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Home My WebLink AboutTEFFT ACRES, LOT 9 REPLAT - PDP - 12-03 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTCompaction Specifications For GW-GC & SW -SC Soils On -site Soils or Approved Minimum Compaction Acceptable Deviation From Imported Soils (ASTM D698) Optimum Moisture Content Beneath Interior Slabs 95%+ t3% Beneath Garage and Exterior Slabs 95% + f3% Backfill and Trenches in Open Areas 90% + f3% Backfill and Trenches under Structures Slabs etc. 95% + f3% Compaction Specifications For NIL, CL, MH, & CH Soils On -site Soils or Approved Minimum Compaction Acceptable Deviation From Imported Soils (ASTM D698) Optimum Moisture Content Beneath Interior Slabs* 93% - 98% 0% to +3% Beneath Garage and Exterior Slabs* 93% - 98% 0% to +3% Backfill and Trenches in Open Areas 90% + 0% to +3% Backfill and Trenches under Structures Slabs etc.* 95% - 98% 0% to +3% ' * MH and CH soils are not recommended in these areas ' Note: This is a standard table and should not be separated from the report. The specifications in the attached soils report supersede the criteria presented in this table. A5 conforming to the most recent procedures of ASTM D698 and AASHTO T99 (standard Proctor) or ASTM D1557 and AASHTO T180 (modified Proctor), whichever applies. Copies of the "Proctor Curves" will be furnished to the contractor. These test results shall be the basis of control for the field moisture/density tests. DENSITY TESTING A 24-hour notice shall be given to the Soils Engineer or testing agency for scheduling compaction tests. The density and moisture content of each layer of compacted fill will be determined by the Soils Engineer, or qualified technician, in accordance with ASTM D2167 and D3017 (nuclear method). Any material found not to comply with the minimum specified density shall be reworked and recompacted until the required density is obtained. Additional lifts shall not be placed until each underlying lift has been approved. The results of all density tests will be furnished to both the owner and the contractor by the soils engineer. A minimum of one compaction test should be conducted for each twelve (12) inch of compacted lift. Trenches should have a minimum of one test every three hundred (300) feet with a minimum or two (2) tests per trench. Sub -excavations have a minimum of one test every twenty-five (25) lineal feet of footing with a minimum of three (3) tests per pad. TRENCH SAFETY All excavations shall comply with current OSHA standards for the soil conditions encountered. The Soils Engineer shall be consulted if there is a question regarding classification of the soils. A4 ' relatively horizontal. Test areas are recommended to determine the optimum lift thickness. ' Thinner lifts may be necessary in order to achieve the required compaction. Each lift shall be approved by the Engineer prior to placing each succeeding lift. COMPACTION When an acceptable uniform moisture content is obtained, each lift shall be compacted by a ' method acceptable to the Soils Engineer to the densities and moisture contents specified in the foregoing report or the attached table of this Appendix and as determined by the standard Proctor ' test (procedures in ASTM D698). Compaction shall be performed by rolling or tamping with approved tamping rollers, pneumatic -tired rollers, three -wheel power rollers, or other equipment ' suited to the soil being compacted. If a sheepsfoot roller is used, it shall be provided with cleaner ' bars attached in a manner which would prevent the accumulation of material between the tamper feet. The roller should be so designed that the effective weight can be increased. If the required ' compaction cannot be achieved with the equipment supplied, thinner "loose -lifts" and/or heavier ' equipment are recommended. MOISTURE -DENSITY DETERMINATION: STANDARD AND MODIFIED PROCTORS. Samples of representative materials to be used for fill shall be furnished by the contractor to the Soils Engineer at least forty-eight (48) hours prior to compaction testing. Wetter samples will require extra time for test results due to the required drying for sample preparation. The sample is to be tested for determination of the maximum dry densities and optimum moisture contents ' (Proctor test) for these materials. Tests for these determinations will be made using methods ' A3 The subgrade surface of the area to be filled shall be thoroughly scarified to a minimum depth of six (6) inches, moistened or dried as specified in the attached tables, and compacted in a manner specified below for the subsequent layers of fill. Fill shall not be placed on frozen or muddy ground. MOISTURE CONTROL The fill material, while being compacted, shall as nearly as practical contain the amount of moisture as required in the attached table of this Appendix. The moisture shall be uniform throughout the fill. In the event that water must be added to the soils or that the soils must be dried to meet the specifications, the soils must be thoroughly pulverized, mixed, blended and cured prior to placement. The effort required for optimum compaction will be minimized by keeping stockpile soils near Optimum Moisture Contents. When moisture is added to dry, clayey soils, a curing period of several days may be needed to allow uniform absorption of the water into the soil. Freezing temperatures and/or inclement weather conditions may impede moisture control and compaction operations. PLACEMENT OF FILL MATERIALS Distribution of material in the fill shall be such as to preclude the formation of lenses of material differing from the surrounding material. The materials shall be delivered and spread on the fill or prepared surface in such a manner as will result in a level, uniformly compacted fill. Prior to compacting, each layer shall have a maximum "loose -lift" height of twelve (12) inches (or as dictated by the compaction equipment and/or soil conditions) and its upper surface shall be WVA APPENDIX A Suggested Specifications for Placement of Compacted Earth Fills and/or Backfills. Note: This is intended to be used as a guideline for this project by the owner or owner's representative. Municipal codes, special construction requirements or other controlling factors may require modifications to these suggested specifications. Supervision and control of the fill operations is not within the scope of this exploration. This is not a claim that Scott, Cox & Associates is the Soils Engineer for the fill and compaction operations. GENERAL Supervision and control of the overlot and structural fill and backfill shall be