The Latest in PA DEP Infiltration Testing: What You Need to Know

If you’re in the world of stormwater management, you know infiltration testing isn’t just about digging a hole and hoping for the best. The Pennsylvania Department of Environmental Protection (PA DEP) has updated its guidelines, placing more emphasis on field testing to ensure accurate assessments. Here’s what’s new.

Better Testing, Better Results

PA DEP is reinforcing the need for real-world testing rather than relying on lab-based estimates. Nature doesn’t always behave as expected, so these updates focus on improving accuracy in the field.

1. Double-Ring Infiltrometer Testing

This method remains a reliable standard for measuring infiltration rates while minimizing lateral flow. Using two concentric rings, it allows for a more precise assessment of how water moves into the soil. The IGS 510HD, 612HD, and 1224HD models are designed for durability and accuracy in the field.

2. Cased Borehole & Downhole Double-Ring Tests

For deeper infiltration assessments, PA DEP now recommends using a cased borehole to minimize sidewall leakage and obtain more reliable vertical infiltration rates. The IGS 35HD Downhole Double Ring Infiltrometer is specifically designed for these applications, allowing for controlled testing in confined boreholes. This method is particularly useful for evaluating infiltration at depths required for stormwater basin design and other subsurface drainage assessments.

3. Increased Testing Requirements

PA DEP now requires at least three infiltration tests per stormwater management footprint to improve data reliability. Tests must also be conducted at the actual infiltration depth, rather than just at the surface, to better reflect field conditions.

4. Soil Evaluations Are Key

Beyond infiltration rates, a greater focus is being placed on soil properties. Evaluations now consider permeability, depth to bedrock, and potential risks such as sinkhole formation. This ensures that stormwater management systems are designed with a more complete understanding of subsurface conditions.

5. Pre-Soaking Before Testing

The new guidelines emphasize the importance of pre-soaking test areas before running infiltration tests. Dry soil can absorb water quickly at first, which can lead to misleading results. Pre-soaking helps simulate real conditions and provides more accurate data on long-term infiltration capacity.

What This Means for You

These updates aim to improve infiltration testing practices, resulting in more reliable data for stormwater management planning. If you’re in geotechnical work or doing geoscience work, keeping up with these changes will help ensure compliance and improve project outcomes.

For accurate and dependable infiltration testing, IGS offers high-quality field equipment designed to meet the latest standards.