A modular system for containing and draining liquid introduced onto a reusable, load-supporting surface without the use of any liners beneath the load-supporting surface, the load-supporting surface including at least two planar mats forming a perimeter thereof, each mat being constructed of impermeable plastic, the modular system characterised by comprising: a plurality of releasably, sealingly interconnected berm members configured to releasably, sealingly engage the load-supporting surface around its perimeter to prevent leakage of liquid from the load-supporting surface around its perimeter without the use of any liners beneath the load-supporting surface, each said berm member being constructed of impermeable plastic, having first and second ends (84, 86) and at least one integrally formed horizontal base and vertical wall, said horizontal base and vertical wall extending from said first end to said second end of each said berm member, each said berm member configured to sealingly engage one or more adjacent of said berm members such as to be arrangeable around the perimeter of said load-supporting surface sufficient to contain liquid introduced onto the load-supporting surface to the full height of said vertical wall thereof; and at least one elongated drain channel constructed of impermeable plastic and configured to extend across the length of the load-supporting surface between adjacent mats of the at least two planar mats on its sides and opposing said berm members at its ends, each said drain channel including at least one fluid passageway extending along the length thereof, said drain channel being configured to collect fluid introduced onto the load-supporting surface and direct the collected fluid off the load-supporting surface, said at least one drain channel being releasably, sealingly engageable with said adjacent mats and said opposing berm members. a plurality of releasably, sealingly interconnected berm members configured to releasably, sealingly engage the load-supporting surface around its perimeter to prevent leakage of liquid from the load-supporting surface around its perimeter without the use of any liners beneath the load-supporting surface, each said berm member being constructed of impermeable plastic, having first and second ends (84, 86) and at least one integrally formed horizontal base and vertical wall, said horizontal base and vertical wall extending from said first end to said second end of each said berm member, each said berm member configured to sealingly engage one or more adjacent of said berm members such as to be arrangeable around the perimeter of said load-supporting surface sufficient to contain liquid introduced onto the load-supporting surface to the full height of said vertical wall thereof; and at least one elongated drain channel constructed of impermeable plastic and configured to extend across the length of the load-supporting surface between adjacent mats of the at least two planar mats on its sides and opposing said berm members at its ends, each said drain channel including at least one fluid passageway extending along the length thereof, said drain channel being configured to collect fluid introduced onto the load-supporting surface and direct the collected fluid off the load-supporting surface, said at least one drain channel being releasably, sealingly engageable with said adjacent mats and said opposing berm members.