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Subsidence Investigation Mathew/Aley Rental Property Claim No. 223968 BCI Project No. 03-15564 November 2007 Page 7 Stratum 2 is comprised of fine-grained quartz sand and variably clayey sand and was encountered below the surficial sands from 12 to 32 feet below grade in boring SPT-l and interbedded within Stratum 3 from 12 to 22 feet below grade in boring SPT-3. Stratum 2 was not encountered in boring SPT-2. Recorded SPT blow counts in Stratum 2 ranged from 12 to 29 blows per foot, indicating a medium dense relative density for the soil unit. Stratum 3 consists of a sequence of variably clayey soils ranging from clayey sand to sandy clay with local minor interbedded sand. The soil unit was encountered from 12 to 32 feet below grade in boring SPT-2 and 8 to 12 feet, 22 to 27 feet, and 32 to 37 feet below grade in boring SPT-3. Stratum 3 was not encountered in boring SPT-1. Recorded SPT blow counts in Stratum 3 ranged from 4 to 23 blows per foot, indicating a firm to very stiff consistency for the soil unit. Stratum 4 was encountered as an in-filling soil unit within the limestone formation and consists of sandy clay with minor clayey sand and local interbedded sand and limestone fragments. The soil unit was encountered from 37 to 52 feet below grade in boring SPT-2 and from 57 to 67 feet below grade in boring SPT-3. Stratum 4 was not encountered in boring SPT -1. Recorded SPT blow counts in Stratum 4 ranged from 8 to 13 blows per foot, indicating a stiff consistency for the soil unit. Limestone (Stratum 5) was encountered at variable depths in the borings, as isolated lenses of consolidated lime silt and quartz sand within Stratum 3, and as a bedrock unit in the middle portions of the borings. The stratum was encountered at depths of 32 feet to the termination depth of 65 feet below grade in boring SPT-l, 18Y2 to 20 feet, 32 to 37 feet, and 52 feet to the termination depth of 60 feet below grade in boring SPT-2, and 27 to 32 feet, 37 to 57 feet, and 72 to the termination depth of 75 feet below grade in boring SPT-3. The limestone was variably indurated, with recorded SPT blow counts ranging from weight-of-rod strength material to greater than 50 blows per foot. An interval of very soft weathered limestone (weight-of-rod to 1 blow per foot) was encountered from 38Y2 to 47 feet below grade in boring SPT-3. During drilling, a loss of drilling fluid circulation was recorded at a depth of 3 7 feet below grade in boring SPT-3. The circulation loss occurred at the soil/limestone contact, just above the zone of very soft limestone.