We were called last fall to a residential site off Battlefield Boulevard where a homeowner was planning a rain garden and drywell system. The soil there was sandy loam over dense clay, and the county required a measured infiltration rate before approving the stormwater plan. That is exactly where a Porchet or double-ring infiltrometer test comes in. We dig a small borehole or seat two concentric rings, fill them with clean water, and record the drop over time. In Chesapeake the water table can sit shallow after heavy rain, so we run the test until we see a steady-state rate. That data then feeds directly into the drainage design.
The steady-state infiltration rate we measure in Chesapeake soils typically ranges from 0.2 to 2.0 inches per hour, depending on the clay content and compaction.
Approach and scope
Site-specific factors
Chesapeake sits on a mix of Coastal Plain sediments, with shallow groundwater that can rise to within 3 feet of the surface after a wet week. If you design a septic drainfield or a bioretention cell without a site-specific infiltration test, you risk failure within the first year. We have seen systems built on soils that looked permeable at the surface but had a clay lens at 18 inches that slowed everything down. A single infiltration test at the wrong spot can give you a rate ten times higher than the actual field average. That is why we run at least two tests per proposed infiltration area and we correlate the results with grain size analysis to check for fines content.
Relevant standards
ASTM D3385-18 (Standard Test Method for Infiltration Rate of Soils in Field Using Double-Ring Infiltrometer), Virginia DEQ Stormwater Management Regulations (9VAC25-870), IBC 2018 Appendix C (Soil Classification and Infiltration)
Related technical services
Double-Ring Infiltrometer Test
ASTM D3385 compliant test using 12-inch and 24-inch steel rings. We pre-soak the test area, record water level drop at one-minute intervals, and report the steady-state infiltration rate in inches per hour. Ideal for stormwater basins, bioretention cells, and permeable pavement designs.
Porchet Borehole Infiltration Test
A cost-effective alternative for deeper soil assessment. We auger a 6-inch hole to the planned invert depth, pre-soak it, and measure the falling head. Commonly used for septic system site evaluations and drywell sizing in Chesapeake residential projects.
Typical parameters
FAQ
How much does an infiltration test cost in Chesapeake?
The typical range for a single-location infiltration test in Chesapeake is US$320 to US$430. This includes mobilization within the city, one test setup (double-ring or Porchet), field logging, and a short report with the measured steady-state rate. Additional locations or deeper boreholes may increase the price slightly.
Do I need an infiltration test for a small residential rain garden in Chesapeake?
Chesapeake requires a stormwater management plan for any land disturbance that creates more than 2,500 square feet of impervious cover. For a small rain garden under that threshold, the test is not mandatory, but we strongly recommend it. Without a measured infiltration rate you risk ponding, overflow, and potential damage to your foundation if the garden sits near the house. The test also helps you size the garden correctly.
What is the difference between a Porchet test and a double-ring infiltrometer test?
The double-ring test uses two concentric rings to force vertical flow through the inner ring, giving a more accurate surface infiltration rate. The Porchet test uses a single borehole and measures lateral plus vertical flow, which can be more representative for deeper percolation. In Chesapeake we often recommend the double-ring for stormwater facilities and the Porchet for septic system or drywell design. Both methods follow ASTM protocols.