under the direction of the Soils Engineer for the project. The soils engineer shall approve all earth materials prior to their use, the methods of placing, and the degree of compaction obtained. A letter of approval from the Soils Engineer will be required prior to the owner's final acceptance of the filling operations. MATERIALS The soils used for compacted fill beneath interior floor slabs and backfill around foundation walls should be relatively impervious and non -swelling for the depth specified in the soils report. No material with a maximum dimension of six (6) inches or greater shall be used for fill. All fill materials shall be subject to the approval of the Soils Engineer prior to placement. SUBGRADE PREPARATION All topsoil, vegetation, frozen materials, old structures or other unsuitable materials, shall be removed to a depth satisfactory to the Soils Engineer before beginning preparation of the subgrade. Al Table 1 Summary of Laboratory Test Results Project No.:1153-11-02-01 Lot/Block or Depth (tt) Soil Properties Consolidation/Swell Sample Description Moisture Dry Density %Passing Liquid Plasticity Unconfined Standard TotalLLo,,Sding .Settlement Settlement Swell Boring No. Content (%) (pcf) No. 10/200 Limit Index Compressive Penetration Swell (Dry) (Saturated) 1 1 Strength (psf) Test (%)(%) (%) (%) TH-1 2-3 5.6 100.7 >9000 3.1 I00 0.0 3.1 Sand, silty, slightly clayey, slightly 500 1.1 moist, dense, dark brown 1000 0.8 2000 2.9 4000 5.8 34 5.1 >9000 41/12 Sand, silty, slightly clayey, trace gravel, slightly moist, dense, dark brown 7-8 15.7 6000 8/12 Sand, very silty, trace gravel, very moist, medium loose, red -brown 15-16 19.1 >9000 26/12 Claystone, weathered, silty, moist, hard, olive -grey 23-24 11.7 124.8 >9000 50/6 5.1 500 0.3 4.8 Claystone, silty, slightly moist, hard, 1000 4.4 olive -grey 2000 3.6 4000 2.5 8000 0.9 16000 0.9 TH-2 2-3 4.4 >9000 20/12 Sand, silty, slightly clayey, trace gravel, slightly moist, dense, dark brown 7-8 6.5 107.5 >3000 0.1 ]00 0.0 0.1 Sand, silty, slightly clayey, trace gravel, 500 0.5 moist, dense, dark brown 1000 1.1 2000 2.0 4000 3.3 8-9 7.9 N/A 8/12 Sand, silty, slightly clayey, trace gravel, moist, dense, dark brown 20-21 26.2 5000 15/12 Clay, slightly silty, very moist, very stiff, olive -grey TH-3 5-6 8.1 >9000 11/12 Sand, silty, slightly clayey, trace gravel, slightly moist, dense, brown Page 1 of 1 Client: L-14- Date of Test: I h q ? Hole Diameter. SCOTT, COX do ASSOCIATES, INC. consulting engineers Lineation: Data of Pre -soda Hole Dsptb (Avg.): ? T Pipe Diameter. Tested br. (. L Project Na Gravel PscW? (Yes) Correction Factor: Area d Test Measurement from tied reference point (ia.) Z Na Ares of Test 1Va Lineation Time H.la N.. Li.l. Na a Hde Na Kok Na Lime Na Hsla Na. o,v,;� mil/,Q au 'fig m33i2, 23t/Z Cband at ' ,�� i 117/g Pere rate (neon) $ , mpi 30 ®pr �� mpi mpi mpi mpi Pere rate mpi mh mpi mpi api xverW mpi overate mpi Gravel Packing Correction: mpi - minutes per iacb Imp - did not percolate Porosity (P)= b-h' h C=dia of hole = h=height of water in can A din of pipe h'=height of water in can B after pouring Correction factor (K) = C: _ Water from A into gravel filled B (For mpi) Cans A & B to be equal size Figure iNo. '7 5110 Granite Stmeet Suite 0 • Loveland, Cobrado do53a 9-0) 66101 38 970) 663-7660 51ry Cobra00'.itn orTi¢ in Sou x+ _xgront LanarW IT M 1 0 -4 TH-11 TH-2 TH-3 (Pert01) -4 OFT. OFT. X m= M M 20/12 41/12 5 FT. . . ............ . ............................... ......... ....... . .......... 5 FT. S/12 S/12 10 FT . . . ............ ................... ..... ............................. 10 FT. V V 15 FT. .............. 26/12 / .............. ....... .. ... ... . .......... ............... ..... ............ Irp FT. X., 20 FT. — — --------- ................. .......................................................................... 15/12 20 FT. 50/6 25 FT. . . ........................................................................................................................ 25 FT. 30 FT. . . ........................................................................................................................ 30 FT, 35 FT. — ------------------------------------------- ............................................................................ T_ 35 FT. Borings drilled 1/13/03 using BAND: silty to v. slltq, al. clayey, tr. gravel, al. moist a 4m diameter, continuous flight L2J to wet, loose to dense, dk- brown to red -brown truck mounted drilling rig. M CLAY. al. silty, very Lplat, tr stiff, olive -brown Groundwater a drilling CLAY5TONE: wx. to competent, silty, T a Groundwater on 1/14/03 Z al. moist to moist, hard, olive -grey c,NE = Groundwater not encountered All soil and/or rock contacts shown on boring logo are approximate and represent subsurface conditions at time of drilling. Boring logo and information presented on logo are subject to discussion and limitations of this report. ArArSCOTT, COX 4 ASSOCIATES,INC. eummARY LOG OF BORINGS I Loveland, Colorado Project No. 1153-11-02-01 Fig. No.: 3 Fill materials / ° Iby sample Gravel `�v Sand Standard Slit Penetration i Test sample Clay i `�v Weathered bedrock - ,Califomia sample' - Slltstone Div Claystone Sandstone � Groundwater level Limestone Igneous 4 Metamorphic _ Denotes caving = rocks of the boring at that level Sbols may be combined to represent mixtures. Soil C aeelfications are based on the Unified Soil Classification system (USGS) and ASTM 0-24W. Groundwater Level A Drilling T e Stabilized Groundwater Level GNE a Groundwater not encountered -� a Depth of Borehole Caving TM I e Boring Location and ID #- .Test Pit Location and ID ,-�7 e Approx. Surface Slope (downward) * Drilling and standard penetration testing were performed In general accordance with ASTM D 1586. Numbers to right of boringe indicate the SPT values for the specified inches of penetration. The SPT test uses a 140 Ib hammer falling 30 Ind -me. Example: '6/12' Indicates six blows providing twelve Inches of penetration. Unified Soil Classification stem (USCS) Coarse Grained Solle, more than 50% Retained on No. 200 elerve More than 50R. of coarse fraction retained on No. 4 Sieve Less then 5% Fires CuZ4 and 15Co53 GW Wall -graded Gavel Cu<4 and/or I>Cc>3 GP Poorl - raded Gravel More than 12% fires Fines clasel ae ML or MH GM $t Gavel Pines claselfg as CL or CH GC Clam Gravel More then 5M passes NoA slave Lose than 5% lines Cu2t6 and i5Oe53 SW Well -graded Sand Cu<6 and/or I>Cc>3 SP Poorl - raded Sand More than 12% fines Fines classify as ML or MH SM SIIt&l Sand Fine ClasslN as CL or CH SC Clagey Sand Fire Grained Soils, more than vSM Liquid Limit lose than 50 Inorganic PI>1 and plots on or above 'A' line CL Low Plastic Cla (Lean) LL&sew/ LL( vtd,i.w < 0.