HomeMy WebLinkAbout10.0 Floodplain AnalysisFLOODPLAIN ANALYSIS
FOR
5 -MILE RANCH GRAVEL PIT
GARFIELD COUNTY, COLORADO
PREPARED FOR:
Elam Construction, Inc.
556 Struthers Ave.
Grand Junction, CO 81501
PREPARED BY:
Rolland Consulting Engineers, LLC
405 Ridges Blvd., Suite A
Grand Junction, Colorado 81507
October 15, 2019
TABLE OF CONTENTS
Project Description
a. Ownership and Application
b. Project Location
c. Property Description
d. Proposed Activity
II. Floodplain Analysis
a. Existing Flood Plain Study
b. Adjustment to NAVD'88
c. Topographic Survey (2012)
d. Proposed Grades and Structures
III. Applicable County Code Sections
a. Section 3-301 Floodplain Overlay Regulations
b. Section 4-109 Development in the 100 -Year Floodplain
c. Section 4-203 (o) Floodplain Analysis
d. Section 7-203 Protection of Waterbodies
IV. Reclamation Plan
V. Conclusions
ENCLOSURES
Vicinity Map
Pages C-76, C-77 and C-78 Army Corps of Engineers Floodplain Study
Floodplain Development Site Plan
CERTIFICATION
I hereby certify that this Floodplain Analysis for 5 -Mile Ranch Gravel Pit was prepared by me
or, or under my direct supervision.
Eric S. Slivon, P.
Registered Professio
State of Colorado, # 36169
I. Project Description
A. Ownership and Application
This Floodplain Analysis is for the Floodplain Development Permit application for the 5 Mile
Ranch Gravel Pit. The subject parcel has a Parcel Number of 240932400138, and has an area of
130.588 acres. The landowner is 5 Mile Ranch, LLC. Elam Construction, Inc. is leasing the
parcel and is the applicant for this submittal. The project has a Special Use Permit approval with
conditions from Garfield County, one of those conditions is obtaining the Floodplain Permit.
Greg Lewicki And Associates, PLLC has submitted a 112(c) application to the Colorado
Division of Reclamation, Mining and Safety. Aside from the site analysis, the Lewicki also
includes a Mining Plan and a Reclamation Plan.
A. Project Location
The 5 Mile Ranch Gravel Pit will be is located about 4 miles southwest of Parachute, Colorado
in SE1/4 of the SE1/4 of Section 28 and in Section 33, Township 7 South, Range 96 West of the
6th Principal Meridian. The Site is southwest of the intersection of US Highway 6 and County
Road 300. The site is bounded by the Colorado River on the south, County Road 300 and the
Una Gravel Pit to the East, Union Pacific Railroad and US Highway 6 to the north, with
Travelers Highlands commercial subdivision further to the north and a vacant parcel owned by 5
Mile Ranch, LLC to the west.
C. Property Description
The site is located adjacent to and north of the Colorado River. The property is approximately
trapezoidal in shape, with the long side being about 5900 feet orientated from the southwest to
the northeast. The northeast leg, along County Road 300 has a length of 2560 feet and the
southwest leg has a length of 327 feet. The property is crossed by 4 drainage channels from the
north that discharge into the Colorado River. The east channel on the east boundary of the parcel
runs along the west side of County Road 300. Another channel crosses at about the midpoint of
the property. Two more channels cross the west half of the property. Elevations on the east half
of the property vary from 5016 to 4986, with a grade of about 1% to the south. Elevations on the
west half vary from 5030 to 4911, with varying from 2% to 5% generally to the south. A near
vertical drop existing along most of the water's edge of the Colorado River. Where it exists, the
vertical drop varies between 6 and 20 feet. Vegetation is primarily native shrubs and grasses.
Larger bushes and trees are located closer to the Colorado River. Wetlands have been delineated
at three locations, two within 200 feet of the Colorado River and thee third about 100 feet from
the River on the west side of County Road 300. The property has various dirt roads and a couple
fenced areas.
D. Proposed Activity
The proposed mining and accompanying activities will take places on 51 acres in the eastern
portion of the parcel. Sand and gravels will be excavated from approximately 40.7 acres. Site
activities will include excavation, crushing, screening and washing of materials. Asphalt and
concrete will also be manufactured on site. Excavations depths will vary from 20 to 33 feet. Top
soil and overburden berms will be constructed along the north and east boundaries for visual
screening and sound dampening. An office trailer, scales and fuel storage will be located in the
far northeast corner of the site. The office will utilize bottled water and porta-potties located
outside. Site access will be to County Road 300.
