SW3221006_Response To Comments_20230419

EAGLE ENGINEERING
44
April 19, 2023
NCDEQ
RE: The Cottages at Wingate
Maye Street, Wingate, NC
Project ID: SW3221006
We are in receipt of your review comments for The Cottages at Wingate — Phase 1 and 2 located on
Maye Street in Wingate, NC. Please find below the edited responses to the requested information.
DEMLR COMMENTS
Contact: Jim Farkas
General Wet Pond Design:
Off -site Drainage:
1) Any off -site drainage area that is not bypassed around the SCM must be accounted for at its full build -
out potential (per 15A NCACO2H .1003(3)(b)). The full build -out potential of the off -site area can be
limited by having the property owners enter into a legal agreement limiting the amount of BUA and
drainage area directed from the off -site area to the SCM or by assuming that the off -site area is 100%
BUA (its full build out potential). It is recommended to bypass off -site drainage areas around the
SCMs (please see note following the comments for more information). Please revise as needed.
i) All off -site areas that have not been bypassed around the site have been included and accounted
for in the design of the stormwater ponds. The off -site areas that drain to the ponds are already
developed residential areas and thus have been analyzed as their full build out potential.
Wet Pond MDC 5b•
2) The excavated bottom elevations of the forebays near the entrance of the forebays must be deeper than
the excavated bottom elevation of the forebays near the exit of the forebays (see Figure 5 in Part C-3
of the Manual). NOTE: There must be at least 6 inches of sediment storage provided over the
excavated bottom of the forebay near the entrance and near the exit per Wet Pond MDC 3.
i) All ponds have been revised to provide 6" of sedimentation volume at the exit of each forebay and
18" of sedimentation volume at the entrance of each forebay. This is now reflected in profile and
plan view of each BMP detail sheet.
3) There appear to be discrepancies between the drainage area information shown in the forms and that
shown in the calculations. One such example is with Wet Pond A2. The Application shows the
drainage area as 459,558 sf while the calculations show 459,674 sf and the Application shows the
BUA draining to this SCM as 174,676 sf while the calculations show 174,713 s£ Please revise the
submittal materials as needed for consistency and correctness. NOTE: The values shown in the
calculations were used to evaluate the designs.
i) The discrepancies between the report, calculations and applications have been corrected and
updated for consistency.
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The Cottages at Wingate
Maye Street, Wingate, NC
Project ID: UNION-2022-098
Wet Pond Al Design:
4) As designed, the flow from FES-100 appears to short circuit to the outlet structure (Wet Pond MDC
4). Please either relocate the outlet structure so that it is further away from this inlet or provide berms
and/or baffles to better maximize the flow path through the wet pond. NOTE: berms and/or baffles
need to extend above the temporary pool surface elevation.
i) An earthen berm is now being proposed within the main pool of the wet pond to increase the flow
path through the pond. Calculations have been updated to reflect this change in volume.
5) As designed, the forebay of this wet pond may be too large (Wet Pond MDC 5b). When determining
the volume of the main pool, the forebay volume is not included (the main pool and forebay combine
together to form the permanent pool). The provided stage -storage table for the main pool appears to
include the forebay. Removing the forebay from the main pool volume calculation results in a forebay
volume that is in excess of 20% of the main pool volume. Please revise as needed.
i) The main pool and forebay have been revised to ensure the combined volume of the two forebays
is 20% of the main pool. Calculations are now updated accordingly.
6) The provided plant density on the vegetated shelf is insufficient (Wet Pond MDC 1 lb). Per the plans,
the vegetated shelf area is 6,481 sf and a total of 1,620 plants are proposed. 1,620 plants / 6,481 sf <
50 plants / 200 sf. Please revise as needed.
i) After revisions to the pond, the new vegetated shelf area is 6,397 s£ 6,397 / 200 sf = 31.99 x 50
= 1599.25. Based on this math, the provided plants have been placed at 1,600.
11) Further, 50 / 200 = 0.25 plants per s£ 1,600 / 6,397 = 0.25 plants per sf.
7) FES-100 & FES-121 are not shown on the plans as discharging to the forebays, they appear to be about
40' short. Please revise as needed.
i) FES-100 and FES-121 are located correctly and will drain into the forebays with the grading
designed as is. The structures were ended short of the pond to reduce the depth of pipe for the
storm drain, but were located in a way such that all drainage would enter the forebay once
discharged.
