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Home My WebLink About1.14 Geologic EvaluationCTLITHOMPSON December 14, 2023 Storied Development, LLC 1103 Ryan Pass Athens, GA 30606 Attention: Jan Fredericks Subject: Garfield County Comments Spring Valley Ranch County Road 115 Garfield County, Colorado Project No. GS06730.000-115 CTLIThompson, Inc. (CTLIT) has performed multiple geologic and geotechnical investigations regarding the Spring Valley Ranch parcel in Garfield County, Colorado. Recently, we were asked to generally evaluate geologic conditions on the property with respect to the currently -proposed development plan. We provided a geologic evaluation for the property under our Project No. G306730.000-115 (report dated February 23, 2023). in a letter dated October 25, 2023, Garfield County made two comments regarding our report. The comments and responses from CTLIT are below. Garfield County Comment 1: Additional geo-hazard analysis on avalanche hazard. The application materials did not mention or include avalanches in the geo-hazard analysis. CTLIT response: Avalanches rarely occur on slopes that are flatter than 30 percent or steeper than 45 percent. Most of the grades within the Spring Valley property are flatter than 30 percent. Slopes of 30 to 45 percent are limited to the incised section of the Landis Creek drainage that separates the Aspen Ridge parcel from the North Mountain parcel. This section is generally from Hopkins Reservoir down to the power lines that cross the drainage. These slopes are forested with aspen and spruce trees and there are no open areas above the slopes. Current plans indicate that lots and/or buildings are not proposed in this area. We judge that avalanche hazard risk is low for buildings and structures proposed within Spring Valley Ranch. Garfield County Comment 2: CTL Thompson — GeoTech report needs to more clearly delineate areas with high hazards including an overlay with PUD Plan Map to demonstrate how the amended PUD Plan addresses identified hazards. CTLIT response: CTLIT has created a map with designated geologic hazards that overlay the current PUD Plan Map, The map is attached to this letter. CTLIThompson, Inc. Denver, Fort Collins, Colorado, Springs, Glenwood _Sorin_gs, Pueblo, Summit _County —Colorado Cheyenne, Wyoming and Bozeman, Montana We are available to discuss the contents of this letter. If you have questions or need additional information, please contact us. CTLITHOMPSON, INC_ 0 U Reviewed by: 38298 mes D. Kellogg E �.* 1 f'/�j Ryan Barbone, P.E. rincipal Engineer •,� �f Division Manager .., keno c#Ithom san.co �aNA�� rbarbone ,ctlthompson.cam Attachment: Figures 1 and 2 — Geologic Hazards in PUD STORIED DEVELOPMENT, LLC Page 2 of 2 SPRING VALLEY RANCH CTLIT PROJECT NO. GS06730.000-115 0 1.000 2,000 SCALE: 1" = 2,000' LEGEND: APPROXIMATE PROPERTY BOUNDARY APPROXIMATE SUB -PARCEL BOUNDARY PUS, -1 POTENTIALLY UNSTABLE SLOPES Pus, NUMERAL INDICATES RELATIVE DEGREE OF HAZARD (1 IS HIGHER RISK THAN 2) Dbf, DEBRIS/MUDFLOW HAZARD. NUMERAL INDICATES RELATIVE DEGREE Dbf, OF HAZARD (1 IS HIGHER RISK THAN 2) ROCKFALL HAZARD APPROXIMATE GEOLOGIC UNIT BOUNDARY T6SR88W SEC 19.20 ( �! OZABOVE GROUND \ �_��` SECT. 20 PUS2 �` - •� // N00°58'37'E xfl+ \ 316.15' I W m bf1+ �' 1 SECT.:MATCH LINE .. . 8 AREA B Pu y�� PUS PLANNING 1429ss' 56, AREA D FND ALUMINUM 13 d5"W 49 ° 9' Rxf + CAP, PLS 5933; SEC 19, 20 L2-3; 0.36' ABOVE FND ALUMINUM'CAR,__� - _ / Dbf, GROUND PLS 5933; Li-14, w NNING ABOVE GROUN AREA B N71° 33' "W 1244. 7' FNNUM- \ - PUS2 �+ CAP,AP, PLSPLS 28036 -I-•++ '1 + ^ am ++ / FND¢^ REBAR WITH 1.5"J/ -'y+++F. •++++h I Dbf1 � ALUMINUM CAP, PL527929; ++ +++ ++. 0.15'ABOVE GROUND -r++++ ++w. + + + t SECT. 28 -T++'{+ i NNING f2 a- +++ +++++++•t+++++t++ O �J- tF +++i+i+++++I + FNDj►' REBAR WITH L5''�+r++++�++++++++++ t ALUMINUM CAP, PLS 27929;}'�.'YB`+++ 0.2'ABOVE GROUND+++++++ +++ + { ++++++t+1-+++ h' + ♦i+++++h+++++++ FND§aeeaa +� +•h BENT +++++}++i,++++ r"`+ t++-F +• t++ . + + + FND$^ REBAR WITH 1.5"� _ WILDLIFE +t+t++ ALUMINUM CAP ILLEGIBLE ti HABITAT RESERVE +r+F+++ BENT; 0.3' ABOVE GROUND - 513 AC.t - • ' r ++ (HATCHED AREA) PLANNING L ING ++ • AREA 11 AREA B FND §REenas PU FND * REBAR WITH 1.5" ALUMINUIvt- 05' BELOW tia� CAP PLS 5933; 0.06BELOW GROUND GROUND. 0 FNO 5" REBAR PLS 5933 BENT; r 0.05' BELOW GROUND FND g^ REBAR WIThi °W ++�+ 1.5"ALUMINUMCAP o r++++++ +}+y+ PL55933; FLUSH w o + ++++++}+ h ++t+++ SECT. 3\ FND �• REBAR WITH L3, ° SECT. 32 +++++ ALUMINUM CAP PLS 593I. 2 N8. 2' S7"VJ D.OB'ABOVE GROUND � eeesz :`NNING 1oa1 7 16n.i6 REA C FNDS" REBAR WITH 1.5" 0 2"E ALUMINUM CAP PLS 5933; N88° 43' 2 Ngg• Og• 20 '(..� 0.12' ABOVE GROUND 838 FND f• REBAR WITH 2.5� v 7 ALUMINUM CAP T6SRBBW FNDk REBAR WIT L3-44-5 SEC 32 GARFIELD 1.5" ALUMINUM CAP 1112.41' 1883.4 COUNTY 1977 W.C.; 0.55' ABOVE ILLEGIBLE; 0.35' NB7° 2221°W GROUND BELOW GROUND NB7` 22' 38'W FND 2" BAR 2.5' ALUMINUM N87° 22- 38"W_/ CAP, 1977 GARCO SUR L5, L6, 55t38' L7 SEC 33 T6SRBBW; (0.86' NO 2.5" ALUMINUM CAP, ABOVE GROUND) T6SRB6W CEN SEC Sal 1 GARFIELD 1977 ;(1.6' ABOVE GROUND) ND 5/8" REBAR 2.5" 'ALUMINUM CAP, 6SRB8W CEN SEC 33r&MFi D 1977; (1.6' ABOVE GROUND) tjus, ^ SECT. 22 xr r Puss , Rxfl+, Puss, PLANNING P AREA F bf1` bb Pus ECD7�i .'VUS2 .