HomeMy WebLinkAboutFile Documents.931 Gibson Ave.0037-2019-BRES (35)ENGR Round 1 Comments 10-22-2019
Page: C201 PROPOSED BASINS
Date: 10/21/2019 10:01:17 AM
File Name: 931 Gibson - Civil Plans.pdf
Please depict flow arrows.
931 Gibson - Civil Plans.pdf (22)
Page: C300 GRANDING & DRAINAGE W/ LA
Date: 10/21/2019 10:24:17 AM
File Name: 931 Gibson - Civil Plans.pdf
Please only depict trees that are
to remain on the site plan for
clarity.
Page: C300 GRANDING & DRAINAGE W/ LA
Date: 10/12/2019 3:34:18 PM
File Name: 931 Gibson - Civil Plans.pdf
Please verify water utility will not
conflict with proposed
landscaping. Several driplines
appear to overlap the alignment.
Page: C300 GRANDING & DRAINAGE W/ LA
Date: 10/22/2019 10:53:19 AM
File Name: 931 Gibson - Civil Plans.pdf
Proposed contours result in a
20% slope for the driveway.
Please adjust grading in this
area to have a maximum slope
of 12%.
Page: C300 GRANDING & DRAINAGE W/ LA
Date: 10/21/2019 10:15:48 AM
File Name: 931 Gibson - Civil Plans.pdf
Transition needs to be longer.
Please extend the transition
further east to the next
remaining dripline.
Please depict flow arrows.
W
W
W
W
W
W
W
W
W
W
93
6
0+75
0+7
5
0 FT
7
9
3
5
0
Please only depict trees that are to
remain on the site plan for clarity.
OSW
W
W
W
+(35.
5
)
4
0
.
5
0+2
5
BACK OF SIDEWALK ALIGNMENT
0+00
7937.74
TW
:
7
9
3
6
.
1
6
@SE
T
B
A
C
K
BW
:
7
9
3
5
.
1
9
7937.84
7
9
3
6
7
9
3
7
Please verify water utility will not conflict
with proposed landscaping. Several
driplines appear to overlap the
alignment.
W W W
W
DRIVEWAY TRENCH
MIN LENGTH: 26'
DRAIN COLLECT PR:1.0
7937
WAY CENTERLINE ALINGMENT0+69
0+50
1.0
0
%
2.5
0
%
TW:
7
9
3
6
.
2
5
@SETBACK
TW:7936.25
BW:7934.61
TD
:
7
9
3
2
.
6
5
+79
3
2
.
7
7
+79
3
2
.
6
5
+:7
9
3
2
.
7
7
+79
3
2
.
5
0
932
.
2
5
7
9
3
4
TD 1 CONNECTION
INV OUT:7931.32 4" PVC
INLET 3
RIM:7932.25
INV IN:7931.26 4" PVC
INV OUT:7931.26 4" PVC
INLET 2
RIM:7937.01
INV OUT:7933.01 4" PVC
0+
0
0
Proposed contours result in a 20%
slope for the driveway. Please
adjust grading in this area to have
a maximum slope of 12%.
W
W
W
W
0+75
1+0
0
1+2
5
0+7
5
1+0
0
1.50 FT
5.00 FT
1.0
0
%
5.0
0
%
7
9
3
5
-2.
0
%
+79
3
3
.
5
5
+79
3
3
.
5
5
+79
3
3
.
2
5
79
3
3
7
9
3
4
PR3.4 AND 3.9 CONNECTION
RIM:7933.18
INV IN:7930.23 4" PVC
INV OUT:7930.23 6" PVC
PR3.10 CO
Transition needs to be longer. Please
extend the transition further east to the
next remaining dripline.
Please see EX1, attached. This exhibit
demonstrates that at a 10-ft driveway
width, the slope does not exceed 12%.
Per our meeting, this is acceptable.
Flow arrows have been added to
show discharge from higher
elevations to lower elevations.
The water service has been located as far
as possible from the existing tree and is
located under existing impervious driveway
area. Per our meeting, this is acceptable.
We have lengthened the transition and
updated the alignment.
We are now only depicting
proposed trees and existing trees.
01/22/2020
Page: C300 GRANDING & DRAINAGE W/ LA
Date: 10/21/2019 10:16:45 AM
File Name: 931 Gibson - Civil Plans.pdf
Several existing and proposed
tree driplines appear to overlap
the proposed sewer lateral
alignment. Please verify utilities
will not be installed directly over
or in close proximity to proposed
landscaping.
Page: C301 GRANDING & DRAINAGE
Date: 10/21/2019 10:18:28 AM
File Name: 931 Gibson - Civil Plans.pdf
Please depict all connections
with sizing and slope
information.
