SW3240801_Response to Comments_20241118

•ESP
North Carolina Department of Environmental Quality— Stormwater
Adelina Phase 1
1st Submittal Review Comments dated 10/15/2024
Date: October 29, 2024
1st Submittal Review Comments:
1. Comment: As designed, SCM 3 is considered to be just a sand filter and not a dry detention basin
& sand filter(the sand filter SCM includes the sand layer in addition to the storage provided
above the sand layer in the sand chamber and sediment chamber). Please revise the submittal
materials as needed to reflect this. Later comments will be made in the context of considering
SCM 3 as only a sand filter. If peak flow attenuation is desired(or required for local ordinances)
this is acceptable,but the SCM, as designed,must meet the Sand Filter MDC. Please also revise
the project documentation to address the following MDC's that were not met:
a. Sand Filter MDC 1 —A SHWT evaluation within the footprint of the SCM as not
provided, so compliance with this MDC could not be verified. For open-bottom sand
filters, a minimum separation of two feet must be maintained from the SHWT.
b. Sand Filter MDC 2—Storage volume in each chamber(sand and sediment)must be
equal. If peak flow mitigation is desired,only the sediment chamber may be the larger of
the two,but both most contain at least half of the design volume.
Response: SCM 3 has be revised to exclude the Dry Pond on the respective documents.
Geotechnical Report have been provided with submittal for the determination of the SHWT
and footprint within the proposed Sand Filter.
2. Comment: Per Wet Pond MDC 5,the entrance of a wet pond's forebay shall be deeper than the
exit. All proposed Wet Pods are not in compliance with this MDC. Please revise the project
package as necessary for compliance with the MDC as well as consistency with the required
revisions.
Response: All Wet Pond's forebays entrances have been revised to meet Wet Pond MDC 5.
Please refer to all supporting documents submitted.
Consistency
3. Comment: Please revise the following for consistency:
a. The BUA fpr Drainage Area 5 on the Application states 277,042 sf and the Drainage
Area Page of the Supplement-EZ form states 276,813 sf.Please revise for consistency.
Response: All proposed drainage area's have been revised to be consistent with calculations
provided with this submittal.Please refer to all supporting documentation.
ESP Associates,Inc.
P.O.Box 7030 • Charlotte,NC 28241
1.800.960.7317 • NC:704.583.4949,fax [phone] • SC:803.802.2440,fax [phone]
www.espassociates.com

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Application
4. Comment: Section IV,4—Please revise this line to indicate the desired project area associated
with this phase of development. This project area should also be delineated by bearings and
distances on the main set of plans.
Response: An exhibit as been added to the plan set to show the following bearings and
distances of the property area and project area.Please refer to sheet C1.1.
5. Comment: Section IV, 6—Please ensure that all surface water within the delineated project area
is accounted for in this section of the Application.
Response: Surface Water has now been accounted for in this section of the application,as
well as accounting for stream offset buffers proposed within the construction plan. Please
refer to supporting documentation for details.
6. Comment: Section IV, 7—Please revise this section to account for the surface waters on-site by
subtraction the surface area associated with the surface waters from the property area listed in
Section IV,4.
Response: Section has been updated per accounting of surface waters within projects scope.
7. Comment: Section IV, 8—Please revise the total project's Percent BUA to reflect the changes in
the above comments.
Response: Section has been updated to reflect the changes to surface water.Please refer to
all supporting documents.
Supplement-EZ Form
8. Comment: On the Cover page please revise the following Line 2 and 4 per comments above on
the Application.
Response: Lines 2 & 4 have been revised to reflect changes to surface water area.
9. Comment: On line 22,Please remove this, as a Dry Pond is not being permitted at this time.
Response: Line 22 has been updated to reflect no Dry Pond.
ESP Associates,Inc.
P.O.Box 7030 • Charlotte,NC 28241
1.800.960.7317 • NC:704.583.4949,fax [phone] • SC:803.802.2440,fax [phone]
www.espassociates.com