II. Floodplain Analysis
A. Existing Flood Plain Study
A flood plain study was prepared by the Department of the Army Sacramento District Corps of
Engineers, dated December 1982 and later revised/released in July 1987. The study was for the
Colorado River and tributaries from Rifle to Parachute and into Mesa County. The study
provides FEMA Flood Zone designations and Base Flood Elevations in the area of the proposed
gravel pit. The original study used topographic data obtained from aerial photogrammetric
methods, with photography taken in November, 1982. The only major change to surrounding
topography since the study has been the Una gravel pit to the east of the site. The Una gravel pit
is nearing the end of gravel extraction, with much of the site in reclamation phases. Material and
overburden stockpiles at the Una pit, along with lowered reclaimed areas as lakes area expected
to have little effect on the results of previous study. The Floodway line is typically closer to the
edge of the existing bank due to the steep sides slopes adjacent to the River.
B. Adjustment to NAVD'88
The existing 1982 study was based on the National Geodetic Vertical Datum of 1929 (NGVD
29). The National Geodetic Survey website, provides conversion between vertical datum based
on location. The conversion from NGVD 29 to North American Vertical Datum of 1988 (NAVD
88) at the Site's location is obtained by adding 3.6 feet. The Base Flood Elevations (BFE) from
the existing study were adjusted, then a straight-line interpolation was used to determine whole
number BFEs on the NAVD 88 datum at two -foot intervals.
C. Topographic Survey (2012)
River City Consultants conducted a topographic survey of the site in February 2012. The edge of
the river was located at that time and used to establish the 200 ft. River Setback as shown on the
Site Plan. The survey was also used to produce an "updated" 100 -Year Floodplain by determined
by extending the NAVD 88 BFEs to existing grade. This new 100 -Year Floodplain closely
resembles the 100 -Year Floodplain from the original study. By comparing the topography from
the 1982 and 2012 surveys it is evident that the bank of Colorado in the eastern 1200 feet of the
site has eroded significantly. It is possible that some of the elevated areas between the delineated
wetlands and the back of the River are from man-made fill and susceptible to erosion.
D. Proposed Grades and Structures
No permanent fill will be placed in the floodplain. One of the four temporary berms shown on
the Site Plan will be located in the floodplain. Material from the berms will used and spread
during final reclamation. During gravel mining and at final reclamation the grades in the gravel
pit area will be lower than existing grades. Screen and Crushing structures will be located at the
bottom of the pit and may move as phases progress. The structures are large and will not be
anchored. Buoyant forces will not be of great concern for these structures. The office trailer will
be located at the far northeast corner of the site. The existing and proposed ground surface at the
office is 5012 (NAVD 88). The 100 -Year BFE is about 5005.5 (NAVD 88), putting the office
about 6.5 feet of the BFE. Fuel storage will also be in this area about 6.5 feet above the 100 -Year
Base Flood Elevation.
III. Applicable County Code Sections
A. Section 3-301 Floodplain Overlay Regulations
A. Use Restrictions in the Floodplain Overlay
Certain uses are restricted in the Floodplain. Gravel pits are allowed in the Floodplain,
but not the Floodway. By establishing a 200 -ft setback (from the 2012 River's edge, the
mining area will not be located within the floodway.
B. General Standards
The office trailer, scales and fuel storage will be located out of the floodplain. The
mining equipment, including crushers, screens, fuel tanks, generators, loaders, dozers and
excavators will be located in the mining area and in the floodplain. The following
General Standards criteria was reviewed with respect to the mining equipment.
1. The mining equipment will not be anchored and is intended to be movable. The
Stormwater Management Plan for Elam Construction, San & Gravel, 5 -Mile Ranch
Pit details flood event preparation and procedures, including removing mining
equipment during a major flood event in Section VI. B.
2. The existing grades at the 200 -foot buffer are elevated enough that the pit will only be
flooded during major flood stage events. Design side slopes being a 1.5H:1V will
help minimize erosion during flood events. An outflow/inflow structure will be
constructed for the primary location for floods waters to enter the pit or for a full pit
to discharge into the river. The flow structure will be a Rip Rap lined weir and
channel and is detailed in the Greg Lewicki And Associates 112(c) Application to the
Colorado Division of Reclamation, Mining and Safety (DRMS)
3. Fuel tanks, generators, loaders, dozers and excavators can all be damaged during
flood events and will be the first items to be moved to high ground. The crusher and
screens are constructed to be flood resistant, but will be moved out of the pit as the
probability of a flooded pit increases (see Stormwater Management Plan). The size of
the Rip Rap material for the overflow structure was chosen to resist erosion during
flood events. The Lewicki detail C-4 specifies a Rip Rap size of 36", a length of 125
feet and a total volume of 422 cubic feet.
4. Any equipment in the pit that requires electrical service will be powered by portable
generators. Generators will be disconnected and removed prior to flood events. There
will be no heating, plumbing and air condition or other service equipment that can't
be easily removed.
