The MPD Infiltrometer replaces the double ring infiltrometer test for saturated hydraulic conductivity (Ksat),
for design and monitoring of stormwater infiltration practices.
Because it is a falling head test, it requires
much less water and can be performed in a fraction of the time required for the double ring.
Since the calculations
and report generation are fully automated by software, summer interns and technicians can easily perform these
tests in the field, (Engineer not required). This reduces the costs of procuring values for Ksat,
bringing this data within budget for projects of all sizes.
Having a site-specific Ksat value improves the design of infiltration practices, allows
verification of construction of these practices, and provides hard data for required annual inspections.
Double Ring Infiltrometer
Test Time: 30 to 60 Minutes
Test time: 4 to 6 hours
Under 1 gallon of water
Hundreds of gallons of water required
Manual - Labor Intensive
Any person can operate
Requires a Licensed Engineer
$100 per test
$1,000+ per test
Average multiple tests per site
Single data point for entire site
All data collection and mathematical processing performed automatically
Use the MPD infiltrometer to provide a site-specific Ksat for design of infiltration practices.
No more relying on vague ranges provided by soil surveys! Also use it to quickly verify the construction
of these practices before authorizing payment to the contractor.
Perform annual Ksat tests on all of your agencies rain gardens, infiltration basins, and swales.
Easily monitor any changes in infiltration capability over time.
The MPD methodology and calculations have a long history dating back to 1911 with the
Green-Ampt theory for estimating infiltration, which incorporates many variables that other methods,
such as Darcy's Law, do not. Some of these variables include: Soil Suction Head, Porosity, Hydraulic Conductivity and Time.
Two men, Philip & Dunne, then furthered this research and developed a methodology that incorporated the
use of a cylinder, filled with water and measured head drop over time. The subsequent math equations incorporate the
to predict the field saturated (or steady state) infiltration rate, also known as Hydraulic Conductivity.
Philip and Dunne published their methodology in 1993 for peer review.
The University of Minnesota modified Philip & Dunne's work with a variation to the equation in 2007,
renaming the method: Modified Philip Dunne or (MPD). This method has been peer reviewed and
vetted in the world-wide academic and scientific communities since 2007, becoming an
ASTM Standard in 2018.