DUDEK - Averting Wet Weather Hazards

Regulatory Compliance

Pre-Rain Prevention Averts Wet Weather Hazards
Rain is a mixed blessing in Southern California. Thirsty plants and reservoirs typically crave a good downpour, but too much of a good thing can be overwhelming. Slope failures, flooding, beach closures, and downed trees have affected the region. Preventative steps can fend off some of these problems the next time around.

A Balance - Drainage Channel Maintenance/Habitat Protection
Water seemed to be everywhere in early 2005 – on the streets, in parking lots, surrounding housing developments, flooding low-lying areas. And it all had to go somewhere.

“When we get rain in San Diego, we get a lot of rapid runoff,” said John Minchin, a registered landscape architect at Dudek with over 24 years of experience in the design, construction, and management of landscape architectural and habitat restoration projects in California. “Storm flows, which are slowed by overgrown vegetation, end up overwhelming wetland areas, causing flooding, erosion and harming water quality.”

However, regular permitted maintenance can help keep water moving in drainage channels and wetlands, preventing some of the flooding outside of the channels.

“In the low rainfall years, plants establish well down the middle of the channel, resulting in dense thickets of vegetation,” said Mark Girard, president of Habitat Restoration Sciences (HRS), a Dudek company. Girard specializes in native habitat installation and maintenance projects. “In anticipation of a high rainfall year, you need to get in there before the winter season and selectively harvest vegetation – especially the less-flexible non-native/exotic species – to reduce the amount of resistance to the flow.”

Erosion caused by the heavier flood flows and surface runoff can be serious. Storm Water Pollution Prevention Plans (SWPPP) and Water Pollution Control Programs (WPCP) detail ways in which construction projects can prevent silt-filled storm water runoff and erosion from negatively impacting water quality.

Maintaining Water Quality in Heavy Rains
“Hydroseeding, selective planting of native species, and the installation of gravel bags, fiber rolls and straw wattle, and silt fencing can help trap as much sediment as possible on construction sites instead of letting the sediment go downstream,” said Girard. This maintains water quality and keeps soil where it belongs. But all could be for naught if a wall of water washes it all away during a storm event.

“During the storm, you have to be diligent in checking to make sure the erosion control measures are still intact,” said Girard. “It takes people in yellow raincoats getting wet all day long replacing gravel bags, getting the shovel out and cleaning up the mud, to even begin to hold back Mother Nature.”

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