-5 ML Silt Organic PI 4 and plots below 'A' line OL Organic Clay or Silt passes tie No. 200 slave -Organic Liquid Limit more than 50 Inorganic PI plots on or above 'A' Iwo CH High Plastic Cla (Pat) PI plots below 'A' line MW High Plastic Slit (Elastic) Organic I LLr.w.e)/ LL[na.aed) < 0.15 OH Organic Clag or Slit ITl I Soils Prhmrlly organic matter F'T Peat Ou • 0,,/r,6 CC . zc—r PI . LL - PL ��so �MoD 60 Fine Grained Soils Coarse Grained Soils ;31owa/ft Coneieteneu $jowa/ft, Relative Deneitu 0-2 V. Soft 0-4 V. Laze ` 3-5 Soft 5-8 Looee o 40 6-10 Firm S - 12 SL Dense 11 - 20 Stiff 13 - 30 Mad Dense T30 21 - 30 V. Stiff 31- 50 Dense N p 31. Herd 50• V. OW06 a 20 a Bedrock Strata DSZryse of Weethsirg � slows/n Walatharkla SlteW Stich decomposition, possible 10 0 - 50 Weathered MoAdw to: sc% decomposition and color clangs tl•roughout. 0 NEENERMWE'S EEEEam PEE �NEEEE /'AMEN " EEFAAF Agoomm 50. Competent Highs Rock hl decoePosed, may be 0 10 20 30 40 50 60 10 So S0 100 extreme!'" y'brokan and dlecoiored. _ Liquid Limit (LL) SIEVE DE81GdATION 400 ohm 90 M0 W % 9D•b 44 UY 3/4' is Ib' 2' S. oa SIZE M MILLS 0.1 10 10 100 FwF.4 !CLAY Alm OLT) I FM fimm I HW WH 6WDB 100ARM001 FM W"Vfite I COARW aRAYMS 1COMRS "SCOTT, COX E ASSOCIATES, INC. LEGEND OF SYMBOLS ��--�-� Loveland, Colorado Fig: No.: 2 m N = b� m a W. Woroetooth Road ICMI rot to .fe Moffet Drive Lot 9A Lot 9B TH-2 c m t T� V1 TH-3 0 (Pere 41) 0 80RING LOCATION Client: Pitner Construction AND SITE MAf= Project: Lot 95, Tefft Acres, Larimer County, Colorado //� SCOTT, COX d ASSOCIATES, INC. �� Approximate Scale: III= 150' Loveland, Colorado Project No. I153-11-02-01 Fig. No: I Lot 9B, Tefft Acres SCA Project No.:] 153-11-02-01 February 3, 2003 report cannot be considered risk -free and are not a guarantee of the performance of the structures. The recommendations included in this report are our best estimates of the measures that are necessary to help ensure that the proposed structures perform in a satisfactory manner. The contractor and owner should discuss and understand the risks of construction at this site, and should agree on what level of risks and measures are acceptable. We recommend that construction be observed by a qualified soils technician trained and experienced in the field to take advantage of opportunities to recognize undetected conditions which might affect the performance of the foundation systems. It is recommended that a copy or summary of this report be provided to any new or future owners of this property. A copy of A Guide to Swelling Soils for Colorado Homebuyers and Homeowners, Colorado Geological Survey Special Publication 43 should also be provided to any new or future owners of the property. The CGS publication states, "It is essential that the homeowner understands how to check and maintain all of the different systems that were designed to protect a house against swelling soil damage." 21 Lot 9B, Tefft Acres SCA Project No.:1153-11-02-01 February 3, 2003 scope of the project has changed from those described in this report such as, the building orientation, location, size, types and depths/elevations of construction, risk acceptance, usage, etc or if any part of this report is used more than one year from the date of the report, additional testing and evaluation by the geotechnical engineer may be required to validate or modify our recommendations. It is the Contractor's and/or Owner's responsibility to inform the Engineer of any changes of the scope of this project as described in this report. No individual, other than the client, should use this report for its intended purpose without first consulting with the geotechnical engineer. The test holes drilled were spaced to obtain a reasonably accurate picture of subsurface conditions for design purposes. Due to the limited number of borings and samples, variations in the subsurface conditions often exist which may not be observable given the scope of this investigation. These variations are sometimes sufficient to necessitate modifications in design. The open hole inspection should be conducted and is the geotechnical engineer's last chance to determine if any subsurface conditions observed substantiate changes in these recommendations. Additional testing and evaluation may be necessary pending the outcome of the open hole inspection. The methodology used to establish recommendations for construction on soils is not an exact science. Engineering judgement and experience, in addition to laboratory and field analyses, are used to make these recommendations. Therefore, the recommendations and solutions made in this 20 Lot9B, Tefft Acres SCA Project No.:1153-11-02-01 February 3, 2003 state and county statutes do not provide an adequate statistical average for scientific analysis but do provide general indications or tendencies of the soil absorptive capacities. Septic systems occasionally fail prematurely due to often undetermined causes. All existing and future owners of the property shall accept responsibility for maintaining the system and outcomes of a poorly maintained or abused system. The type and size of the septic system described in this report is only a reference to the ISDSR for the county health department and are not to be considered recommendations by the Engineer. Due to the many variables of soil conditions, construction procedures, usage and maintenance practices, we can provide no warranty, expressed or implied, of the performance of the septic system. The county health department has final acceptance over these test results and referenced system. All construction shall be in compliance with the septic system permit. GEOTECHNICAL LIMITATIONS The data presented herein were collected to help develop designs and cost estimates for this project. Professional judgments and estimates on design alternatives and criteria are presented in this report. These are based on evaluation of technical information gathered, our understanding of the characteristics of the structure proposed, and our experience with subsurface conditions in this area. We do not guarantee the performance of the project in any respect, but only that our engineering work and judgments rendered meet the standard of care of our profession. This investigation was conducted for a unique set of project specifications. In the event that the 19 Lot 9B, Tefft Acres SCA Project No.:1153-11-02-01 February 3, 2003 Trench systems are preferred since they can provide better treatment of the