Get Full Government Meeting Transcripts, Videos, & Alerts Forever!
Get email alerts on the Stormwater Septic Safety topic
No spam. Unsubscribe anytime.
Presenter and planning board debate pool runoff design over septic risk
Summary
Philipstown planning board members pressed a presenter on whether a proposed private pool’s runoff and overflow could undermine a downhill septic system and harm downstream water quality; staff described cover-box dimensions and the board requested revised plans with swales or diversion measures.
Presenter (S1) described a proposed pool and patio drainage system and said the engineering calculations were meant to capture the first 1.5 inches of runoff from the pool when it begins raining. Chair (S2) and other board members pressed for clarifications about where overflow would go and whether the design could harm a septic system downhill.
The board sought the missing calculations and asked the applicant to show the site plan locating the septic field relative to the pool. Chair (S2) said the septic is below the pool and warned that “if the pool were overflowing, particularly in a catastrophic rain event, that it could undermine the septic and and that would flow down to the train tracks and, worse yet, the river.” Presenter (S1) said the design intent was to handle the 90th-percentile storm and explained the assessment used pool area to size captured runoff, adding, “the 90th percentile is is more frequent than a 1 year storm.”
Staff member (S4) described the pool cover-box and drain details, saying the cover box will be 14 inches wide and 24 inches deep, with the top set 6 inches below the top of the pool; he said it would require substantial inundation to overflow the pool top. Board members nevertheless recommended site changes to further reduce risk: suggestions included a freestanding wall pitched away from the septic, a small swale to route sheet flow downhill away from the septic field, or moving infiltrators farther downhill where feasible.
Committee members asked for reassurance about debris clogging drains and noted that heavy storms (for example, several inches in a 24-hour period) and fallen leaves or branches can create unexpected backups. One resident (S6) and committee participants urged conservative design changes—“better safe than sorry”—and the board indicated it had provided sufficient input that the applicant should return with modified plans for a permit.
The board did not take a formal vote at the meeting. Next steps recorded on the record were that the applicant will revise drainage details to address the septic-safety concerns and resubmit materials so staff can proceed with final permit review.