•ESP
10. Comment: Drainage Area Page
a. Please complete this page(lines 9,10, and 12). The BUA accounting present on this page
should reflect what is shown in Section IV, 10 of the Application. The Entire Site column
may not necessarily be a sum of the other columns on all lines but should reflect the site
as a whole.
b. Line 18—Please complete this line.
c. Line 21 —This line refers to the calculation method used to find the minimum required
treatment volume.Please revise as necessary.
Response: Lines 9,10,and 12 have been completed, and been shown to reflect Section IV,
10.Line 18 has been completed.Line 21 is correct, and the minimum treatment volume on Line
2 has been updated to reflect the method used.
11. Comment: Wet Pond Page Line 2—Please revise the entries on this line to correspond to the
Minimum required Treatment Volume calculated using the mrthod outlined on Line 21 of the
Drainage Areas Page.
Response: Line 2 has been updated to reflect the method used to calculate the minimum
required treatment volume.Please refer to the Supplement-EZ form.
12. Comment: Wet Pond Page Line 8—Please revise to indicate compliance with General MDC 5.
Response: A concrete emergency spillway has been added to comply with Line 8 of the Wet
Pond General MDC 5.
13. Comment: Line 35-Please revise this line to indicate the actual design volume of each Wet Pond.
Please note that the design volume of a wet pond is the volume stored between the elevations of
the permanent pool and the invert of the lowest bypass device.
Response: The design volume of all proposed Wet Ponds have been updated on line 35 to
reflect the stated specifications above.Please refer to line 35 and calculation package
provided with this submittal.
14. Comment: Line 43 and 44—See earlier comment with regard to Wet Pond MDC 5.
Response: Lines 43 and 44 have been updated per Wet Pond MDC 5.
15. Comment: Wet Pond Page Line 53—Wetland seed mixes may not be used as vegetation for Wet
Ponds. Please revise the grass to be used sop that compliance with Wet Pond MDC 11 may be
verified.
Response: Line 53 has been updated to reflect a Tall Fescue grass type instead of a wetland
seed mix.
ESP Associates,Inc.
P.O.Box 7030 • Charlotte,NC 28241
1.800.960.7317 • NC:704.583.4949,fax [phone] • SC:803.802.2440,fax [phone]
www.espassociates.com

•ESP
16. Comment: Sand Filter Page Line 8—Please revise to indicate that there will be an overflow or
bypass for inflow volumes in excess of the design volume,as required by General MDC 5. There
appears to be a riser structure provided that will act as a bypass device.
Response: Line 8 has been updated to reflect the use of the riser structure as the bypass
device.
17. Comment: Sand Filter Page Line 9—A drawdown orifice to dewater the SCM for maintenance
could not be found on the provided set of plans. Please include and indicate this orifice or revise
the type of drawdown device to be used for maintenance on this line of the Supplement-EZ form.
Response: Drawdown orifice to be attached to the riser structure to dewater the Sand Filer
for maintenance.
18. Comment: Sand Filter Page Line 18—Per Sand Filter MDC 1,the minimum separation between
the lowest point of the Sand Filter System and the SHWT shall be two feet for open-bottom
designs.A SHWT evaluation inside the footprint of the SCM was not provided with this
submission, so compliance with the MDC could not be verified. Please provide a SHWT boring
within the footprint of the SCM and revise this line to indicate the elevation of the SHWT so that
compliance with the MDC can be verified.
Response: A Survey/Geotechnical boring location and SHWT table report have been
submitted with this submittal.
19. Comment: Sand Filter Page Line 23-29—Please complete this section of the Supplement-EZ
form. Please note that, as designed,the forebay of the"dry pond"is considered the sediment
chamber of the Sand Filter SCM, and the information entered here should reflect its design and
dimensions.
Response: Lines 23-29 have been updated.
20. Comment: Sand Filter Page Line 30—For a Sand Filter,the volume retained in the sand chamber
is considered to be the only inclusive of the volume stored directly above the and surface between
the top of the sand layer and the invert of the lowest bypass device. Please revise this line to
indicate that volume.
Response: The volume of the sand filter has been recalculated and updated per the
information above.
ESP Associates,Inc.
P.O.Box 7030 • Charlotte,NC 28241
1.800.960.7317 • NC:704.583.4949,fax [phone] • SC:803.802.2440,fax [phone]
www.espassociates.com