5. There will be no manufactured homes in the floodplain. The office trailer will be
located out of the floodplain, approximately 6 feet above the 100 -year Base Flood
Elevation (BFE).
6. The office and site will not have a potable water service supply. Bottled water will be
brought in to the site.
7. The site will be serviced by portable toilets. The portable toilets will be located next
to the trailer, out of the floodplain, or if located in the pit will be some of the initial
items removed for flood stage preparation (see Stormwater Management Plan).
8. On-site waste disposal will be located out of the flood plain at the office area. Section
VI. B. of the Stormwater Management Plan covers practices and method of Waste
Management and Disposal.
C. Specific Standards
1. (Residential Construction) The office trailer, scales and fuel storage will all be
located out of the 100 -year floodplain and approximately 6 feet about the BFE. An
Elevation Certificate will be submitted if required.
2. (Nonresidential Construction) Same response as above. Additional standards in this
section do not apply, due to sufficient elevation above the BFE.
3. (Enclosures) There are no proposed enclosure subject to flooding.
4. (Manufactured Homes) There are no proposed manufactured home to be located on
site. The office trailer will be located out of the 100 -year floodplain and
approximately 6 feet about the BFE.
5. (Recreational Vehicles) There are no planned recreational vehicles to be placed on
site. If recreational vehicles are parked on site, the location will be out of the 100 -year
floodplain and the length of time, license and requirement from paragraph 4 of this
section will be met.
D. Floodway
The 1982 Army Corps of Engineers Study shows a long dash line, that with a high level
of confidence, likely represents the floodway, though it is not labeled as such nor does it
show up in the legend on the individual panel sheets included at the end of this Report.
1. All proposed construction, improvements and structures are located outside of the
area described above as the floodway.
2. Same response as above.
3. Same response as above.
E. Standards for Areas of Shallow Flooding
Though not specifically called out as an area of shallow flooding (Zone AH or AO) the
base flood elevation across the site resemble an area of shallow flooding.
1. No new residential construction is being proposed in this area.
2. There are no substantial improvements of nonresidential structures. The office trailer
will be located out of the 100 -year floodplain and approximately 6 feet about the
BFE.
3. There are no structures being proposed in this area.
F. Properties Removed from the Floodplain by Fill
Section does not apply — Property will not be removed from the floodplain by fill.
G. Alteration of a Watercourse
Section does not apply — The project does not propose to alter the course of the Colorado
River.
H. Standards for Critical Facilities
Section does not apply — The proposal is not considered a critical facility nor provide an
essential service.
B. Section 4-109 Development in the 100 -Year Floodplain
A. Overview
This Report (Analysis) is being submitted as a part of the Application for Floodplain
Development Permit.
B. Review Process
This Report will be amended to address any questions or comments from the review
process.
C. Review Criteria
1. The danger to life and property will be minimal. An important factor to consider
about flooding of the Colorado River is that these events are not "flash flood" events.
Flood stage events are typically forecasted weeks in advanced and occur when high
snow -pack years are combined with rapid increase in springtime temperatures.
Danger to life and property will be minimized by removing equipment from the pit
and ceasing mining operations when high flood levels are forecasted (see Stormwater
Management Plan).
2. Equipment, such as fuel tanks, generators, loaders, dozers and excavators can all be
damaged during flood events and will be the first items to be moved to high ground.
The crusher and screens are constructed to be flood resistant, but will be moved out of
the pit as the probability of a flooded pit increases (see Stormwater Management
Plan).
3. The danger that material will be swept away (to the injury of others) is minimized
when the equipment can be removed from the pit during flood events; as is planned.
4. The use is compatible with the adjacent Una gravel pit and the commercial/industrial
uses to the north and northeast.
5. The access to the property from County Road 300 will be located out of the 100 -year
floodplain. The access road to the office trailer and fuel storage will also be
completely out of the 100 -year floodplain. The pit itself will become flooded, but
with the expected advanced notice equipment can be removed and personnel work
operation will cease prior to a major flood event. It should be noted that the driveway
location approved with the Garfield County Driveway Permit is approximately 315
feet north of the driveway location shown on the Lewicki plans. The Floodplain
Development Site Plan submitted as an attachment to this Report shows the correct
driveway location.
6. There are no proposed improvements that will be the public's or County's
responsibility to repair after flood events.
7. The expected flood depth in the pits during the 100 -year flood would range from 17
to 27 feet. The depths and extent of flooded area will also decrease the velocities,
chance of sediment transport and effects of wave action. As with flooding events of
the Colorado River, the duration of high water could last several days.
8. Gravel pits and the resources being mined are sometimes only found or only cost
effective to extract adjacent to rivers.
9. The site adjacent to the river is necessary and alternate locations away from the river
are rare.
10. The 2030 Comprehensive Plan identifies this site as having Category 1 — High
potential for aggregate, sand and gravel resources.
