The Carroll St Site falls within the drainage basin of Owls Head Wastewater Treatment Plant represented by the purple symbol. This covers much of the western half of Brooklyn. I found this link helpful when finding that fact:
Water will that misses my site, in normal weather conditions, will flow into this plant, and subsequently Owls Head releases the water into the Upper NY Bay. It is a tier 2 water treatment plant which combined with other tier 2’s releases 20% of the total 13.5 billion gallons of CSO pollution annually. However, when rains come, water that misses my site flows into the orange CSO outfalls along the Gowanus Canal.
Stormwater runoff that escapes the site flows into the drainage catchbasins on the street. These catchbasins also collect wastewater. So stormwater and wastewater combine together in the underground pipes and flow towards either an orange CSO outfall or towards Owls Head.