GEOLOGIC HAZARDS EVALUATION 1155 CHARLES GROVE LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY FILING NO. 1-A COLORADO SPRINGS, COLORADO 3535 0 GEOLOGIC HAZARDS EVALUATION 1155 CHARLES GROVE LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY FILING NO. 1-A COLORADO SPRINGS, COLORADO Prepared for: DR. HEMSWORTH Clo CLIFFORD TAYLOR ARCHITECTS 11 South 25?h Street, Suite 220 Colorado Springs, Colorado 80904 Project No. 0517193-105 July 29, 2008 Revised August 29, 2008 Final September 19, 2008 5240 Mark Dabling Colorado Springs, Colorado 80918 I Telephone: 719-528-8300 Fax: 719-528-5362 TABLE OF CONTENTS SCOPE ..1 SUMMARY ..2 SITE CONDITIONS ..2 PROPOSED CONSTRUCTION ..4 PREVIOUS GEOLOGIC MAPPING ..4 SUBSURFACE INVESTIGATIONS ..5 SUBSURFACE CONDITIONS ..6 Ground Water ..6 Piezometers ..6 Inclinometers ..7 SITE GEOLOGY ..8 Fill (at) ..8 Debris Flows (Qdf) ..9 Landslide Deposits (le) ..9 Pierre Shale (Kp) ..9 POTENTIAL GEOLOGIC HAZARDS AND ENGINEERING CONSTRAINTS ..1D Landslide (Map Unit 6) ..10 Expansive Soils and Bedrock ..11 Potentially Unstable Slopes ..12 Debris Flow (Map Unit 4C) ..12 Grading Fill (Map Unit 8A) ..12 Seismic Hazard (Seismicity) ..12 Radioactivity (Radon) ..13 Hillside Overlay Zone ..14 Flooding ..14 Subsurface and Surface Mining ..14 SITE DEVELOPMENT CONSIDERATIONS ..14 Landslide Deposits ..15 Expansive Materials ..15 FOUNDATION CONCEPTS ..15 SURFACE DRAINAGE I IRRIGATION ..16 LIMITATIONS ..16 APPLICATION FORM FOR GEOLOGIC HAZARD REPORT REFERENCES DR. HEMSWORTH CIO CLIFFORD TAYLOR ARCHITECTS 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A CTLIT PROJECT NO. C817193-105 TABLE OF CONTENTS PAGE 2 FIG. 1 LOCATION OF EXPLORATORY BORINGS FIG. 2 SURFICIAL GEOLOGY FIG. 3 ENGINEERING CONDITIONS APPENDIX A SUMMARY LOGS OF EXPLORATORY BORINGS, CTL THOMPSON, INC. PROJECT NOS. AND CS16502-120 AND JOB NOS. 05-8319, 05-7322, CS-6870, CS-6369, CS-5807, AND CS-3490 APPENDIX COLORADO GEOLOGICAL SURVEY REVIEW LETTER DR. HEMSWORTH CID CLIFFORD TAYLOR ARCHITECTS 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A CTLIT PROJECT NO. CS171 93-1 05 8363170004 7499108171 93.00011 051.2. ReportsICS1 71 93-105-R1-Final.duc SCOPE This report presents the results of our Geologic Hazards Evaluation as requested by the City of Colorado Springs Planning Department for the development plan for Lot 1, Barons Ridge at Broadmoor Resort Community, Filing No. 1-A with an assigned address of 1155 Charles Grove, in Colorado Springs, Colorado. We have reviewed the Development Plan prepared by NES titled ?Broadmoor Clusters?, dated December 4, 1997, with the City Planning No. BS DP95-251-A2 (96). A note on the plans indicates that Lots 7, 8, 9, and 10 where approved on November 24, 1997. Under the approved Development Plan dated December 4, 1997, the subject lot was numbered Lot 7. Under the current platting, based on available City of Colorado Springs and El Paso County records, the subject lot is numbered Lot 4 of Filing No. 1. Our purpose was to evaluate for the occurrence of geologic hazards and their potential affect on site development and construction. This report includes our interpretation of site geology and our opinion of the potential influence of these conditions on site development. We believe this study was completed in general conformance with the requirements of the City of Colorado Springs Zoning Code, Chapter 7, Article 4, Part 5, Geologic Hazard Study and Mitigation (1996, revised 1996, 1999, 2001). The report was prepared based on conditions interpreted from field reconnaissance mapping of the site, review of previous investigations, conditions encountered in exploratory borings, engineering analysis, comments from the Colorado Geological Survey, and our experience. Site-specific subsurface investigations or observations made during grading and construction may indicate conditions that require revision or re-evaluation of some of the criteria presented in this report. The criteria presented are for the development as described. Revision in the scope of the project could influence our recommendations. If changes occur, we should review the development plans and their effect on our recommendations. Environmental site assessments for occurrence of potentially hazardous materials, erosion problems, and flooding are beyond the scope of this investigation. DR. HEMSWORTH CID CLIFFORD TAYLOR ARCHITECTS 1 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. ?l-A PROJECT NO. C317193-1 U5 SUMMARY 1. The primary conditions we identified that pose hazards or constraints to development include the occurrence of landslide deposits, expansive materials, slope stability issues, and debris flow. It is our opinion the property can be developed for construction of a single-family residence. 2. Subsurface conditions encountered on the lot consisted of clayey, gravelly, sand fill with layers of sandy clay over natural, clayey, gravelly sands to sandy clays underlain by claystone and then shale to the maximum depths drilled of 25 and 45 feet. The sand and clay fill varied in thickness from 5 to 21 feet. The natural, clayey, gravelly sands and sandy clays varied from 11 to 20 feet in thickness. Ground water was encountered in exploratory boring TH-1 at a depth of 32 feet at the time of drilling. When the borings were checked three to five days after the completion of drilling, ground water was measured at a depth of 28.5 feet in boring TH-1 only. 3. Foundations designed to consider the impact of expansive soils and the boulder retaining wall will be appropriate for the site. 4. Elimination of intense irrigation of landscaping is recommended to reduce problems often associated with expansive soils and bedrock and reactivation of landslide deposits. Ponding of water should be avoided. Vegetation species native to a semi-arid climate are recommended. Overall plans should provide for rapid conveyance of surface runoff to centralized drainageways. SITE CONDITIONS Barons Ridge at Broadmoor Resort Community is located approximatelyz miles west of Highway 115 and South Academy Boulevard. The proposed Lot 1 of Filing No. 1-A has been assigned the address 1155 Charles Grove and is located at the southeast side of the cul-de-sac at the north end of Charles Grove, in Colorado Springs, Colorado. The parcei is zoned with hillside overlay and is serviced by public utilities. The general shape and location of the site investigated are shown on Fig. 1. Figure 1 also shows the lot layout approved on November 24, 1997 for Lots 1 through 10, per City records, and the current plat of Lots 1 through 4 of Filing No. 1 based on DR. HEMSWORTH CIO CLIFFORD TAYLOR ARCHITECTS 2 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A CTLIT PROJECT NO. 0317193-1 05 City and County plat records available online. This parcel was part of Lots 6 and 7 of the 1997 plat, or Lot 4 of the more recent plat and the adjacent parcel 2, as shown on Fig. 1. At the time of our investigation, the west side of the lot appeared to have had till placed behind a boulder retaining wall. The ?ll was graded with two levels and a central slope to create a walkout basement condition similar to the adjacent lots to the southwest. Several boulders were piled near the center of the lot. The boulderwall was up to 11 feet in height with the top boulders located from 90 to 115 feet from the edge of the existing curb. Boulders were generally from 18 to 36 inches in size and placed with a face slope of approximately 0.8 to 1 (horizontal to vertical). The wall started at the north side of the lot and crossed the lot to the south, continuing across the adjacent lots. The building envelope was located in the area between the street and the wall. The street and curb had been constructed and utilities were all in place. Vegetation on the upper levels of the site (building envelope) above the boulder wall consisted of grass and weeds and the lower southeastern portion of the site had pine trees and scrub oak and appeared to be undisturbed. The north part ofthe lotwas typically in natural condition. However, utility lines, including an old steel water line, had been installed in an easement which is adjacent to the site. The lot slopes down to the southeast with a step from the walkout grading and the drop at the boulder wall. Natural grades below and southeast of the boulder wall were approximately 20 percent, similar to that shown by the topography indicated on a site plan provided to us. The site plan indicated the natural contour of the site prior to grading to be relatively consistent from front to rear property lines, indicating the natural grade below the ?lled portion of the site. We anticipate the existing fill placed in a controlled manner to be 15 feet or less in thickness. Existing single-family homes are located on the adjacent lots to the southwest. The remaining property around the site was vacant. Figure 1 shows the size and shape of the investigated lot as well as the vicinity of the site. DR. HEMSWORTH CID CLIFFORD TAYLOR ARCHITECTS 3 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A CTLIT PROJECT N0. 