Erosion and Sediment Control

Erosion control prevents soil particles from detaching by protecting surfaces and controlling runoff velocity. Sediment control captures particles after they move using barriers, traps, basins, filters, or settling. Harrowgate uses both. A perimeter barrier cannot replace stabilized slopes, and mulch alone cannot capture sediment carried from active excavation or haul routes.

Controls are installed before clearing, stripping, excavation, or stockpiling creates a sediment path. Perimeter protection, entrances, clean-water diversions, inlet protection, and designated stockpile zones come first. As grading changes, measures move or are added. Temporary controls remain until permanent surfaces, drainage, and vegetation are established and the approved removal criteria are met.

Silt fence is intended for sheet flow from small areas, not concentrated channel flow. Water concentrated in a ditch can overtop, tear, or undercut it. Harrowgate uses check dams, sediment traps, lined channels, diversion, or other designed measures in ditches, while silt fence is placed along contours with keyed ends and proper trenching.

Inspection frequency follows the approved plan and permits, with additional checks before and after significant rain, snowmelt, dewatering, and major grading changes. Active entrances and inlets are observed daily. Harrowgate records condition, sediment depth, tears, undercutting, overtopping, scour, maintenance, and upgrades so controls remain functional rather than merely present.

The inlet measure is selected for drainage area, sediment load, traffic, and required overflow. Inserts, filter berms, gravel collars, or temporary covers are installed with an approved emergency path. Sediment is removed before capacity is lost. Harrowgate also stabilizes upstream soil so the catch basin is not expected to filter the entire site.

Pumped water passes through settling tanks, filter bags, media, sediment basins, or other approved treatment before the permitted outlet. Flow is spread or energy-dissipated so it does not erode the discharge area. Turbidity and required water-quality parameters are monitored, and filters are changed before blinding, rupture, or bypass sends sediment downstream.

Removal occurs after disturbed areas are permanently stabilized, drainage works are operating, vegetation has established to the approval criterion, and accumulated sediment is cleaned out. Controls are removed in a sequence that does not release trapped soil. Harrowgate restores trenches, post holes, stone areas, and flow paths, then documents final condition and any ongoing maintenance items.

Common causes include excessive drainage area, concentrated flow, poor trenching, weak posts, overtopping, undercutting, damage, or accumulated sediment. The right control and maintenance must match the flow.

Removal follows stabilization and project acceptance criteria. Vegetation, stone, pavement, or other permanent cover must be established, drainage must function, and disturbed areas from removal must be restored.