� / / \ FND B' REBAR ;Tli� 1.5" ALUMINUM \ D PLS 5933, LOT 14 �II S01°05'21"W .� 525.17-_ 319.72 26417.44' 1 > N88° 12' O4"W ^\ N88° 09' 52"W \, •FND 1" PIPE WITH 2" J ND 5!8' RE6AR BRASS CAP GLO; 1/4 1.5" ALUMINUM SEC 27 & 34 1' ABOVE GROUND $' CAP, PLS 5933; W �6 SEC 34 FND 2" PIPE WITH 2.5" BRA CAP, 1914; CORNER SE: 27.26, n' g 34 & 33, 2' ABOVE GROUND b llj+ SECT. 34 U S2 _-FND 5/8" REBAR 1.5" 03' 14"W ALUMINUM CAP, PLS 5933 1997; CV" SEC 34 FND 5/B" REBAR 1.5" ALUMINUM CAP, PLS 5933 1996111SEC 33 & 34 a_tI� SECT. 23 NI$ Pus, SOO° 59' 44"W --162.76- FND 1" IRON POST WITH 2" BRASS CAP, USGLO 1924,1 SEC. 26 & 28 (0.70' ABOVE GROUND) S T.26 Ll o h ° m PUS, NO °26' 4 16144 �,{ND USGLO BRASS a 1. 1.�.., �AP•4 SEC-26 y \se5" 46. 23-w FND* REBAR WI `FND@" REB, 1.5" ALUMINUM CAP, 1.5" ALUMIN PLS 5933 LOT 13 & 14 SECT. 35 ki STORIED DEVELOPMENT, LLC GEOLOGIC SPRING VALLEY RANCH CTLlT PROJECT NO. GS06730.000-115 HAZARDS IN PUD FIG. 1 0 1,000 2,000 7t �7--- SCALE: 1' = 2°000' LEGEND: APPROXIMATE PROPERTY BOUNDARY APPROXIMATE SUB —PARCEL BOUNDARY PUS, -1 POTENTIALLY UNSTABLE SLOPES. NUMERAL INDICATES RELATIVE DEGREE Pus, OF HAZARD (1 IS HIGHER RISK THAN 2) Dbf, DEBRIS/MUDFLOW HAZARD. NUMERAL INDICATES RELATIVE DEGREE Dbf, OF HAZARD (1 IS HIGHER RISK THAN 2) ROCKFALL HAZARD APPROXIMATE GEOLOGIC UNIT BOUNDARY FND 1.75" ALUMINUM, CAP, PLS 5933 1996; T6SR88W SEC 17, 12, 19. 20; 0.6 ABOVE GROUND W R FND 1.75" ALUMINUM CAP, PLS 5933 1997; T6SRBBW SEC 19, 20; 0.2' ABOVE GROUND NOW 58'37"E \ 316.15' W FND 5I8" REBAR WITH) 1.5" ALUMINUM CAP PLS 593370SEC 17 8 20; 0.80' ABOVE GROUND S87° 11' 00"E 262�� Dbf1+ $ AREA B PU Z '429.59' FND ALUMINUM ` 13' 45-W CAP, PLS 5933; SEC 19, 20 L2-3; 0.36' ABOVE FND ALUMINUM'CAP-,_ GROUND PLS 5933; L7-14p0.4' ARIL\/F f,Rffl IN1�� FND IRON PIPE WITH 2.5" BRA CAP TfiSR88W SEC B, 98 16; 0. ABOVE GROUND ND 1' PIPE WITH 2.5' BRASS ND US GLO BRASS NOt° 03' 47"E FND 2' PIPE WITH 2.S BRASS 344 �, CAP 1924 US GLO4$ g g tfi NO 1924 US GLO; S 9, 1D, 15 816AP;A SEC. 10 8 15 ND 5" REBAR WITH T6SR88W; 1' ABOVE GROUND 1 325" ALUMINUM T6SR68W; VABOVE GROUND FND IRON PIPE WITH 2. S88" 57 38'E S88° 56' 36'E S88° 54' 29'E SEC. 10 8 15 1�1 S8B° 57' 44'E BRASS &IT; CAP T6SRB8W SEC 16 2 ' 45"W - 2637.BT \ 2638 56'� 1318.31' ND 3.5" ALUMINUM CAP, PLS 6 17; 0.9' ABOVE GROUND N"7 22' 45"W FUTURE N01 ° 06' 54"E 349.BT \ /_ EMHE GLEN /� n m 15710 1994; NBO SEC. 15 8 16; 977.15' ABOVE GROUND D>!" REBAR WITH FND IRON PIPE WITH 2. D' REBAR WITH,? I \� (TM 3.25' ALUMINUM BRASS CAP T6SR88W SEC 16 ' 3,S�AL�IMINUM CAPl \ C/ F TURE J /�!/,a/,'(-,F,C,i^CJAP, PLS 15710; 1*1 8 17; 0.9' ABOVE GROUND /PLS 5933, ELS/�• I \ R bS (TY��) SECT. 5 /' C. 14815 N04` 41 SBB° 59' OTE $8B' S3' 39"E FND�RE6AR WITFi��-�252,06' PUSI \ 1.5' ALUMINUM CAP _ `FND b +� L� , ' �•�317.6TJ`/.P.1 F-\ _ND PLS 5933; FLUSH L", REBAR SECT. 16 U 7 T 6'REBAR WITH N01" 06'S4"E 3.25'ALUMINUM 1047.99'—�- S89° 38' 06"E . "'� / 51 .."� ° '�CAP, PLS 15710; NV*l 334,10' SEC. 14 (0.20' ABOVE NOW 5T OWE / _i° LANDIS CR N GROUND) 340JO0� -. /Dbf2 1 �- \/ ' EXISTING HOPKINS FND IRON PIPE WITH 2.5' 1 J � I ED u V ESERVOIR (AS Cf'20 —fND6' REBAR WITH 2.5' BRASS CAP USGLOTA w 17; TABOVE GROUND f w PLA NING FND¢ REBAR WITH 2"\ g I y-DLIFE AREA H ALUMINUM CAP, PLS 5933; \ ABIPAT RESET'Pus, ft S 1, 16 8 17; 1.2' ABOVE \\Z I ' � 587 AC3 I GROUND ( (14ATCHED AREA) \ N01�64'53-E J FND 2' IRON PIPE WITH 2. BRASS CAP; T65RBBW SE ? HOPKINS RESERVOIR DAM 20-16 8 I" USGLO 1924; BREAK INUNDATION AREA 0.8O' ABOVE GROUND I ,,i�J, (NO HABITABLE BUILDINGS) S87°10'41"E I ' ---_. .. _... .. 2 t` Doff+i 5 'Dbff,=✓ SECT. 20 \PPU bbff+ _ .Pllc.. i c(MATCH LINE R,. fly l PUS PLANNING f } AREA D Db�NING;\\ OU7PAfYCEL; ALUMINUM CAP, PLS Dbf 59331t SEC. 14 BEARS HO KIN S62°46'08'W 4.04' R ERVOIR ND 6" REBAR WITH L5" I ALUMINUM CAP, PLS ` 5933; W1$ SEC. 14 8 23 f (0.15' ABOVE GROUND) ( TION S88" 54' 33'E `•�a.1 .1: ; 1: 3TYP. ,316-.�1w�` \ ti J FND U&23 LOal SEC. 1448 23 3 1 Pusf ( g SECT. 22 I CT. 23 1 / P Pus, , Pusf \v\ Rxf l+ Li STORIED DEVELOPMENT, LLC GEOLOGIC SPRING VALLEY RANCH CTLfi' PROJECT NO. GS06730.000-115 HAZARDS IN PUD FIG. 2 =rrrrawr r■ ■ � rrrr =::ate ,- -u'ded in , , " GEOLOGIC EVALUATION SPRING VALLEY RANCH COUNTY ROAD 115 GARFIELD COUNTY, COLORADO Prepared for: STORIED DEVELOPMENT, LLC 9875 N. Tuhaye Paris Drive Kamas, UT 84036 Attention: Rich Wagner Project No. G806730.000-115 February 23, 2023 CTLIThompson, Inc. Denver, Fork Collins, Colorado Springs, Glenwood Springs, Pueblo, Summit County — Colorado Cheyenne, Wyoming and Bozeman, Montana TABLE OF CONTENTS SCOPE........................................................................................................ PREVIOUS INVESTIGATIONS.................................................................. SITEDESCRIPTION.................................................................................. Pasture..................................................................................................... MiddleBench............................................................................................ WestRidge............................................................................................... NorthMountain......................................................................................... AspenRidge............................................................................................. SoutheastSlope....................................................................................... PROPOSED DEVELOPMENT.................................................................... GEOLOGIC SETTING AND STRUCTURAL GEOLOGY ......................... — GEOLOGIC CONDITIONS.......................................................................... BedrockUnits........................................................................................... SurficialDeposits...................................................................................... GEOLOGICHAZARDS................................................................................ Potentially Unstable Slopes..................................................................... DebrisFlow/Mudflow................................................................................ RockfalI..................................................................................................... GroundSubsidence.................................................................................. Radiation.................................................................................................. LIMITATIONS.............................................................................................. FIGURE 1 —AERIAL PHOTOGRAPH FIGURE 2 — PROPOSED DEVELOPMENT FIGURES 3 AND 4 — GEOLOGIC MAP FIGURES 5 AND 6 — GEOLOGIC HAZARD MAP 1 1 2 2 2 3 3 4 4 12 STORIED DEVELOPMENT, LLC SPRING VALLEY RANCH CTLIT PROJECT NO. GS06730.000-115 SCOPE CTLIThompson, Inc. (CTLIT) has performed multiple geologic and geotech- nical investigations regarding the Spring Valley Ranch parcel in Garfield County, Colorado. These investigations addressed previous development concepts by oth- er clients. Recently, we were asked to generally evaluate geologic conditions on the property with respect to the currently -proposed development plan. This report provides an overview of site conditions, geology, and geologic hazards within the approximately 5,908-acre parcel. We utilized data from our previous geologic and geotechnical engineering investigations at the site, as well as observations from our recent site reconnaissance to prepare this report. PREVIOUS INVESTIGATIONS CTLIT previously performed numerous geologic and geotechnical studies on the Spring Valley Ranch property. Most of this work was completed between August 1998 and December 2000 and included geologic evaluations, slope stabil- ity analyses, and preliminary geotechnical engineering investigations. Our studies concentrated on potential development areas for buildings and water tanks, as well as proposed road alignments. Our scope for these investigations included re- view of published geologic mapping, site reconnaissance, exploratory drilling and excavation, laboratory testing, and engineering analysis. The most recent studies at the site by CTLIT were a geologic evaluation (Job No. GS-3976-A; report dated November 24, 2003) and a preliminary ge- otechnical investigation (Job No. GS-3976-13; report dated November 24, 2003). The preliminary geotechnical investigation included drilling 23 exploratory borings and excavating 24 exploratory pits spaced across the property. Laboratory testing was performed on many of the subsoils obtained from the borings and pits. The geologic evaluation utilized a review of published geologic maps, analysis of aerial photographs, and site reconnaissance to characterize the site. Deliverables for STORIED DEVELOPMENT, LLC 1 SPRING VALLEY RANCH CTLIT PROJECT NO. GS06730.000-115 these reports included detailed mapping of geologic conditions and hazards, as well as logs of exploratory borings and pits. SITE DESCRIPTION The Spring Valley Ranch property is an approximately 5,908-acre parcel above and to the northeast of the Roaring Fork River Valley in the central part of western Colorado. Ground surface topography generally steps down to the south- west via a series of topographic benches. Ground surface on the benches is com- paratively gently -sloping with steeper grades separating the benches. This topog- raphy has been deeply incised by Landis Creek and other drainage channels, which generally trend down to the southwest. Current development plans divide the Spring Valley Ranch Parcel into six sub -parcels. An aerial photograph that in- dicates these areas is included as the attached Figure 