Page: C301 GRANDING & DRAINAGE
Date: 10/22/2019 10:48:05 AM
File Name: 931 Gibson - Civil Plans.pdf
A 2' full section of asphalt must
be removed and replaced to
allow for construction of curb &
gutter. Please depict full removal
limits and milling limits on plans
for all asphalt cuts.
Page: C301 GRANDING & DRAINAGE
Date: 10/21/2019 10:18:33 AM
File Name: 931 Gibson - Civil Plans.pdf
Please show roof drains and
downspouts on the drainage
plan. Clearly show how runoff is
routed to the BMPs.
Page: C301 GRANDING & DRAINAGE
Date: 10/21/2019 10:36:57 AM
File Name: 931 Gibson - Civil Plans.pdf
Floating sidewalk detail is
included, but limits of installation
are not included within plans.
Please include stationing for
beginning and end of floating
sidewalk.
OSW
S
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
NEW 2" TYPE K COPPER W
NEW TAP MIN 18" FROM OL
ABANDON EXISTING SERV
-2.0
%
-2.0
%
79
3
6
79
3
7
7937
69
DRIVEWAY CENTERLINE ALIGNME
0+00
BACK OF SIDEWA
0+00
0+2
5
0+5
0
FLOWLINE ALIGNMENT
0+00
0+2
5
0+5
0
1.00 FT
4.00 FT
0%
-2.0
%
-2.
0
%
-4.3
%
-4.6
%
-2.
0
%
7937.26
7937.60
7937.51
7937.77
7937.74
7937.35
7937.27
7937.53
7937.61
7937.03
TW:
7
9
3
6
.
16 FT
7937.68
0+30
ROAD CROSS-SECTION
0+00 7937.57
7937.07
7937.84
7937.71
7937.34
793
7
7
9
3
6
7
9
3
7
PR3.11 CONNECTION ALT 2
RIM:7937.01
INV OUT:7933.01 4" PVC
10 CONNECTION ALT 2
7935.00
N:7932.37 4" PVC
OUT:7932.37 4" PVC
0+0
0
Several existing and proposed tree driplines appear to
overlap the proposed sewer lateral alignment. Please verify
utilities will not be installed directly over or in close
proximity to proposed landscaping.
5
%
1.0
0
%
00%
+79
3
4
.
7
5
793
2
.
5
0
+
793
2
.
7
5
+
TW
:
7
9
3
Please depict all
connections with
sizing and slope
information.
W
W
25.00 FT
1+4
1
1+2
5
1+5
11+5
0
79
3
2
PR3.7 CONNECTION
A 2' full section of asphalt must be removed and replaced to
allow for construction of curb & gutter. Please depict full
removal limits and milling limits on plans for all asphalt cuts.
W
7
7937
END DRIVEWAY CENTERLINE ALINGMENT0+69
2.5
0
%
7
9
3
5
TD
:
7
9
3
2
.
6
5
+79
3
2
.
7
7
+:7
9
3
2
.
7
7
+79
3
5
.
2
5
0+
0
0
Please show roof
drains and
downspouts on the
drainage plan. Clearly
show how runoff is
routed to the BMPs.
W
W
W
W
W
W
W
W
W
79
3
6
+75
0+5
0
0+7
5
7
9
3
5
0+30
Floating sidewalk detail is included, but limits of
installation are not included within plans. Please include
stationing for beginning and end of floating sidewalk.
The requested information is provided on
the pipe profiles. Per our meeting, this is
acceptable.
The proposed sewer service has been
moved slightly to the west and is now
outside of the existing drip line.
We have depicted the 2' section.
Gutters are shown, connections are
called out. Per our meeting, our existing
annotation is acceptable.
Stationing has been updated to indicate
location of floating sidewalk.
01/22/2020
Page: C301 GRANDING & DRAINAGE
Date: 10/22/2019 7:49:54 AM
File Name: 931 Gibson - Civil Plans.pdf
How is drainage handled within
window well? Window wells
must be free draining or tie to
the stormwater BMP. Please
verify.
Page: C400 DRIVEWAY PLAN & PROFILE
Date: 10/21/2019 10:20:48 AM
File Name: 931 Gibson - Civil Plans.pdf
Surface appears to have hump
on south side of sidewalk.
Appears to possibly be a
bottoming out issue for vehicles.
Page: C400 DRIVEWAY PLAN & PROFILE
Date: 10/21/2019 10:22:52 AM
File Name: 931 Gibson - Civil Plans.pdf
Flowline must be outside of
walking surface. Please provide
detail to ensure sidewalk is
outside flow conveyance.