0817193405 ReponleS17193-105-R1-Final.doc PROPOSED CONSTRUCTION A single-family residence of (insulated concrete form) construction is planned for this lot. Discussions with the client indicate the residence will be two stories with a walkout basement. The residence will also have two attached garages: a deep, single-wide garage on the basement level with access from the north and a two car garage off the main level accessed from the west. Basements are commonly finished during construction of custom homes in the Broadmoor Resort development. Exterior finish will likely consist of partial stone veneer and stucco. We expect foundation loads to range from 1,000 to 3,000 pounds per lineal foot of wall. Interior column loads will probably be 25,000 pounds or less. We believe slab-on-grade floors are desired in the garage, basement, and other at?grade areas. Excavations will likely extend about 2 to 13 feet below present site grades. Final grades and landscaping may result in greater depths of backfill. PREVIOUS GEOLOGIC MAPPING AND INVESTIGATIONS The site was mapped by the United States Geological Survey (USGS) in 1973 by Scott Wobus and in 1979 by Trimble Machette. Charles Robinson Associates, Inc. mapped the area for El Paso County in 1977. Carroll Crawford mapped the site forthe Colorado Geological Survey (CGS) as part of the Colorado Spring Quadrangle in 2000. Scott Wobus, Trimble Machette, Charles Robinson Associates, Inc. and Carroll Crawford all mapped the site as a combination of alluvial fan and landslide deposits. Wait White with the C68 mapped the site as a mapped landslide and landslide susceptible. CTL Thompson, Inc. has performed several previous investigations, which included this site and surrounding area, as well as observation and testing of placement of fill. A Preliminary Geologic Hazards investigation report (Job No. CS- 5807), dated September 6, 1995, was performed followed by a Geotechnical Hazards Risk Evaluation and Mitigation Report (Job No 03-7037), dated October 23, 1996. Another investigation, Geotechnical Hazards Risk Evaluation and Mitigation Report DR. HEMSWORTH CIO CLIFFORD TAYLOR ARCHITECTS 4 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A CTLIT PROJECT NO. (25171934105 (Job No. CS-7190), dated January 24, 1997, covering a similar area of the subdivision, was performed. Representatives of CTL Thompson, Inc. were present in the area of this site periodically from May 3 to October 29, 1996 and reportedly visited Lot 4 between April 12 and April 26, 1996 to observe and test fill placement. Observation and test results were provided in daily reports (Job No. 03-6231). We also installed piezometers and inclinometers on Lot 9 of the Broadmoor Resort Community Estates and Lot 4 of Barons Ridge (November 1997 lot layout, shown on Fig. 1), and presented the results of the monitoring in a series of letters in 1999 and 2000 (Job No. CS-7322). Soils and Foundation Investigations with reports under Job No. CS-8319 (dated March 2, 1998) and Project No. 0514,976-120 (dated November 22, 2004) were performed on this site by CTL Thompson, Inc. The geologic hazards listed in previous reports are expansive soils, potentially unstable slopes, debris flow, ancient landslides, and recent landslides as well as the regional hazards of seismic activity and the potential for radon gas. We have evaluated the subject lot for the occurrence of these hazards, their impacts on the planned construction, and methods of mitigation. This report summarizes our assessment of the potential geologic hazards recognized at this site and our recommendations for mitigation or risk reduction. SUBSURFACE INVESTIGATIONS Subsurface conditions for the lot were explored by drilling four borings during the previous investigations at the approximate locations presented on Fig. 1. Graphic logs of the conditions found in our borings are presented in Appendix A. The locations of additional nearby borings from other previous investigations are also shown on Fig. 1 with the boring logs also in Appendix A. In addition to the borings, two piezometers and two inclinometers were installed in 1996 for monitoring ground water levels and lateral earth movements, respectively. DR. HEMSWORTH CIO CLIFFORD TAYLOR ARCHITECTS 5 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADNIOOR RESORT COMMUNITY, FILING NO. 1-A PROJECT NO. CS17193-105 SUBSURFACE CONDITIONS The exploratory borings on the parcel encountered clayey, gravelly, sand fill with layers of sandy clay over natural, clayey, gravelly sands to sandy clays underlain by claystone, and then shale to the maximum depths drilled of 25 and 45 feet. The sand and clay fill varied in thickness from 5 to 21 feet. The natural, clayey, gravelly sands and sandy clays varied from 11 to 20 feet in thickness. In boring TH-3, claystone extended from a depth of 24.5 feet to 39 feet where shale was encountered to the maximum depth explored, 45 feet. The fill exhibited consolidation (0.8 percent) and low to moderate measured swell (0.2 to 2.6 percent) when wetted under an applied pressure of 1,000 psf. The natural, clayey sand and sandy clay exhibited low measured swell (0.0 to 1.4 percent). One sample of fill and one sample of natural, sandy clay contained 54 and 52 percent silt and clay-size particles (percent passing the No. 200 sieve), respectively. Laboratory test results are summarized on the Logs of Exploratory Borings, in Appendix A (Project No. CS14976-120 and Job No. 08-8319). Based upon laboratory test results and our experience, we judge the fill and natural, clayey sand and sandy clay to possess nil to moderate swell potential. Ground Water Free ground water was encountered in exploratory boring TH-1, for Project No. at a depth of 32 feet at the time of drilling. When the borings were checked three to five days after the completion of drilling, ground water was measured at a depth of 28.5 feet in the same boring and the others were dry. The presence and amount of ground water may change seasonally and after development in response to precipitation, irrigation, and changes in surface drainage patterns. Piezometers Piezometers were installed on Lot 9 of the Estates and the Lot 4 of the 1997 plat for Barons Ridge at the locations shown on Fig. 1. The table below summarizes the data obtained from the piezometers. The developer declined further monitoring after DR. HEMSWORTH CIO CLIFFORD TAYLOR ARCHITECTS 6 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A CTLIT PROJECT NO. C517193-105 2000, and removed Lot 9 and Lots 1 through 6 of the 1997 plat of Barons Ridge from development. Date Depth to Water (feet) Lot 9 Lot 4 6196 30 Dry 2197 32 Dry 6197 25 Dry 12197 30 Dry 4198 27 Dry 10198 28 Dry 9199 17 Dry 12199 49 44 3100 25 42 6100 22 50 9100 23.5 43 We attempted to measure water levels in both piezometers as requested by the Colorado Geological Survey (CGS), but neither could be located. The one on Lot 9 was likely destroyed during the construction of a patio by the current owner of the property. Inclinometers lnclinometers were installed on Lot 9 of the Estates and Lot 4 of the 1997 plat for Barons Ridge at the locations shown on Fig. 1. The readings obtained from the inclinometers prior to discontinuing the readings in 2000 are shown in Appendix (attached to November 18, 1999 Thompson letter). The readings from the inclinometer installed on Lot 9 indicated lateral earth movement of about 314 of an inch at a depth of about 68 feet between May 1998 and September 1999. The inclinometer in Lot 4 does not appear to indicate any movement during the previous readings. As requested by the CGS, we attempted to make additional measurements of the inclinometers. The one located on Lot 9 appears to have been destroyed during the construction of a patio by the current owner of the property. We were able to read the DR. HEMSWORTH 010 CLIFFORD TAYLOR ARCHITECTS 7 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. PROJECT N0. 0517193-1 05 inclinometer that was within the Lot 4 (1997 plat) of Barons Ridge, which is located north of the end of the cul-de-sac and is not on the parcel covered by this evaluation. The inclinometer reading we obtained does not appear to show any distortion of the casing indicative of lateral earth movement, such as a landslide. We were not able to compare the readings with the previous readings since the original data files are not available. In our opinion, the inclinometer on Lot 4 (1997 plat) does not indicate any lateral earth movement since it was installed. It should also be noted that a welded steel waterline that runs along the northeast side of the property continues to the north across the scarp area where Mr. White of the CGS has his highest concerns. To our knowledge, this water line has been in continuous operation for over thirty years with no reported problems. SITE GEOLOGY The site lies within the Front Range topographic province. The landform that covers the site is fill over landslide deposit in the northern edge of a landslide formed valley. The southern scarp of another landslide valley is located about 150 feet to the north. The landslide deposit consists of displaced clay and claystone, with occasional sand and gravel pieces. The landslide deposit appears to have moved to the northeast. The site is part of a large landslide complex (hundreds of acres). Our interpretation of the site geology is shown on Fig. 2. Debris flow deposits have been mapped along the southern edge of the lot. The fill, colluvium, landslide, and debris flow deposits in the area are underlain by Pierre Shale. The geologic units are described further in the following paragraphs. Fill Fill was placed on the site at different times over the last 50 years, generally for access roads to facilities operated by the Broadmoor Hotel. More recent grading was for the construction of Charles Grove, other recent developments, and related public utilities. Representatives of CTL Thompson, Inc. were present in the area of this site periodically from May 3 to October 29, 1996 to observe and test fill placement. DR. HEMSWORTH CID CLIFFORD TAYLOR ARCHITECTS 8 1155 CHARLES GROVE, LOT 1. BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A PROJECT NO. C317193-105 Observation and test results were provided in daily reports (Job No. 08-6231). The materials used to construct the fill were typically gravelly clays and sands compacted to at least 95 percent of maximum standard Proctor dry density (ASTM 698). The older