1. General descriptions of site conditions within these sub -parcels are below. Pasture The Pasture is comprised of about 730 acres on the floor of Spring Valley, southwest of County Road 115. Most of this part of the property is gently -sloping down to the west and southwest. Moderate slopes are along the perimeter. This area is predominantly irrigated hayfields. More hummocky terrain is in the south- east part of the Pasture. Elevation ranges from about 7100 feet in the southeast to 6870 feet in the northwest. Vegetation in this area is a mixture of hayfield and nat- ural scrub oak and sage. Middle Bench The Middle Bench is approximately 1,356 acres located above the north- east side of County Road 115. Steep, southwest -facing slopes rise from the road alignment a total elevation of about 500 to 700 feet to the upper part of the bench STORIED DEVELOPMENT, LLC 2 SPRING VALLEY RANCH CTLIT PROJECT NO. GS06730.000-115 area. Ground surface is variable, ranging from gently -sloping meadows to low ridges that separate minor drainage basins. Elevation ranges from about 7900 feet in the north part of this area to approximately 7070 feet adjacent to the county road. The northeast extent of the Middle Bench is along the toe of steep slopes that rise to the northeast. Overhead powerlines cross the property near this transi- tion. Vegetation on the Middle Bench consists of meadows with grasses and weeds intermixed with areas of oak brush. Sloping ground is generally vegetated with sage brush, grasses, and weeds with areas of dense scrub oak. Several buildings that are part of a historic homestead are in the east part of the Middle Bench. West Ridge The West Ridge sub -parcel is approximately 500 acres in the west part of the Spring Valley Ranch PUD property. This area is west of the Landis Creek drainage. Topography in the West Ridge area is defined by several knobs that sur- round a lower central area. Elevation within this sub -parcel varies from about 7770 feet in the north to 7030 feet along the county road. Ground surface slopes on the knobs are generally moderately sloping. Steeper slopes are adjacent to the access road that is within the creek drainage. Numerous outcrops of basalt bedrock are exposed along both sides of the drainage. Vegetation is predominantly oak brush and sage. The central part of the sub -parcel is irrigated hayfield. North Mountain The North Mountain area consists of approximately 934 acres within the northwest part of Spring Valley Ranch, PUD. Topography is irregular, but overall slopes are down to the south and southwest. The slopes are incised by numerous natural drainages. Ground surface elevations range from about 9200 feet at the northeast to 7950 at the southwest. Vegetation is a mixture of oak brush and as- pen forest. STORIED DEVELOPMENT, LLC 3 SPRING VALLEY RANCH CTLIT PROJECT NO. GS06730.000-115 Aspen Ridge The Aspen Ridge sub -parcel is approximately 1,214 acres within the north- east part of the Spring Valley Ranch property. Topographically, this part of the property can generally be visualized as hummocky slopes that generally step down to the southwest and the Middle Bench area. Several knobs are within the central and northeast parts of the Aspen Ridge area. A localized basin in the north contains Hopkins Reservoir. This local area slopes down to the northwest toward Landis Creek. Several minor drainages within the south part of the area trend down to the southwest. Ground surface elevations vary from approximately 9,400 feet in the northeast to about 7900 feet in the southwest. Vegetation ranges from aspen and coniferous trees in higher areas to oak brush on the lower slopes. Southeast Slope The Southeast Slope area is about 755 acres within the southeast part of the property. A localized ridge trends from southeast to northwest in the central part of this area. A small valley to the north and northeast of the ridge connects to a drainage that trends down the south. A larger drainage on the northwest sepa- rates the ridge from hummocky land to the north and northwest. Ground surface elevations in the Southeast Slope area range from about 8600 feet in the north- east to 7600 at the southwest. Vegetation is predominantly oak brush and sage. Grass -covered meadow is within the small valley. PROPOSED DEVELOPMENT The currently proposed Spring Valley Ranch development will be for resi- dential use with several amenity parcels, one 18-hole golf course, and one short course. A small ski area is also contemplated. We were provided with a conceptu- al plan by Storied Development (dated January 27, 2023). The conceptual devel- opment is shown on the attached Figure 2. Infrastructure construction will include STORIED DEVELOPMENT, LLC 4 SPRING VALLEY RANCH CTLIT PROJECT NO. GS06730.000-115 roads, utilities, and one new small reservoir. We anticipate that water and sewer systems will be centralized. On -site Wastewater Treatment Systems (OWTS) are reasonable to consider for many lots. General descriptions