Page: C402 FLOWLINE PLAN & PROFILE
Date: 10/21/2019 10:26:56 AM
File Name: 931 Gibson - Civil Plans.pdf
Please call out beginning station
and end station for transition.
Page: C402 FLOWLINE PLAN & PROFILE
Date: 10/21/2019 10:38:09 AM
File Name: 931 Gibson - Civil Plans.pdf
Road cross section is not in
plans. Cross sections need to be
included for all remaining trees
on the eastern side of the
property to understand tree
impacts per email on 8/8/19.
ABANDONED
10' HOLY CROSS
ELECTRIC
EASEMENT
10.00 FT
10.00 FT
13.68 FT
1.0
0
%
3.
6
5
%
2
1.0
0
%
7932
.
5
0
+
TW:
7
9
3
2
.
5
0
79
3
2
79
3
2
PR2.0 AND 2.1 CONNECTION
RIM:7931.83
CLEANOUT 4 PR3.5 AND 3.6 CONNECTION
RIM:7932.48
INV IN:7930.38 6" PVC
INV IN:7930.38 4" PVC
INV OUT:7930.38 6" PVC
CLEANOUT 4
RIM:7932.42
INV IN:7930.24 6" PVC
INV OUT:7930.24 6" PVC
DEPTH: 17.67'
WQCV REQUIRED (FS=1.5): 199 CF
100-YR RETENTION REQUIRED: 614 CF
VOLUME PROVIDED: 653 CF
INV IN:7929.50 6" PVC
INV IN:7929.50 6" PVC
1+0
0
E
N
D
P
I
P
E
A
1+
3
6
1+4
1
How is drainage handled within window well?
Window wells must be free draining or tie to
the stormwater BMP. Please verify.
7937
7938
2.00%
-9.1
2
%
Surface appears to
have hump on south
side of sidewalk.
Appears to possibly
be a bottoming out
issue for vehicles.
El
e
v
a
t
i
o
n
7935
7936
7937
7938
2.00%
9.12
%
E
Flowline must be outside of walking surface.
Please provide detail to ensure sidewalk is
outside flow conveyance.
W
W
NEW 2" TYPE K COPPER WATER SERVICE
NEW TAP MIN 18" FROM OLD
ABANDON EXISTING SERVICE PER COA STANDARDS
DRIVEWAY CENTERLINE ALIGNMENT
0+00
FLOWLINE ALIGNMENT
0+00
1'.
2.TRA
CUR
3.SIDE
EAS
4' W
4.CUR
1.5' C
ALLO
0+75
5.SIDE
A 5'
ALLO
0+75
Please call out beginning station and
end station for transition.
0+30
Road cross section is not in plans. Cross
sections need to be included for all remaining
trees on the eastern side of the property to
understand tree impacts per email on 8/8/19.
The hump is approximately
1.5". We did not find
bottoming out to be a
problem.
See C400. Flowline is at driveway
station 0+1.00, end of sidewalk is
at station 0+5.67.
Based on our site visit with Engineering and
Parks, we determined the acceptable
sidewalk widths. The drawings have been
revised to show these widths.
Window wells will drain to the foundation
drain system. A typical window well
detail has been added to C500.
Stationing has been added.
01/22/2020
Page: C402 FLOWLINE PLAN & PROFILE
Date: 10/21/2019 10:26:07 AM
File Name: 931 Gibson - Civil Plans.pdf
How is conveyance addressed
at tie in location? Project must
tie into existing curb and gutter
to the west. Please clarify.
Page: C402 FLOWLINE PLAN & PROFILE
Date: 10/22/2019 8:52:20 AM
File Name: 931 Gibson - Civil Plans.pdf
Spread must be examined with
curb and gutter per email on 8/8.
Please include exhibits as
needed to ensure spread meets
requirements in Table 4.1 of the
URMP for a collection road. If
spread is great than maximum,
addition of an inlet maybe
required.
Page: C500 DETAILS 1
Date: 10/21/2019 10:35:27 AM
File Name: 931 Gibson - Civil Plans.pdf
Need to include detail for 18"
curb and gutter with a 8.3%
gutter cross slope. This cross
slope maximizes capacity in
smaller than standard gutter.
Page: C600 UTILITIES
Date: 10/12/2019 3:08:05 PM
File Name: 931 Gibson - Civil Plans.pdf
Clarify what is happening with
the existing sewer lateral. Is the
existing being removed and
replaced?
Page: C600 UTILITIES
Date: 10/21/2019 10:29:41 AM
File Name: 931 Gibson - Civil Plans.pdf
Vertical separation between
water service and sanitary main
must be examined. 18" minimum
separation at crossing. Please
provide information on plans that
demonstrate this is possible.
