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HAR-.16-66 14.46 FROM. AGUIR~£NCINEERB INC. ID, • PACE 6 Mr. end Mrs. Tatum March 16, 1995 Pepe 4 understand that coal Is being extracted by long well mining methods In the area northeast of the residence, on the north aide of the Purgatolre River Valley. Previously, mining has taking place beneath the hillside south of the galley, south of the residence. M(ning in that area was by room and pillar methods. We understand that the mining operators Intended to connect the two portions of the mine by mining a zone extending from the south that would.have passed directly beneath the residence. This 62b feet wide room end pillar zone was extending northward towards the residence when the mining effort was abandoned. We understand the mine encountered wet ground conditions and a weak floor. We understand the area has since been flooded and sealed off. Based on maps provided to us by Mr. Gerity, it appears that the mining from a depth of about 480 feet came wthin 200 to 300 feet of the residence. a h • ~. , ~~ Because of loss of ground, aubsldsnce can oocur over areas of mining. There are differences between the subsidence potential over room and pillar and long wall mined areas. In long wall mining, coal is completely extracted whhln a Inrge area known as a panel. As a result, subsidence at the surface may approach the thickness of the eMraction zone beneath. With room end pillar mining, unless the pillars ors removed, ordinarily surface subsidence should not be as greet es with long wall mining. We understand there was an effort to. control or minimize surface disruption as the mining proceeded northward, as only about 40% of the coal was extracted. Typically, this would minimize surface disruption. However, according to Mr. Gerity, the soft floor of the mine may have resulted In pillar failure in the area of the mina nearest the residence. If that occurred, then surface disruption could be more analogous to long wall mining than room and pillar mining. Mining engineers and rock mechanic experts have attempted to develop methods to predict surface subsidence over Coel mining. A concept has been developed called the "angle of draw", within which the affacta at mining might be felt. The angle of draw is a fairly simple representation of possible earth movsmeMS and conalsts of a plane extended upward from the outer toe of the mine towards the ground surface. The angle of this plane from the vertical is called the angle of draw. Depending on the geology and other conditions, angles of draw would typically be In the range of 26 to 35 degrees. It ie our understanding that the Tatum residence may be located very clwa to the zone where the angle of draw would encounter the ground surface. P08918LE CAUSES OF RE8IQ~NCE DAMAGE In order to evaluate likely causaa of the damage to the residence, a number of possible scenarios have been suggested or may exist. Vye present each of these with our comments. r~brepen~leoraoi.n, •-