of proposed develop- ment of the sub -parcels is below. The Pasture sub -parcel area will remain largely without buildings or roads. Approximately 75 community housing units are anticipated in the southeast, near the intersection of Spring Valley Road and County Road 115. A looped access road is contemplated for the residences. At this writing, the Middle Bench sub -parcel will include about 200 single- family lots. This area will include one 18-hole golf course, one short course, and a clubhouse village. Maintenance facilities for the golf courses and metro district, as well as a fire station are also contemplated within the Middle Bench. One small reservoir is proposed. We anticipate these will be non -jurisdictional, water im- poundment structures. Roads and utilities will be constructed throughout the de- velopment. The conceptual plan indicates that about 100 residential units are proposed for the West Ridge sub -parcel. Lot sizes will vary from about 1 acre to greater than 5 acres. An amenity parcel is planned in the central part of the sub -parcel. This parcel could include a community center and/or fitness center. Roads and utilities will be constructed from the Landis Creek drainage. Relatively sparse development is anticipated within the North Mountain sub - parcel. The current conceptual plan indicates 21 single-family lots of 2 acres to greater than 5 acres. A central amenity parcel may include an open pavilion or similar structure. Some of the roads and utilities constructed to access the devel- opment area will climb and traverse steep slopes. STORIED DEVELOPMENT, LLC 5 SPRING VALLEY RANCH CTLIT PROJECT NO. GS06730.000-115 La The Northeast Aspen Ridge is expected to include 121 single-family resk dences on lots of variable sizes. Some roads will traverse steep slopes. The cen- tral amenity parcel could include a restaurant. Improvements to Hopkins Reservoir are planned. A small ski area is contemplated within the Northeast Aspen Ridge sub -parcel. Construction would include three chairlifts and a ski lodge. The lodge is proposed near Hopkins Reservoir. The Southeast Slope sub -parcel is likely to include about 54 single-family lots. The sizes of the lots will range from about 3 acres to more than 5 acres. Some roads and utilities will climb and traverse steep slopes. It does not appear that an amenity parcel will be within the Southeast Slope area. GEOLOGIC SETTING AND STRUCTURAL GEOLOGY Spring Valley Ranch is located in an area of complex regional geology at the conjunction of several structural geologic elements. The White River Uplift is to the north and the Sawatch Uplift is to the east. The Elk Mountains are to the south and the Grand Hogback is to the west. These large-scale features are related to the continental tectonic setting. The degree of geologic activity at Spring Valley Ranch is primarily influ- enced by a smaller -scale feature known as the Carbondale Collapse Center, which has an aerial extent of approximately 200 square miles. Glenwood Springs, Carbondale and the lower part of the Roaring Fork and Crystal River Valleys are within the boundaries of the feature. It is generally accepted that the Carbondale Collapse Center is the result of evaporite minerals in the Pennsylvanian aged Ea- gle Valley Evaporite being dissolved and removed by circulating groundwater. Where this dissolution process undermines overlying bedrock units and surficial deposits, collapse of the overlying materials has resulted in ground subsidence. STORIEb DEVELOPMENT, LLG 6 SPRING VALLEY RANCH CTLIT PROJECT NO. GS06730.000.115 La Basalt flows in the vicinity of Spring Valley Ranch range in age from approx- imately 3 million years to 22 million years old. Based on radiometric dating by the Colorado Geologic Survey (CGS) and elevation differences in numerous Quater- nary to Tertiary aged Basalt Flows, total subsidence within the Carbondale Col- lapse Center has been estimated between 3,000 to 4,000 vertical feet. Based on the radiometric dating of basalts and salinity output of various hot springs in the Roaring Fork and Colorado River Valleys, it is estimated that the subsidence oc- curred over a span of at least 3.7 million years. The collapse mechanism is con- sidered to have a low degree of activity with respect to human development and construction. GEOLOGIC CONDITIONS Bedrock units below the Spring Valley Ranch property include the Pennsyl- vanian -aged Eagle Valley Evaporite and Eagle Valley Formation, the Pennsylvani- an to Permian -aged Maroon Formation, and Quaternary to Tertiary -aged basalt flows. These bedrock units have been fractured and faulted by regional collapse that originated in the Eagle Valley Evaporite. The Maroon Formation and basalt flows are closest to the ground surface and across most of the site are the only bedrock units with outcrops. Geologic conditions are shown on Figures 3 and 4. Additional discussion of the geology is in the sections below. Bedrock Units The Eagle Valley Evaporite