fills on the site were removed and replaced during the grading operations. Debris Flows lef) Areas mapped as debris flow have experienced erosion and deposition related to debris flows. The debris flow deposits generally consist of masses of silt, sand, gravel, boulders, and organic debris that moved and were deposited as a viscous mass. The debris flow deposits overlie bedrock and older landslide deposits. Landslide Deposits (le) Areas mapped as landslide deposits have experienced large blocks or masses of locally derived material moving downslope, generally along a defined failure zone. These areas can experience lateral movement in the future along the existing failure zone under similar conditions to those that triggered the initial movement. The landslide deposits shown on Fig. 2 are generally older and stable. More recent lateral movements have occurred to the north and east within the Broadmoor Mountain Golf Course and on Lot 9 of the Broadmoor Resort Community Estates. These movements occurred in the 19805 and 905. No evidence of recent movement has been documented or noticed on this lot. Pierre Shale (Kp) The site and surrounding area are underlain by Upper Cretaceous age Pierre Shale. The Pierre Shale is generally a gray to dark gray marine shale and interbedded siltstone and sandstone that contains occasional bentonite beds and weathers to brown and olive green clay. DR. HEMSWORTH cro CLIFFORD TAYLOR ARCHITECTS 9 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A PROJECT NO. 0817193405 POTENTIAL GEOLOGIC HAZARDS AND ENGINEERING CONSTRAINTS A Preliminary Geologic Hazards Investigation (Job No. (38?5807, report dated September 6, 1995) was performed by CTL Thompson, followed by a Geotechnical Hazards Risk Evaluation and Mitigation (Job No 03-7037, report dated October 23, 1996) for Barons Ridge at Broadmoor Resort Community, both of which included the subject lot. The hazards we identified include the occurrence of landslide deposits, expansive soils and bedrock, debris flow, and man placed fill as well as the regional hazards of seismic activity and the potential for radon gas. We believe a low risk exists of damage to a residential structure built on this property due to lateral earth movement. Occurrence of expansive materials will impact design of foundation and floor systems. Regional geologic conditions that may affect the site include seismicity and radon. We believe these conditions can be mitigated with engineering design and construction methods commonly employed in this area. Figure 3 shows our interpretation of the engineering geology modified from the system used by Charles Robinson Associates (1977). The following subsections discuss our assessment of the potential geologic hazards recognized at this site and our recommendations for mitigation of risk reduction. Landslide (Map Unit 6) Materials we believe are associated with historic landslide events were encountered in past and recent borings we drilled within the overall region. The site lies within and near the head scarp of an old landslide complex. To date, we have seen no evidence of lateral ground movements within the Barons Ridge development. Lateral movement was measured in an inclinometer in Lot 9 of the Estates located to the northwest of Charles Grove, and impacted the development on that and adjacent lots. Although evidence suggests the ground beneath the parcel to be stable, risk of reactivation of the ancient landslide exists. In order to evaluate this risk, slope stability analyses were conducted as part of the previous reports. The results of these analyses indicated the ground beneath Barons Ridge to be stable. We believe that there is low risk of reactivation of the landslide considering the mitigation measures employed DR. HEMSWORTH CIO CLIFFORD TAYLOR ARCHITECTS 10 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. ?l-A PROJECT NO. CS17193-1 O5 05-R1-Final.doc during the development of the subdivision, and the recent installation of the drains on the Broadmoor Mountain Golf Course. The Broadmoor Mountain Golf Course was rebuilt after installation of a deep drainage system to stabilize the landslide movements that occurred in the 19905.To our knowledge, the landslide movements that occurred within the golf course in the 1990s have been controlled by the drainage improvements, and the ground movements have ceased. We have also contacted maintenance personnel with the Broadmoor Mountain Golf Course and they have not noticed any recent movements on the course. Additionally, there is a welded steel waterline that runs along the northeast side of the property that continues to the north across the scarp area where Mr. White has his highest concerns. The waterline runs adjacent to the northeast side of the lot and extends across the valley to the north below where the inclinometer in Lot 9 indicated movement. This waterline is relatively brittle and would like break if there were concentrated lateral movement at any point along its alignment. To our knowledge, this waterline has been in continuous operation for over thirty years with no reported problems. This indicates that little, if any, movement has occurred across the Waterline alignment, which generally follows the alignment of the disturbed area on the northeast side of the lot shown on Fig. 2. Expansive Soils and Bedrock The sandy clays, clayey sands, and claystone bedrock underlying the area exhibit low to high volume change characteristics with variations in water content. Subsurface conditions encountered in our exploratory borings consisted of medium stiff to stiff, gravelly, sand and clay fill over medium dense to dense, clayey, gravelly sand underlain by claystone and then shale to the total depths investigated of 25 to 45 feet. The claystone was found to be about 10 feet or more below anticipated foundation levels. We believe the risk of foundations experiencing movement and associated damage due to swelling soils is low for the subject lot. DR. HEMSWORTH CIO CLIFFORD TAYLOR ARCHITECTS 1 1 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A CTLIT PROJECT NO. 0317193-1 05 Potentially Unstable Slopes The building pad area of this particular lot does not possess slopes considered to be potentially unstable. Construction plans for the residence should be formulated such that excavations made for foundation construction, driveways or on-site grading do not adversely impact slope stability on the lot and adjoining preperties. Performance and stability of soils and bedrock are influenced, to a large degree, by the moisture conditions existing within the materials. We recommend overall drainage be planned to provide for rapid removal of runoff away from the structure or discharge into lined channels such as streets to promote rapid removal of runoff in a controlled manner. Surface drainage should be directed around the boulder wall and not be allowed to flow over or through the wall. Foundation drains installed around the residence should discharge into the existing subdivision underdrain system or into a surface drainage. Automatic lawn sprinkler systems should be limited. A natural or xeriscape landscape design is recommended. Debris Flow (Map Unit 40) The southern edge of the lot is located in an area of the subdivision that is considered to be subject to debris flow. Mitigation of debris flow risk was addressed during development of the subdivision. Therefore, for this lot, debris flow is not considered to be a hazard. Grading Fill (Map Unit 8A) We believe the fill existing on this site does not pose a hazard to proposed construction. We observed and tested the fill as described above under Fill ja?. The boulder wall was constructed during this site grading operation. Seismic Hazard (Seismicityi The Ute Pass Fault, located about 1I2-mile west of the site, is one of the major DR. HEMSWORTH CEO CLIFFORD TAYLOR ARCHITECTS 1155 CHARLES GROVE. LOT 1. BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO.1-A PROJECT NO. C517193-105 structural geologic features of the region. Evidence for movement during the last two million years (Quaternary) exists for some Front Range faults, including the Ute Pass Fault. The Ute Pass Fault is considered to be potentially active by the Colorado Geological Survey. This area, like most of central Colorado, is subject to a degree of seismic activity. The Colorado Geological Survey considers this area of Colorado to be in Seismic Zone 2 of the Uniform Building Code (U30), 1997. We understand the City of Colorado Springs has adopted the 2003 International Residential Code (IRC). Radioactivity (Radon) Radon is an inert gas that by definition does not react or combine with elements in the ground. Since it is a gas, it is free to move through the soil and air, but can become trapped in enclosed structures. Trace amounts of radioactive nuclides are common in igneous and metamorphic rock and in the soils and sedimentary rock that underlie this region and the site. Radon is a by-product of the natural decay of uranium and radium. Radon itself is not harmful to humans. It is an unstable element that further decays into several radon decay products or radioactive elements. These decay products include different forms of polonium, lead, and bismuth. It is the decay products that present the health risk associated with this gas. Information presented by the Western Regional Radon Training Center indicates that the ambient air within El Paso County on average has approximately 5.3 picoCuries of radon per liter of air. This level exceeds the Environmental Protection Agency standard action level of 4 picoCuries of radon per liter of air. Within the continental United States, average outdoor air measurements are approximately 0.4 picoCuries of radon per liter of air. Based