As a result of heavy rains received overnight May 28 to 29, 2009 and
previous rain events earlier in the week, there was some overflow of
water from the Containment (cap) Area (CA) into a drainage feature (the
South Swale) outside of the CA and possibly into the new basin. While
the overflow is not desirable, all features worked in the way they were
intended to work in keeping contaminated water from exiting the site.
The discharge from the new basin is blocked off so no water or sediment
was released off-site into Sulphur Creek.
Some battery casing pieces and sediment that floated out of the CA
with the water were removed and placed back into the CA. After the
sediment and battery casings were placed back into the CA, the overflow
area on the berm was tested for lead using an XRF. Two of the thirty-six
XRF results on the berm were found to be above the performance standard
(500 ppm). Six inches of soil was removed from the berm in the area
where these two results above 500 ppm were detected. The area was then
retested. The results were well below the performance standard. XRF
testing was also performed at three locations in the South Swale where
sediment accumulated from the overflow. The results for these locations
were all below the performance standard.
The water accumulating in the low area inside the perimeter of the CA
was pumped out and discharged into contaminated areas of the site in
accordance with the specifications. SCE created a diversion berm at the
northern part of the Site to redirect and prevent water from clean areas
of the Site from entering the CA. This minimized the amount of water
going into the CA and should prevent overflow of the CA from occurring
in the future.