is a heterogeneous rock unit consisting mostly of evaporite minerals interbedded with siltstone, sandstone and limestone. Under lithostatic pressure the evaporite material is susceptible to plastic flow defor- mation, which resulted in a high degree of bending and contorting of the original bedding. STORIED DEVELOPMENT, LLC 7 SPRING VALLEY RANCH CTLIT PROJECT NO. GS06730.000-115 The contorted bedding results in random pockets of highly soluble evaporite minerals that are intermixed with low -solubility sandstone, siltstone and limestone. Where the soluble minerals are overlain by bedrock, small to large blocks have been down -faulted to create surface subsidence. Overburden soils can collapse into the voids, resulting in sinkholes. Depending on the amount of soluble miner- als, groundwater circulation, and strength and thickness of overburden materials, varying amounts of surface subsidence has occurred at the site. The Eagle Valley Formation (map unit Pev) is a transitional bedrock unit. This formation contains increasing amounts of siltstone, sandstone and limestone interbedded with decreasing amounts of evaporite beds. Outcrops of Eagle Valley Formation are in the northwest part of the North Mountain sub -parcel The Maroon Formation (map unit P-Pm) consists of interbedded conglomerates, sandstones, siltstones, and claystones. Outcrops are predomi- nately located within the North Mountain and Aspen Ridge sub -parcels. A charac- teristic of the Maroon Formation and its derived surficial deposits is a red color due to a large content of oxidized iron. Much of the surficial soil deposits within the north part of the Spring Valley Ranch property were derived from the Maroon For- mation. The most widespread rock outcrops at the site are comprised of basalt flows (map unit QTb). The basalt flows in the area likely occurred sporadically since late Tertiary time. These flows at the site appear to be above down -faulted blocks of Maroon Formation. In many places they are interlayered with surficial soil deposits. Surficial Deposits Geologic conditions at Spring Valley Ranch have produced a varied and complex assortment of Quaternary -aged surficial deposits. The development of STORIED DEVELOPMENT, LLC SPRING VALLEY RANCH CTLIT PROJECT NO. GS06730.000-115 the surficial deposits has been primarily controlled by the collapse process and simultaneous weathering, erosion, and mass -wasting. Faulting has reduced some of the bedrock to rubble and generated an underlying stair step structure. Throughout the down -faulting process, weathering and erosion of the Maroon Formation, basalt flows, and rubblized derivatives pro- duced deposits of slopewash, colluvium (map unit Qc) and alluvium. Colluviurn grades into slope failure complexes (map unit Qsfc) where the colluvium has been draped over down -faulted bedrock blocks. Some areas have been identified as landslides (map unit Qls) and rock - slides (map unit Qrs). Within dawn -faulted basins and along major drainages, allu- vium and colluvium are inter -fingered producing undifferentiated deposits (map unit Qac), Lacustrine deposits (mapped unit Qlc) have accumulated in some of the down -faulted basins. debris flow fans are found at the mouths of several drainag- es. Some of the debris fans are recent and may be active (map unit Qdf), other debris fans are ancient and appear dormant (map unit Qdfo). GEOLOGIC HAZARDS Our geologic study identified several geologic conditions that need to be considered during planning for the project. The geologic conditions identified will not prevent development of the property for the intended uses, but mitigation may be required at some locations. Geologic hazards interpreted by CTLIT are shown on Figures 5 and 6. Geologic hazards at the site include potentially unstable slopes, debris flowlmud#low, and rockfall. Other concerns related to geologic con- ditions include regional issues of subsidence and radiation. STORIED DEVELOPMENT, LLC SPRING VALLEY RANCH CTLIT PROJECT NO. GS06730,000.115 Potentially Unstable Slopes The most widespread potential geologic hazard identified at the site is po- tentially unstable slopes. Erosion has deeply incised slope failure complex depos- its and other surficial deposits at the site, which suggests stability during the last several thousand years. In our opinion, most slope failure deposits on the Spring Valley Ranch property are ancient, dormant, and stable. During our recent site re- connaissance, we did not observe evidence of large-scale slope movement on the property. We delineated potentially unstable slopes into the categories, Pus, and Pusz, as indicated by the geologic hazard mapping. Potentially unstable slope ar- eas are generally designated as those steeper than approximately 30 percent. Where the slopes are underlain by slope failure complex deposits (Qsfc), we con- sider the stability to be lower. Those slopes are mapped as higher risk, Pus,, on the Geologic Hazards Map. Where the slopes are not underlain by