wastewater than the bed systems. We recommend that an effluent filter be installed in or after the septic tank to prolong the life of the system. Refer to the ISDSR for the County, component manufacturer and other readily available literature for system maintenance requirements. This percolation investigation was conducted in compliance with local statutes and guidelines and to current accepted industry standards for this region. The test results are based on those standards. The locations and elevations tested were controlled by those statutes, site conditions and/or the client's preference. The contractor and/or owner must carefully plan the elevations of the structures if gravity flow of the wastewater to the septic system is desired. We recommend that the top of the bed or trenches be at least one (1) foot below any floor level with gavity sewer. Otherwise, a pump system may be required. The profile hole drilled indicates the subsurface conditions at that location and has limited access to visual observation which may not allow the detection of some soil layers. We recommend that a test pit be excavated prior to construction, inspected by the Health Department or Engineer to determine if these conditions exist. Subsurface conditions described from the boring may vary from visual observations of the test pits and may necessitate changes in the referred system. Soil percolation is not an exact science. The minimum number of percolation holes required by Lot 9B, Tefft Acres SCA Project No..-] 153-11-02-01 February 3, 2003 Hole No. 3 (Perc #1) indicate silty sands to the depths explored. Groundwater was not encountered. There were no limiting conditions observed. Based on these conditions, the site conditions meet the County's criteria for a conventional absorption system. Based on the conditions described above, a standard absorption system should be applicable for the area tested. The following minimum sizes are based on the individual sewage disposal regulations for Larimer County and the conditions described above. Number of bedrooms 3 4 5 Septic Tank Size (gal.) 1000 1250 1500 Standard Bed Area (ft) 792 1056 1320 Standard trench Area (ft2) 634 845 1056 Infiltrator Bed Area (ft) 600 787.5 975 Number of Units 32 42 52 Inside footprint Area (ft) 496 651 806 Infiltrator Trench Area (W) 487.5 675 843.75 Number of Units 26 36 45 Inside footprint Area (fe) 403 558 697.5 The Infiltrator sizes are based on a 40% maximum reduction for beds and a 50% maximum reduction for trenches, allowing 15.5 square feet for each standard Infiltrator chamber. The number of units are rounded to result in a simple configuration. The sizes apply only to standard Infiltrator chambers. 17 Lot 9B, Tefft Acres SCA Project No.:1153-I1-02-01 February 3, 2003 not be used next to the foundation wall. We recommend the use of a landscape fabric which will allow normal evaporation, in lieu of a plastic membrane. All plants located next to the foundation should be hand -watered using only the minimum amount of water. Sprinkling systems should not be installed within ten (10) feet of the structure, and spray from sprinklers should not fall within five (5) feet of the foundation. Gutters and downspouts are recommended and should be arranged to carry drainage from the roof at least five (5) feet beyond the foundation walls. SLOPE CONSIDERATIONS - The scope of this report does not include a slope stability analysis. At a minimum, the structure placed adjacent to slopes of 3h:ly (33.3%), or more, should have the setbacks from the toe of the slope as described in Section 1806.5 of the UBC 1997 Volume 2 if a slope stability analysis is not to be conducted. PERCOLATION INVESTIGATION A percolation investigation was conducted to determine the percolation rates and subsurface conditions for septic system considerations. The percolation tests were conducted in accordance with procedures described in the I.S.D.S. regulations of the Larimer County Health Department. Three (3) percolation test holes were excavated in the vicinity of Test Hole No. 3 (Perc #1) as shown on the boring location map, Figure 1. Percolation rates of 18.5, 30 and 16 minutes per inch with an average of 22 minutes per inch were obtained. Exposed subsurface conditions in Test 16 Lot 9B, Tefft Acres SCA Project No.:1153-11-02-01 for recommended moisture contents. February 3, 2003 COMPACTION- Suggested recommendations pertaining to compaction of the soils are included in Appendix A of this report. Municipal codes, special construction requirements or other controlling factors may require modifications to those recommendations. LANDSCAPING AND DRAINAGE- Every precaution should be taken to prevent wetting of the subsoils and percolation of water down along the foundation elements. Controlling the drainage will lessen the chances of water related damage. Finished grade should be sloped away from the structure on all sides to give positive drainage. A minimum of twelve (12) inches fall in the first ten (10) feet (10%) is recommended. Where asphalt or concrete adjoins the foundation walls, the slope can be reduced to four (4) inches fall in ten (10) feet (3.3%). Any cracks or joints shall be sealed and maintained so that surface waters cannot penetrate the surface. If the concrete or asphalt extends no further than five (5) feet from the foundation, the remaining slope away from the foundation should be ten percent (10%) as described above. Positive drainage away from the foundation should be maintained throughout the life of the structure. In the event that the backfill settles, the original grade must be restored so that the site drains effectively. Planted areas are not recommended around the perimeter of the foundations. However, if the owners are willing to accept the risks of foundation and slab movement, low water -use (xeriscape) plant varieties could be used. An impervious horizontal membrane, such as polyethylene, should 15 Lot 9B, Tefft Acres SCA Project No.:] 153-11-02-01 EARTHWORK February 3, 2003 SITE PREPARATION- Recommendations pertaining to site grading are included below and in Appendix A of this report. We recommend the upper ten (10) inches of the topsoil below building, filled and paved areas be stripped and stockpiled for reuse in planted areas. The upper six (6) inches of the subgrade below paved and filled areas should be scarified and recompacted within plus or minus two percent (+2%) of optimum moisture to at least ninety-five percent (95%) of standard Proctor density ASTM D-698-78 (See Appendix A of this report). Underground water- lines, sewer -lines and perimeter drains should