Asphalt and Concrete Are Different Jobs
Asphalt: high pressure damages asphalt. It erodes the binder holding the aggregate, ravels the surface and shortens pavement life. Asphalt lots are generally swept, spot-treated for oil and stains, and washed only at low pressure where necessary. Anyone proposing to power wash a whole asphalt lot is proposing to damage it. Concrete: sidewalks, entries, aprons, pads, curbing and islands take real pressure, best applied with a surface cleaner for an even finish. Pavers and decorative hardscape need moderate pressure, and joint sand has to be replaced after cleaning.
The High-Value Targets on a Commercial Site
Dumpster pads and enclosures: grease, leachate and odor — a degreaser-plus-dwell job followed by pressure, then enzymatic treatment for the odor. This is also the single biggest stormwater exposure on the property. Entry sidewalks and vestibule aprons: gum, drink spills, and the traffic-darkened path — highest visibility per square foot on the whole site. Gum removal is a separate technique using heat or steam since pressure alone smears it. Drive-through lanes: food, drink and tire residue in a concentrated strip.
See also: Restaurant & Storefront Pressure Washing · Warehouse & Industrial Exterior Cleaning · Commercial Exterior Winter Prep
Stormwater Compliance, in Plain Terms
A parking lot drains to an inlet. That inlet goes to a storm system, and a storm system generally goes to a stream, a river or the Delaware. It is not treated. Under the federal NPDES stormwater framework, administered here by PA DEP, NJDEP and Delaware DNREC, discharging wash water containing detergents, oils or other pollutants into a storm drain is generally prohibited. Compliant work means inlet protection installed before any water flows, vacuum recovery of wash water on pads and docks, filtration or separation as required with approved disposal, and documentation of volume recovered and where it went.