slope failure complex deposits, we judge the slopes are relatively stable. These slopes are mapped as lower risk, Pusz. Several of the landslides mapped northwest of Landis Creek (see Figure 4) exhibited evidence of recent and possibly active soil creep, such as deformed tree trunks and scarp -like features. Site -specific geotechnical investigations will be needed to address slope stability prior to each construction phase. Construction which disturbs the landsides will need to be evaluated on a case -by -case basis. Mitigation such as slope retention and subsurface drainage systems could be re- quired for some buildings and sections of roads. Debris Flow/Mudflow We judge that debris flow/mudflow hazards on the Spring Valley Ranch property are limited to debris fans (Qdf) and drainages. In these areas, surface STORIED DEVELOPMENT, LLC 10 SPRING VALLEY RANCH CTLIT PROJECT NO. GS06730.000-115 runoff is concentrated into narrow drainages where turbulent flow can be confined, allowing sediment loads to achieve sufficient concentrations to produce debris flows and/or mudflows. We did not observe evidence of recent mudflows or debris flows during our recent site reconnaissance. The most significant potential debris flow/mudflow hazard is associated with Landis Creek and its tributary drainages. A second area of potential hazard is as- sociated with the drainage in the south-central part of the property. In our opinion, the risk from debris flows and/or mudflows can be mitigated by avoidance of con- struction within steep -sided drainages and potential construction of detention structures for sediment -laden water. Rockfall Rockfall hazards on the Spring Valley Ranch property are generally limited to the sides of the Landis Creek drainage, as well as the slopes that separate the Aspen Ridge and Southeast Slope sub -parcels from the lower Middle Bench sub - parcel. Some mitigation, such as scaling, rock bolting, and impact structures, could be required. During our site reconnaissance, our observation indicated that small- scale rockfalls actively occur at the site. We qualitatively rate the overall degree of rockfall hazard as low to moderate. Design of rockfall mitigation should be based on site -specific evaluation with respect to the planned development. Ground Subsidence We did not observe recent ground subsidence or sinkholes during our site reconnaissance. Reservoirs on the Spring Valley Ranch property should be con- structed with synthetic liners to reduce the probability of water infiltration and ground wetting, which can be a significant factor in soil subsidence and formation of sinkholes. In our opinion, the potential for subsidence is greatest near the faults that are indicated on Figures 3 and 4. STORIED DEVELOPMENT, LLC 11 SPRING VALLEY RANCH CTLIT PROJECT NO. GS06730.000-115 The faults shown on our geologic map are likely more complex than the ap- proximate locations indicated. We believe the faults are a complex array of shears and micro -faults that create a fault zone that is at least 10 to 20 feet wide. In gen- eral, we judge that the potential for fault movement at Spring Valley Ranch is simi- lar to other nearby developments, such as the Colorado Mountain College - Spring Valley Campus. We are not aware of damage to buildings and structures at nearby sites due to fault movement. In our opinion, it is reasonable and appropriate to site roads and buildings in potential fault influence zones at Spring Valley Ranch. Radiation Elevated concentrations of radioactive materials are not generally associat- ed with the geologic conditions that occur at the Spring Valley Ranch property. During previous investigations at the site, CTLIT performed a radiation survey by spot -screening widely -spaced locations for gamma radiation. Measurements were taken with a Ludlum Instruments, Model 19, Micro-R-meter carried at arm's length approximately 2 feet above the ground surface. Our readings ranged from approx- imately 10 to 17 micro -roentgens per hour. In our opinion, these levels of radiation are consistent with normal background radiation in the area. LIMITATIONS The discussion of geologic conditions and hazards in this report is general- ized and preliminary. Our geologic mapping and delineation of potential hazards is an interpretation based on our site reconnaissance, as well as exploratory drilling and excavation for our previous geotechnical investigations at the site. More de- tailed studies need to be performed as development plans progress to develop recommendations for construction of roads, utilities, buildings, and structures. STORIED DEVELOPMENT, LLC 12 SPRING VALLEY RANCH CTLIT PROJECT NO. GS06730.000-115 This report provides information for use by the client during initial planning construction concepts for roads, buildings, and structures at the site. Site -specific, design -level geotechnical engineering investigations will be needed to develop recommendations for these project components. Additional subsurface