C. Section 4-203 Description of Submittal Requirements
0. Floodplain Analysis
The Floodplain Analysis by the Army Corps of Engineers, described in Section II. of this
Report, was found to be reasonably valid for today.
1. A Floodplain Specific Site Plan has been prepared for this proposal. Plan sheets from
the Army Corps of Engineers 1982 Study where stitched together, scanned and
inserted as a background to the Site Plan. The Site Plan meets the requirements as
outlined in Code Section 4-203(0)(1.) and listed below:
a. The Flood Boundary and water surface elevation have been determined relative to
the NAVD 88. Base Flood Elevations had to be adjusted from NGVD 1929 to
NAVD 1988 by the procedure described in Section II. of this Report.
b. The 1982 Army Corps of Engineers Study shows a long dash line, that with a high
level of confidence, likely represents the floodway, though it is not labeled as
such nor does it show up in the legend on the individual panel sheets included at
the end of this Report. This line is labeled as "FLOOD WAY" on the Site Plan.
c. The existing river channel is shown by a blue shaded area on the Site Plan. The
extents of which were obtained from recent aerial imagery and adjusted for actual
survey data of the north shoreline surveyed on February 15, 2012.
d. Existing and proposed contours are shown within the Site. The existing contours
are from a survey conducted by River City Consultants in February 2015.
e. Note 6 on the Site Plan describes existing and proposed elevations for the office
trailer. The office trailer will be located approximately 6 feet about the BFE.
f. The office will not be flood -proofed, since it will be located far outside and above
the floodplain.
g. The proposed Screening Berms are described in the Lewicki DRMS Application
Exhibit D - Mining Plan subsection 4 - Topsoil and Overburden Handling. The
berms will follow the Typical Section shown on page 7 of the Project Information
and Staff Comments from the Board of County Commissioners meeting on July
13, 2009, continued from 6/1/09.
h. The existing and proposed impervious areas are described in Note 7 on the Site
Plan.
i. There is no existing or proposed water supply and irrigation water is not available
to the site.
2. The office will not be flood proofed, therefor a certificate will not be required.
3. An Elevation Certificate for the office trailer will be submitted if required. The
existing and proposed grade at the office site is approximately 6 feet above the Base
Flood Elevation (see Site Plan).
4. The project does not propose to alter the course of the Colorado River.
5. Engineer's Report — This document serves as the Engineering Report.
D. Section 7-203 Protection of Waterbodies
A. Minimum Setback
1. A setback of 35 feet is required from the Typical and Ordinary High Water Mark
(TOHWM). The surveyed line from February 2015 has be offset 200 feet to create the
limit of mining. Though this line is probably close to a low water mark, a 200 -foot
setback from this far exceeds a 35 -foot setback from the TOHWM. The detention
basin will be set back 100 feet from the survey line. The 35 -foot setback will also be
respected for the drainage channel crossing the mid -point of the property or at the
western edge of mining operations. The drainage channel on the east side of the
property is considered to be a roadside ditch and not a waterbody as it pertains to this
Code Section. The screening berm will be located adjacent to the roadside channel. A
reasonable setback will be determined in the field.
2. The 35 -foot setback applies, even though the typically dry drainage channels
bordering the site are not considered "streams".
3. The 100 -foot setback requirement for hazardous materials and sand or salt used on
roads will be met.
B. Structures Permitted in Setback
None of the permitted items will be located within the setback to the Colorado River.
C. Structures and Activity Prohibited in Setback.
1. Vegetation will not be removed within 100 feet of the February 2015 Survey line or
within the 35 -foot setback from the TOHWM of the Colorado River.
2. Natural drainage patterns or topography will not be disturbed within the 35 -foot
setback. There is evidence of bank erosion that has been occurring adjacent to the
Colorado River in the eastern portion of the Site. This area will be monitored and if
necessary, a proposal will be made to Garfield County (and the Army Corps of
Engineers) for river bank stabilization.
D. Compliance with State and Federal Laws
State and federal laws will be followed. Construction Stormwater Discharge and
Dewatering Permits will be obtained from Colorado Department of Public Health and
Environment. The project has already been under the review of a 112(c) Application to
the Colorado Division of Reclamation, Mining and Safety.
IV. Reclamation Plan
The Lewicki DRMS Application includes a Reclamation Plan for post -mine operation
conditions. The screening berms containing topsoil and overburden will be used for backfill
during reclamation. The mine slopes will be backfilled to a 3:1 slope. Exhibit Map F-1 in the
Lewicki DRMS Application shows final reclamation contours and reclaimed lakes. Of the 51
acres of disturbed ground approximately 1/3 will be reclaimed lakes and 2/3 will be dry
rangeland. The reclaimed lakes will have a water surface elevation of 4989 or if there is no
approved DRMS approved water right for exposed groundwater, the bottom grade will be 4990.
