Feb 4, 2013 Meeting w/ Notes

753191
ATTACHMENT A 841681
LAND ANNOTATION
DURANGO., COLORADO PROCESSING SITE
NORTHERN, MIDDLE AND SOUTHERN PARCELS
T1 e Uranium Mill Tailings Radiation Control Act (Public Law 95 -604), Section 104, requires
th t the State notify any person who acquires a designated processing site of the nature and
e ent of residual radioactive materials removed from the site, including notice of the date when
su h action took place, and the condition of the site after such action. The following information
is 3rovided to fulfill this requirement.
Durango, Colorado processing site originally consisted of three separate land parcels. The
kern parcel contained the mill site, two tailings piles arid remnants of old buildings. The
hem parcel, located approximately 0.5 miles to the south, contained raffinate ponds, which
used for the disposal and evaporation of contaminated liquids from the mill process. The
sites are connected by a currently impassable service road cut into the face of Smelter
mtain which is the third parcel.
Ar proximately 2,500,000 cubic yards of contaminated materials which included 1) tailings; 2)
sut pile soils; 3), surficial materials in the mill yard; 4) windblown materials; and 5) raffinate
poi ds and contents were removed from the sites from 1987 to 1990. The remediation was
conducted in accordance with regulations promulgated by the United States Environmental
Prc tection Agency (EPA), in 40 CFR 192. These regulations require that the concentration of
rad ium-226 in land averaged over any area of 100 square meters shall not exceed the background
le 1 by more than: 5 pCi/g (picocuries per gram), averaged over the first 15 cm (centimeters) of
soi below the surface, and 15 pCi/g averaged over 15 cm thick layers of soil more than 15 cm
bet w the surface.
A r remediation was complete the sites were backfilled with approximately 230,000 cubic
yar Is of clean material, graded for drainage and revegetated. Backfill materials were routinely
an yzed for radium -226 and were determined to have concentrations near background. Material
wit i radium -226 concentrations less than 5 pCi/g were used for surface backfill. Excavation of
res dual radioactive material was also conducted for Thorium -230 on the southern parcel. For
tho ium -230, the cleanup standard was determined as a projected 1,000 year Radium -226
co entration based on the eventual decay of the thorium to radium. This resulted in a thorium -
23 concentration of approximately 35 pCi /g as the clean-up standard. All verification soil
s ples from the two sites met the EPA standards of 5 and 15 pCi/g radium 226 plus background
(l. pCi /g) except for grid H -38 -20 which, including the thorium -230 results, after 1000 years
wot Id have a projected concentration of 18.6 pCi/g of radium -226. (The actual concentrations at
this location are 49.4 pCi /g thorium -230 and 13 pCi /g radium -226). This and is located on the
sou hem parcel, as shown on the attached map. This grid is covered with 2.5 to 5 feet of clean
.EXHIBIT -C i