Elevation of sanitary line must
be included.
25.00 FT
1+4
1
1+5
11+5
0
79
3
2
How is conveyance addressed at tie in
location? Project must tie into existing curb
and gutter to the west. Please clarify.
W
W
W
W
W
W
W
W
W
W
W
W
79
3
6
79
3
7
0+5
0
0+75
0+2
5
0+
5
0
0+7
5
1.00 FT
FT
-2.
0
%
793
793
7
9
3
5
0+
ROAD CROSS-SECTION
0+00 7
7
Spread must be examined with curb and gutter per email on
8/8. Please include exhibits as needed to ensure spread
meets requirements in Table 4.1 of the URMP for a collection
road. If spread is great than maximum, addition of an inlet
maybe required.
Need to include detail for 18" curb and gutter
with a 8.3% gutter cross slope. This cross
slope maximizes capacity in smaller than
standard gutter.
S
W
W
W
W
W
W
W
W
W
W
W
T
T
T
T
T
T
T
T
T
T
T
SANITARY SEW
MANHOLE
1.00 FT
Clarify what is happening with the
existing sewer lateral. Is the existing
being removed and replaced?
OSW
S
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W W W
W
W
W
W
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
N
N
A
7937
1.00 FT
4.00 FT
16 FT
Vertical separation between water service and
sanitary main must be examined. 18" minimum
separation at crossing. Please provide information
on plans that demonstrate this is possible.
Elevation of sanitary line must be included.
Per our site visit, we are no longer required to
provide curb and gutter west of the property
line.
The sewer line will be removed and
replaced.
Spread has been analyzed. Calcs and
discussion have been added to the report.
See additional detail C500.
Crossing detail provided on C501 as
discussed during our meeting.
01/22/2020
Page: C600 UTILITIES
Date: 10/21/2019 10:31:55 AM
File Name: 931 Gibson - Civil Plans.pdf
Please depict new telephone
pedestal location as well as
appropriate electrical
infrastructure at tie in location. Is
there a transform with capacity
in this location? Please provide
electrical capacity verification.
Page: C600 UTILITIES
Date: 10/21/2019 11:40:52 AM
File Name: 931 Gibson - Civil Plans.pdf
The fire suppression letter states
a 1.5" is sufficient. Please adjust
plans to utilize a 1.5" K-copper
line.
Page: COVER & INDEX
Date: 10/22/2019 8:11:15 AM
File Name: 931 Gibson Temp Shoring Plans.pdf
Plans must be stamped and
signed by a Colorado
Professional Engineer.
931 Gibson Temp Shoring Plans.pdf (6)
Page: NOTES & DETAILS
Date: 10/22/2019 8:10:35 AM
File Name: 931 Gibson Temp Shoring Plans.pdf
Provide substantiation for all soil
parameters. Also note, the
coefficient of friction does not
appear to reflect the
recommended value in the soil
report, which states, "Resistance
to sliding at the bottoms of the
footings can be calculated based
on a coefficient of friction of
0.45."
Page: PLAN VIEW
Date: 10/22/2019 8:05:07 AM
File Name: 931 Gibson Temp Shoring Plans.pdf
How will excavation occur for the
20' deep drywell in this corner of
the property? Please clarify.
E
E
E
E
ECT
V
CT
V
CT
ELECTRIC METER
CATV PED
EXISTING BOULDER WALL
EEEEE
Please depict new telephone pedestal
location as well as appropriate electrical
infrastructure at tie in location. Is there a
transform with capacity in this location?
Please provide electrical capacity
verification.
R
W 2" TYPE K COPPER WATER SERVICE
W TAP MIN 18" FROM OLD
ANDON EXISTING SERVICE PER COA STANDARDS
The fire suppression letter states a
1.5" is sufficient. Please adjust
plans to utilize a 1.5" K-copper line.
195 Lodgepole Circle
Parachute, Colorado 81635
970-903-3028
www.rocksolidblasting.com
on
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SHEET INDEX
1. COVER AND INDEX
2. NOTES AND DETAILS
3. PLAN VIEW
4. PROFILE AND SECTIONS
RING WALLS
EN, COLORADO
Plans must be stamped and signed by
a Colorado Professional Engineer.
2 CONTINUOU
#4 BAR
A36
STEEL PLATE
8"x8"x1 "
1.0 GENERAL NOTES
1.1 Per H-P Kumar report dated 6/29/2017 and Kumar and
Associates report dated 4/4/2019, soils to be retained
are assumed to be dense silty sand with gravel and
scattered cobbles. Subsurface conditions may be
discovered at the time of construction that may require
modifications to this design. Conditions may include,
but are not limited to, groundwater, trash debris, soil
shear strength, and grout/soil pullout resistance.
