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Ch. 15, Art. 10-7
<br />(C) free of cracks or gaps; and
<br />(D) designed and installed to completely surround the tank and to cover all surrounding earth likely to come
<br />into contact with the waste if released from the tank(s) (i.e., capable of preventing lateral as well as vertical migration
<br />of the waste).
<br />(2) Vault systems shall be:
<br />(A) designed or operated to contain 100 percent of the capacity of the largest tank within its boundary;
<br />(B) designed or operated to prevent run-on and infiltration of precipitation into the secondary containment
<br />system unless the collection system has sufficient excess capacity, in addition to that required in subsection (e)(2)(A)
<br />of this section, to contain run-on and infiltration. Such additional capacity shall be sufficient to contain run-on and
<br />infiltration of precipitation from a 25 -year, 24-hour rainfall event;
<br />(C) constructed with chemical -resistant water stops in place at all joints (if any);
<br />(D) provided with an impermeable interior coating or lining that is compatible with the waste being
<br />transferred, stored or treated and that will prevent migration of waste into the concrete;
<br />(E) provided with a means to protect against the formation of and ignition of vapors within the vault, if the
<br />waste being transferred, stored or treated:
<br />1. meets the definition of ignitable waste under section 66262.21 of this division, or
<br />2. meets the definition of reactive waste under section 66261.23 of this division and may form an ignitable or
<br />explosive vapor; and
<br />(F) provided with an exterior moisture barrier or be otherwise designed or operated to prevent migration of
<br />moisture into the vault if the vault is subject to hydraulic pressure.
<br />(3) Double -walled tanks shall be:
<br />(A) designed as an integral structure (i.e., an inner tank within an outer shell) so that any release from the
<br />inner tank is contained by the outer shell;
<br />(B) protected, if constructed of metal, from both corrosion of the primary tank interior and the external
<br />surface of the outer shell; and
<br />(C) provided with a built-in, continuous leak detection system capable of detecting a release within 24 hours
<br />or at the earliest practicable time, if the owner or operator can demonstrate to the Department, and the Department
<br />concurs, that the existing leak detection technology or site conditions will not allow detection of a release within 24
<br />hours.
<br />(f) Ancillary equipment shall be provided with full secondary containment (e.g., trench, jacketing, double -
<br />walled piping) that meets the requirements of subsections (b) and (c) of this section except for:
<br />(1) aboveground piping (exclusive of flanges, joints, valves, and connections) that are visually inspected for
<br />leaks on a daily basis;
<br />(2) welded flanges, welded joints, and welded connections that are visually inspected for leaks on a daily
<br />basis;
<br />(3) sealless or magnetic coupling pumps and sealless valves, that are visually inspected for leaks on a daily
<br />basis; and
<br />(4) pressurized aboveground piping systems with automatic shut-off devices (e.g., excess flow check valves,
<br />flow metering shutdown devices, loss of pressure actuated shut-off devices) that are visually inspected for leaks on a
<br />daily basis.
<br />(g) The owner or operator may obtain a variance from the requirements of this section for existing above-
<br />ground tanks in place, if the Department finds, as a result of a demonstration by the owner or operator, either that
<br />alternative design and operating practices, together with location characteristics, will prevent the migration of
<br />hazardous waste or hazardous constituents into the ground water or surface water at least as effectively as
<br />secondary containment during the active life of the tank system, or that in the event of a release that does migrate to
<br />ground water or surface water, no substantial present or potential hazard will be posed to human health or the
<br />environment.
<br />(1) In deciding whether to grant a variance based on a demonstration of equivalent protection of ground
<br />water and surface water, the Department will consider:
<br />(A) the nature and quantity of the waste;
<br />(B) the proposed alternate design and operation;
<br />(C) the hydrogeologic setting of the facility, including the thickness of soils between the tank system and
<br />ground water; and
<br />(D) all other factors that would influence the quality and mobility of the hazardous constituents and the
<br />potential for the constituents to migrate to ground water or surface water.
<br />(2) In deciding whether to grant a variance, based on a demonstration of no substantial present or potential
<br />hazard, the Department will consider:
<br />(A) the potential adverse effects on ground water, surface water, and land quality taking into account:
<br />1. the physical and chemical characteristics of the waste in the tank system, including its potential for
<br />migration,
<br />2. the hydrogeological characteristics of the facility and surrounding land,
<br />3. the potential for health risks caused by human exposure to waste constituents,
<br />4. the potential for damage to wildlife, crops, vegetation, and physical structures caused by exposure to
<br />waste constituents, and
<br />5. the persistence and permanence of the potential adverse effects;
<br />(B) the potential adverse effects of a release on ground -water quality, taking into account:
<br />Unofficial Title 22 0 2005 State of California, all rights reserved. May not be commercially reproduced or sold. 6/9/08
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