PERMFILE131211

• Permit No: C1982057A
• IBM Index Class Name: Permit File
• Doc Date: 1/11/2007
• Doc Name: Pond 016 Spillway Certifiation
• Section_Exhibit Name: Tab 13 Attachment 13-5F Appendix 1
• Media Type: D
• Archive: Yes

•

MONTGOMERY WATSON
Mining Group
SENECA COAL COMPANY
MOISTURE-DENSITY TESTING FOR SENECA COAL COMPANY
POND 16
u
•
Seneca Coal Company constructed Pond 76 during August and September 2000. Montgomery
Watson Mining Group was retained to conduct density testing during the construction efforts. The
following is a chronology of testing events and results of the testing conducted as the pond
embankment was constructed.
16-Aug-00: Two samples of fill material were collected For pazticle size and Atterberg Limit analysis
to verify the design parameters assumed during the engineering of the pond embankment. Only one
sample was tested because both samples were similar based on visual classification. These analyses
are included in Attachment A, Field and Laboratory Data. The results of these analyses conducted on
the sample indicate the fill material placed has the index properties shown in Table 1, Summary of
Ivboratory Terting.
TABLE 1
SUMMARY OF LABORATORY TESTING
Pond 16 Fill Sam le Proctoz Test Sam le
Li uid Limit 37% 27%
Plastid Index 22% IS%
-#200 Sieve 83.0% 86.0%
Proctor ASTM D698 No Test 110.5 cf
These results closely match the physical characteristics of the proctor test sample taken at the site
during the 1999 pond construction season. Therefore, a conservative proctor value of 111.0 pcf was
used for all in-situ density testing at Pond 16 during construction.
16-Aug-00 to 18-Sept-00: Twenty one (21) nuclear moisture/density tests was taken during the
construction of the Pond 16 embankment. Tests were taken at random locations as the ftll was
placed from the base of the embankment up to the spillway crest elevation. The required percent
compaction for fill placed was 95% of the soils maximum dry density determined by the Standazd
Proctor method (ASTM DG98). All test results indicated that fill placed met or exceeded 95%
compaction with the exception of four (4) tests. Three tests had results of 94.9% and one test was
94.8% for compaction. These test areas were recompacted but were not tested. Since these test
results aze so close to 95°/q the difference is inconsequential to the performance of the embankment.
Density test information is presented in Table 2, Denrity Tert Summary.
P.O. Box 774818
1475 Pine Grave Road
Steamhoa[ Springs, Colorado
68477
Tel; 970 875 6268
Fax: [phone]
Serving the World's Environmental Needs