Either scenario creates a finished grade/water surface between 10 and 17 feet below existing
grades. The dry rangeland around and in between the lakes will be between 0 and 4 feet below
existing grades. In no case will final reclaimed surfaces be higher than pre -mine elevations.
Topsoil will be spread across the site and seeded with a Reclamation Seed Mix (see Lewicki
DRMS Application). The rip rap lined flow structure and site entrance will remain with the final
reclaimed site. The reclaimed site will meet or exceed the requirement and review criteria as
detailed above for the project in its mining state.
V. Conclusion
The 5 Mile Ranch Gravel Pit will be located adjacent to the Colorado River about 4 miles
southwest of Parachute. A floodplain study by the Army Corps of Engineers from 1982 was
determined to still be valid and was used for this analysis. The Base Flood Elevations (BFE)
from the study were converted to the North American Vertical Datum of 1988 to match the
topographic survey of the site. The mining operations will be located with in the 100 -year
Floodplain, but out of the Floodway. The office trailer, scales, fuel storage and ports -potties will
be located out of the floodplain and about 6 feet above the BFE. Only temporary fill will be
located in the floodplain (not in the floodway) including material stockpiles and screening berms.
The screening berms will be removed during restoration phases. The Gravel Pit operations and
final reclaimed site will have a "Zero Rise" effect on the Base Flood Elevations of the Colorado
River. A major flood event for the Colorado River will typically be predicted to occur with
advanced noticed. This will allow the mine operators sufficient time to prepare the gravel pit for
flooding. A flood event in the gravel pit will not jeopardize the public's safety nor place any
financial burden on the County.
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BASIS OF HORIZONTAL CONTROL THE
COLORADO STATE PLANE COORDINATE
SYSTEM, CENTRAL ZONE, LAMBERT CONFORMA
CONIC PROJECTION. THE FOLLOWING (USC B G
AND/OR USGS) TRIANGULATION STATIONS
WERE USED
NAME ORDER COORDINATES
CATHERINE 2nd 3=1,516,508.42
Y. 581,255.78
GNAT aro X. 1,231,566.60
Y. 523,643.10
BASIS OF VERTICAL CONTROL• USC B GS
SEA LEVEL DATUM BASED ON THE
FOLLOWING BENCHMARKS
NAME ORDER ELEVATION
D-156 2nd 6192.284
467074PS 2n6 4069.860
LEGEND
▪ HORIZ CONTROL
0 VERTICAL CONTROL
X BENCHMARK
a.x2 PHOTO CENTER
GRID POINT
CROSS SECTION
POLE
FENCE
TREE
BRUSH or SCRUB
—T7
1 FOUNDATION or RUINS
SECTION LINE
▪ FOUND SECTION CORNEF
= UNFOUND SECTION CORNER
APPROY, SECTION LINE
COMPILATION BY PHOTOGRAMMETRIC METHOD'
FROM 6" CF. L. VERTICAL AERIAL
PHOTOGRAPHY TAKEN NOV. 15,16,5 17, 1982
THIS MAP COMPLIES WITH NATIONAL MAP
ACCURACY STANDARDS
PREPARED Br
ANALYTICAL SURVEYS, INC
4167 SINTON ROAD
COLORADO SPRINGS, CO- 80907
303-593-0093
SCALE IN FEET
200 0 0 200 400
CONTOUR INTERVAL - 2 FEET
COLORADO RIVER AND TRIBUTARIES
FLOOD PLAIN STUDY
DEPARTMENT OF THE ARMY
SCRAMMED 5151810, CORPS DE ENGINEERS
650 CAPITOL MALL
SACRAMENTO, CALIFORNIA 9581447,1
PREPARED FOR
GARFIELD 9 MESA COUNTIES, COLORADC
IN COOPERATION WITH
COLORADO WATER CONSERVATION BOARD
DENVER, COLORADO
DECEMBER, 1982
JUL 1947
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x
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x •S
5001 3
50017 x
x
20
209
N 577,736
E 1,264,024
203
N 578,513
E 1,264,769
4996 8,1
• �{ •
\l _ ' x49991
a 96 9_
Jj'x ga
-4990
203
N 579,220
E 1,264,798
204
N 578,524
E 1,264,812
\(0• COLORADO t5'
y
,�/ 49993
n X
'.
X5000 3
5000.9
X
Zone AEI
49992
206 _
-
206 t_ 47
N 579,506 \�7'
E 1,265,597
0
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-
--- 4998 2' 5003-5000 B 4�
50- 03
X
4998'.
ei► --. x •
951
•
J 207: 207 ---
▪ N 560.77
,4//„.4-4, E I,2=:,423
Y:-
17
5
x499 4994 7
X 1
90 _
X 000 r
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x
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x "14
x
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1
5005 7 0
X 0
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5001.7 - x5005 2
x
003.1
ti
999.2
204
N 579,247
E 1,264,843
205
N 578,520
E 1,264,870
X
49956
4 996.8
X49
7 '4995,3
X
49969
205
N 579,269
E 1,264,901
X •y.