1.2 Concrete/Shotcrete: fc' = 4,000 psi, 28-day unconfined
compressive strength
Grout: fc' = 3,000 psi, 28-day unconfined compressive
strength
Reinforcement Steel: Fy = 60,000 psi
1.3 Soil Parameters:
ɸ = 35°
c = 10 psf
ɣ = 125 pcf
Qa = 15 psi
1.4 Soil Nails will be Williams Form Geo-Drill bar or
All-Thread Bar or equivalent as indicated in plans.
Williams Form Couplers will be used as necessary.
1.6 Verification and/or proof tests may be conducted as
determined in the field by the Engineer.
1.7 Cement grout will be installed in sufficient quantity to
fully encapsulate the bar to the collar of the hole.
1.8 Groundwater is not anticipated. If groundwater is
encountered during excavation, the excavation shall
to prevent the flow of water into the excavation or
behind the support of excavation.
1.12 These plans are not to be used for the layout of the lot
or the proposed house. Survey of the proposed footer
locations shall be complete prior to RSS personnel
mobilizing to the site.
1.13 Survey and layout of wall by others. Excavation by
others.
1.14 The temporary shoring system has been designed for
a minimum factor of safety of 1.3 and a maximum
design life of 3 months. The designed shoring system
should show no observable deflection on neighboring
properties.
1.15 These shoring plans are based on an Architectural site
plan by F&M Architects dated 6/20/2019 and a
foundation plan by Silver Town Structures dated
5/15/2019.
2.0 SOIL NAIL CONSTRUCTION
2.1 Locations and quantities of nails are approximate and
will be finalized during construction.
2.2 The slope will be excavated in 4 or 5-foot stages (by
others).
2.3 Construction Sequence
2.3.1 Excavate wall location (by others).
23.2 Drill and grout Soil Nail.
Provide substantiation for all soil parameters. Also note, the coefficient
of friction does not appear to reflect the recommended value in the soil
report, which states, "Resistance to sliding at the bottoms of the footings
can be calculated based on a coefficient of friction of 0.45."
ED
1:1
0+00
How will excavation occur for the
20' deep drywell in this corner of
the property? Please clarify.
PLANS ARE NOW STAMPED
SEE RESPONSE 2. ON 2019-10-31 RSS
response to City of Aspen Comments.pdf
Drywell location (per sheet C301) and shoring has been added to plan set dated10/23/19.
The transformer will be replaced as
necessary. See note as discussed
during our meeting. The Telephone
Ped will be relocated to the SE corner.
Size has been changed to 1.5".
01/22/2020
Page: PLAN VIEW
Date: 10/22/2019 8:06:30 AM
File Name: 931 Gibson Temp Shoring Plans.pdf
Please depict location and depth
of utilities located within vicinity
proposed system.
Page: PLAN VIEW
Date: 10/22/2019 8:09:29 AM
File Name: 931 Gibson Temp Shoring Plans.pdf
Please verify with geotechnical
engineer that 1:1 slope is
achievable.
Page: PLAN VIEW
Date: 10/22/2019 8:06:09 AM
File Name: 931 Gibson Temp Shoring Plans.pdf
Wall location appears to be
within drip-lines of existing trees.
Please obtain approval from
Parks Department to locate wall
here or adjust design.
Page: 2
Date: 10/12/2019 3:56:51 PM
File Name: 931 Gibson_Civil_20190830_Report.pdf
Signature, stamp, and date
required.
931 Gibson_Civil_20190830_Report.pdf (15)
Page: 3
Date: 10/12/2019 3:56:05 PM
File Name: 931 Gibson_Civil_20190830_Report.pdf
Correct link errors.
2+00
WALL C
ATCHED
EA AT 1:1
2+20
Please depict location and depth of utilities
located within vicinity proposed system.
DIG HATCHED
AREA AT 1:1
Please verify with geotechnical
engineer that 1:1 slope is achievable.
1-SID
AROU
75 1+35.75
1+28.5 1+132'
2'
DIG HATCHED
Wall location appears to be within drip-lines of
existing trees. Please obtain approval from Parks
Department to locate wall here or adjust design.
License No.
Signature, stamp, and
date required.
................................................... 5
................................................... 5
................................................... 5
................................................... 6
................................................... 6
................................................... 6
................................................... 6
................................................... 6
................................................... 6
................................................... 6
.... Error! Bookmark not defined.
