A decades-old stormwater solution that helps recharge groundwater in Modesto is also a major contributor to yearly street flooding and a potential source of contamination.
Modesto’s stormwater system is different from most other cities of its size in California. Instead of a traditional system using pipes that flow into rivers or out into the ocean, it heavily relies on thousands of rock wells — gravel-filled holes that drain untreated rainwater directly into the ground.
“It’s basically a hole that’s drilled straight into the ground with filler rock that creates voids around the rocks and gives a space for the water to go,” said Robert Englent, the Modesto wastewater collection system superintendent…