Drainage Contractor

Step 1, trace the water. Harrowgate checks rainfall behaviour, topography, roof and pavement discharge, downstream constraints, historic changes, maintenance records, and signs of sediment or surcharge. CCTV, flushing, dye testing, survey, test pits, infiltration observations, or flow monitoring may be used to distinguish blockage from grade or capacity failure.

Step 2, confirm the approved route. The design establishes catchment, inlet locations, pipe sizes, slopes, storage, treatment, and legal outlet. Municipal connection permits, conservation-authority requirements, easements, and environmental approvals are addressed where applicable. Private water cannot simply be redirected to a road, neighbouring property, or sanitary sewer.

Step 3, locate services and control excavation water. Utility records and field locates are reviewed, daylighting is used at conflicts, and trench support follows soil and depth requirements. Bypass pumping, sump pumping, or dewatering is planned so pipe bedding is placed on a stable surface and sediment-laden water is not discharged without the specified controls.

Step 4, install from the outlet upstream. Starting at the known downstream elevation protects the grade available for every branch. Bedding is prepared to line and invert, pipe joints are cleaned and seated, structures are set from survey control, and laterals enter at the designed elevation and orientation. Laser and survey checks continue throughout the run.

Step 5, inspect before backfill. Pipe, joints, connections, bedding, haunch support, inverts, sumps, frames, and protection details are checked while visible. Testing, mandrel inspection, CCTV, leakage checks, or flushing follow the contract and pipe type. Selected embedment is placed evenly so pipe is not displaced or distorted.

Step 6, restore grades and commission. Trench backfill is compacted in controlled lifts, pavement and landscape grades are rebuilt to feed the inlets, and grates are adjusted to final surface. The system is cleaned, outlets and controls are confirmed, deficiencies are corrected, and as-built coordinates and inverts are recorded.

We begin with the civil or landscape drainage plan, the geotechnical report where one exists, and the municipal stormwater requirements for the site. Survey control establishes the invert elevations for every catch basin, pipe run, and outlet before excavation starts, so the finished system actually drains by gravity to the point of discharge rather than relying on guesswork.

Trenches are excavated, shored where required, and dewatered as needed to keep the work area workable. Bedding is placed to the specified depth, and pipe, catch basins, manholes, oil-grit separators, and culverts are installed on line and grade, with joints and connections made to the manufacturer's and municipality's requirements. Backfill is placed and compacted in controlled lifts so the completed trench does not settle and disrupt the pipe grade later.

Surface elements, including catch basin grates, French drain outlets, and swales, are built to the finished grading plan so water is captured at the low points and routed to the underground system rather than pooling on pavement or against building walls. Where a site discharges to a stormwater management pond or an oil-grit separator, Harrowgate confirms the facility is built and functioning to its design before the upstream drainage is connected to it.

Our process is consistent from first call to closeout. Harrowgate checks the site or the available drainage plan, visits to confirm grading, soil, and existing structures, and returns a written quote for the scope. Once approved, we perform the excavation, installation, and backfill, and close out with as-built information showing what was actually installed and where.