Sayre Report - Hazard Mitigation Web Portal - State of California

• Potential effects to water quality downstream of the burned area due to
an increase in water turbidity. Increase turbidity downstream is
expected as a result of increase sediment and debris coming from the
burn area.
• Potential impacts to water quality from burned anthropogenic (manmade)
sources.
B. Conditions of Values at Risk
Areas with the high soil burn severity produce the greatest changes. High soil
burn areas exhibit hydrophobicity, a condition of water repellency created by
heat of the fire which volatizes the organic matter. High soil burn areas also
have little organic material left, or display white ash. Areas with moderate soil
burn severity produce less change, with more organic material present. Areas
with low soil burn severity produce very little change and unburned areas
produce no change. In light of the defining conditions above, most of the
observed burn areas in the Sayre fire are moderate to low burns.
Because the precipitation is not absorbed as it usually is, and instead is
immediately mobilized, the effects from burned areas are probably the most
severe during the first significant storm event, which is also dependent on the
amount of precipitation. Consequently, years with expected higher rainfall
should expect compounded effects from the fire regarding erosion, turbidity,
and debris flows.
Excluded from the general term of moderate burn above is the Oakridge
Mobile Home Park (Oakridge) which is located at the base of the foothills in
Sylmar. Approximately 480 mobile homes burned to the ground. Much of the
remains of most of the mobile homes were the metal frames that were not
consumed in the combustion. However, it is assumed that because the
structures were lost, are on a slope, and that burned anthropogenic materials
remain, the potential for these materials to be mobilized is increased during a
rain event. If that is the case, there is potential for impact to waters of the
state or U.S. if the drainage from the materials at Oakridge is not diverted,
contained, or sent to a water treatment facility.
On Thursday, December 11, 2008, I and another member of the Sayre Fire
team made a return inspection to Olive View Hospital (Hospital) because of
concerns of purported possible hazardous materials exposed onsite. We met
a Compliance Officer at the Hospital who indicated that a “county hazmat
team” had previously visited the site with instructions regarding specific
burned areas. With that in mind, we toured the area with the hospital facility
planner staff. Some areas were fenced off and being cleaned up with
attendant personnel. No outstanding hazardous materials seemed to be
exposed during our inspection.