A flood-control channel on Brookhurst Street in Garden Grove had become an underground refuge for homeless drug addicts, and with it, a mountain of debris and a litany of quality-of-life issues for the surrounding community — not to mention the denizens of the makeshift encampment themselves. Today, an eight-foot high, tamper-proof fence surrounds the entrance to the county-owned channel, which is now free of people and trash. Credit goes, in large part, to the efforts of the Garden Grove Police Department’s Special Resources Team (SRT). A triangular patch of grass implanted with overgrown foliage, bordered by the 405 and 22…