investiga- tion will be required as park of the design -level, geotechnical engineering investiga- tions. This geologic evaluation was conducted in a manner consistent with that level of care and skill ordinarily exercised by geotechnical engineers currently practicing under similar conditions in the locality of this project. No warranty, ex- press or implied, is made. If we can be of further service in discussing the contents of this report, please call. CTLITHCMPSCN, INC amen D. Kellogg, P senior Consultant ;elloaa(&ctlthomosc I je o �,v 38298 ; Z"V2' ��NAL Reviewed by: �:' k 1, 3J, " - _' i). & - Ryan R. Barbone, P.E. Division Manager rbarboneCa)-ctlthomoson.com STORIED DEVELOPMENT, LLC 13 SPRING VALLEY RANCH CTLIT PROJECT NO. G306710.000-115 0 1,500 3,000 SCALE: 1' = 3,000' LEGEND: APPROXIMATE PROPERTY BOUNDARY APPROXIMATE SUB -PARCEL BOUNDARY APPROXIMATE ROAD LOCATION NOTE: SATELLITE MAGE FROM MAXAR (COPYRIGHT 2023) STORIED DEVELOPMENT, LLC SPRING VALLEY RANCH CTL/T PROJECT NO. GS06730.000-115 AERIAL PHOTO FIG 0 1,500 3,000 SCALE: 1" = 3,000' NOTE: BASE IMAGE FROM SWABACK, PLLC (DATED JANUARY 27, 2023) LEGEND: APPROXIMATE PROPERTY BOUNDARY APPROXIMATE SUB -PARCEL BOUNDARY APPROXIMATE ROAD LOCATION �-COUNTY ROAD 115 ! COUNTY ROAD 115 SPRING VALLEY ROAD STORIED DEVELOPMENT, LLC SPRING VALLEY RANCH CTL/T PROJECT NO. GS06730.000-115 DEVELOPMENT PLAN u Fig. 2 0 1.000 2,000 SCALE: 1 " = 2,000' NOTE: SATELLITE IMAGE FROM GOOGLE EARTH (COPYRIGHT 2023) LEGEND: APPROXIMATE PROPERTY BOUNDARY' APPROXIMATE SUB —PARCEL BOUNDARY Q f EMBANKMENT FILL QC QUATERNARY AGED COLLUVIUM Q4C QUATERNARY AGED ALLUVIUM AND COLLUVIUM (UNDIFFERENTIATED) I (d f I QUATERNARY AGED DEBRIS FAN (YOUNG AND POTENTIALLY ACTIVE) f Qdfo QUATERNARY AGED DEBRIS FAN (OLD AND DORMANT) QSfC QUATERNARY AGED SLOPE FAILURE COMPLEX QIC QUATERNARY AGED LACUSTRINE DEPOSTIS QIS QUATERNARY AGED LANDSLIDE QrS QUATERNARY AGED ROCK SLIDE QUATERNARY TO TERTIARY AGED BASALT FLOW IP—Pm PENNSYLVANIAN TO PERMIAN AGED MAROON FORMATION fPeV PENNSYLVANIAN AGED EAGLE VALLEY FORMATION APPROXIMATE FAULT LOCATION C`. "D" INDICATES DOWN THROWN BLOCK U INDICATES UP THROWN BLOCK STORIED DEVELOPMENT, LLC GEOLOGIC SPRING VALLEY RANCH CTL/T PROJECT NO. GS06730.000-115 MAP FIG. 3 0 1,000 2,000 SCALE. 1" = 2,000' NOTE: SATELLITE IMAGE FROM GOOGLE EARTH (COPYRIGHT 2023) LEGEND: APPROXIMATE PROPERTY BOUNDARY F I' APPROXIMATE SUB —PARCEL BOUNDARY (: Qf EMBANKMENT FILL (�C QUATERNARY AGED COLLUVIUM QaC QUATERNARY AGED ALLUVIUM AND COLLUVIUM (UNDIFFERENTIATED) QUATERNARY AGED DEBRIS FAN (YOUNG AND POTENTIALLY ACTIVE) Qdfo QUATERNARY AGED DEBRIS FAN (OLD AND DORMANT) I F QSfC QUATERNARY AGED SLOPE FAILURE COMPLEX QIC QUATERNARY AGED LACUSTRINE DEPOSTIS QIS QUATERNARY AGED LANDSLIDE MICi BEr QIS QUATERNARY AGED ROCK SLIDE QTb QUATERNARY TO TERTIARY AGED BASALT FLOW IP—Pm PENNSYLVANIAN TO PERMIAN AGED MAROON FORMATION f •. fP@V PENNSYLVAN4W AGED EAGLE VALLEY FORMATION " `��'•= Yu APPROXIMATE FAULT LOCATION I'D" INDICATES DOWN THROWN BLOCK U INDICATES UP THROWN BLOCK I A STORIED DEVELOPMENT, LLC GEOLOGIC SPRING VALLEY RANCH CTL T PROJECT NO. GS06730.000-11 s MAP FIG. 4 0 1,000 2,000 we%�� SCALE: 1' = 2,000' —�-�� Pus2' Pusl - -- Dbf, Dbf,+ h Pus Rxfl+ _�F Rxfl+ Pus, Pus2 2 ,rf Pus2 MATCH LINE Pus, Pus, \t Rxfl+ Pus ~\. Rxfl+ ' Dbf, Dbf, PUs2 i LEGEND: Db PUS, 1 1 Pus2 _ SOUTHEAST NOTE: SATELLITE IMAGE FROM LANDSAT PASTURE Dbf2 ) Pus,+ SLOPE (COPYRIGHT 2023) Dbf2 ' Dbf, - APPROXIMATE PROPERTY BOUNDARY Dbf,+1 Pus2 . Pus2 APPROXIMATE SUB —PARCEL BOUNDARY !Pus,' Pus2 PUS Dbf2 POTENTIALLY UNSTABLE SLOPES. ] NUMERAL HAZARD INDICATES RELATIVE (1IS HIGH R FRISK THAN 2) ` O ®bf, Dbf - V 'Pus2+ ]DEBRIS/MUDFLOW HAZARD. ` Y. ? _ NUMERAL INDICATES RELATIVE DEGREE _ Dbf, MIDDLE BENCH OF HAZARD (1 IS HIGHER RISK THAN 2) d'. O Dbf,+fr'. j Dbf2 —:� — Pus2 ROCKFALL HAZARD 1 Dbf, APPROXIMATE GEOLOGIC UNIT BOUNDARY�,- i - � � �a.L�� 4 .t•. w • r �N a L � f. STORIED DEVELOPMENT, LLC GEOLOGIC SPRING VALLEY RANCH CTL/T PROJECT NO. GS06730.000-115 HAZARD MAP FIG. 5 0 1,000 2,000 SCALE: 1' = 2,000'I LEGEND: NOTE: SATELLITE IMAGE FROM LANDSAT (COPYRIGHT 2023) APPROXIMATE PROPERTY BOUNDARY APPROXIMATE SUB -PARCEL BOUNDARY PUS, POTENTIALLY UNSTABLE SLOPES. Pus2 NUMERAL INDICATES RELATIVE DEGREE OF HAZARD (1 IS HIGHER RISK THAN 2) Dbf, DEBRIS/MUDFLOW HAZARD. DbfZ NUMERAL INDICATES RELATIVE DEGREE OF HAZARD (1 IS HIGHER RISK THAN 2) ROCKFALL HAZARD APPROXIMATE GEOLOGIC UNIT BOUNDARY STORIED DEVELOPMENT, LLC SPRING VALLEY RANCH CTL/T PROJECT NO. GS06730.000-115 1 4 � _ -_ .a,-ls ... ��. 1- �j - _—\ i—,+'' hr .r•: .:.:c gyp... (�f,?. Pus, PuS2 - ... - Dbf + ' NORTH 2� MOUNTAIN Pus, `ti . _ Dbf2+ - Pus,ASPEN Dbf2 . ;.. a RIDGE Pus, I Dbf,+ Dbf,+ PuS2 - - _ / Puy Pus, WEST RIDGE Dbf,+1 PUS2 Dbf,+ !/ Pus, h ` ` PUS 2 ��— p PUS, RXfI+ t Pus Rx Dbf, Dbf,+ / 2 2 fl+ Rxfl+ Pus' Pus Pus2 MATCH LINE Pus, Pus, ' Rxfl+ � Rxfl+ -Dbf, Dbf, ! Pus, - Pus2 '- DPus, bf 1 PUs2 SOUTHEAST PASTURE }�\Dbf2 Pus,+ SLOPE 1 T .vDbf GEOLOGIC HAZARD MAP FIG. 6