•ESP
21. Comment: Sand Filter Page Line 33—The physical depth of the sand chamber is the depth from
the lowest bypass invert(Line 35)to the lowest excavated point of the sand chamber(below the
underdrains).
Response: Line 33 has been updated based off the information provided above.
22. Comment: Sand Filter Page Line 34—The ponding depth of the sand chamber is the depth from
the lowest bypass invert(Line 35)to the top of the sand layer(Line 31).
Response: Line 34 has been updated based off the information provided above.
23. Comment: Dry Pond Page.Please remove this page.
Response: Dry Pond page has been removed.
24. Comment: On the Plan set,Please revise the provided Wet Pond details to indicate all relevant
elevations(bottom, sediment storage,forebay entrance and exit, etc.)as required by 15A NCAC
02H.1042(2)(h)(i).
Response: All wet pond details have been updated to provide the information requested
above.
25. Comment: On the Plan set,please indicate the type of grass that will be planted for each Wet
Pond on the planting plans, so that compliance with Wet Pond MDC 11 may be verified. Wetland
Mixes may not be used.
Response: The type of grass to be used will be Tall Fescue on all proposed Wet Ponds.
Please refer to the Wet Pond Details on the plan set.
26. Comment: On the Plan set,The maintenance accesses and easements required by General MDC's
8 and 9 could not be found on the main set of plans. Please revise the provided plan sheets to
indicate these accesses and easements or direct the reviewer to this information. Please note that
maintenance accesses and easements shall be at least 10 feet in width, contain no slopes steeper
than 3:1, and contain all portions of the SCM,including outlet structures.
Response: The maintenance access and easements have been called out as "Prop. 12' Access
Drive Easement,as well the SCM easement has now been highlighted on the plan set to
easily identify the proposed accesses and easements.
ESP Associates,Inc.
P.O.Box 7030 • Charlotte,NC 28241
1.800.960.7317 • NC:704.583.4949,fax [phone] • SC:803.802.2440,fax [phone]
www.espassociates.com

•ESP
27. Comment: On the Plan set,Please revise the orifice diameters provided to be consistent with what
is shown in the calculations and on the Supplement-EZ Form.
Response: All orifices calculations have been updated and now remain consistent with the
calculation package and Supplement-EZ form.
28. Comment: Please delineate the project area associated with this phase of development on the
main set of plans with bearings and distances, as required by Section VI, 8i of the Application.
Response: A Property and Phase boundary Exhibit has been provided with this submittal,
Please refer to Sheet C1.1 for all boundary information bearings and distances.
29. Comment: O&M Agreement Form—Please provide a revised O&M Agreement with the Dry
Pond information removed, as it is not being permitted at this time.
Response: Dry Pond Page has been removed front the O&M Agreement form.
30. Comment: O&M Agreement Form—The elevations given with the O&M Agreement are not
currently shown on the provided set of plans, as indicated in earlier comments. When this is
revised,please ensure these elevations are consistent with what is shown in the O&M Agreement.
If the elevations on the O&M Agreement are inaccurate,the will need to be revised.
Response: The O&M Agreement Form has been updated with the correct elevations
according to the calculation method used in the Supplement-EZ form.
31. Comment: Calculations—For wet pond calculations,the Equation 3 average depth when the shelf
is partially or fully submerged and the shelf is being excluded from the average depth calculation,
the value of Vpp should be the main pool volume at the permanent pool elevation. The provided
calculations use the total volume of the permanent pool. Please revise these calculations.At this
time,the draw down calculations are unverifiable due to the average depth discrepancy.
Response: The average depth calculation has been updated to the information provided
above.
ESP Associates,Inc.
P.O.Box 7030 • Charlotte,NC 28241
1.800.960.7317 • NC:704.583.4949,fax [phone] • SC:803.802.2440,fax [phone]
www.espassociates.com