49963
.4996 207"
x5rr
dNei.
_•=7-
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RUIN' J - .fir— -L
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x
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/
TRAVELERS HIGHLANOS SUBDIVISION _207
2061G0: RSI.
5040 6
0
O 206
O N 578,476
E 1,266,864
E 1,266,000 N 576,000
N 577,000
•
207
N 579,903
E 1,266,531
207
N 578,945
E 1,267,525
ane
5019 1
x
N 578,000
f
rO
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— _ _ - /'-/ iI
20 5 1•.-_
N 579,998 ......„.-.--.=2....._.
E 1,265,397
C -77
BASIS OF HORIZONTAL CONTROLTME
COLORADO STATE PLANE COORDINATE
SYSTEM, CENTRAL ZONE, LAMBERF CONFORP
CONIC PROJECTION. THE FOLLOWING CUSC 8
AND/OR USGS) TRIANGULATION STATIONS
WERE USED
NAME ORDER COORDINATES
CATHERINE 2n2 9:1,516,508.42
Y. 581,255.76
GNAT 3,2 3:1,231,566.60
Y. 523,643.10
VASIS OF VERTICAL CQNTROL USC 8 GS
SEA LEVEL DATUM BASED ON THE
FOLLOWING BENCHMARKS
NAME ORDER ELEVATION
D-156 2n3 6192.284
487074 PS 2n2 4869.860
LEGEND
• HORIZ. CONTROL
O VERTICAL CONTROL
X BENCHMARK
4,22 PHOTO CENTER
GRID POINT
CROSS SECTION
• POLE
▪ FENCE
TREE
•. BRUSH or SCRUB
—It
— _ 1 FOUNDATION or RUINS
SECTION LINE
FOUND SECTION CORNER
—�� UNFOUND SECTION CORNS
------ APPROX. SECTION LINE
COMPILATION BY PMOTOGRAMMETRIC METH(
FROM 6" CF. L. VERTICAL AERIAL
PHOTOGRAPHY TAKEN NOV, 15,16,8 17, 1982
THIS MAP COMPLIES WITH NATIONAL MA
ACCURACY STANDARDS
PREPARED 8Y+
ANALYTICAL SURVEYS, INC.
4167 SINTON ROAD
COLORADO SPRINGS, CO. 80907
303-593-0093
SCALE IN FEET
200 0 0 200 4(X
CONTOUR INTERVAL - 2 FEET
COLORADO RIVER AND TRIBUTARIEI
FLOOD PLAIN STUDY
DEPARTMENT OF THE ARMY
SACRAMENTO DISTRICT, CORPS OF ENGINEERS
650 CAPITOL MALL
SACRAMENTO, CALIFORNIA 958144794
PREPARED FOR
GARFIELD 8 MESA COUNTIES, COLORA
IN COOPERATION WITH
COLORADO WATER CONSERVATION BOARD
DENVER, COLORADO
DECEMBER, 1982
JUL 1987
0
0
w
O
O
0
025.2
N 577,000
196
iN 576,649
E 11258,027
• 196
N 575,938
E 1,258,390
197
N 576,786
E 1,258,580
19,7
198
N 576,970
E 1,259,198
199
N 578,163
E 1,259,846
199--
5028.9
5041.2 5039.2 X
5030
196 o
H10
5028.8 DENVER •,'._' -
4 zaQk
x, 13.3
450 0397X
05039
O
WEER R
ORpNOE_,y.
5020ST
N 579,000
14 580,000
200
N 579,773
E 1.260,4 54
50467 �+
X
5040
5037.8
21
5041.7^
Gx�
5020- r
15019 6`
s-kr-
501.•
4998 6�
502g7-.
Y•�`OxnCs 50+3'5
50
5001 8
St�cry
A41T
' 268
9R9^�
u
section
e Coo.. co,,,
ala
5020
3A
X
4997.5
rte• J 00S)b°x Got-- -
13.`G A9B0
Z'4 e 4E
498'$ 8
ti
9
x
4986 2
7,959
; 4991,1 x4986.2
1,261,45__ •�
•f.X 4989 I
•
s 4985 8 _ _
x
4987.1. 4988.9= _•�'
0
0
10
0
0
cv
toN
498911117
4986 2
X
- 34984.7 , `rr°
i
83,7
x
4986.5
x
4984.7
X _
A990
N
w .