be bedded with at least twelve (12) inches of granular material over the pipe. The water and sewer bedding should not be used within ten (10) feet of the foundation to minimize the transfer any groundwater which may enter the bedding to the foundation. The foundation and retaining walls should be well -cured and well braced prior to backfilling. FILL MATERIALS- In our opinion, most ofthe on -site soils encountered could be used as backfill against foundation walls and utility trenches provided the recommendations for compaction, moisture control and testing are followed. If imported backfill materials are used next to the foundation walls, they should be relatively impervious and non -expansive. Past experience has shown that severe damage could occur to the foundation walls if excessively expansive material is placed for backfill and allowed to become wet. The soils should be well pulverized and the proper moisture blended prior to placement for compaction. Refer to Appendix A of this report 14 Lot 9B, Tefft Acres SCA Project No.J153-11-02-01 February 3, 2003 The drainage system should contain a four (4) inch diameter perforated drain pipe encased in a minimum of twelve (12) inches of clean, 3/4 inch minus gravel. The drain pipe should extend around the lower level perimeter with the invert at the high end of the drain being placed a minimum of four (4) inches below the bottom of the footing. The drain should be run to a non - perforated sump pit or to daylight well away from the foundation at a minimum slope of 1/8 inch per foot to facilitate efficient removal of water. The gravel should be placed a minimum of eight (8) inches over the pipe for the full width of the trench. For exterior perimeter drains, the entire system should be covered with geotextile fabric to minimize clogging of the gravel by backfill material. For underslab drains, lateral drains should be installed in addition to the perimeter drain, at a maximum spacing of ten (10) feet on center. The sump pit should be a minimum of eighteen (18) inches in diameter by three (3) feet deep and should be surrounded by at least six (6) inches of clean gravel similar to that provided around the drain. In the event that free water is observed in the sump, a pump designed to discharge all flow from the sump for a minimum of five (5) feet beyond the backfill zone should be installed. Drains which are to discharge downslope by means of gravity (daylighted) should either be connected to a sump pit or have a cleanout installed to facilitate monitoring and maintenance. The discharge area should be protected from damage due to animal activity, vegetation and traffic. The discharge area should be placed so that it does not interfere with adjacent properties. 13 Lot 9B, Tefft Acres SCA Project No.: 1153-11-02-01 February 3, 2003 beneath the slab. No particles smaller than 3/8" should be permitted in the gravel. Other methods of moisture proofing may be required by the floor covering manufacturer. 6. All exterior slabs should be constructed using a more durable sulfate -resistant concrete containing Type LM cement and with higher air contents and lower water - cement ratios. 7. Slabs should be reinforced with wire mesh, fiber mesh, or equivalent to help control crack separation. 8. To avoid settlement and distortion of exterior slabs due to improper compaction, we recommend that concrete slabs that must span the backfill be supported by the foundation walls. This is conventionally done by use of a brick ledge or haunch. Exterior slabs should not be doweled to the foundation wall. The slab should be reinforced as necessary for the span involved. 9. Slab -on -grade areas should not be finished for at least two (2) years (preferably three (3) years) from the issuance of the Certificate of Occupancy to allow for initial movement. 10. Refer to ACI 301.R for additional recommendations for design and construction of floor slabs. BELOW -GRADE FLOORS AND SUBDRAINS The ambient groundwater table at the site could rise to a level which would affect conventional full basement level construction. Based on our past experience in this area, we feel groundwater in this area could rise significantly from present levels. Due to the potential of significant groundwater fluctuations in this area, we recommend that the maximum depth of the excavation be no greater than six (6) feet below existing grade. Due to the potential for groundwater fluctuations and to alleviate hydrostatic pressures behind the foundation walls, below -grade floor levels should be constructed with an interior (underslab) and exterior perimeter drainage system. 12 Lot 9B, Tefft Acres SCA Project No.:] 153-11-02-01 February 3, 2003 (crawl -space) between the floor and the soil. This allows the soil to expand and contract independently of the floor and any interior fixtures. Structural concrete and structural steel floors ' require less than the eighteen (18) inch void space required for wood floors. Another alternative which can reduce the amount of movement and cracking of interior and exterior slabs would be to remove at least two (2) feet of the soil under the slab and replace with moisture and density controlled on -site or imported soil. Refer to Appendix A of this report for compaction, testing guidelines. All fill shall be tested, inspected and approved by the Engineer. ' Where slabs -on -grade are chosen and the owners are willing to accept the risks associated with slab movement, the following recommendations should be followed: 1. Slabs should be constructed to be "free floating". The slabs should be isolated from all structural components and utilities which penetrate the slab. Isolation may be achieved with %2 inch isolation material or by sleeving. 2. A one and one-half (1'/z) inch void should be constructed under all partition walls located over slabs. The void should be monitored periodically by the owner for the life of the structure. The void should be immediately re-established if the voids are within one-half (%x) inch of closing. 