ILM Circle K - Erosion Control - Comment Responses
5410 TRINITY ROAD, SUITE 102 • RALEIGH, NC 27607 • PHONE 919.866.4951 • FAX 919.859.5663• WWW.TIMMONS.COM
Project: Circle K – NTI Airport Blvd Wilmington – NC.115 Date: 12/03/2020
Type of Review: New Hanover County – Erosion Control - 1st Review
Project Contact: Brian Downs
Phone: (919) 866-4504
Email: Brian.Downs@timmons.com
Response to review comments have been added below comment and are in bold.
NEW HANOVER COUNTY – ENGINEERING DEPARTMENT
1. Ensure the skimmer is sized for the difference between the temporary and permanent
pool elevation. Please show how the skimmer was sized (Sec. 23-248). Please also
show what type skimmer you are specifying on the detail. The outlet in Pond 101B has
a potential to allow water to outlet. So, it must dewater from the surface. Need sealed
calculation and the skimmer sizes (Sec. 23-248).
RESPONSE:
The skimmer was sized using NCDEQ’s method for determining simmer
and orifice size located in section 6.64 of their erosion control manual. The
equation is now shown on in our calculation package highlighted in yellow.
The skimmer sized have been revised to accommodate water quality
elevation/depth
We will be using a Faircloth skimmer, which is now called out in the
keynote and detail.
We are now proposing a skimmer and baffles in pond IIIB during Phase 2 of
erosion control, this will allow our pond to outlet from the surface until the
site is stabilized.
The two ponds are proposed dry ponds, so the skimmers in both have now
been sized for the difference to the water quality elevation since there is no
permanent pool elevation.
Riser 101B has now been relabeled as Riser 202B on sheet C3.8 to remain
consistent with the Grading Sheets.
2. It appears the horseshow filter is a rock pipe inlet protector that requires sealed
sediment storage calculation and storage dimensions (Sec. 23-236 & 23-248).
RESPONSE: The horseshoe inlet protection has now been relabeled as “Rock
Pipe Inlet Protection. Keynotes EC117A and EC117B have been edited to reflect
minimum dimension. Sealed calculations have now been included in the design
package, with dimensions called out on the plans. The rock pipe inlet protections
proposed in phase 2 have been replaced with check dams to allow areas around
inlets to be brought to finished grade while also protecting them from sediment.
5410 TRINITY ROAD, SUITE 102 • RALEIGH, NC 27607 • PHONE 919.866.4951 • FAX 919.859.5663• WWW.TIMMONS.COM
3. Ensure no more than ¼ acre drains to 100 feet of silt fence (Sec-236).
RESPONSE: Additional Silt fence and outlets have been included and adjusted to
ensure that no more than 0.25 acres drain to 100 feet of silt fence.
4. May need to protect the relative permanent water with silt fence on either side in Phase
I during clearing and add possibly another construction entrance for accessor logging
mats (Sec. 23-236). It doesn’t appear a silt fence stone outlet designed for that much
flow and may not be allowed I relative permanent water for erosion control.
RESPONSE: Silt fence has been added to both sides of the permanent water area
in Phase I. A temporary timber mat and detail have been added to allow access
across this area. The silt fence and silt fence stone outlet downstream of the
permanent water area has been removed.
5. There does not appear to be a horseshoe filter detail, temporary inlet protection filter
detail, silt fence detail or check dam detail on the plans (Sec. 23-248).
RESPONSE: Temporary rock pipe inlet protection, temporary inlet protection
(yard and catch basin), silt fence, and check dam details have been added to the
plans on sheet C7.1. Details have now been labeled the same for plan clarity.
6. Need maintenance for the skimmer sediment basin, silt fence, rock pipe inlet protector
or horseshow filter, temporary inlet protection, and check dam details on the plans.
RESPONSE: Maintenance for the skimmer basin, skimmer, silt fence, rock pipe
inlet protection, inlet protection and check dam have now been added to the
details on sheet C7.0 and C7.1.
7. Silt fence across the existing ditch (Sec. 23-236).
RESPONSE: Silt fence has been removed across all existing ditches.
8. There does not appear to be any erosion control for the 2 vegetated filter prior to
stabilization (Sec. 23-236).
RESPONSE: Silt fence has now been added along the perimeter of both
vegetative filter strips to protect them from surround sediment. Both filter strips
are outlined in their detail to be lined with North American Green S75 matting.
Due to the flatness of both filters, we do not believe a check dam is necessary in
these areas. Keynotes EC122 and EC229 have been added to sheets C4.0 and
C4.3.
9. Need tree approval prior to issuance of the land disturbing permit or any activity onsite.
(Sec. 18-457)
RESPONSE: Noted.
5410 TRINITY ROAD, SUITE 102 • RALEIGH, NC 27607 • PHONE 919.866.4951 • FAX 919.859.5663• WWW.TIMMONS.COM
Additional information requested which is voluntary and has no bearing on the approval
of the project is as follows:
1. Need a site address for the application (Sec 23-248).
RESPONSE: The address for the Circle K will be 1620 Airport Boulevard.
2. What does NTI stand for?
RESPONSE: “New to Industry.” It is used within Circle K to differentiate new
stores from remodels.
3. Ensure silt fence does not cross the front R/W swale as the LOD line blocks this area
out.
RESPONSE: The silt fence in that area is now confirmed not shown in front of the
R/W swale.
4. Might be a good idea to show silt fence over the fill on top of pipes so sediment doesn’t
wash into ditches for the driveway pipes, north side of the 15-inch pipe and above the
end of the 36-inch pipe.
RESPONSE: Unclear which pipes are being referenced.
5. Need a copy of a valid wetland delineation when its available.
RESPONSE: A copy of the USACE jurisdictional determination with wetland
determination is included in this submittal.
6. Need a pdf on a CD and 2 pages of any plan changes.
RESPONSE: A CD has been provided that includes a pdf of the plans, 2 copies of
paper plan sets have also been included.