Wet Pond A2 Design:
8) An additional forebay design sheet (with a provided forebay volume of 7,036 cf provided between
elevations 510.0' & 514.0') was provided in the calculation booklet. Please clarify the presence of this
design sheet.
i) The second forebay design sheet (showing a 14% volume) is an errant, old design sheet that should
not have been included. It has been removed from the stormwater report.
9) FES-200 is not shown on the plans as discharging to the forebay, it appears to be about 40' short.
Please revise as needed.
i) FES-200 is located correctly and will drain into the forebays with the grading designed as is. The
structures were ended short of the pond to reduce the depth of pipe for the storm drain, but were
located in a way such that all drainage would enter the forebay once discharged.
Wet Pond A3 Design:
10) As designed, the forebay of this wet pond may be too large (Wet Pond MDC 5b). Removing the
forebay from the main pool volume calculation results in a forebay volume that is in excess of 20%
of the main pool volume. Please revise as needed.
i) The main pool and forebay have been revised to ensure the combined volume of the two
forebays is 20% or less than that of the main pool. Calculations are now updated accordingly.
Wet Pond B Design:
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The Cottages at Wingate
Maye Street, Wingate, NC
Project ID: UNION-2022-098
11) As designed, the forebay of this wet pond may be too large (Wet Pond MDC 5b). Removing the
forebay from the main pool volume calculation results in a forebay volume that is in excess of
20% of the main pool volume. Please revise as needed.
i) The main pool and forebay have been revised to ensure the combined volume of the two
forebays is 20% pr less than that of the main pool. Calculations are now updated accordingly.
Application
12) Please have the other property owner, Shelby Cattle Farm, LLC sign Section IX (allowing the
applicant, H&H Construction of Fayetteville, LLC, to apply for the permit) and provide their
contact information in Section III, 2.
i) The application has been updated.
13) Section IV,10 — Please refer to later comments with regard to BUA accounting. The information
in this table should reflect the drainage area columns of the Drainage Areas Page of the
Supplement-EZ Form. Please revise as needed. NOTE: The On- site Buildings/Lots item should
correspond to the BUA allocated to the individual lots (Line 9 of the Supplement-EZ Form).
i) All BUA information has been updated per the Supplement-EZ Form.
Supplement-EZ Form:
Cover Pau.
•
14) Line 2 — Please use the project area, 118.64 ac, instead of the total property area.
i) This has been updated to 118.64
15) Line 7 — Please include this item (refer to 15A NCAC 02H .1003(4) & .1017(10) for more
information).
i) The width of the setback is 25' and is shown in the table
16) Lines 8 & 9 — Please answer these items with regard to the vegetated setback from surface waters.
i) The setback will remain vegetated and there is no BUA proposed within the vegetated setback.
Drainage Areas Page:
17) Please complete the entire site column. The entire site column is an accounting of the entire project
area (similar to how the drainage area columns are an accounting of the areas draining to the SCMs).
When the items for this column ask for the "drainage area" please enter the project area. NOTE:
Any BUA that does not drain to an SCM should be accounted for in this column.
i) The `Entire Site' column has been completed. All values should be made up of the pond
drainage areas in columns 1-4 with the exception of the drainage area which has been noted as
the project area.
18) Lines 5 & 6, Drainage Area 3 —The provided values, 459,674 sf, do not correspond to the values
shown in the Application, 459,558 sf. Please revise as needed.
i) The Supp EZ form and Application form were correct for these lines. The Stormwater Report
comps have been updated to the correct drainage area of 459,674 s.f.
19) Line 9 — This item should be BUA that is allocated to the individual lots. Per the deed restriction
document, the 299 (180 in Phase 1, 119 in Phase 2) lots are allocated 3,764 sf of BUA each for a
total of 1,125,431 sf. The sum of the values shown for this line only adds up to 686,356 s£ Please
revise as needed. NOTE: BUA allocated to the individual lots should be shown on this line and
BUA in the common areas should be shown on Lines 10 & 12.
i) The deed restriction document has been updated to reflect that each lot is allocated 2,739 s.f. of
BUA. This results in a total BUA on subdivided lots of 818,854 s.£ which is equal to the total
amount of BUA specified in line item 9. The total amount of BUA for both on and off lots is
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2013-A Van Buren Avenue
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The Cottages at Wingate
Maye Street, Wingate, NC
Project ID: UNION-2022-098
equal to the total BUA of each specific drainage area as shown in the calculations within the
stormwater report.