upon the geologic setting of El Paso County and the information presented by the Western Regional Radon Training Center, we believe elevated levels of radon can occur within structures built in this region. DR. HEMSWORTH CIO CLIFFORD TAYLOR ARCHITECTS 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A PROJECT NO. C517193-105 It is our recommendation the proposed residence be equipped with a relatively inexpensive passive radon control system and be tested for radon after completion. If high levels of radon are detected, a passive system can readily be upgraded to an active system, increasing the level of mitigation. Our experience indicates high radon concentrations within dwellings have been successfully mitigated in the El Paso County region through commonly employed measures. Hillside Overlay Zone The site lies within the Hillside Overlay Zone of Colorado Springs as shown on the City of Colorado Springs CityView webpage, dated July 21, 2008, prepared by the Planning, Development, and Finance Department. Flooding This site lies within Zone as shown on Flood Insurance Rate Maps prepared by the Federal Emergency Management Agency. Zone is outside the 100-year flood plain with no base flood determined. Based on the topography, flooding is an unlikely occurrence. The development-specific drainage report should address flooding limits and mitigation. Subsurface and Surface Mining The site is not included in the Colorado Springs Subsidence Investigation, State of Colorado, Division of Mined Land Reclamation, prepared by Dames Moore, dated April 1985. The study was conducted specifically for known or suspected areas of underground coal mining in Colorado Springs. We did not observe evidence of subsurface mining at the site. SITE DEVELOPMENT CONSIDERATIONS From an engineering point-of?view, the more significant subsurface conditions DR. HEMSWORTH CLIFFORD TAYLOR ARCHITECTS 1155 CHARLES GROVE, LOT BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A PROJECT NO. 08171934 05 found are the landslide deposit and expansive soil. The following sections discuss the impacts of these conditions on development of this property. Landslide Deposits The site is located on a historic, old landslide deposit that we believe is currently stable. Our observations indicate the head scarp above the site has been stable for some time, considering the presence of old vegetation and the weathering processes that have occurred in the Pierre Shale and Verdos Alluvium formations. We believe the slopes on and above the site are stable with the current conditions and configuration. Intensive irrigation involves the risk of activating movement. The lot-specific risk for activating future movement can be reduced by limiting surface irrigation, maintaining positive surface drainage, and installation ofa subsurface foundation drain system. We believe the global risk of future movement affecting the parcel is relatively low with the remedial work that was performed on the golf course and the lack of indication of movement in the inclinometer on Lot 4 (1997 plat) to the north of the lot. Expansive Materials Clay soil lenses within the sand and gravel exhibited low to moderate swell potential. Occurrences of expansive materials that in?uence foundation design should be expected across the site. Expansive soils are not uncommon to the Colorado Springs area. Problems associated with the existence of expansive materials are typically mitigated through currently utilized foundation and floor system selection. The Soils and Foundation Investigation conducted for the lot addresses specific building and development procedures for mitigating problems associated with expansive soils. FOUNDATION CONCEPTS Foundation design and construction issues related issues are discussed fully in DR. HEMSWORTH CLIFFORD TAYLOR ARCHITECTS 15 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, NO. 1-A PROJECT NO. 0517193-1 05 our Soils and Foundation Investigation (Project No. 6314,976-120, dated November 22, 2004) for the lot. SURFACE DRAINAGE I IRRIGATION The overall mountain front and adjacent high plains region are considered to be sensitive to the addition of supplemental moisture. Landscaping concepts should concentrate on the use of native plants that require little or no supplemental irrigation after the establishment period. Generally, surface drainage should be designed to eliminate ponding of water and provide for the rapid removal of runoff. Automatic irrigation systems should be limited. LIMITATIONS The recommendations and conclusions presented in this report were prepared based upon conditions disclosed by exploratory borings, our geologic reconnaissance, and our experience. Variations in the subsurface conditions not indicated by the borings are possible and should be expected. We believe this report was prepared using the standard of care normally used in this area at this time. No warranty, express or implied, is made. If we can be of further service in discussing the contents of this report or the . . Reviewed by: if 1 wm? LI. Thomas A. Ter . . . William C. Hoffmann, Jr., P.E. Geological Eng 1-w- . Senior Principal Engineer (2 copies sent) 5 cc: City Planning Department, Attn: Ms. Heather Rose DR. HEMSWORTH CID CLIFFORD TAYLOR ARCHITECTS 16 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING N0. CTLIT PROJECT NO. CS1T193-105 LAND USE DIVISION PLANNING DEPARTMENT OF COLORADO SPRINGS APPLICATION FORIVI FOR GEOLOGIC HAZARD REPORT Applicant: Clifford Taylor Architects Telephone 719?633-0801 Fax 719-633-4592 Address: 1 1 South 2511' Street, Suite 220, Colorado Springs, CO Zip Code 80904 email Premises Involved: Development Plan/Subdivision Plat Name: Lot 1, Barons Ridge at Broadmoor Resort Community, Filing No. Tax Schedule No(s). 7501305012 (This can be obtained from the El Paso County Tax Assessor located at 27 E. Vermijo Avenue on the 211d Floor; phone: 520-6600 or at their web site GEOLOGIC HAZARD REPORT REQUIRED (Five (5) preliminary copies) An application review fee will be required to accompany these applications (checks to made payable to City of Colorado Springs). The fee schedule is as follows: City Planning Fee: $300 plus any Colorado Geological Survey Review of Geologic Hazard Reports Review Cost Over $300 City Engineering Fee: $267 The following documents have been included and considered as part of this report (checked off by individual(s) preparing the geologic repo?): Development Plan: Lot 1, Barons Ridge at Broadnioor Resort Filing No. l?A Landscape Plan (if applicable): Grading Plan: Drainage Report (necessary if debris and/or mud ?ow hazard is present): ENGINEERS STATEMENT I hereby attest that I am quali?ed to prepare a Geologic Hazard Study in accordance with the provisions of Section 504 of the Geologic Hazards Ordinance of Colorado Springs. I am qualified as: Professional Geologist as defnied by CRS 34-1-2018); or, Professional Engineer as defined by Board Policy Statement 15: ?Engineering in Designated Natural Hazards Areas? of the Colorado State Board of Regis de?ned by CRS 12?25?1070). Submitted by: Thomas A. Terry This Geologic Hazard Study is amended. City Engineer Date City Planning Director Date Geologic Hazards Report 2-1-2007 OFFICIAL CITY PLANNING ENIAL: City 11g?1eering Date Received we Denied: Mme: Denial Date: ConditionsiReasons: City Planning Approved: Denied: Approval Date: 0 5/ Denial Date: Conditions/Reasons: DO NOT REMOVE THIS PAGE IT MUST BE KEPT WITH THE ORIGINAL APPLICATION The City ofCoiorado Springs-Planning Group is committed to ensuring that a? ofoiir services are accessible to those with disabilities. We encourage participation by individuais. Ifyou have a advance notification of any speciai needs will heIp as better serve you. Please Gail Gladys Akbari at 385-535 I to request any special service ihaiyou may require. A one (1) week advance notice to a?ow MS to accommodate your request is appreciated. 8/1/2003 2 REFERENCES Carroll, C.J. Crawford, T.A., 2000, Geologic Map of the Colorado Springs Quadrangle, El Paso County, Colorado, Colorado Geological Survey, Open File Report 00-3 Charles Robinson and Associates, lnc., 1977, El Paso County, Colorado - Potential Geologic Hazards and Surficial Deposits, Environmental and Engineering Geologic Maps and Tables for Land Use City of Colorado Springs, 1996, revised 1996, 1999, 2001, Zoning Code, Chapter 7, Article 4, Part 5, Geologic Hazard Study and Mitigation City of Colorado Springs, Subdivision Document Viewer, City of Colorado Springs Planning, Development Finance Department, Zoning Maps, June 12, 2007. Colorado Geological Survey, 1991, Results of the 1987-88 EPA Supported Radon Study in Colorado with a Discussion on Geology. Colorado Geological Survey Open File Report 91?4 CTL Thompson, lnc., August 10, 2007, Soils and Foundation Investigation, 1185 Charles Grove, Lot 1, Barons Ridge at Broadmoor Resort Community, Filing No. 1, Colorado Springs, Colorado, Project No. CS16502-105 CTL Thompson, lnc., November 22, 2004, Soils and Foundation Investigation, 1155 Charles Grove, Lots 4 and Z, Barons Ridge at Broadmoor Resort Community, Colorado Springs, Colorado, Project No. CTL Thompson, lnc., November 20, 2000, Groundwater and Inclinometer Readings, Lot 9 Broadmoor Resort Community Estates, Colorado Springs, Colorado, Project No. CS-7322 CTL Thompson, lnc., November 20, 2000, Groundwater and Inclinometer Readings, Lot 4, Barron?s Ridge, Colorado Springs, Colorado, Project No. 08-7322 CTL Thompson, lnc., November 8, 1999, Lot 9 Broadmoor Resort Community Estates, Lots 1 through 6, Barons Ridge, Colorado Springs, Colorado, Project No. 05-7322 CTL Thompson, Inc,, October 27, 1999, Site Grading, Barons Ridge at Broadmoor Resort Community, Colorado Springs, Colorado, Job No. 03?6231 CTL 1 