into inlets.

Sump pumping collects water after it enters the excavation and suits localized seepage or stormwater where soil remains stable. Wellpoints lower groundwater outside or beneath the cut through screened points connected to a vacuum header, which is useful in shallow permeable soils. Harrowgate selects from soil, depth, inflow, stability, and drawdown requirements.

We use properly selected well screens and filter packs, graded sump stone, geotextile where designed, low intake velocity, controlled pumping rates, and staged treatment. Turbidity, settlement, piezometric level, and base condition are monitored. Running sand, cloudy discharge, or new settlement triggers immediate adjustment because the system must remove water without mining the ground.

Critical systems use duty and standby pumps sized for design flow, backup power, automatic level controls, high-level alarms, spare hoses and fittings, protected electrical or fuel supply, and emergency storage or alternate discharge. The reserve depends on inflow and consequence of failure. Harrowgate tests standby operation and keeps access clear for service during storms and off-hours.

Treatment is selected from flow and water quality. Settling or weir tanks remove heavier solids, filter bags and media capture finer particles, and additional systems address pH, oil, metals, or other project parameters. Samples and field readings confirm compliance before discharge. Tanks and filters are cleaned before accumulated sediment reduces residence time or causes bypass.

Shutdown occurs only after the structure, backfill, utilities, and permanent drainage can resist groundwater and storm inflow. Harrowgate follows the engineer's sequence, reduces pumping gradually where required, monitors rebound and movement, and decommissions wells or sumps with approved seals. Premature shutdown can uplift slabs, flood work, soften bedding, or overload incomplete drainage.