................................................... 7
................................................... 7
Correct link errors.
Utility locations have been added to plan set
dated 10/23/19. The water line will be
below the soil nail wall or sleeved through the
shotcrete facing.
An estimate of the on-site soils was made by two Rock Solid Professional Engineers withspecialties in Geotechnical Engineering. A sloped configuration in accordance withOSHA Regulations 29CFR 1926 Subpart P Appendix B was selected for stability of thesoil on site. The on-site soil is estimated to be classified as Type B soil as defined in 1926Subpart P Appendix A. A 1:1 slope is allowed for Type B soils. If the soils on site arenot cohesive enough to allow this configuration, the Rock Solid Professional Engineer onsite will direct the excavation and stabilization team to modify the slope stabilizationarea. The Rock Solid engineers are comfortable with this situation and will be on site to monitor slope stability.
Trees to be removed, per plan sheet L2.00, are
shown in red on the plan set dated
10/23/19. Shoring walls are outside the drip
lines of all trees that will remain.
Signature, stamp, and date added.
Corrected Link errors
01/22/2020
Page: 5
Date: 10/12/2019 4:22:08 PM
File Name: 931 Gibson_Civil_20190830_Report.pdf
NRCS web soil survey indicates
soil Type 108-Uracca is HSG
type B. Please revise.
Page: 6
Date: 10/22/2019 8:27:57 AM
File Name: 931 Gibson_Civil_20190830_Report.pdf
Street may have capacity, but
spread needs to be verified as
per 8/8 email. Please include a
section of calculations and
exhibits that demonstrate the
flooding spread of each storm
event meets requirements of
Table 4.1 of the URMP for a
Collector street.
Page: 6
Date: 10/21/2019 12:59:40 PM
File Name: 931 Gibson_Civil_20190830_Report.pdf
Describe changes to land use,
topography, ground cover,
drainage patterns, and receiving
systems, or if no change. No
change to off-site drainage
patterns, as described in Section
2.3, is noted.
Page: 6
Date: 10/22/2019 8:27:44 AM
File Name: 931 Gibson_Civil_20190830_Report.pdf
The addition of curb and gutter
affects the offsite drainage that
currently drains onto property.
This must be examined within
the drainage report to ensure
roadway meets standards.
Page: 11
Date: 10/22/2019 8:30:03 AM
File Name: 931 Gibson_Civil_20190830_Report.pdf
Please touch on why a drywell it
being utilized as it is a last resort
BMP per the URMP.
1.Introduction
This report was prepared to meet the requirements of a City of Aspen Engineering Department Grading and
Drainage Report for a Major Design. The report was prepared for a single family housing project at 931
Gibson Avenue, Aspen,Colorado,81611 (the “Site”).Facilities providing water quality capture volume
and retention have been designed in this report and the associated plan.
2.General Site Description
2.1 Existing Condition
The property was address as 931 Gibson Avenue, Aspen. Based on the topographical improvement survey,
the lot area is approximately 15,497 square feet.
The Site is located on the east side of Aspen (see Figure 1). The NRCS describes the hydrologic soil group
as “Type A”(See Appendix A). The lot is currently occupied by a single family apartment.
NRCS web soil survey indicates soil
Type 108-Uracca is HSG type B.
Please revise.
constructed.
ntrolling triggers when determining the
ea. Based on these two triggers, Woody
pture volume (“WQCV”) and detention
he southwest. Drainage basins are delin-
The basins are described in the following
described.
e capacity to convey the 100-year event.
1, below, describes the impervious area,
, basin slope, runoff coefficients for the
s for the minor (10-yr) and major (100-
eet C200 (Appendix C, C200), they are
were evaluated for the Site using a time
age patterns.
onal)
)Tc (min)Intensity (5yr)
(in/hr)
Intensity (10yr)
(in/hr)
Intensity
(100yr) (in/hr)
PEAK FLOW
5YR (CFS)
PEAK FLOW
10YR (CFS)
PEAK FLOW
100YR (CFS)
78 10.8778 2.3243 2.7964 4.4669 0.050 0.149 0.556
0.050 0.149 0.556
onal)
)Tc (min)Intensity (5yr)
(in/hr)
Intensity (10yr)
(in/hr)
Intensity
(100yr) (in/hr)
PEAK FLOW
5YR (CFS)
PEAK FLOW
10YR (CFS)
PEAK FLOW
100YR (CFS)
Street may have capacity, but spread needs to be
verified as per 8/8 email. Please include a section of
calculations and exhibits that demonstrate the flooding
spread of each storm event meets requirements of
Table 4.1 of the URMP for a Collector street.
single family home will be constructed.
or/Minor
the “URMP”) has two controlling triggers when determining the
n and exterior disturbed area. Based on these two triggers, Woody
mined that water quality capture volume (“WQCV”) and detention
rea that slopes at 4.4% to the southwest. Drainage basins are delin-
pendix C, C200 & C201). The basins are described in the following
V treatment BMPs are also described.
s that the street has adequate capacity to convey the 100-year event.
