Storm Drain Installation in Hillsboro, Oregon

Quick Verdict

Storm drain installation in Hillsboro is the excavation and pipe work that collects surface water at catch basins and carries it away to the storm system or an approved outfall, often with water-quality treatment along the way. Hillsboro sits on the flat Tualatin Valley floor in Washington County, where the soil is heavy clay and the grades are gentle, so properties need engineered drainage to move water. What sets Hillsboro apart is the regional stormwater program: Washington County's clean-water rules commonly require that runoff be treated, not just piped away, using features like water-quality swales or filters. A proper install manages the flat clay ground and meets those water-quality standards.

The Tualatin Valley Setting

Hillsboro lies in the Tualatin Valley, a flat lowland drained by the Tualatin River and creeks like Rock Creek and Dawson Creek. The native ground is largely clay, which drains poorly, and the terrain is level, giving little natural fall. It is also the heart of the Silicon Forest, so alongside homes there is a great deal of commercial, campus, and industrial development that all needs stormwater management.

On this ground, water does not leave on its own. Left unmanaged it causes:

• Ponding in lots, drive aisles, and low yards
• Saturated ground that stays soft for months
• Water intrusion at foundations and slabs
• Pavement failure from a waterlogged base

A designed storm drain system, with treatment where required, is the standard answer.

Water Quality: What Makes Hillsboro Different

In much of Washington County, stormwater is not just collected and discharged; it is treated to protect the Tualatin River and its tributaries. The regional clean-water program commonly requires runoff to pass through a water-quality feature before it leaves the site.

Common treatment approaches:

• Water-quality swales. Vegetated channels that filter runoff as it flows.
• Filter systems and catch-basin inserts. Media that captures pollutants.
• Detention. Holding runoff and releasing it slowly to avoid overwhelming creeks.
• Rain gardens and bioretention. Landscaped areas that soak and filter water.

This treatment requirement means Hillsboro storm drainage is often a system of collection plus treatment, not just pipe to an outfall. It is part of the broader storm drain and catch basin installation discipline, with an added water-quality layer specific to the region.

Installing on Flat Clay Ground

The physical install has to overcome flat grades and clay:

1. Locate utilities and call 811.
2. Excavate trenches to the design grade, holding careful slope on level ground.
3. Bed pipe on compacted granular material so it does not sag.
4. Set catch basins level at the low points.
5. Build any required water-quality swale, filter, or detention feature.
6. Backfill in compacted lifts and grade the surface to the basins.
7. Connect to the storm system or approved outfall.

Clay drains poorly, so the surface capture, catch basins, and grading are critical; water has to be led to the inlets because it will not soak away. And on flat ground, the pipe slope has to be held precisely to keep the line from silting up.

What to Expect on Job Day in Hillsboro

Because the Tualatin Valley clay is heavy and holds water, timing matters: the roughly May-through-October dry window is when the ground is firm enough to trench cleanly and stage the work without churning a lot to mud. Every job opens with a free 811 locate, which is especially worth doing carefully across Hillsboro's mix of older residential streets and newer tech-corridor development, where utilities can be dense. A typical residential day runs from opening the trenches and setting invert elevations, to bedding and laying pipe, dropping the catch basins level at the low points, building whatever water-quality feature the design calls for, and finishing with compacted backfill and surface grading to the inlets. The treatment feature is the piece that sets Hillsboro apart from a plain pipe-to-outfall install -- a swale or filter takes its own excavation, media, and grading, and it has to be built to the regional standard, not improvised. On commercial and campus sites in the Silicon Forest, detention and treatment can be the largest part of the job.

Rules and Permits in Hillsboro

Storm drainage here is regulated by the city and the regional clean-water program, plus state rules on larger sites.

Consideration	Why It Matters
Regional water-quality standards	Runoff often must be treated before discharge
City and county stormwater rules	Govern connection and how much runoff you can release
Connection permits	Required to tie into the public system
Erosion and sediment control	Protects the Tualatin River watershed

The water-quality requirement is the piece people miss. In much of Hillsboro and greater Washington County the regional wastewater and stormwater utility, Clean Water Services, sets the design and water-quality standards that a storm system has to meet, working alongside the city. Assuming you can simply pipe water to the street can lead to a redesign, so confirm the treatment and permit requirements early. A contractor working in Washington County knows the program and designs the treatment in from the start rather than bolting it on later.

What Storm Drain Installation Costs in Hillsboro

Cost depends on catch basins, pipe length and depth, and especially any required treatment features.

Item	Baseline Range
Excavator + operator, hourly	$150 - $350+ per hour
Trenching, per linear foot	$8 - $40+ per linear foot
Crushed gravel / bedding, delivered	$45 - $110+ per cu yd
Catch basin, each	varies by size and depth
Water-quality feature	varies by type and size
Residential permit pull	$100 - $600+ (varies by jurisdiction)

Industry Baseline Range: A residential storm drain system in Hillsboro commonly runs $3,000 to $15,000+; commercial sites with treatment and detection features run substantially higher.

These are industry baseline ranges for planning only -- actual pricing depends on site conditions, soil, access, depth, haul-off, and current market conditions. Get a site-specific quote.

Current Market Reality

Treat the table as a floor. Hillsboro jobs often run two to three times baseline once the required water-quality feature, a swale, filter, detention, or bioretention, is added, and that treatment can be the biggest single line item. Heavy clay that will not compact and has to be swapped for imported gravel, longer flat runs to reach an outfall, and dense utilities on tech-corridor sites all push cost up. A design that has to be revised late because treatment was not planned for is the most expensive surprise of all, which is why confirming the Clean Water Services requirements up front pays off.

Where a driveway crosses a ditch, this often pairs with culvert installation in Hillsboro.

Collect and Treat, the Hillsboro Way

Draining a Hillsboro site means beating flat clay ground and meeting the region's water-quality expectations. Catch basins, carefully sloped pipe, sound bedding, and the required treatment feature together keep the property dry and the Tualatin watershed protected. For how drainage fits a full site plan, see the excavation contractor guide for Oregon.

The Bottom Line

Storm drain installation in Hillsboro combines standard drainage on flat Tualatin Valley clay with the region's water-quality treatment requirements. Get both right and your site drains cleanly and legally. Cojo is CCB licensed and insured, based in Hood River and serving Hillsboro and statewide Oregon. See our excavation services or request a free estimate for your Hillsboro drainage project.