Converse Expertise Ensures Dam Safety During Floods

When the recent storms closed roads and drove most Southern Californians indoors, Scot Mathis, an engineering geologist with Converse Consultants headed into the mountains to assist with the safe operation of the New Lake Arrowhead Dam.

The original Lake Arrowhead Dam was completed in 1915. The 1971 Sylmar earthquake prompted a review that showed the old dam could be damaged by a similar quake. The modern New Lake Arrowhead Dam was completed in 1977, just downstream of the old dam, with the newly formed Papoose Lake filling the space between the old and new dams. Converse conducts quarterly geotechnical monitoring to verify the condition of the New Lake Arrowhead Dam.

Several days of heavy December rain filled Lake Arrowhead and Papoose Lake to capacity. Scot Mathis responded to San Bernardino County’s request to check the condition of the dam and to assist with a safe and controlled release of water.  Papoose Lake was rising over an inch per hour so enough water had to be released to stabilize the lake at a safe and acceptable level. Unlike most dams, the New Lake Arrowhead Dam does not have a spillway. When Papoose Lake fills, water must be released through a series of pipes and valves. Opening the release valves too far could contribute to the already extensive downstream flooding.

Working closely with the dam caretaker, Converse Consultants determined the optimal valve openings for a range of conditions that occurred during the storms. A new Emergency Action Plan for the dam, currently being prepared by Scot and other Converse Consultants geology staff, will include this critical information, providing dam personnel with quick and easy access to exsiting and updated procedures in a single document.

Our long relationship with the County of San Bernardino and familiarity with their requirements facilitated quick and decisive action.  Converse has worked with various departments within the County of San Bernardino for over three decades.

Converse Consultants has provided engineering and geology services during the design and construction of dams nationwide, and currently provides safety monitoring for several dams in California.

Converse Consultants provides a full range of geotechnical, geologic, environmental and groundwater sciences, as well as QA/QC and materials laboratory service during construction. For more information please contact Beth George at bgeorge@converseconsultants.com.

Wicked Weather Causes Severe Damage

Landslides, flooding and downed trees are causing problems in Orange County beach communities as stormy weather continues in Southern California.  Downtown Laguna Beach was closed Wednesday morning because of flooding, and there are mudslides in the San Clemente hills.

Blizzard conditions have left up to about 20 inches of snow in Long Island, still-snarled highways, a paralyzed mass transit system and shutdown airports. And a picture is emerging of beach erosion and damage to waterfront homes.

Motorists in the Irvine, CA area can expect increased traffic into next week as about 10 miles of toll road remains shut down until crews can clear mud and debris left by the recent rainstorms.  Highway 241, between the 133 and the 261, is expected to be closed until Wednesday.  Water continues to seep out of the hills, adding to the water already flooding the road.  The closure will increase congestion on nearby freeways.

As of Christmas morning, Pacific Coast Highway was also closed at the L.A. County-Ventura County line because of storm damage.

Gale force winds combined with heavy snow are expected to continue across northeast New Jersey and southern New England Monday afternoon, creating dangerous blizzard conditions.

These are just a few of the ordeals reported Monday as commuters and long-distance travelers across the country end the Christmas weekend by dealing with paralyzed public transit systems, roads closures and flooding.

Federal and State Highway officials and local Public Works agencies are in high gear to restore mobility to a nation battered by winter storms.  More heavy weather is on the way.

Converse Consultants is actively involved in the investigation of roadway failures and design and construction of storm damage repairs.  From Southern California’s mudslides, flash flooding in the Southwest, to the frozen Northeast, our professional staff is working to assist agency staff.

Converse Consultants provides a full range of geotechnical, geologic, environmental and groundwater sciences, as well as QA/QC and materials laboratory service during construction.  For more information please contact Beth George at bgeorge@converseconsultants.com.