Thompson, lnc., April 6, 1999, Lot 9 Broadmoor Resort Community Estates, Lots 1 through 6, Barons Ridge, Colorado Springs, Colorado, Job No. CS-7322 DR. HEMSWORTH CIO CLIFFORD TAYLOR ARCHITECTS 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. PROJECT ND. C317193-105 CTL Thompson, lnc., March 2, 1998, Soils and Foundation Investigation, Barons Ridge Cluster Home Development, Lots 1 through 4, Colorado Springs, Colorado, Job No. 08-8319 CTL Thompson, lnc., December 16, 1997, Barons Ridge at Broadmoor Residential Resort, Filing No. 1, Charles Grove Cul-de-sac, East of Stone Manor Heights, Colorado Springs, Colorado, Project Nos. CS-7037 and CS-7322 CTL Thompson, Inc., August 25, 1997, Soils and Foundation Investigation, The Villas at Log Hollow, Phases II and Ill, Stone Manor and Governors Point, Colorado Springs, Colorado, Project No. 08-73223 CTL Thompson, Inc., August 17, 1997, Broadmoor Resort Community, Phase I, Colorado Springs, Colorado, Project No. CTL Thompson, lnc., January 24, 1997, Geotechnical Hazards Risk Evaluation and Mitigation Report, Villas at Log Hollow, Phase II, Stone Manor Heights and Governors Point, Colorado Springs, Colorado, Project No. CS-7190 CTL Thompson, Inc., October 23, 1996, Geotechnical Hazards Risk Evaluation and Mitigation Report, Barons Ridge Cluster Home Development, Charles Grove Cul?de- sac, East of Stone Manor Heights, Colorado Springs, Colorado, Project No. 08-7037 CTL Thompson, Inc., September 17, 1996, Soils and Foundation Investigation, Lot 9, Broadmoor Residential Community, 4475 Stone Manor Heights, Colorado Springs, Colorado, Job No. CS-6870 CTL Thompson, June 28, 1996, Geotechnical Investigation, The Villas at Log Hollow, Phase I, Stone Manor and Governors Point, Colorado Springs, Colorado, Job No. CS-6540 CTL Thompson, lnc., April 24, 1996, Geologic Hazards Mitigation, The Villas at Log Hollow, Job No. CS-5807B CTL Thompson, lnc., April 8, 1996, Summary of Potential Geologic Hazards and Mitigation, Broadmoor Residential Resort Phase Job No. CTL Thompson, lnc., March 29, 1996, Summary of Potential Geologic Hazards and Mitigation, Broadmoor Residential Resort Phase I, Job No. CS-5807 CTL Thompson, Inc., October 31, 1995, Geologic Hazards Mitigation, Broadmoor, Phase I PUD Developpment Plan, Job No. CS-5807A CTL Thompson, Inc., September 6, 1995, Preliminary Geologic Hazards Investigation, Phase I, Broadmoor South Development, Job No. CS-5807 CTL Thompson, lnc., December 16, 1993, Geotechnical Investigation, Broadmoor South Golf Course, Colorado Springs, Colorado, Job No. CS-3490 DR. HEMSWORTH CLIFFORD TAYLOR ARCHITECTS 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A PROJECT NO. C317193-105 Dames Moore, April 1985, Colorado Springs Subsidence Investigation, Colorado Division of Mined Land Reclamation El Paso County Assessor?s Office Public Record Property Information, July 11, 2008. Federal Emergency Management Agency, August 23, 1999, Flood Insurance Rate Map, Community Map Number 08041 CD738F Himmelreich, J.W. Noe, 0.0., 1999, Map of Areas Susceptible to Differential Heave in Expansive, Steeply Dipping Bedrock, City ofColorado Springs, Colorado. Colorado Geological Survey, Map Series 32 International Code Council, 2003, International Building and International Residential Codes Jones, David C., Schultz, Janet E., Murray, D. Keith, 1978, Coal Resources and Development Map of Colorado, Colorado Geological Survey Map Series 9 Kirkham, R.M. Rogers, W.P., 1981, Earthquake Potential in Colorado, Colorado Geological Survey, Bulletin 43 Nelson-Moore, J.L., Collins, D.B. Hornbaker, A.L., 1978, Radioactive Mineral Occurrences of Colorado and Bibliography Colorado Geological Survey, Bulletin No.40 Noe, David C., 2007, A Guide to Swelling Soils for Colorado Homebuyers and Homeowners, Second Edition revision, Colorado Geological Survey, Special Publication 43 Scott, G.R. &Wobus, R.A., 1973, Reconnaissance Geological. Map of Colorado Springs and Vicinity, Colorado, U.S. Geological Survey Miscellaneous Field Studies Map, MF-482 Trimble, D.E., Machette, M.N., 1979, Geologic Map of the Colorado Springs-Castle Rock Area, Front Range Urban Corridor, Colorado, U.S. Geological Survey, Miscellaneous Investigation Series, Map Wait, T.C. White, J.L.. 2006. Rockfall Hazard Susceptibility in Colorado Springs, El Paso County, Colorado. Colorado Geological Survey, Open-File Report 06-3 White, J.L. Wait, T.C. 2003. Map of Potential Areas of Landslide Susceptibility in Colorado Springs, El Paso County, Colorado. Colorado Geological Survey, Map Series 42 Widmann, B.L., Kirkham, R.M., Rogers, WP. (1998). Preliminary Quarternary Fault and Fold Map and Database of Colorado. Colorado Geological Survey, Open File Report 98-8. DR. HEMSWORTH CID CLIFFORD TAYLOR ARCHITECTS 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A CTLIT PROJECT NO. (317193-105 Widmann, B.L., Kirkham, R.M., Morgan, M.L. Rogers, W.P. with contributions from Crone, A.J., Personius, S.F. and Kelson, and GIS and web design by Morgan, K.S., Pattyn, GR. and Phillips, R.C. (2002). Colorado Late Cenozoic Fault and Fold Database and Internet Map Server. Colorado Geological Survey Information. Series 60a. DR. HEMSWORTH CIO CLIFFORD TAYLOR ARCHITECTS 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A PROJECT N0. 0517193-1 05 05'12. VICINITY MAP (NOT TO SCALE APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. JOB NO. CS-3490. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. JOB NO. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. JOB NO. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. JOB NO. CS-6870. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL INC. JOB NO. CS-7322B. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. JOB NO. CS-8319. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. PROJECT NO. CS14976-120. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. PROJECT NO. 0816502405. EXISTING TOPOGRAPHY. LOCATION OF PROPOSED RESIDENCE. PROPERTY BOUNDARY. RECENT PROPERTY LINE AND LOT NUMBER. PROPERTY LINE AND LOT NUMBERS, PLATTED NOVEMBER 1997. LOT INVESTIGATED. BASE DRAWING WAS PROVIDED BY CLIFFORD TAYLOR ARCHITECTS. PC, RECEIVED JULY 16, 2008. DR. MICHAEL HEMSWORTH CID CLIFFORD TAYLOR ARCHITECTS 1155 CHARLES GROVE LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. PROJECT NO. (3517193405 Location of Exploratory Bo?ngs FIG. 1 NOTES: 1. BASE DRAWING WAS PROVIDED BY CLIFFORD TAYLOR LEGEND: 2 APPROXIMATE LOCATION OF TEST HOLE CONSIDERED APPROXIMATE. THEY ARE BASED UPON A CTL I THOMPSON: SUBJECTIVE INTERPRETATION OF PUBLISHED GEOLOGIC - - MAPS, AERIAL PHOTOGRAPHS AND AN INITIAL FIELD RECONNAISSANCE. CHANGES IN THE MAPPED BOUNDARIES SHOWN ARE POSSIBLE AND SHOULD BE EXPECTED WITH MORE DETAILED WORK AND FURTHER INFORMATION. ALL INTERPRETATIONS AND CONDITIONS SHOWN ARE PRELIMINARY AND FOR LAND-USE PLANNING ONLY. MAP LEGEND IS MODIFIED FROM CHARLES S. ROBINSON APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. JOB NO. 08-5807. NEIL: I 13$? APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL INC. JOB NO. CS-6869. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSONI INC. JOB NO. CS-6870. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. JOB NO. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. JOB NO. CS-8319. 6 APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. PROJECT NO. 0814976. A APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. PROJECT NO. 0816502405. EXISTING TOPOGRAPHYLOT INVESTIGATED. GEOLOGIC UNITS DEBRIS FLOWS: MASS OF CLAY. SILT, SAND. GRAVEL, BOULDERS, AND ORGANIC DEBRIS THAT MOVED AND WAS DEPOSITED AS A VISCOUS MASS. QC COLLUVIUM: CLAYEY OR SILTY SAND DERIVED PRIMARILY FROM IN-PLACE WEATH ERING OF BEDROCK DEPOSITED BY GRAVITY AND SHEET WASH. af ARTIFICIAL FILL QIS LANDSLIDES: DEPOSITS WITH EVIDENCE OF PAST MASS MOVEMENT. GEOLOGIC CONTACTS. DISTURBED AREAS. WIVKV ARTIFICIAL FILL. nun-n- 1965 DEBRIS FLOW DEPOSITS. i In L. .3. -- SCALE: 1'200 . . I I I. I 1 I i-l?l rfICIal DR. MICHAEL HEMSWORTH cIo CLIFFORD TAYLOR ARCHITECTS 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING MD. PROJECT NO. 0517193405 FIG. 2 NOTES: 1. 2. BASE DRAWING WAS PROVIDED BY CLIFFORD TAYLOR ARCHITECTS, PC, RECEIVED JULY 16, 2008. ALL GEOLOGIC BOUNDARIES SHOWN SHOULD BE CONSIDERED APPROXIMATE. THEY ARE BASED UPON A SUBJECTIVE INTERPRETATION OF PUBLISHED GEOLOGIC MAPS, AERIAL PHOTOGRAPHS AND AN INITIAL FIELD RECONNAISSANCE. CHANGES IN THE MAPPED BOUNDARIES SHOWN ARE POSSIBLE AND SHOULD BE EXPECTED WITH MORE DETAILED WORK AND FURTHER INFORMATION. ALL INTERPRETATIONS AND CONDITIONS SHOWN ARE PRELIMINARY AND FOR PLANNING ONLY. MAP LEGEND IS MODIFIED FROM CHARLES S. ROBINSON ASSOCIATES, INC., GOLDEN, COLORADO. DATED 1977. I I . -v SCALE: 1? 200' DR. MICHAEL HEMSWORTH cio CLIFFORD TAYLOR ARCHITECTS 1155 CHARLES GROVE LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1A PROJECT NO. (3317193405 LEGEND: G) APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON. INC. JOB NO. 08-3490. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. JOB NO. 08-5807. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. JOB NO. 08-6869. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. JOB NO. CS-BBTO. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. JOB NO. CS-73228. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. JOB NO. CS-8319. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. PROJECT NO. APPROXIMATE LOCATION OF TEST HOLE DRILLED UNDER CTL THOMPSON, INC. PROJECT NO. CS16502-105. EXISTING TOPOGRAPHY. LOT INVESTIGATED. ENGINEERING UNITS 4C SC TB 8A OLD ALLUVIAL FAN DEPOSITS THAT HAVE BEEN PARTIALLY DISSECTED BY MODERN STREAMS. EMPHASIS ON SURFACE DRAINAGE, SHEET WASH AND EROSION. UNSTABLE OR POTENTIALLY UNSTABLE COLLUVIUM OR BEDROCK ON STEEP SLOPES. EMPHASIS ON SLOPE STABILITY, CONTROL OF CUTS AND SURFACE DRAINAGE. LANDSLIDE DEPOSITS. EMPHASIS ON SLOPE STABILITY, BEDROCK STRUCTURE AND DRAINAGE. DEBRIS FLOW DEPOSITS. EMPHASIS ON FREQUENCY, MAGNITUDE AND CONTROL OF WATER ENTRAINED DEBRIS. AREAS OF CONTROLLED FILL. FILL IS KNOWN TO HAVE BEEN PLACED IN AN CONTROLLED MANNER. GEOLOGIC CONTACTS. Engineering Conditions FIG. 3 APPENDIX A SUMMARY LOGS OF EXPLORATORY BORINGS CTL THOMPSON, INC. PROJECT NOS. CS14976-120 AND 0816502420, AND JOB NOS. 03-8319, CS-7322, CS-6370, CS-6869, CS-5807, AND DR, HEMSWORTH CIO CLIFFORD TAYLOR ARCHITECTS 1155 CHARLES LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING N0. CTLIT PROJECT N0. C517193-105 ELEVATION FEET EI. 101 ?-105 ?100 13112 ?-95 sw=0.1 23:12 wc=17.4 ?90 sw=1.7 -200=61 - I I I 32112 ?85 I I I 113312 ?80 5?1 ?75 THE ELECTRA GROUP 1185 CHARLES GROVE PROJECT NO. 08165024 3:18816500-1 20E. RE PO 6502-1 TH-Z El. 102 29112 3011 2 WC =26 .8 150112 ELEVATION - FEET LEGEND: IKJ I41 FILL, SAND. VERY CLAYEY AND CLAY, VERY SANDY, MEDIUM DENSE (SANDS) VERY STIFF (CLAYS), OCCASIONAL GRAVELS, MOIST, MEDIUM BROWN. CLAY, SANDY, VERY STIFF, MOIST, MEDIUM BROWN (CL). DRIVE SAMPLE. THE SYMBOL INDICATES 18 BLOWS OF A 140-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.5-INCH O.D. SAMPLER 12 INCHES. WATER LEVEL MEASURED AT TIME OF DRILLING. WATER LEVEL MEASURED ONE DAY AFTER DRILLING. NOTES: 1. THE BORINGS WERE DRILLED DECEMBER 26, 2006 USING A DIAMETER, CONTINOUS-FLIGHT AUGER AND A TRUCK-MOUNTED DRILL RIG. THE BORING ELEVATIONS ARE APPROXIMATE AND WERE SURVEYED BY A REPRESENTATIVE OF OUR FIRM USING A HAND LEVEL REFERENCING THE STAKED BASEMENT FLOOR SLAB. 00 FEET). THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS, AND CONCLUSIONS AS CONTAINED IN THIS REPORT. WC - INDICATES MOISTURE CONTENT DD - INDICATES DRY DENSITY (PCF). sw - INDICATES SWELL WHEN UNDER 1 KSF LOAD (96). ?200 INDICATES PASSING NO. 200 SIEVE mo. 35 - INDICATES WATER-SOLUBLE SULFATE CONTENT Summary Logs of Exploratory Borings FIG. An1 100 6 12 =9.4 I. 90 6/12 l. wc=17.2 13/12 oo=109 wc=11.5 . - ?2ao=54 . .4. 15/12 - 33=o.034 2 .. 12/12 80 20/12 - sw=a.5 (I: -. sw=1.4 - - 50/9 0 22/12 . a. . . 21/12 Lu 70 wc=7.3 :3 00:13:: sw=o.o - - 36/12 50/9 so 50 4O MR. JACK MEYER 1155 CHARLES GROVE Job No. 24/Elevation?Feet LEGEND: Fill, sand, gravelly, cla ey to clay, sandy, loose to medium dense (sand), medium stiff to stiff clay), moist to very moist, medium to dark brown, gray. Sand, gravelly, clayey with sandy clay layers, medium dense to very dense, moist to very moist, light to medium brown, gray. (SC) Bedrock. Claystone, soft to hard, moist to very moist, medium brown, gray, rust. Bedrock. Shale, very hard, moist to moist, dark gray. Drive Sample. The symbol 6 12 indicates that 6 blows of a 140?pound hammer alling 3 inches were required to drive a 2.5?inch O.D. sampler 12 inches. .23., Indicates the level of groundwater and the number of days after drilling the measurement was taken. OTES: 1. The borings were drilled between October 20 and 22, 2004 using a 4?inch diameter, continuous?flight, truck?mounted, power auger. 2. The elevations shown are approximate and were determined using a surveyors level and the benchmark shown on Fig. 1. The borings are subject to the explanations, limitations, and conclusions as contained in the report. WC Indicates natural moisture content DD Indicates dry density (pct). SW Indicates percent swell when sample wetted under an applied pressure of 1000 psf. Negative values indicate sample compressed. ?200 Indicates the percent passing the No. 200 sieve. SS Indicates water?soluble sulfate concentration 255-? Logs of Exploratory Bo?ngs Fig. 2 LOT 1 LOT 2 1 10 105 100 21/12 Ex=o,3 Elevation?Feet L0 U1 14/12 32/12 WC: 18.4 ?200=61 1 I 1 I ]15/12 46/12 THE CHEYENNE LAND C0. BARONS RIDGE, LOTS 1?4 Job No. LOT 3 6/12 31/12 45/12 30/12 LOT 4 121:9? 18/12 22/12 wc=15.4 31/12 90 Elevation?Feet LEGEND: Fill, erractic combination of clay, sand, gravel, moist, brown, red?brown maist to very mois, olive brown. Clay, sandy, gravell very stiff, q. Sand, clayey. gravelly, very dense, moist, brown, olive brown. 7 I Weathered claystone, medium hard, 4 moist to very moist, olive brown. .11.. The mbol 21/12 indicates that 21 blows of a 140?pound hammer alling 30 inches were required to drive 0 Drive Sample. 2.5?inch O.D. sampler 12 inches. 0 Indicates the groundwater level and the number of days after drilling the measurement was taken. NOTES: 1. The borings were drilled February 1998 using a 4?inch diameter, continuous?flight, truck?mounted, power auger. 2. The elevations shown are approximate and were determined using a hand level and the benchmark shown on Fig. 1. .3. The borings are subject to the explanations, limitations, and conclusions as contained in the report. 4. WC Indicates natural moisture content DD Indicates dry density (pct) -200 lndicates percent passing the No. 200 sieve. (Z). EX Indicates percent expansion when sample wetted under a surcharge pressure of 1000 psi Logs of Exploratory Bo?ngs Fig. 2 50/4 '5 I I 40 - 50/6 - 50/5 50/5 BARONS RIDGE BROADMOOR RESORT COMMUNITY Job No. - 50/8 50/5 TU 20 .30 40 Depth?Feet LEGEND: Interbedded sand, clayey and clay, sandy. scattered I: gravel, medium dense to dense. moist. brown, red?brown GP, 00). Erotic combinations of silt. clay. sand and gravel with cobbles and boulders. may include debris flow and slope wash deposits, medium dense to dense. stiff to ver stiff, moist to very moist. red?brown. brown. gray 80p, GC. GM). Clay. sandy. scattered gravel, stiff to very stiff. moist to moist. brown, red?brown and gray?brown (CL). Claystone. hard to very hard. moist. occasional wet zones, blocky to massive, olive?brown, rust. medium gray. dark gray, some layers, maybe diSplaced. Pierre shale. very' hard, moist, fissel. dark to black. appears to be intact. indicates practical drill rig refusal Boring Terminated Drive Sample. The mbol 50/4 indicates that 50 blows of a l40?pound hammer alling .30 inches were required to drive a 2.5?inch O.D. sampler 4 Indicates the level of groundwater and the number of days after drilling the measurement was token. NOTES: 1. 2. The borings were drilled January 19 and 20. 1998 using a 4?inch diameter. continuous?flight. truck?mounted, power auger. The borings are subject to the explanations. limitations. and conclusions as contained in the report. Logs of ExPloratory Bo?ngs Fig. 2 Ei.=896 asses 39; 2-32}: 38 12 =13wgzes =9.o ~200=15 3.2 5; -2oo=24 - its is so 12 --15 3.15:; 40/12 3 25/1 2 ?~20 wc=e.2 - h? ~200=12 =5 . :3 35- 3 50/12 5l?ii41 12 "?30 - wc=zol4 DD=1os 50/3 50 . 1-H DEPTH TO 70 50/1 .. SHALE DEPTH AT 64- FEET 75 LOGS OF EXPLORATORY Job No. 4o 12 Do=1os 5 10 15?- 20s50-? LEGEND: Sand, gravelly to gravel, sandy, silty to silty, cobbles and - boulders, medium dense to very dense, moist to moist, brown to reddish~brown (SM. SP, GP) Sand, clayey, gravelly, dense, moist to moist, brown (SC) Clay, sandy to sandy, greveily, Very Stiff: mOESts brow? CH Weathered claystone, medium hard to very hard: ?mm to mom: 1 - alive to grey Claystone shale, very hard, mOiS?t, grey Drive Sample. The mbol 50/12 indicates that 50 blows of a 40?pound hammer alling 30 inches were required to drive a 2.5?inch 0.0. sampler 12 inches. Indicates level of groundwater and number of days after drilling he measurement was taken. NOTES: Boring l?Q was drilled June 12, 1998. Borings and were drilled August 20, 1995 using a 4?inch diameter continuous?flight, trucks?mounted, power auger. The elevations are approximate and established based upon provided topographic mapping. The borings are subject to the explanations, limitations, and conclusions as contained in the report. 4. WC lndicates natural moisture content (75) DD - Indicates dry density (pcf) ?-200 Indicates percent passing no. 200 sieve EX Indicates percent expansion when sample wetted under a surcharge pressure of 1000 a Depth?Feet is; ?zz-{r34 it] 40/12 gig-j: wc=1s.1 3:133: 3 50/6 30/9 1195:: 35 5 3 WCi?i? ?2ao=5 50/5 50/2 a i 4 50/3 ?l 50/1 LOGS OF EXPLORATORY BORINGS Depth?*Feet LEGEND: erotic combinations of sand, gravel, cobbles and boulders with 53:} varying percentages of clay and silt. Medium dense to very, dense, moist to moist, brown (SM. SC. GP. GM. GO) Claystone bedrock, hard to very hard, moist to moist, olive brown, olive gray. possibly displaced indicates practical drill rig refusal (OMB-45) I Drive Sample. The mboI 50/3 indicates that '50 blows_of a 140~pound hammer ailing 30 inches were reqwred to drive a .O.D. sampler 3 Inches. NOTES: 1. The borings were drilled June 12 and August 20, 1996 using a shinch diameter, continuous-?ight, truck?mounted. power auger. 2 Groundwater was not encountered in the borings either at the time of drilling or when the borings were checked days later. 3. The borings are subject to the explanations, limitations, and conclusions as contained in the report. 4 WC Indicates natural moisture content (2'43) DD Indicates dry density (pct) - ?200 Indicates percent passing no. 200 sieve EX Indicates percent expansion when sample wetted under a surcharge pressure of 1000 Fig. 58-3 Depth Feet i3 3 Job No. (25?58073 7 ?713: 20/12 33/12 50/10 50(11 I I, 35112 50110 0 ?2 flaw/12 50/9 50/6 gg?? - a 50/8 .3, (l 9,25 {1320112 50110 son z, 50M i?nmnz SUNS 50/0 LOGS OF EXPLORATORY BORINGS 10"? 20-? 