module 2 as best seen in fig3 the trough base 90 has two opposing sloped portions 91 the sloped portions 91 each slope downwardly away from an opposing wall 5 toward the center of the trough 60 and the drain pipe 105 to move liquid contained within the trough toward the drain pipe in a preferred embodiment of the invention the trough base 90 is inclined toward the drain pipe 105 at approximately a 2 grade the 2 grade is shallow enough to prevent the trough 60 from interfering with the lower surface 69 of the recessed well 68 but is steep enough to drain liquid from the trough into the drain pipe 105 other embodiments include grades such as in the range of approximately 1 4 or other grades shallow enough to prevent the trough 60 from interfering with the lower surface 69 but sufficiently steep so as to drain liquid from the trough into the drain pipe 105 the trough 60 is joined to the drain pipe 105 with a drain assembly 100 as best seen in fig2 the drain assembly 100 includes a hollow cylindrical drain 101 having a lip 106 extending around the periphery of one end of the drain and having external threads 103 located beneath the lip the drain 101 extends through a drain aperture 95 in the base 90 of the trough 60 such that the lip 106 engages an upper side 104 of the trough base around the drain aperture and the external threads 103 are positioned below a lower side 118 of the trough base the.