Describe changes to land use, topography, ground
cover, drainage patterns, and receiving systems,
or if no change. No change to off-site drainage
patterns, as described in Section 2.3, is noted.
capture volume (“WQCV”) and detention
o the southwest. Drainage basins are delin-
1). The basins are described in the following
also described.
uate capacity to convey the 100-year event.
le 1, below, describes the impervious area,
gth, basin slope, runoff coefficients for the
rates for the minor (10-yr) and major (100-
Sheet C200 (Appendix C, C200), they are
nts were evaluated for the Site using a time
ainage patterns.
Tc (Regional)
(min)Tc (min)Intensity (5yr)
(in/hr)
Intensity (10yr)
(in/hr)
Intensity
(100yr) (in/hr)
PEAK FLOW
5YR (CFS)
PEAK FLOW
10YR (CFS)
PEAK FLOW
100YR (CFS)
10.8778 10.8778 2.3243 2.7964 4.4669 0.050 0.149 0.556
0.050 0.149 0.556
Tc (Regional)
(min)Tc (min)Intensity (5yr)
(in/hr)
Intensity (10yr)
(in/hr)
Intensity
(100yr) (in/hr)
PEAK FLOW
5YR (CFS)
PEAK FLOW
10YR (CFS)
PEAK FLOW
100YR (CFS)
10.2667 5.0000 3.2911 3.9596 6.3251 0.108 0.134 0.230
10.8778 10.8778 2.3243 2.7964 4.4669 0.020 0.061 0.227
10.8778 10.8778 2.3243 2.7964 4.4669 0.016 0.035 0.114
10.0444 5.0000 3.2911 3.9596 6.3251 0.033 0.040 0.067
10.0500 5.0000 3.2911 3.9596 6.3251 0.040 0.049 0.082
10.0667 5.0000 3.2911 3.9596 6.3251 0.021 0.026 0.044
10.0667 5.0000 3.2911 3.9596 6.3251 0.000 0.001 0.001
The addition of curb and gutter affects the offsite
drainage that currently drains onto property. This
must be examined within the drainage report to
ensure roadway meets standards.
n is 5 minutes. The resulting 100-year flowrate is 0.003
m and foundation drywell.
w well on the west side of the historical structure. The
pervious for calculation purposes. Based on a flow path
n is 5 minutes. The resulting 100-year flowrate is 0.004
m and foundation drywell.
outing
le to provide WQCV.
n the design process.
water requirements early in the process.
mwater quality treatment.
s utilized to increase the time stromwater is in contact
dscape buffer is used in the driveway and a portion of
Please touch on why a drywell it being utilized
as it is a last resort BMP per the URMP.
We revised this statement to state type
B.
A spread analysis was completed. The
requirements for a local street are met.
A spread analysis was completed. The
requirements for a local street are met.
The section has been updated.
A section was added that states: "A drywell is being utilized
because this is an HPC project. During HPC approvals, the use
of a drywell was approved to reduce the visual impact to the
historical structure."
01/22/2020
Page: 12
Date: 10/22/2019 8:30:25 AM
File Name: 931 Gibson_Civil_20190830_Report.pdf
Make this conclusion using the
estimated peak runoff, in gpm.
How do you know the 208.91
gpm is sufficient?
Page: 14
Date: 10/22/2019 8:35:14 AM
File Name: 931 Gibson_Civil_20190830_Report.pdf
Please include a drain time
calculation to ensure drywell
drains within the required 24 hrs.
Page: 15
Date: 10/12/2019 7:36:23 PM
File Name: 931 Gibson_Civil_20190830_Report.pdf
For dry well, iclude a description
of access for maintenance
operations, maintenance
schedule, and contact
information for party responsible
for maintenance.
Page: 52
Date: 10/12/2019 5:41:56 PM
File Name: 931 Gibson_Civil_20190830_Report.pdf
Revise to 0.08 for HSG B.
Page: 55
Date: 10/12/2019 7:00:54 PM
File Name: 931 Gibson_Civil_20190830_Report.pdf
Where do these areas come
from? Is the 50% clogging factor
accounted for? [is this what the
2x safety factor is from the
report?]
mal and designed with public safely in mind.