30?? ?10? Depth Feet WEEKS vice: LEGEND: Fill, sand, gravel, silty, clayey, moist, glass, steel Clay, sandy, gravelly, medium stiff to stiff, very moist, rust?brown (CL) Sand, gravelly, clayey, medium dense, very moist, olive?brown (CC) Gravel, sandy, silty, cobbles and boulders, dense to very dense, wet, brown Weathered bedrock, claystone, possibly displaced, medium hard. to hard, moist, olive?brown Bedrock, claystone, hard, moist, olive?brown and gray Shale, hard, moist to moist, dark gray Indicates a gradual change in strata. indicates practical drill drill refusal (Diedrich Drive Sample. The symbol 15/12 indicates that 15 blows of a lilo?pound hammer falling 30 inches were required to drive a 2.5 inch 0.0. sampler 12 inches. Indicates free ground water Notes: 1. The borings were drilled September 5, 1995, using. a 14?inch diameter, continuous flight, power auger. These logs are subject to the explanations, limitations, and conclusions as contained in this report. Fig. Log of Bo?ng JOB NO. DATE DRILLED 5/7l93 PROJECT Broadmoor South Golf Course CTL ITHOMPSON, INC. BORING NO. 0-14 LOCATION DRILLING CONTRACTOR Custom Auqer DRILL RIG CME-55 ELEVATION 6502.0 Boring Method HOLLOW STEM ALIGER CONTINUOUS FLIGHT AUGER ROTARY AIR ROTARY CASING DEPTH CONSULTING GEOTECHNICAL 4" AND MATERIALS ENGINEERS SHEET 1 OF 1 0.00 IEI 19.00 DRILLER MT ENGINEER JH GROUND WATER LEVEL 34 Sampling Method 8 - STANDARD SPLIT SPOON - CALIFORNIA SAMPLE A -AUGER CUTTINGS -CORE NX SIZE 0 - CORE PO. SIZE -SHELBY TUBE 3.0 INCH -HAND DRIVE - BULK SAMPLE 1.. SAMPLE LIJ ?f c: BLOW COUNT DESCRIPTION Lu 3] (BLOWSI a) Clay, Siity, mixed send and gravel, moist to very moist, stiff to very stiff, brown. 9r12 ?72- - 30;]0 Refusal 10 feet. in. y: 16112 Mixed cobble and boulders at 17 feet. Weathered CLAYSTONE, Silty, medium stiff to hard, moist to very moist, olive?brown. SHALE, Silty, very hard, moist, dark gray, low angle bedding, fissile. 60H 2 16(12 More moist at 24 feet. 38/12 17/12 Free water at 34 feet. 24;12 Change to gray at 39 feet. 50I2 End of boring 44.3 feet. BORING ff C-1 4 Log of CTLITHOMPSON, INC. Boring CONSULTING GEOTECHNICAL AND MATERIALS ENGINEERS JOB NO. 08-3490 DATE DRILLED 5I10f93 PROJECT Broadmoor South Goif Course SHEET 1 OF 1 BORING N0. 0-15 LOCATION (N) 0.00 IEI 20.00 DRILLING CONTRACTOR Custom Auger DRILLER MT ENGINEER JH DRILL RIG Boring Method HOLLOW STEM AUGER El CONTINUOUS FLIGHT AUGER ROTARY AIR ROTARY CASING DEPTH ELEVATION 6526.0 Sampling Method STANDARD SPLIT SPOON - CALIFORNIA SAMPLE A - AUGER CUTTINGS - CORE NX SIZE 0 - CORE PO SIZE GROUND WATER LEVEL None T.D. -SHELBY TUBE 3.0 INCH -HAND DRIVE - BULK SAMPLE SAMPLE BLOW COUNT IBLOWSI INCH) INTERVAL SYMBOL TYPE DESCRIPTION DEPTH- FEET 14112 I I 30(12 50H2 3OI12 26(12 SOHO 50M SOB Clay, SiIty, Sandy, graveIIy, brOWn moist to very moist, stiff Very Highly Weathered CLAYSTONE, Silty, Very siiff to hard, moist, olive-brown and light gray. CLAYSTONE, SiIty, moist, hard to very hard, gray with some iron oxide stains on fractures. - SHALE, Silty, very hard, moist to moist, dark gray. End Of boring 45 feet. BORING - (3-1 5 Log of Bonng JOB No. CS-3490 DATE DRILLED 5/10/93 PROJECT Broadmoor South Golf Course CTL THOMPSON, INC. CONSULTING GEOTECHNICAL BORING NO. C-16 LOCATION DRILLING CONTRACTOR Custom Auger DRILL RIG CME-55 ELEVATION 6536.0 Boring Method El HOLLOW STEM AUGER (KI CONTINUOUS FLIGHT AUGER ROTARY El AIR ROTARY CASING DEPTH AND MATERIALS ENGINEERS SHEET 1 OF 2 0.00 IEI 21.00 DRILLER MT ENGINEER JH GROUND WATER LEVEL 45 Sampling Method STANDARD SPLIT SPOON - CALIFORNIA SAMPLE A -AUGER CUTTINGS -CORE NX SIZE -CORE PO SIZE -SHELBY TUBE 3.0 INCH -HAND DRIVE - BULK SAMPLE I. SAMPLE :3 BLOW 0: Lu COUNT DESCRIPTION IBLOWSI a) INCH) 0 Very Highly Weathered CLAYSTONE, Silty, some local scattered gravel, stiff to medium hard, moist. olive-brown. 14112 10 24112 33!? 2 20 50/12 . . . CLAYSTONE, hard, mOIst. fractured, sulfates on fractures, no distinct observed, olive-brown. SOIQ 30 50H 1 50!? 40 50l5 50H 0 ?5:4 SHALE, Silty, Very hard, moist, dark gray. Some gypsum parallel to low 50 50B angle bedding some iron oxide staining also parallel to bedding. Continued Next Page BORING - C-1 6 JOB NO. (38-3490 BORING NO. (3-16 SHEET 2 OF 2 l? SAMPLE L5 BLOW 8 COUNT DESCRIPTION g; 502 End Of boring 55 feet. BORING ?7 - (3-16 Log of Bo?ng JOB NO. (28-3490 PROJECT Broadmoor South Golf Course DATE DRILLED CTL I THOMPSON, INC. CONSULTING GEOTECHNICAL AND MATERIALS ENGINEERS r1 BORING NO. C-17 LOCATION SHEET 1 OF 1 INI 0.00 22.00 DRILLING CONTRACTOR Custom Auqer DRILL RIG CME-55 ELEVATION 6518.0 Boring Method HOLLOW STEM AUGER CONTINUOUS FLIGHT AUGER El ROTARY AIR ROTARY CASING DEPTH DRILLER MT ENGINEER JH GROUND WATER LEVEL None T.D. Sampling Method 8 -STANDAFID SPLIT SPOON - CALIFORNIA SAMPLE A -AUGER CUTTINGS -CORE NX SIZE 0 -CORE PO SIZE TUBE 3.0 INCH - HAND DRIVE 8 - BULK SAMPLE I. SAMPLE LLI ?j .1 <1 BLOW 8 COUNT DESCRIPTION Weathered CLAYSTONE, Silty, medium hard, moist, sulfates on fractures, olive-brown. 41112 CLAYSTONE, hard, moist tO moist, Olive-brown. 10 50l12 44.312 20 SOIS 5015 SHALE, Silly, very hard, moist, dark gray. 5013 53:0 3?03- _Ib?u_ 50"3 End of boring 34.3 feet. BORING - (3-1 7 Log of Bo?ng JOB NO. CS-3490 PROJECT Broadmoor South Golf Course BORING No. 88-3 LOCATION DATE DRILLED 6/11393 CTL INC. CONSULNNC GEOTECHMCAL AND MATEWALS ONGNEERS SHEET 1 OF INI 0.00 [El 51.00 DRILLING CONTRACTOR Custom Auqer DRILL RIG CME-55 ELEVATION 6600.0 Boring Method [3 HOLLOW STEM AUGER CONTINUOUS FLIGHT AUGER El ROTARY El AIR ROTARY CASING DEPTH DRILLER MT ENGINEER PO GROUND WATER LEVEL 35 Sampling Method 3 SPLIT SPOON CALIFORNIA SAMPLE A -AUGER CUTTINGS - CORE NX SIZE 0 CORE Po SIZE TUBE 3.0 INCH -HAND DRIVE 8 - BULK SAMPLE SAMPLE ?j BLOW u] COUNT (BLOWSI CI u) 0 FILL, sand, gravelly, silty and clayey, looss to medium dense, moist, brown, glass, rebar. 15H 2 VERY HIGHLY WEATHERED CLAYSTONE. stiff to medium hard, moist to very moist, olive?brown. - 10 13.? 2 20H 2 20 30f12 CLAYSTONE, hard to very hard, moist, olive-brown. 50? ?l 30 50/12 SHALE, hard to very hard, moist to moist, dark gray. 0. i - -139:? 50m End of boring 39.0 feet. APPENDIX COLORADO GEOLOGICAL SURVEY REVIEW LETTER DR. HEMSWORTH C10 CLIFFORD TAYLOR ARCHITECTS 1155 CHARLES GROVE, LOT 1, BARONS RIDGE AT BROADMOOR RESORT COMMUNITY, FILING NO. 1-A CTLIT PROJECT NO, 0317193405 STATE OF COLORADO COLORADO GEOLOGICAL serving the people of Colorado Department of Natural Resources 1313 Sherman Street. Room 715 Denver, CO 80203 Phone: (303) 866-2611 Fax: (303) 866-2461 GS LUR N0. EP-09-0003 NATURAL August 12, 2008 RESOURCES MS. Heather R086 Bin Rigel-I Jr. Colorado Springs Flaming Community Development Governor 30 3. Nevada, Suite 301 Harris D. Sherman Colorado Springs, CO 80903 Executive Director Vincent Matthews Division Director and RE: Barons Ridge at Broadmoor Resort Filing N0. geologic hazard State review Dear Ms. Rose: Thank you for this single-lot development application and the delay of this formal response due to travel. At your request the CGS is providing to the city of Colorado Springs a review of the packet of plan materials you sent to this of?ce, which included plan sheets, a drainage report, and a Soils and Foundation Investigation by CTL/Thompson dated November 22, 2004. The site is located in the gated Broadmoor Resort Community near the Cheyenne Mountain Zoo. Please consider our comments as you further review this deveIOpment plan. The site is located in a complex geologic environment where ancient landslide terrain has been modi?ed by deposition of alluvial debris sediments that were washed from the ?ank of Cheyenne Mountain. This ancient landslide recently reactivated in the Mountain Golf Course below this site from 1995 through 1999. Migration of the movement occurred to the nearby slopes. We do not know whether movement continues. In previous review letters to the city for the surrounding resort community developments (The Estates, Broadmoor Villas, Villas at Log Hollow, Village at Stone Manor, and Barons Ridge) the CGS expressed concern whether the landslide hazard was being appropriately recognized and the risk properly analyzed, especially those intermediate slump blocks and steeper slopes that approximate the scarp of the ancient landslide when active landsliding was occurring below them. In response to our earlier concerns from 1996 through 1997 and requests for de?nitive monitoring of potential landslide movement, CTL drilled and installed two inclinometers: one at a promontory to the northwest near Stone Manor Heights (formerly lot 9 of the Estate development) and Lot 4 of the original Baron?s Ridge development plan (which may be this lot). Measurements of the inclinometer near lot 9 of The Estates from 1998 and 1999 showed southeastward lateral ground movement at a depth of about 68 feet. CTL stated, in a letter report (Job No. CS-7322) dated November 8, 1999 to Cog Land and Development Company, Atm: Mr. Tom Schmidt: ?We recommend not constructing on Lot 9 of the Estates and Lots 3, 4, and 5 at Baron?s Ridge at this time.? They also recommended that water level monitoring and inclinometer readings be continued quarterly to see whether movement rates decreased or stopped, and whether lateral movement was advancing across Charles Grove cul-de-sac into the Baron?s Ridge lots. This was a complete reversal of an earlier, generally favorable, recommendation made in an earlier letter report dated April 6, 1999. This work from Job Number 7322 is not listed in the Previous Investigation section of the 2004 report submitted for Filing No. l-A CTL believes there is low risk of reactivation of a landslide at this location. With ground movement detected at depth near this lot in 1999 and the let?s location on steeper slepes above the large active landslide in the golf course, CGS would not characterize the long-term risk of lateral movements of the underlying and surrounding slope as ?low.? We believe the long-term risk is higher. We recommend the following prior to any city approval: 1. CTL revise and update their report to include: all data from their Job No. 322; discussion of the movement data, earlier recommendations, and implied long?term risks; and whether additional monitoring they was completed and is available. 