Parking Lot Drainage in Eugene, Oregon: Stop the Ponding

Why Eugene Parking Lots Pond

If you manage commercial property in Eugene, you already know the rainy season is long. The southern Willamette Valley collects runoff from the Coast Range and the Cascades, and Eugene sits low enough that water has to be actively moved off your asphalt — it will not simply evaporate during eight months of gray skies. When a parking lot ponds, it is almost never the rain's fault. It is a grading, drainage, or maintenance problem that water simply revealed.

Standing water on a lot off West 11th, Coburg Road, or Gateway is more than an eyesore. It accelerates asphalt failure, undermines the base, breeds potholes, freezes into a liability hazard in winter, and washes out striping. The good news is that ponding has a finite list of causes, and each one has a known fix. This guide walks through what causes it in Eugene's wet, valley-floor conditions and what it takes to correct it.

For the wider picture of how surface and subsurface water moves on a property, start with our guide to property and site drainage in Oregon. For the engineering side of lot grading, see parking lot drainage design in Oregon.

The Common Causes of Lot Ponding in Lane County

Flat or Negative Slope

A parking lot needs roughly a 1 to 2 percent slope to drain — about a quarter-inch of fall per foot. Eugene's valley-floor lots were often built on naturally flat ground, and over years of traffic loading the asphalt settles unevenly. Low spots form, slope flattens, and water has nowhere to go. Once a "birdbath" appears, it tends to grow, because standing water softens the asphalt beneath it.

Clogged or Undersized Catch Basins

Eugene's tree canopy is one of its best features and one of drainage's worst enemies. Leaves, needles, and silt fill catch basins and storm lines through the fall, and by the first heavy November rain the inlets back up. A catch basin that worked fine in summer can overflow completely once it is half-full of organic debris.

Failing Sub-base

Lane County's valley soils hold water. When the gravel base under your asphalt stays saturated through the wet months, it loses load-bearing strength, the surface sinks, and new low spots appear. This is why a lot can drain well for years and then start ponding seemingly overnight.

Crushed or Disconnected Storm Lines

Older lots near downtown Eugene and along the river frequently have storm pipe that has shifted, cracked, or separated at the joints over decades. Water enters the catch basin and then has nowhere to go.

How Parking Lot Drainage Gets Fixed in Eugene

The right repair depends entirely on the cause, which is why a site assessment comes first. The common solutions include:

• Regrading and an asphalt overlay — For lots that have lost their slope, milling the surface and laying a new overlay re-establishes positive drainage toward the inlets. This is the most durable fix for widespread ponding.
• Adding or relocating catch basins — If water collects in a spot with no inlet nearby, a new catch basin tied into the storm system gives it somewhere to go. Eugene's leaf load makes accessible, cleanable basins a priority.
• Trench drains — Across entrances, loading areas, and drive aisles, a linear trench drain captures sheet flow before it crosses the lot.
• Storm line repair or replacement — Cracked or collapsed pipe gets excavated and replaced, often with larger-diameter line to handle Eugene's peak winter flows.
• Targeted patch-and-level — Isolated birdbaths can sometimes be corrected with infrared patching or a leveling course, a cost-effective option when the rest of the lot is sound.

Our excavation services cover the grading, trenching, and catch-basin work these fixes require.

What Parking Lot Drainage Costs in Eugene

Drainage corrections are priced by the foot, by the structure, and by the volume of excavation — not by a flat rate — so any figure here is a starting reference, not a quote. Industry baseline ranges that contractors commonly reference include:

Work	Industry Baseline Range
Catch basin installation (each)	$1,200–$3,500
Trench drain (per linear foot)	$50–$150
Storm line / French drain run (per linear foot)	$25–$60
Asphalt overlay for regrading (per sq ft)	$2–$5

Actual Eugene pricing depends on how deep the excavation runs, whether existing pipe can be reused, how far the nearest storm tie-in sits, and how much asphalt has to be removed and replaced. A lot that only needs a new catch basin and a short run of pipe sits at the low end; a full regrade with new storm infrastructure runs well above it. The only way to budget accurately is a site assessment.

Why a Site Assessment Matters Here

Two Eugene lots with identical ponding can need completely different repairs. One may have a flat slope correctable with an overlay; the next may have a collapsed storm line under the asphalt that no amount of resurfacing will fix. A proper assessment checks slope with actual measurements, inspects and flushes the existing catch basins and lines, evaluates the sub-base, and locates the nearest viable storm connection. Skipping this step is how property owners end up paying twice — first for a cosmetic patch, then for the real repair after it ponds again the next winter.

Get Your Eugene Parking Lot Drainage Quote

Cojo Excavation & Asphalt helps Eugene and Lane County property managers stop ponding for good. We assess your lot's slope, inspect your drainage structures, and recommend the most cost-effective fix for your actual conditions — not a one-size-fits-all overlay.

Request a free drainage assessment and we will respond within 24 hours. Learn more about our full range of excavation services for commercial properties across the southern Willamette Valley.