3. Eliminate underslab plumbing where feasible. Where such plumbing is unavoid- able, it should be pressure tested during construction to minimize leaks which would result in wetting of the subsoils. I4. Divide slabs -on -grade into panels by use of control joints. We recommend joints be placed no more than twelve (12) feet on center in each direction. Control joints 1 should also be located at potential weak areas such as the corners of driveway slabs. The depth of the control joints should be one -quarter (1/4) of the slab thickness. ' 5. Slabs should be underlain with a four (4) inch layer, or more, of clean gravel to help distribute floor loads and to provide a capillary break should moisture collect 11 Lot 9B, Tefft Acres SCA Project No..1153-11-02-01 February 3, 2003 and/or retaining structures. The design lateral earth pressure reported may need to be revised pending the outcome of the open hole inspection. FLOOR SYSTEMS AND SLABS -ON -GRADE The samples of the soils encountered at the site exhibited very low to low swell potentials as moisture contents are increased. Strata may be present which could exhibit higher and lower swelling than detected during this exploration. Floor slabs placed on or near potentially swelling soils are expected to heave and crack to some degree. Most of the movement will be differential or uneven. It is impossible, with the current state of technology, to predict with certainty how much slab movement will actually occur. From an engineering perspective, slab movements on the order of '/2 inch or so would be considered low, whereas 1'/z inches or more would be considered moderate to high. Ultimately, though, it should be the owner who determines whether inch of slab heave is low or high. In some cases, the amount of movement maybe considered to be intolerable. Slabs placed on the native, unaltered silty sands may experience slight heaving and cracking, but, in our opinion, should not be excessive. Slabs placed on the moderately or higher swelling clays or bedrock strata may experience excessive heaving and cracking. Where floor movement and/or cracking cannot be tolerated by the owner, we recommend that structural floors be constructed in place of slabs -on -grade. Structural wood floors are typically constructed eighteen (18) inches or more above the natural soils, creating a zone of separation 10 Lot 9B, Tefft Acres SCA Project No.:] 153-11-02-01 February 3, 2003 forms prior to placing concrete. S. Footing and pads shall not be placed on sloped surfaces unless provisions for dowels or keyways are designed to accommodate these conditions. 9. To avoid disturbance of supporting native soils, excavations in the soft soils should be conducted with equipment which does not produce wheeled traffic in the excavation. The assignment offoundation types and these recommendations should not be considered absolute. Due to the inherent variability ofsoil conditions at any given site, the type offoundation is subject to change if conditions encountered in the actual excavation are inconsistent with the findings of this report. We recommend the completed excavation be observed by a member of our technical staff to identify the groundwater level and to verify that the actual soil conditions are consistent with those encountered during this exploration. LATERAL PRESSURES- Lateral earth pressures are affected by wetting of the backfill soils, backfill compaction densities, type and slope of backfill materials, allowable wall movements and surcharge loading. Hydrostatic pressures could also be imposed from water collecting behind the foundation walls. Additional lateral forces may be imposed from the equipment used during backfilling operations. All of these factors shall be taken into account when calculating the backfill pressures and designing the foundation walls. We recommend a perimeter drain system as outlined in the BELOW-GRADEFLOORSAND SUBDRAINS section of this report to minimize the accumulation of water behind foundation walls. A minimum equivalent fluid density of 35 pcf (active) should be used for normally compacted, on -site soils when designing the foundation walls 0 Lot 9B, Tefft Acres ' SCA Project No.:] 153-11-02-01 February 3, 2003 should extend a minimum of two (2) feet beyond the edges of the pads. All fill should be placed, compacted, tested and approved in accordance with the recommendations contained in the Section t "Site Grading and Utilities", and Appendix A of this report. ' The following recommendations should be followed in the design of the foundation system: 1 1. All footings and pads should bear below frost depth. Frost depth in this area is considered to be thirty (30) inches. 2. Foundation walls should be reinforced with rebar to span an unsupported length of ten (10) feet. Rebar should be run continuously around corners and should be properly spliced. Foundations should be designed by a Registered Engineer for the conditions described in this report. 3. All footings and pads should bear on similar strata. 4. We recommend the performance of an excavation inspection to make a final determination of foundation type and validate these recommendations. A test ' pit should be excavated at least three (3) feet deeper than the foundation elevations to expose the supporting soils for the inspection. The test pit shall be excavated at least five (5) feet away from any footing or pad locations. The test pits shall be filled and well compacted after all observations have been made. 5. Refer to the FLOOR SYSTEMSAND SLABS -ON -GRADE section of this report for recommendations for below -grade floor systems and slabs -on -grade. 6. To prevent over -drying, over -moistening or deterioration of the exposed soils prior , to placement of the footings, the excavation should not be left open for an extended period of time. In the event that the excavation is left open for more than one week after the open hole inspection, or if rain, snow melt or groundwater has accumu- lated in the excavation, the engineer shall be notified for a re -inspection to determine the condition of the supporting materials and make recommendations for remediation accordingly. 7. Footings or pads shall not be constructed on frozen ground, topsoil, unapproved fills or other deleterious materials. Loose soil 'shall be removed from the footing ' 8 , Lot 9B, Tefft Acres SCA Project No.:1153-11-02-01 February 3, 2003 SPREAD FOOTINGS- Based on conditions observed in the field, laboratory tests and the ' anticipated bearing loads, we feel that the structure could be supported by a continuous spread footing and isolated pad foundation. The footings should be placed on the undisturbed native silty sands, and should be kept at least six (6) feet above the groundwater. The footings should be designed for a maximum allowable bearing pressure of 1000 pounds per square foot (dead load 1 plus live load) with a minimum dead load kept as high as practicable. In the event that low strength soils are encountered in the excavation, a layer of crushed gravel ishould be compacted in the excavation to provide a stabilizing layer underneath the footings. The gravel should have a nominal particle size ranging from 3/4" to 1 %" with no more than 5% passing the #4 sieve. The recommended layer could range in thickness from two (2) to five (5) feet ' and should be determined after observation and evaluation of the excavation by the Engineer. The gravel should be worked with heavy equipment until stabile. The placement operations should be observed by the Engineer to help assure compliance with these recommendations. 