200• •
N 577,489
E 1,261,354
Z311L
+
49884 -
X
G
4988 81
X
49902
X
X
49908
1 I
■
4992
X
3040.E ,5p4I0
r}. f J 198 -503
50396 199 9.0 `
196
N 576,510
E 1,260,329
—. ---r' —
5030
49906
4992 9
4991 I x
49891 u;
2 X - 4 991 8
49901 f� X r
49893! 11
X_
90.3
4992 3 x 1 •
X
4990 7 X
4990 5 4990.3
X I
C) 4992 2
49893 X _
4992 3
4999
499. ,r --'\--
X
491'3,----.::g
201
0
1—
x
0
5033 8
1517' '-+^L_.—+
5010
666
197
9 575,634
+-. E 1,259,467
197
N 574.870
E 1,260,359
34¢509
N 575,000
198
N 576,224
E 1,261,257
199
N 577,167
E 1,260,983
199
N 576,340
E 1,261,429
200
N 576,305
E 1,261,623
{
-7_
,
49910• {
•
r()f �• •. LTR
`��`
SU BDIV
v^�y-
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5000
5001.2•
X )7a
5010-5016 2
rho+•
50255
N 576,000
V,
3040
15045.6
201
N 578,503
E 1,262,92
201
N 577,636
E 1,263,765
201
C -7P
BASIS OF HORIZONTAL CONTROL• 1HE
COLORADO STATE PLANE COORDINATE
SYSTEM, CENTRAL ZONE, LAMBERT CONFORM[
CONIC PROJECTION. THE FOLLOWING (USC B 1
AND/OR USGS) TRIANGULATION STATIONS
WERE USED -
NA ME
SED
NAME
CATHERINE
ORDER
2n0
GNAT 3rd
COORDINATES
V. 1,516,508.42
Y= 581,255.78
x= 1,231,566.60
Y : 523,643. 10
BASIS OF VERTICAL CONTROL USC B GS
SEA LEVEL DATUM BASED ON THE
FOLLOWING BENCHMARKS•
NAME
0-156
487074 P5
0
X
a 22
ORDER
2nd
2nd
LEGEND
HORIZ. CONTROL
VERTICAL CONTROL
BENCHMARK
PHOTO CENTER
ELEVATION
6192, 284
4869860
GRID POINT
CROSS SECTION
o POLE
FENCE
I•I
1
TREE
BRUSH or SCRUB
FOUNDATION or RUINS
SECTION LINE
FOUND SECTION CORNER
UNFOUND SECTION CORNER
APPRO5, SECTION LINE
COMPILATION BY PHOTOGRAMMETRIC METHODS
FROM 6" GFL VERTICAL AERIAL
PHOTOGRAPHY TAKEN NOV, 15,16,a 17, 1902
THIS MAP COMPLIES WITH NATIONAL MAP
ACCURACY STANDARDS
PREPARED BY:
ANALYTICAL SURVEYS, INC.
4167 SINTON ROAD
COLORADO SPRINGS, CO 80907
303-593-0093
SCALE 1N FEET
200 0 0 200 400
CONTOUR INTERVAL - 2 FEET
COLORADO RIVER AND TRIBUTARIES
FLOOD PLAIN STUDY
DEPARTMENT OF THE ARMY
SACRAMENTO DISTRICT, CORPS OF ENGINEERS
650 CAPITOL MALL
SACRAMENTO, CALIFORNIA 95814-4794
PREPARED FOR
GARFIELD B MESA COUNTIES, COLORADO
IN COOPERATION WITH
COLORADO WATER CONSERVATION BOARD
DENVER, COLORADO
DECEMBER, 1982
JUL r 1987
/
i
WEL•
L
/
Sec
/
SO1 "53'42"E
157.90'
/
�"
c
t
7 /per 1
7 x'5013
34
S27/28
33/34
BLM 1982
EL: 5012.21
f
/
7
i
i
i
i
O
5020
ACCESS ROAD
PROPOSED
CULVERT
WELL
1.5H:1V SLOPES
100 -YR FLOOD PLAIN
1982 FLOOD STUDY
ctr -rd
h
c
M
DIRE
APPROX. 00 -YR FLOOD PLAIN
ADJUSTED OR 2015 SURVEY
EXISTING ACCESS
TO UNA GRAVEL PIT
M NING
DIRECTION
EXISTING WETLANDS
DELINEATION
1 4972
9.55 an
4970
MINI
DI
G
CTION
BASE FLOOD ELEVATION
1982 FLOOD STUDY
ZONE AE
9 FLOOD TUDY
o
OUTFALL 001
SAMPLING POINT
V -NOTCH WEIR
5°19'03"
WELLo
EXISTING W
DELINEATI
UNION PACIFIC (UP) RAILROAD ROW
��•� �` ��'. /> ' i i 100 -YR FLOOD PLAIN � c
..��.• ' *1�jf'a/ ; _1 _I 'I:
11982 FLOOD STUDY
••//: I I\ g(le'‘\ (11:
/�
///— _X�,�`J111
j)/
NOTES:
BASE FLOOD ELEVATION
1982 FLOOD STUDY
EASEM NT
1/4 CORNER'
S.33 S.34
STONE
/Q9
`1co
n4 e
LI f
= m
LiJ
2 eti-
csS
Cr
W Cr
4 '!
