HomeMy WebLinkAboutSUB201600092 Review Comments Road Plan and Comps. 2021-01-22COMMONWEALTH of VIRGINIA
DEPARTMENT OF TRANSPORTATION
Stephen C. Brich, P.E. 1401 East Broad Street
Commissioner Richmond, Virginia 23219
December 18, 2020
County of Albemarle
Department of Community Development
401 McIntire Road
Charlottesville, VA 22902
Attn: Matthew Wentland, P.E.
Re: SUB-2016-00092 - North Pointe Subdivision, Section 1 — Road Plans
Review #8 (Revised)
Dear Mr. Wentland:
(804) 786,2701
Fax: (804) 786,2940
The Department of Transportation, Charlottesville Residency Transportation and Land Use
Section, has reviewed the above referenced plan as submitted by Townes Site Engineering,
revised 12 November 2020, and offers the following:
1) Central Office reviewed the details provided by Concrete Pipe & Precast for the side -by -side
10'x6' box culvert under 15 - 20' fill for the above project:
a) Based on the road plans, the box culvert layout shown on the shop drawings seem
appropriate for the site.
b) The design of the culvert using the specific steel areas provided appears to be
satisfactory. The "Precast Reinforced Concrete Box Section Data" page in the box culvert
submittal shows the reinforcing steel expected to be used.
c) Please confirm the Invert elevation of 375 shown on the page 1 of the details provided by
Concrete Pipe & Precast. Road plans sheet 11 shows outlet elevation of 375.30
2) Wall Plans, General:
a) Based on the information presented we (VDOT C.O. S&B — Geotech) are not sure if the
"Anchor Vertica" wall system will be acceptable. The wall system is on our approved list
(VDOT S&B Design Manual File 18.08-5 dated April 30, 2020), however, it is with the
stipulation that the wall system does not support highway loadings within the failure
wedge producing active earth pressures. The failure wedge is defined as the distance
back from the face of the wall to the edge highway loading, this distance is estimated as
1.3 times the wall height or 10 feet, whichever is greater.
b) Based on the Roadway Plans, the maximum wall height appears to be about 16 feet,
which means the failure wedge distance could be up to about 20 feet. Based on the
Global stability output, the live load from the roadway appears to be about 15 feet. In
order for us to further evaluate whether the "Anchor Vertica" wall system will be
VirginiaDOT.org
WE KEEP VIRGINIA MOVING
acceptable for this project, please clarify the distance from the wall face to edge of
roadway loading for the various wall heights.
c) Please clarify if vertical slip joints are needed.
d) Submission should make reference that the design is to be in accordance with VDOT
Special Provision (SP) for MSE Walls (Segmental Block Facing) provided in the VDOT
S&B Manual File 10.10-1 through 10.10-8 dated February 2017.
e) Submission should reference that the design is to be in accordance with the current
version of the VDOT R&B Specification.
f) Design does not appear to be based on the most recent version of LRFD even though
Note 3 on Sheet 1 of the Roadway Plans state that the design should be performed in
accordance with applicable AASHTO specifications. Retaining walls should be designed
per AASHTO LRFD, not ASD. References to bearing pressures and bearing capacities
are ASD and should be revised to factored bearing pressures and factored bearing
resistances per LRFD.
g) Note 3 on Sheet 1 of the Roadway Plans state that the design should be performed in
conjunction with a Geotechnical Engineering Report. A geotechnical report does not
appear to be provided or referenced in the retaining wall plans.
h) Note 5 on Sheet 1 of the Roadway Plans states that the subsurface exploration performed
for the retaining wall must be in accordance with the minimum guidelines set forth in
Chapter 3 of the VDOT Manual of Instruction (MOI). There does not appear to be a
reference to a subsurface exploration being performed for the retaining wall structure.
i) Design Loads (factored and service) should be provided and based on the applicable limit
state events provided in AASHTO LRFD.
j) Recommend adding a "Design Responsibility Section" which would clarify the Engineer
of Record (EOR) and the Geotechnical Engineer of Record (GEOR) for this project.
k) Per Section 2.Le of the SP, are there any locations along the wall alignment where pipes
or utilities will penetrate or go under the wall? If so, it needs to be shown on the plans,
elevations, as well provide a typical detail.
