SW6220703_comments_20221130

site
November 23, 2022 solutions
Jim Farkas civil engineering I land surveying
NCDEQ Stormwater Program RFcF—i +�—[)
512 N. Salisbury Street
Raleigh, NC 27604 NOV 3
RE: MAGNOLIA HILLS S/D ADDITIONAL COMMENTS D,MLRStQrMwaterprogram
SW6220703
Jim;
We are re-submitting the portions of the stormwater application and documents that
have been revised/created per the comments received on November 15.
Please correct the following:
- General:
°Ao The provided Swale velocity&flow depth information shown in the
Supplement EZ Form should reflect the permanent design conditions, not on
the temporary matting. For example,the provided calculations show the l
unreinforced vegetated Swale#2 as having a 10-year design flow of 3.65 fps,
however the Supplement-EZ Swale Table shows the actual velocity of this Swale
as 5.69 fps (based on the calculations for the temporary C125 matting). Please
revise the Vallowable,Vactual, F Depth, Liner,&SF columns in the table to
reflect the permanent design conditions.
■ The chart has been updated to reflect the velocities and flow depth for
the permanent conditions.The columns for the liner and safety factor
were removed.
- Vegetated Conveyance Design:
o Please provide a source for the allowable velocities of the vegetated
conveyances if using values other than those found in Part C-11 of the Manual.
■ The allowable velocities were modified to match the manual.
o The slope of Swale#1 is shown to be 3.0%in the Swale Table of the
Supplement-EZ Form and 0.7% in the calculations. Please revise as needed.
■ The slope in the Swale table was modified to 0.7%to match the
calcuations. i
o The ditch detail on plan sheet C-6.0 indicates to"see plans"for the bottom
width of the ditches. I didn't see the ditch bottom widths shown in the plans.
Please ensure that this information is specified in the plans.
■ The ditch detail has been modified to indicate all ditches have a 0.5'flat
bottom unless otherwise specified on the plans. Ditch 1 &31 have their
widths noted on the plans.
- Supplement-EZ Form:
o Low-Density Page:
■ Revise as needed in accordance with the earlier comments.
409 Chicago Drive,Suite 112, Fayetteville,NC 28306
office 910-426-6777 fax [phone]
On time,every time. wwwADsitesotutions.con-i

• Document was updated to reflect the revised maximum
velocity.
If you have any questions or comments, please contact me at your earliest convenience.
Sincerely,
4D Site Solutions Inc.
Scott Brown, PE
[e-mail]
Enclosure
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