SW6220505_Response To Comments_20230414

Bowman
Project: Utility Improvements to Serve Shahbain Reserve — Phase 1
Location: Rockfish Road, Raeford, Hoke County
Jurisdiction: NCDEQ
Date: 3/23/23
Subject: SW Comments SW6220505
4006 Barrett Drive, Suite 104
Raleigh, North Carolina, 27609
TEL [phone]
Comment
Response
Infiltration Basin SCM2
Response
The drawdown time calculations show the surface area of the infiltration
✓
Design calculations have been revised.
basin as 15,675 sf whereas the stage -storage table shows 7,230 sf. The surface
area of the infiltration basin that should be used for this calculation is the
cross -sectional area of the bottom of the infiltration basin (some infiltration
will occur on the side slopes of the basin, but it is negligible, see Part C-1 of
the Manual for more information). Using the cross -sectional area of 7,230 sf
will still result in a drawdown time within the required 72 hours so the design
does not need to be changed, just the calculations and Supplement-EZ Form
(Infiltration Page, Line 44. Please revise as needed.
Supplement EZ Form
Response
Wet Pond Page:
✓
Lines 2 has been revised for all wet ponds.
• Line 2 — Please list the minimum required treatment volume
(calculated water quality volume) instead of the design volume. For
example, for Wet Pond 1, the minimum required treatment volume is
shown in the calculations as 31,555 cf (while the design volume is
32,182 cf).
Infiltration Page:
✓
Line 2 has been revised.
• Line 2 — Please list the minimum required treatment volume
(calculated water quality volume) instead of the design volume. For
Line 45 — Drawdown time has been revised.
example, for the infiltration basin, the minimum required treatment
volume is shown in the calculations as 14,480 cf (while the design
volume is 62,235 cf).
• Line 45 — See earlier comment.