1) Per Section 2.2 of the SP, design calculations shall be provided. No calculations
regarding geogrid design, settlement, sliding, overturning, or bearing resistance appear to
have been provided. Please note that the design elements of the wall system and the
geotechnical stability of the wall system with respect to AASHTO LRFD Design
Specifications could not be verified in the absence of design calculations.
m) Wall Plans, Cover Sheet
n) Per Section 2.La of the SP, Elevations of the top of the wall shall be provided at intervals
of no greater than 50 feet. It appears that some of the top of wall elevations provided
exceed 50 foot intervals. Please clarify.
o) Per Section 2. Lb of the SP, Elevations at the top of leveling pad at step breaks shall be
provided.
p) What is the basis for the soil design parameters that were used? i.e. How were they
selected?
q) Note 3 states the fill for the reinforced zone shall have a Liquid Limit less than or equal
to 40, a Plasticity Index of less than or equal to 15, and less than or equal to 40% fines
passing the No. 200 sieve. However, Section 3.5 of the SP states that the material for the
reinforced zone shall have a Plasticity Index less than 6, less than 15% fines, and a
maximum internal friction angle of 34 degrees. Please see Section 3.5 of the SP for
further information (which includes electrochemical requirements of aggregate in contact
with geosynthetic soil reinforcements).
r) Note 8 states to compact fill material to within 3 percent of the optimum moisture
content. Per Section 4.5 of the SP, the material shall be compacted to optimum moisture
content or 2 percent below it.
s) Note 8 states to compact fill material to in loose lifts of 8 inches for soil and 10 inches for
crushed aggregate. Per Section 4.5 of the SP, the material shall be placed in loose lifts
not exceeding 8 inches.
t) Wall Plans, Sheet 4
u) Detail D2 and D3: Leveling pad shall be Class B2 concrete per Section 3.8 of the SP.
v) Wall Plans, Sheet 5
w) Detail DI: Please clarify the embedment depth at the front face of the wall.
x) Detail DI: Please clarify the slope configuration above the wall.
y) Detail DI: Leveling pad shall be Class B2 concrete per Section 3.8 of the SP.
z) Please depict the limits of the reinforced 21A aggregate.
aa) Geomembrane should be in accordance with VDOT R&B Spec Section 245.03.g
bb) A non -woven filter fabric should be used to separate the drainage aggregate (No. 57)
from the reinforced fill (No. 21A). The fabric should be in accordance with VDOT R&B
Spec Section 245.03.C. See Section 3.7 of the SP for more information.
cc) Wall Plans, Sheet 6
dd) Section 2.01.A: Please clarify the 28-day compressive strength of the segmental blocks.
Per Section 3.1 of the SP, the minimum compressive strength at 28 days shall be 4,000
psi.
ee) Section 2.01.A: States maximum water absorption shall be limited to 7%, however, per
Section 3.1 of the SP, the maximum water absorption shall be 5%. Please clarify.
ff) Section 2.01.A: Is a Concrete block freeze -thaw test required on the plans? The ASTM
method (C1262) is referenced in Section 1.02.B.2 of the notes. See Section 3.1 of the SP
for further information. Please clarify.
gg) Section 2.01.G: Drainage pipe shall be in accordance with Section 232.02(i),I of the
VDOT R&B Specification.
hh) Wall Plans, Sheet 6, Section 3.04.A: The foundation shall be compacted in accordance
with the embankment requirements of VDOT R&B Spec 303.04(h).
ii) Retaining Wall Global Stability Output (RWGSO):
No calculations regarding global slope stability other than one sheet with no explanation
regarding where it is located, or why this particular wall section was chosen.
kk) The output provided appears to be based on a long-term (drained) condition. Please
clarify.
ll) Please clarify if a short-term (undrained) condition was evaluated.
mm) Please clarify if a block failure analysis was performed in addition to the circular
failure analysis provided.
nn) Was ground water encountered in the subsurface exploration borings?
oo) Note 3 on the Wall Plans Cover Sheet states that the retained soil will have a unit weight
of 125 pcf, however, the RWGSO shows 120 pcf for this material. Please clarify.
pp) An internal friction angle of 36 degrees for 21A aggregate seems ambitious. What is the
basis for this soil/aggregate design parameter?
If further information is desired, please contact Max Greene at 434-422-9894.
A VDOT Land Use Permit will be required prior to any work within the right-of-way. The
owner/developer must contact the Charlottesville Residency Transportation and Land Use
Section at (434) 422-9399 for information pertaining to this process.
Sincerely,
Adam J. Moore, P.E.
Area Land Use Engineer
Charlottesville Residency