20190623 Ver 1_B-4819_Final_Approval_20190510

NCFMP and NCDOT MOA Project Review
PROJECT INFORMATION
Project TIP:
Sch Let Date:
CLOMR Case Number:
Municipality:
County:,
CID Number:
Project Engineer:
Project Reviewer:
MODEL STATUS
B-4819
9/25/2019
N/A
N/A
Stokes
370362
Reid B. Robol, PE
Matthew Dudley, PE
Type of Study (detailed, limited, redelineated):
Effective Model on File?
Effective Model Format (HEC-RAS, HEC2, Other):
Proposed Model Format (HEC-RAS, HEC2,
Other):
PROJECT SPECIFIC NOTES (pre -model review)
Stream Name:
Snow Creek
Route Number:
SR 1697
Road Name on Panel:
Pitzer Rd.
Effective FIS Date:
5/16/2007
Panel Number:
6966
Panel Effective Date:
5/16/2007
Bounding Stations:
Station 7500/290
Limited
YES
HEC-RAS 3.1.2
HEC-RAS 5.0.3
This project has a maximum decrease of 0.30-ft and will be submitted as a MCA type 2a.
REVIEW COMMENTS:
1. Upon review of the model, the Revised plan was not executed; therefore, results are not able to
be reviewed. The plans should be executed before being submitted. The reviewer executed a
copy of the model to complete the first -round review. Please execute the Revised plan before
resubmitting. Revised model has been executed for this re -submittal.
Verified. No action needed.
2. If possible, please resolve the negative surcharge at the station 400 BR U. Multiple attempts
were made to eliminate the negative surcharge but none were able to get it eliminated.
Verified. No action needed.
3. Encroachments outside of project limits should not be altered. Since the right encroachment at
RS 341 is moved to the left by 11.6-ft from the Corrected Effective to the Revised plan, please
consider extending the downstream project limits to RS 290 or revert the encroachment
modification. Project limits have been extended to RS 290 as shown in the FEMA Coordination
Form.
Verified. No action needed.
4. For the structure at 400, the Corrected Effective and Revised ineffective stations are placed at
contraction and expansion ratios as follows:

UPSTREAM CORRECTED: The upstream left and right ineffective stations are 59.8-ft and 37.9-ft
off the structure opening, respectively. The upstream cross section is 35.1-ft off the structure
opening (left contraction ratio of 1:0.59 and right contraction of 1:0.93).
UPSTREAM REVISED: The upstream left and right ineffective stations are 16.4-ft and 45.9-ft off
the structure opening, respectively. The upstream cross section is 29.1-ft off the structure
opening (left contraction ratio of 1:1.77 and right contraction of 1:0.63).
DOWNSTREAM CORRECTED: The downstream left and right ineffective stations are at 46.1-ft
and 43.4-ft off the structure opening, respectively. The downstream cross section is 44.5-ft off
the structure opening (left expansion ratio of 1:0.97 and right expansion of 1:1.03).
DOWNSTREAM REVISED: The downstream left and right ineffective stations are at 55.1-ft and
28.3-ft off the structure opening, respectively. The downstream cross section is 39.7-ft off the
structure opening (left expansion ratio of 1:0.72 and right expansion of 1:1.40).
Please justify the current ineffective station placement or consider revising them to ensure a
consistent approach between the Corrected Effective and Revised plans. The generally accepted
contraction ratio is 1:1 and expansion ratios generally range from 1:1 to 1:4. For this project,
the contraction and expansion ratios were drawn in the workmap at a 1:1 line in the direction
of flow from the bridge abutment and measured from the stream centerline along the cross
section. Because of the sinuosity of the stream, the distance from the structure to the cross
sections will not calculate at a 1:1 ratio. We believe measuring along the cross section will be
more representative of the effective flow area. This has also been added to the narrative.
Verified. No action needed.
CORRECTED EFFECTIVE:
— 0 X
ft ua argon 1' T..b Riwl. Nep
J.rt
•
nm:
35.1-ft ++
®o
a
e
44.5-ft
J.. _ _. — ___. ___.. _.-- —.._ _ __ —J _

fie Yc, 0q H4
37.9-ft
REVISED:
- o x
ti w rpeom r uae roa, osm,, wp
Tr
J.ct
s
29.1-ft
n i
i
I
i
I
i
i
39.7-ft
i
i

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- o x
TY [N O,uwn Yw Lhle i.tl. (iS t.tl. Heq
MNF;t
I.
�,� q.q pv.em, Wx5ntm4P.i:
6.:
•
29.1-ft
i
m
0-
r.n
e
i
{
39.7-ft
- -- - - - - ------
MINOR COMMENTS
1. Please consider renaming the .dgn file to follow the nomenclature "20180827 B4819 MOA".
The .dgn file has been renamed to the above nomenclature.
Verified. No action needed.
2. Our review of the submitted HEC-RAS hydraulic model revealed that the Corrected Effective and
Revised plans water surface elevations do not tie-in within 0.00 feet of each other at the
upstream limit listed on the FEMA coordination form (cross section 7000). Please consider
extending the comparisons to cross section 7500 where the difference in BFE is 0.00. Please
revise the FEMA coordination form accordingly. FEMA coordination form has been modified to
extend the project limits to IRS 7500.
Verified. No action needed.
NOTES FOR NCFMP
None
FINAL DETERMINATION:
This project is recommended for approval as a type 2a project.
i 4 J Wy _ 3/07/,
Matthew B. Dudley, PE, CFM Date
ESP — Project Manager
A R 0!
E S S
a SEAL r-�:
7018