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4 buildings and utilities shall be constructed to mitigate the effects of differential settlement. All utility connections 0 0 () g g tY shall be designed with flexible connections and utility collars; (5) utilities shall not be installed in or below any low permeability layer of final cover; (6) pilings shall not be installed in or through any bottom liner unless approved by the RWQCB; (7) if pilings are installed in or through the low permeability layer of final cover, then the low permeability layer must be replaced or repaired; and (8) periodic methane gas monitoring shall be conducted inside all buildings and underground utilities in accordance with section 20933 of Article 6, of Subchapter 4 of this Chapter. (f) The EA may require that an additional soil layer or building pad be placed on the final cover prior to construction to protect the integrity and function of the various layers of final cover. (g) All on site construction within 1,000 feet of the boundary of any disposal area shall be designed and constructed in accordance with the following, or in accordance with an equivalent design which will prevent gas migration into the building, unless an exemption has been issued: (1) a geomembrane or equivalent system with low permeability to landfill gas shall be installed between the concrete floor slab of the building and subgrade; (2) a permeable layer of open graded material of clean aggregate with a minimum thickness of 12 inches shall be installed between the geomembrane and the subgrade or slab; (3) a geotextile filter shall be utilized to prevent the introduction of fines into the permeable layer; (4) perforated venting pipes shall be installed within the permeable layer, and shall be designed to operate without clogging; (5) the venting pipe shall be constructed with the ability to be connected to an induced draft exhaust system; (6) automatic methane gas sensors shall be installed within the permeable gas layer, and inside the building to trigger an audible alarm when methane gas concentrations are detected; and (7) periodic methane gas monitoring shall be conducted inside all buildings and underground utilities in accordance with Article 6, of Subchapter 4 of this chapter (section 20920 et seq.).