Complex sentence: The Red Hook Treatment plant collected waste from the existing Bond Street sewer that had been dumping into the harbor, but did not take up any additional waste that still spills into the canal from the sewer system's 14 Combined Sewer Overflow (CSO) points.
Split into simpler sentences: The Red Hook Treatment plant collected waste from the existing Bond Street sewer that had been dumping into the harbor. It did not take up any additional waste that still spills into the canal from the sewer system's 14 Combined Sewer Overflow (CSO) points.