CONTACTS
|
July 09 Issue - Employee Monthly Magazine
Lab employees restore and protect local watersheds
Steve Veenis poses in front of the last in a series of log dams designed to reduce stormwater sediment transport from eroding the canyon wall in Los Alamos Canyon. Photo by Sandra Valdez
Laboratory Water Stewardship Program managers Danny Katzman and Steve Veenis know well the challenges posed by stormwater runoff.
Nine years after the Cerro Grande fire destroyed 232 homes in Los Alamos and burned about 48,000 acres of Los Alamos, San Ildefonso Pueblo, and Santa Clara Pueblo land, the Laboratory, together with other organizations and volunteer groups, is still mitigating its effects on local watersheds.
In its wake, the fire left scorched landscapes and damaged watersheds. Hillside erosion spiked as precipitation from summer storms ran off the burned areas, instead of soaking into the ground. Water was able to run off and generate flash floods because the thick organic deposits on the forest floor that previously had absorbed the rainfall had burned and were washed away, Katzman said.
In the first two years after the fire, the Laboratory and others conducted assessments to evaluate the risk associated with potential exposure to contaminants contained in the runoff. The studies all showed that no unacceptable risk existed, said Katzman, who holds a master’s degree in geology from the University of New Mexico and a bachelor’s degree, also in geology, from the University of Texas, Austin.
Although the increased runoff caused by the fire has largely stopped, the Laboratory continues to take steps to ensure the longterm stability of the watersheds in Los Alamos and Pueblo canyons, to slow erosion, and to reduce the transport of contaminated
sediment.
Under a program managed by Veenis, the Lab has put in place tried-and-tested “best management practices” (BMP), such as constructing basins to catch sediment, building berms to divert surface-water runon, and strategically planting vegetation to help stabilize mesa
slopes. “These BMPs help reduce sediment and contaminant
transport from historical contaminant sites,” said
Veenis, who holds a bachelor’s degree in geology from Fort
Lewis College in Durango, Colorado.
The Laboratory also is constructing structures in Los Alamos
and Pueblo canyons. These include “cross-vanes,” or arrays
of large boulders arranged across a channel in a V shape
pointing upstream. Cross-vanes serve to reduce some of the
energy in the runoff, thereby decreasing the potential for
flood erosion, said Katzman, who is heading the project.
Danny Katzman stands among willows planted in Pueblo Canyon in 2008 by Lab employees to stabilize banks and trap sediment. Photo by Sandra Valdez
Further down in Pueblo Canyon, below the effluent release point for the Los Alamos County Wastewater Treatment Plant, Lab employees and volunteers have planted more than 10,000 willows to stabilize channel banks and slow flood water that spills over the banks, Veenis said. The willows, obtained from Los Lunas, New Mexico, and planted from 2006 to 2009, are growing quickly. “The high nutrient content of the treatment plant’s effluent is ideal for vigorous growth of the willows,” Veenis said.
Additional structures are planned, he said. A “wing” ditch will be dug this summer in Pueblo Canyon to reduce the energy of water flowing down the canyon. The ditch will divert floodwater out of the main channel and onto a nowdry floodplain.
In addition, two “grade-control” structures will be constructed this fall, one in lower Pueblo Canyon and the other in DP Canyon, Katzman said. By far the most significant endeavor from an engineering perspective, the Pueblo Canyon structure will anchor the terminus of an existing wetland, thereby preventing erosion and reestablishing wetland that was eroded after the Cerro Grande fire.
Similar structures already exist, such as the one visible from the parking area along State Road 4 across from the Tsankawi unit of Bandelier National Monument, and have been proven to be effective, he said.
All these measures will support Santa Fe’s Buckman Direct Diversion Project. “The city of Santa Fe and Santa Fe County will be diverting surface water from the Rio Grande at a location downstream of the confluence of Los Alamos Canyon,” Katzman said. “The measures implemented in the Los Alamos and Pueblo Canyon watershed will substantially reduce sediment transport into the Rio Grande.”
--Tatjana K. Rosev
Other Headlines
 |
Issues
|