20) Line 10 — Line 10 should be the sum of the items of Line 12 and should not include any BUA
allocated to the individual lots. NOTE: The sum of Lines 9, 10, 11, and 15 is equal to Line 8.
i) Line 10 has been updated and is now the sum of the items from Line 12. The items in Line 12
have been updated to be ONLY the BUA that is not allocated to each individual lot. Line 8 is
now also equal to the sum of Line items 9, 10, 11 and 15.
21) Line 11— See earlier comment.
i) Offsite BUA has been updated to the correct amount which is only within Column 1.
22) Line 12, Roof — As noted above, Line 12 is only for common area BUA and would not include the
roof area of the individual houses.
i) The BUA for the roof line has been corrected to be 0 as there is no roof BUA outside of the
individual lots.
23) Line 18 — This value, 40%, does not correspond to the value shown in the application, 38%. Please
revise as needed.
i) The percent BUA for each column has been updated to match the computations shown in the
stormwater report and the application form.
24) Line 20 — The design volume of the SCMs should correspond to the values shown on Line 35 of the
Wet Pond Page of the Supplement-EZ Form (see later comment).
i) The design volume of each SCM has been updated to correctly reflect the value shown on Line
35 from the Wet Pond Page.
25) Line 21— The design volume for the SCMs is determined using either the Simple Method or the
Discrete NRCS Method (The Simple Method appears to be used in the Calculations).
i) The design volume determination method on Line 21 has been updated to the correct method
(Simple Method).
Wet Pond Pau:
26) Line 5, Column B — Please include this item.
i) The side slopes of the SCM for Pond B have been updated.
27) Line 26 — Please ensure that the surface area of only the main pool is used for this item. The surface
area of the forebay should not be included.
i) Surface area of the forebay has been removed from the line item and it now only includes the
surface area of the main pool.
28) Line 27, Columns Al, A3, & B — Please revise the main pool volume calculation so that the volume
of the forebay is not included.
i) Pond Al, A3, and B have been updated for Line 27 so that the main pool volume no longer
includes the volume of the forebay.
29) Line 28, Columns Al, A3, & B — Please revise the average depth calculations with the revised main
pool surface area and volume.
i) The average depth calculations for Ponds Al, A3, and B have been updated after re -calculating
the main pool volume for each Pond (and removing the forebay volume).
30) Line 32, Column A3 — The provided value, 3,545 cf, does not correspond to the value shown in the
calculations, 4,089 cf. Please revise as needed.
i) Line 32 has been updated for Ponds Al, A3, and B for the revised main pool and forebay
calculations. The forebay and main pool volumes should now accurately reflect the correct
volume per the stormwater report.
31) Line 34 — The cleanout depth of the forebay is the distance from the permanent pool surface
elevation to the top of the sediment storage zone, measured in inches.
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2013-A Van Buren Avenue
Indian Trail, NC 28079
Ph 704 882 4222
Fax [phone]

The Cottages at Wingate
Maye Street, Wingate, NC
Project ID: UNION-2022-098
i) The cleanout depth of the forebay has been updated to reflect the correct distance (in inches) per
the stormwater report (permanent pool elevation — top of sediment removal elevation).
32) Line 35 — The design volume of the SCM is the volume that can be stored above the permanent pool
surface elevation and below the invert of the lowest bypass elevation (these values are provided in
the calculations). Please revise as needed.
i) The design volume of each SCM has been updated to the volume between the permanent pool
elevation and the lowest bypass elevation (weir in the riser).
33) Lines 36-39 — These items refer to the method used to drawdown the temporary pool to the
permanent pool (orifice). Please revise as needed.
i) The drawdown method has been changed from the weir to the orifice and the correct orifice
diameter has been reflected on each pond. Drawdown times have also been updated as well.
34) Lines 43 & 44 — This item is measured from the permanent pool surface elevation to the excavated
bottom elevation of the forebay near the entrance (Line 43) or near the exit (Line 44). NOTE: Line
44 > Line 43 >= 6" + Line 34.
i) The elevations of the depths of the forebay at the entrance and exit have been revised per the
new forebay calculations. The depth of the forebay at the exit is now 6" greater than the cleanout
depth and the depth of the forebay at the entrance is 18" greater than the cleanout depth for the
forebay.
35) Line 48 — Per the provided details, the drawdown orifice appears to drawdown from below the
permanent pool surface.
i) Line 48 has been corrected to accurately reflect the orifice drawdown takes place from below the
permanent pool surface.
As you have any questions, please do not hesitate to contact our office.
Sincerely,
Eagle Engineering Inc.
Michael Prophet
Project Manager
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2013-A Van Buren Avenue
Indian Trail, NC 28079
Ph 704 882 4222
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