1 1 If isolated areas of unacceptable soils, fill or trash are exposed during final footing excavation, these areas should be removed down to acceptable soils prior to placement of the footings. Footings can then be placed directly on the acceptable soil, or the excavation can be backfilled up to the desired footing bearing elevation with select, approved fill. The fill should extend a Iminimum 1 % times the footing width beyond the edges of the footings. Fill beneath the pads - 7 Lot 9B, Tefft Acres SCA Project No.:1153-11-02-01 February 3, 2003 immediately after completion and twenty four (24) hours after the drilling operation. At the time of our field exploration, free groundwater was encountered in Test Hole Nos. 1 and 2 at depths ranging from twelve (12) feet to fifteen (15) feet. The groundwater table can be expected to fluctuate throughout the year depending on variations in precipitation, irrigation ditch usage, surface irrigation, and runoff on the site. Based on other explorations our company has performed in this area, we feel groundwater in this area could rise significantly from present levels. The groundwater levels recorded and/or described represent the free, static water levels after equalization of hydrostatic pressures in the borings. This means that the groundwater levels recorded in the borings may not be present at those levels in the excavations. Flow rates, seepage paths, hydrostatic pressures, seasonal groundwater fluctuations, water quality and other factors were not determined in this exploration. Aprogram, which may include special well construction, test procedures, long-term monitoring program and analysis, would be necessary to determine these factors. FOUNDATION RECOMMENDATIONS Due to the potential of significant groundwater fluctuations and our experience with groundwater conditions in this area, we recommend that the maximum depth of the excavation be no greater than six (6) feet below existing grade. G Lot 9B, Tefft Acres SCA Project No.: / 153-11-02-01 February 3, 2003 loose to dense, and dark brown to reddish brown in color. The sands exhibit low bearing capacities with very low to low swell potentials as detected in our tests. CLAY- Clays with slight amounts of silt were encountered from below the upper sands and extended to the depths explored of Test Hole No. 2. The clays appear to be very moist, highly 1 plastic, stiff, and olive -brown in color. The clays exhibit moderate bearing capacities with anticipated swell potentials to be high. ' CLAYSTONE- Claystone bedrock strata with moderate amounts of silt were encountered from below the upper soils to the depths explored. The upper four (4) feet appear to be slightly to moderately weathered. The competent claystone bedrock exhibits high bearing capacities with a high swell potential as detected in our test. Our experience with the bedrock in this area has shown Iit to have low to very high swell potential. Due to the often variable nature of soil deposits and sedimentary bedrock formations, it is ' impossible to fully characterize the strength and swelling properties of these materials at all 1 depths at any given site. Strata may exist at the site which possess higher or lower swell potentials than these tests indicate. GROUNDWATER- Groundwater levels were recorded as the borings were advanced, 1 5 Lot 9B, Tefft Acres SCA Project No.:1153-11-02-01 February 3, 2003 One dimensional swell/consolidation tests were performed on selected samples to evaluate the expansive, compressive and collapsing nature of the soils and/or bedrock strata. h1 the swell/consolidation test, a trimmed specimen is placed in a one-dimensional confinement ring and a vertical load of 100 psf and/or 500 psf is applied. The sample is then inundated with water and allowed to swell or consolidate until no further change in volume is recorded. The confining load is then incrementally increased until the specimen is compressed to its original volume. Results of those tests are presented at the end of this report. A calibrated hand penetrometer was used to estimate the approximate unconfined compressive strength of selected samples. The calibrated hand penetrometer has been correlated with unconfined compression tests and provides a better estimate of soil consistency than visual examination alone. SUBSURFACE CONDITIONS In summary, silty sands were encountered over silty clays and claystone bedrock strata to the depths explored. Free groundwater was encountered in two (2) of the three (3) borings. Refer to the attached boring logs and summary of laboratory tests. SAND- Sands with moderate to high amounts of silt, slight amounts of clay, and trace amounts of gravel were encountered in the upper fourteen (14) to nineteen (19) feet of Test Hole Nos. 1 and 2 and to the depths explored of Test Hole No. 3. The sands appear to be slightly moist to wet, 0 Lot 9B, Tefft Acres SCA Project No.:1153-11-02-01 February 3, 2003 descriptions of the soil and/or bedrock strata are based, primarily, on visual and tactual methods which are subject to interpretation pending other methods, classification systems and/or tests. An index of relative density and consistency was obtained in general accordance with the procedures of the standard penetration test, ASTM Standard Test D-1586. The penetration test result listed on the log is the number of blows required to drive the two (2) inch diameter split - spoon sampler twelve (12) inches (or as shown) into undisturbed soil by a one hundred forty (140) pound hammer dropped thirty (30) inches. Undisturbed samples for use in the laboratory were collected using three (3) inch O.D. thin wall samplers (Shelby) in general accordance with sections of ASTM D-1587. In this procedure, a seamless steel tube with a beveled cutting edge is pushed hydraulically into the ground to obtain a relatively undisturbed sample of cohesive or moderately cohesive soil. A two and one-half (2'/2) inch O.D. California Barrel Sampler was also used to collect partially disturbed samples. All samples were sealed in the field and preserved at natural moisture content prior to testing. LABORATORY TESTING PROCEDURES The recovered samples were tested in the laboratory to measure their dry unit weights, natural water contents, and for classification purposes. Selected samples were tested to determine strength and stability characteristics such as swelling, compressibility, collapse and shear strength. 