CC 0
C7 tJ z
Y,
p z
� w
a Y
4
p'
_ a
cc
ko
E. 2fl
000
(]u_o
OX. 100 -YR FLOOD PLAIN
ADJUSTED FOR 2015 SURVEY
5040
- -
BASE FLOOD ELEVATION
1982 FLOOD STUDY
7
Cj
Ni
•
011
0/
{
'cr
0 co
ft, cy
4,�
0 ft,ra
•
0'
200'
400'
600'
IIN
SCALE: 1" =200'
LEGEND
Phase Line
Parcel Lines
Subject Boundary Line
Building
Fence
Gas and Water Wells
Existing Contour
Existing Index Contour
Proposed Contour
Proposed Index Contour
Range or Township labels
Section line
Section numbers
Asphalt Road
Unimproved Road
Railroad
Drainage Ditch/Stream
Buried Utility Line
Survey Monument
River/Pond
Wetlands
100 -Year Flood Plain
1982 Army Coprs of Engineers
100 -Year Flood Plain
Adjusted to 2015 Topographic Survey
Base Flood Elevations
1982 Army Coprs of Engineers
0 0
'WELL
R1E T2N
1-36
O
lr 1111M,
4994 (NGVD'29)
Base Flood Elevations
Adjusted to NAVD'88 4998 (NAVD'88)
BASE FLOOD ELEVATIONS (NGVD '29) WERE OBTAINED FROM A 1982
FLOOD PLAIN STUDY BY THE ARMY CORPS OF ENGINEERS. THE 1982
STUDY IS SHOWN AS A BACKGROUND IN THIS SITE PLAN.
2. EXISTING SITE TOPOGRAPHY (NAVD '88) FROM A 2012 SURVEY BY
RIVER CITY CONSULTANTS.
3. ELEVATION DATUM CONVERSION FOR THIS SITE: NAVD'88=NGVD'29+3.6'.
4. BASE FLOOD ELEVATIONS (NAVD '88) WERE DETERMINED IN THE MAIN
RIVER CHANNEL BY DIRECT CONVERSION. BASE FLOOD ELEVATIONS
(NAVD '88) AND THE 100—YR FLOOD PLAIN LIMIT OVER THE SITE WERE
DETERMINED BY USING THE DATUM CONVERSION AND TAKING INTO
CONSIDERATION THE UPDATED SITE TOPOGRAPHY.
5. THE OFFICE TRAILER WILL BE SET ON A TEMPORARY FOUNDATION.
BOTTLED WATER WATER WILL BE BROUGHT IN AND PORT—A—POTTIES
WILL BE LOCATED OUTSIDE.
6. THE EXISTING GRADE AND APPROXIMTAE FINAL GRADE AT THE OFFICE IS
5012 (NAVD'88). THE 100—YEAR BASE FLOOD ELEVATION AT THE
OFFICE IS 5005.5 (NAVD'88). THE OFFICE WILL NOT BE
FLOOD—PROOFED.
7. THE ONLY EXISTING IMPERVIOUS AREA WITHIN THE SITE'S BOUNDARY IS
THE PAVEMENT FOR COUNTY ROAD 300, WHICH HAS A LENGTH OF
2300 FEET AND A WIDTH OF ABOUT 24 FEET FOR AND AREA OF 1.3
ACRES. NEW IMPERVIOUS AREAS WILL BE LIMITED TO THE PROPOSED
OFFICE TRAILER.
8. IRRIGATION WATER OR LATERALS ARE NOT LOCATED ON THIS SITE.
9. THE PROJECT DIES NOT PROPOSE TO ALTER THE COURSE OF THE
COLORADO RIVER.
J
i
0
z
3 �.
N 0
wcc
J 4
z
0 di
(11r
Q
CC
X Li
0
0
as
GI
4.
0
V
Z
(1J
0
Z
0
C70
0
u.0
Rolland Consulting Engineers, LLC
405 Ridges Blvd. Suite A
Grand Junction, CO 81507
Voice: (970) 243-8300
Fax: (970) 241-1273
www.rcegj.com
ELAM CONSTRUCTION, INC.
5 VILE RANCH PIT
FLOODPLAIN DEVELOPMENT
SITE PLAN
Drawn
1
Designed ESS
Checked
Proj B9430
File Name: C:\PROJECTS\B9430 5 MILE PIT RCEbase.dwg
Rv: Sheet
Date 10/15/19 Of