DS Inlet Grates. Trench Drain 1 (“TD1”) is a 26 ft
These inlets collect runoff from basin PR:1.0 which
Each of the three inlets provide 68.19 gpm for a to-
afety of 2 applied, the two inlets provide a capacity
es an additional 213.24 gpm (106.62 gpm with a
three inlets and slot drain in total have a capacity of
y the tributary runoff.
Make this conclusion using the
estimated peak runoff, in gpm. How do
you know the 208.91 gpm is sufficient?
ix, the total retention volume is 654.55 cf. Therefore, the 6’ diameter drywell has capacity
00-year event.
s Buffer
ntrance sidewalk leading from the sidewalk in the ROW to the historic element. This side-
ded WQCV by a grass buffer to the west. No detention is provided as the total discharge
Basins 1.0 and 1.1 totals of 0.342 cfs versus the historical discharge was 0.556 cfs.
ration and Maintenance
o types of BMPs used on the property: grass buffers and a drywell. An operation and
task and schedule list is provided for each of the BMPs below.
Please include a drain time calculation to
ensure drywell drains within the required 24 hrs.
valuate the drain-down time of the dry well to ensure the maximum time of 24 hours
exceeded. If drain-down times are exceeding the maximum, drain the dry well via
d clean out the percolation area (the percolation barrel may be jetted to remove sedi-
mulated in perforations). Consider drilling additional perforations in the barrel. If slo
rsists, the system may need to be replaced.
For dry well, iclude a description of
access for maintenance operations,
maintenance schedule, and contact
information for party responsible for
maintenance.
US
RUNOFF
COEF. 5YR
RUNOFF
COEF. 10YR
RUNOFF
COEF. 100YR
FLOW PATH
LENGTH (FT)
FLOW PATH
SLOPE (FT/FT)
Tc (Computed)
(min)
Tc (
0.06 0.15 0.35 158.00 0.0443 14.44 1
----
Revise to 0.08 for HSG B.
TION *FORMULA USED:
FLOOR)Q = 448.2 x Cd x A x √2gh
9.10 A (SQUARE FEET)
3.00 h (FEET)
68.19
Where do these areas come from? Is the
50% clogging factor accounted for? [is
this what the 2x safety factor is from the
report?]
We revised this to 0.08
The section states that the tributary runoff is 103.22 gpm. The
section states that the three inlets and the trench drain provide a
total capacity of 208.91 gpm with a factor of safety applied.
Therefore, there is adequate capacity.
We have provided a drain time calculation which demonstrates
that the drywell will drain within 24 hours..
The requested information has been added.
The 9.1 square inch grate area comes
from the grate information found on C500
for the 6" round grate. We analyzed the
inlets with 3" of head. This results in a
flow cacity of 68.19 gpm. Our 2x factor of
safety is the same thing as a 50%
clogging factor. Divided 68.19 gpm by 2
results in a grate capacity of 34.1 gpm.
01/22/2020
Page: 56
Date: 10/12/2019 7:01:04 PM
File Name: 931 Gibson_Civil_20190830_Report.pdf
Where do these areas come
from? Is the 50% clogging factor
accounted for? [is this what the
2x safety factor is from the
report?]
Page: 57
Date: 10/12/2019 7:23:58 PM
File Name: 931 Gibson_Civil_20190830_Report.pdf
Provide calculations for the total
100-year, runoff volume.
Page: 58
Date: 10/12/2019 7:31:44 PM
File Name: 931 Gibson_Civil_20190830_Report.pdf
Per URMP requirements, use
most conservative percolation
rate from test, which is 2 in/min.
OOR)Q = 448.2 x Cd x A x √2gh
156.00 A (SQUARE FEET)
0.10 h (FEET)
213.42
Where do these areas come from? Is the
50% clogging factor accounted for? [is
this what the 2x safety factor is from the
report?]
0.255 in **Based on 76%
132.30 cf Imperviousness.
1.50
198.45 cf
1.23 in
0.00 cf
1.00
613.67 cf
6 ft
7.04 ft
2 ft
28.26 cf/ft
95.68 sf
Provide calculations for the total
100-year, runoff volume.
5 in/min
8E-04 ft/s
13.67 cf
51.14 square feet required
0.785 square inches
65
Per URMP requirements, use most
conservative percolation rate from test,
which is 2 in/min.
The calculation is provided in the appendix.
The calculation was changed to 2 in/min.
The open grate area of the trench drain is shown
on C500. The open area is 0.47". The length of
the trench drain is approximately 27.5 ft long. The
grate area then is 27.6 ft X 12in/ft X 0.47"=156 sq.
in. Yes, the FS=2x is the same as a 50% clogging
factor.
01/22/2020