3 Lot 9B, Tef tt Acres SCA Project No.:1153-11-02-01 February 3, 2003 west-southwest. A small irrigation lateral was noted towards the east property line and is approximately one hundred forty (140) feet east of the proposed leachfield area. FIELD EXPLORATION The field exploration was conducted on January 13, 2003. The field exploration consisted of drilling, logging and sampling three (3) borings within the approximate building envelope on the site, as indicated on the Boring Location Map. The borings were drilled to depths ranging from eight (8) to twenty four (24) feet using a truck -mounted continuous flight auger drilling rig. Percolation tests were conducted on January 14, 2003. The boring locations were established by Scott, Cox & Associates, Inc. personnel based on a site plan provided by Mr. Richard Pitner of Pitner Construction Inc.. Distances from the referenced features are approximate and were made by pacing. Angles for locating the borings were estimated. The boring locations should be considered accurate only to the degree implied by the methods used to make those measurements. Logs of the boring operations were compiled by a representative of our firm as the borings were advanced. The graphical logs of the borings are presented in Figure No. 3. Soil sampling was concentrated at approximate foundation -influence elevations. The approximate location of soil and rock contacts, free groundwater levels, samples and standard penetration tests are shown on each boring log. The transition between different strata can be, and often is, gradual. . The 2 ' Lot 9B, Tefft Acres SCA Project No.:] 153-11-02-01 SCOPE February 3, 2003 The following report presents the results of our geotechnical and percolation exploration for Lot 913, Tefft Acres, Larimer County, Colorado. The building is anticipated to be of typical wood frame construction. Full basement construction with a cast -in -place concrete foundation is anticipated for this structure. The depths of foundation construction are anticipated to range from three (3) to six (6) feet below grades which existed at the time of this exploration. It is anticipated that final grades may be adjusted to accommodate drainage and construction depths. It is recommended that we review the final grading plan to determine if any revisions to the recommendations presented in this report are necessary. The purpose of this exploration was to identify subsurface conditions and obtain the test data necessary to provide recommendations for design and construction of foundations, below -grade Door systems and slabs -on -grade and sewage disposal system. The conclusions and recommen- dations presented in this report are based upon the acquired field and laboratory data and on previous experience with subsurface conditions in this area. SITE DESCRIPTION The site is located west of Fort Collins, west of South Taft Hill Road, north of Horsetooth Road and on the west side of Moore Lane. The site is generally in a plains area and is primarily vegetated with grasses and weeds. At the time of our exploration the site was partially developed with utilities and paved roads. The building site on the 4.7+ acre parcel has a gentle slope to the 1 TABLE OF CONTENTS SCOPE.................................................................... 1 SITE DESCRIPTION........................................................ 1 FIELD EXPLORATION...................................................... 2 LABORATORY TESTING PROCEDURES ..................................... 3 SUBSURFACE CONDITIONS ................................................. 4 FOUNDATION RECOMMENDATIONS ........................................ 6 FLOOR SYSTEMS AND SLABS -ON -GRADE ................................... 9 BELOW -GRADE FLOORS AND SUBDRAINS.................................. 11 EARTHWORK............................................................ 12 PERCOLATION INVESTIGATION ........................................... 15 GEOTECHNICAL LIMITATIONS ............................................ 18 APPENDIXA.............................................................. Al LIST OF FIGURES BORING LOCATION AND SITE MAP ..................................... Figure 1 LEGEND OF SYMBOLS ............................................... Figure 2 SUMMARY LOG OF BORINGS ......................................... Figure 3 PERCOLATION TEST FORM ........................................... Figure 4 SUMMARY OF LABORATORY TEST RESULTS ........................... Table 1 1 SCOTT, COX & ASSOCIATES, INC. consulting engineers February 3, 2003 Pitner Construction Inc. ' 3209 Moore Lane Fort Collins, Colorado 80526 RE: Geotechnical and Percolation Exploration for Lot 9B, Tefft Acres, Larimer County, Colorado Scott, Cox & Associates, Inc. Project No.:1153-11-02-01 Gentlemen: The enclosed report presents the results of a geotechnical and percolation exploration for Lot 9B, Tefft Acres, Larimer County, Colorado. This report contains the results of our exploration and recommendations concerning design and construction of the foundation, ground -level floor systems and slabs -on -grade. In summary, silty sands were encountered over silty clays and claystone bedrock strata to the depths explored. Although the soils and/or rock appear to be suitable for support of the proposed home, care will be needed in both the design and construction of the building to minimize the potential for foundation and floor slab movement. Site conditions indicate that a standard absorption sewage disposal system is suitable at the test site. We appreciate the opportunity to be of service to you on this project. If you have any questions, please feel free to call. Sincerely, SCOTT, COX & ASSOCIATES, INC. �t Aazl <� ; Gary J. Higgins, :p betteE R.B "Chip " Lead 4 . \ r'III ',� ' Geologist Chief Geotechnical Erigiii ,,��,G �+NAL. ti G. IGeotechnicallReportslPitner, DickM Tefft AcreslS & P report.wpd 110602 5110 Granite Street, Suite D • Loveland, Colorado 80538 • (970) 663-0138 • Fax: (970) 663-1660 Serving Colorado with offices in 9 Boulder • Longmont • Loveland GEOTECHNICAL AND PERCOLATION EXPLORATION FOR LOT 913, TEFFT ACRES, LARIMER COUNTY, COLORADO Prepared for: Pitner Construction Inc. 3209 Moore Lane Fort Collins, Colorado 80526 February 3, 2003 Project No.:1153-11-02-01 Prepared By SCOTT, COX & ASSOCIATES, INC'. 5110 Granite Street, Suite D Loveland, Colorado 80538