2. The plat geologic hazard disclosure statement should be revised to include this revised report with the movement data that postdates the 1998 report on record. 3. An assessment made whether the active landslide has been controlled in the golf course and ground movements have ceased. 4. Forwardng this report to CGS for further review. The city should ensure that there will be complete disclosure of the potential geologic hazards for this lot in the future. If you have any questions about the content of this review, please contact this of?ce at (303) 866-3 551 or e-mail: ionathan.white@state.co.us. Sincerely, Jonathan L. White Senior Engineering Geologist Attachment: CTL November 8, 1999 letter to Cog Land and Development Company J-?kur November 8, 1999 Cog Land and Development Company 4775 Broad Lake View Colorado Springs, Colorado 80906 Attention: Mr. Tom Schmidt Subject: Lot 9 Broadmoor Resort Community Estates Lots 1 through 6, Baron?s Ridge Colorado Springs, Colorado Job No. CS-7322 Gentlemen: Since submittal of our letter oprril 6, 1999 the region has experienced a 100 year historic precipitation event resulting in nearly double the annual precipitation falling during the Spring and early Summer months. The Colorado Geologic Survey has always expressed a concern that if high ground water levels develop on portions of the subject sites, and if the soils have the lower bound strength values utilized in our stability analysis, lateral ground movement could occur. Recently we measured ground water levels in several piezometers located in the area of concern and made measurements of inclinometers on Lot 9 of the Estates and Lot 4 of Baron?s Ridge. The purpose of this letter is to discuss our measurements, our interpretation of the data as it relates to our slope stability analysis, and our opinions. Table summarizes ground water level measurements taken including September, 1999. The measurements indicate that at most locations, while an apparent rise in the ground water elevations occurred, levels did not rise to near the ground surface as hypothesized in one set ofslope stability calculations conducted for the various cross sections. However, ground water levels at Lot 9 of the Estates rose 11 feet which, in our opinion, is substantial, We stated on numerous occasions that if the high ground watertables utilized in one set of calculations developed, and if the subsoils had the lower bound strength values, lateral ground movement would be reflected in our inclinometers. Readings taken on Lot 4,do not indicate lateral ground movement. However, lateral ground movement was detected on Lot 9. The magnitude of movement between May, 1998 and September, 1999 appears to be on the order of 314 of an inch in a southeasterly direction. Appendix A summarizes our inclinometer readings since July 1996. We recommend not constructing on Lot 9 of the Estates and Lots 3, 4, and 5 at Baron?s Ridge at this time. We recommend monitoring the ground water levels in test holes near these properties and making inclinometer readings on lots 9 and 4 at least quarterly. Our previous slope stability analysis indicate the displaced clay and claystone INC. CONSULTING ENGINEERS 5240 MARK DABLING BLVD. I COLORADO SPRINGS. COLORADO 80918 I (719) 528-8300 _jl. would need to have equivalent to 700 cohesion and an angle of internal friction of 11 degrees in order for movement to occur at lot 9. Using these strength values factors of safety generally higher than 1.4 have been calculated for cross sections which include lots within Barons Ridge for the high ground water level, which did not develop during this season. Using ground water levels near those measured this season, the factor of safety exceeds 1.6. Based upon the results of information gathered recently and the results ofour previous analysis we believe the risk of a slope failure effecting Lots 1, 2, and 6 through 10 of Baron?s Ridge is low. We believe the data recently acquired confirms that Lots 1, 2, and 6 through 10 at Barons Ridge can be built on. We maintain it is imperative to control and minimize irrigation on these properties so that the subsoils do not experience deep wetting or result in a substantial rise in the ground water table artificially. We also maintain that permanent cut slopes should be no steeper than 3:1 (horizontallvertical). The conclusions presented in this letter were developed based upon information gathered since 1995, our experience, and engineering analysis. Should you have any questions regarding the contents of this letter or the project from a geotechnical point of view, please call. Very truly yours, CTLITHOMPSON, William C. Hoffmann, Jr., P.E. Principal (5 copies sent) cos LAND AND DEVELOPMENT CTUT 05-7322 2 Table! GROUNDWATER MEASUREMENTS Job No. 08?7322 LOCATION DATE GROUNDWATER LEVELIDATE INSTALLED 6196 2197 6197 12197 2198 . 4193 10198 9199 Lot 9 6196 306196 +75' 3197 +50' 36' 32' 31' 3197 13' 13' 1198 31? 30' 28' 22' P-Z 1198 +40' 18? 18' 16? 3-5 4197 +50' +50' +50? +50' +50' 44' u?iI? APPENDIX A 10' 30? I Depth in feet .52. C) 60* BDRRES (3?4 ?709/26/96 9/13/97 g?m? 19/15/97 3 5/38/-U.7 43:4? 90.1 0.2 0.5 0.8 initial 7/11/96 Depth in feet BDRRES 9/96/96 3/19/97 113/1 5/97 5/39/93 801 I I E- 9224/99 -10 -0.7 -04 -0.1 0.2 0.5 0.8 Initial 07/11/99 LOT 4, RIDGE, BROADMOGR RESORT COMMUNSTY Depth in feet BDRRES E-9 BDRRES E-Q 0 0 10- i 20- 20- 30- 30- 4'3- (3 Depth in feet C3 50' 500 60" 60? 70- 8/38/97 g+ 10/15/97 g?a?s/fisxea I .. 2+ 9/24/99 3 5 2 a 2 5+9xi23/99 80 . I i . ?0.6 03 0.0 0.3 0.6 0.9 1.2 -0.6 ?0.3 0.0 0.3 0.6 0.9 1.2 Initial 7/11/96 initiai 7/11190 LOT 9, BROADMOOR RESORT COMMUNITY, ESTATE LOTS APPENDIX TABLE ?x SUMMARY OF GRAPHICAL ANALYSIS GRAPHICAL SUMMARY 0? SLQPE COG LAND 8. DEVELOPMENT COMPANY 03-7322 TABLE I SUMMARY OF SLOPE STABILITY CALCULATIONS CROSS SECTION LOCATION OF COHESEON ANGLE OF 1-1201 1-1202 NO. FAILURE ITYPE ENTERNAL 15.5. F.S. (DEGREES) 1 Stone Manor 10 200 11 1.42 1.50 TH-6 . 700 14 1 .83 (Circle) 0 11 0.513 0.70 0 '34 0.72 0.90 1 10 88-3 700 11 1.48 (Block) 700 14 1.55 . 11 0.65 14 {3.83 1 88-3 to ?00 11 2.19 Carriage Hausa 700 14 2. 48 (Block) 0 11 1.06 0 14 1.36 1 Shane Manor 1c: ?00 11 2.29 Carriage House 700 14 2.61 (Black) 0 11 1.13 0 14 1.45 1 $843 to THEE ?700 11 2.22 (Block) 7'00 14 2.53 0 11 1.09 0 14 1.39 1 71-1?23 10 700 11 2.45 Carriage House 700 14 2.79 (Block) 0 11 1.17 0 14 1.49 2 Below 700 14 2.11 2.37 (Circle) 2 Carriage House 700 11 2.11 2.27 to South 700 14 . 2.38 2.53 (Circle) 0 11 0.95 1.14 0 14 1.22 1.47 2 TH-12 to South 700 11 2.03 2.21 (Block) 700 14 2.29 2.53 0 14 1.2 1.44 COG LAND AND DEVELOPMENT COMPANY CTUT 03-7322 CROSS SECTION LOCATION OF COHESION ANGLE 0F H201 H202 N0. TYPE (PSF) INTERNAL F.S F.S. FRICTION (DEGREES) 3 Charles Grove to 700 11 1.56 TH-2 700 14 1.74 (Block) 0 11 0.59 0 14 0.79 3 TH-2 to South 700 1 1 1.74 (Block) 700 14 2.21 0 11 0.?1 14 0.96 3 711-4 to Seuth 700 11 2.25 {Block} 700 14 2.54 1 1 0.97 0 14 1.24 South Slope (Block) 700 11 1.06 3.01 3 7GB 14 1 .21 (CircieEast (Biock) 7'00 11 1.53 766 14 1.?4 (Qircie) 3700 ?11 '1 .45 790 14 1.55 COG LAND AND DEVELOPMENT COMPANY (384322 STATE OF COLORADO COLORADO GEOLOGICAL serving the people of Colorado Department of Natural Resources 1313 Sherman Street, Room 715 Denver. CO 80203 Phone: (303) 866-2611 Fax: (303) 666-2461 CGS LUR No. em er 5 pt '3 15:2003 RESOURCES Ms. Heather Rose Colorado Springs Planning Community Development Bill Ritter, Jr. 30 S. Nevada, Suite 301 Governor Colorado Springs, CO 30903 Harris D. Sherman Executive Director RE: Barons Ridge at Broadmnor Resort Filing 0. l-A geologic hazard Vincent Matthews resubmittal review Division Director and State Geologist Dear Ms. Rose: As you requested via e?mail on September 2, 2008 we have reviewed the revised draft Geologic Hazard Evaluation for 1155 Charles Grove (Lot 1, Baron?s Ridge at Broadrnoor Resort Community) by CTL Thompson that has a revision date of August 29, 2008. Our original comments were submitted to you in a letter dated August 12, 2008. Please consider our additional comments as you further review this 1-lot development plan. The CTL report has now appropriately disclosed the conditions at the site that we had expressed concerns about in our first letter, as well as discussing the nearby ground movements they detected in 1999. CTL has stated that the reactivated landslide is currently stable and, based on the drainage work that was done to mitigate slope instability on the golf course below and lack of detectable ground movements at the pipeline as well as the inclinometer casing at the original lot 4 of Baron?s Ridge, they consider the risk to be low that lateral ground movements will damage the proposed residence on this lot. We feel that the long?term risk may be somewhat higher as stated in our August 28, 2008 letter. Please bear in mind that CTL also states: These areas can experience lateral movement in the?xture along the existing failure zone under similar conditions to those that triggered the initial movement. We concur that drainage and landscaping designs should minimize introduction of water to the subsurface soil. The homeowner must understand and accept the risk for this lot, and the city needs to ensure that there will be complete disclosure of this risk to any prospective buyer of this home in a future resale. It is very important that the geologic hazard report of record, shown on the Filing No. l-A plat notes, be the ?nal version of this most recent CTL report (Project No. CS 171 93?105) that includes these CGS reviews in the appendices. If you have any questions about the content of this review, please contact this of?ce at (303) 866-3551 or e?mail: ionathan.white@state.co.us. Sincerely, Jonathan L. White Senior Engineering Geologist