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Home My WebLink About20250070.tiffGEOTECHNICAL EXPLORATION FOR LOT A, RECORDED EXEMPTION NO. 0805-06-03, RECX 17-0026, PART OF THE WA OF THE WA OF SECTION 6, TOWNSHIP 6 NORTH, RANGE 66 WEST, WELD COUNTY, COLORADO FOR MATT LEMKE CDS ENGINEERING CORPORATION LOVELAND, COLORADO PROJECT NUMBER 20-0401 JULY 9, 2020 CDSEngineering Corporation July 9, 2020 Project No. 20-0401 Mr. Matt Lemke 1234 103rd Avenue Greeley, CO 850634 Dear Matt, Enclosed is the report you requested of the geotechnical exploration for the proposed residence to be located on Lot A, Recorded Exemption No. 0805-06-03, RECX 17-0026, Part of the W1/2 of the Wi/2 of Section 6, Township 6 North, Range 66 West, Weld County, Colorado. The site appears to be suitable for the construction of the proposed residence, provided the design criteria and recommendations given in this report are followed. If you have any further questions concerning the information in this report, please contact this office. Respectfully, FOR AND ON BEHALF OF CDS ENGINEERING CORPORATION V / Kevin F. Becker!? Enclosures ~St. • :�s:.. rt r h us," la" 7si ins!, 4. • #.:..rutfS to �; .a"f D 'kY a a Y A, • 0 4 0 t1• c i 6 k ` 0 04404,412e. u o• 0 f. 165 2nd Street S.W. • Loveland, CO 80537 • (970) 667-8010 • Fax (970) 667-8024 • www.cds-eng,net TABLE OF CONTENTS Page Letter of Transmittal Table of Contents Scope Site Investigation Site Location and Description Subsurface Conditions Foundation Recommendations - Continuous Spread Footing and Isolated Pad Foundation Lateral Earth Pressures Slab Construction Foundation Drain System Conclusions ATTACHMENTS Location of Test Borings Symbols and Soil Properties Log of Borings Swell -Consolidation Test Results Summary of Test Results Post -Construction Site Preparation and Maintenance Typical Perimeter Drain Details Placement of Compacted Fill Materials ii i ii 1 1 2 2 2 2 3 4 5 5 Figure No. 1 Figure No. 2 Figure No. 3 Figure No. 4 Table No. 1 Appendix 1 Appendix 2 Appendix 3 1 SCOPE This report presents the results of a geotechnical exploration for the proposed residential building to be located on Lot A, Recorded Exemption No. 0805-06-03, RECX 17-0026, Part of the W1/2 of the W1/2 of Section 6, Township 6 North, Range 66 West, Weld County, Colorado. The building is anticipated to be of typical wood or steel frame construction. Slab -on -grade construction is anticipated for this structure, with the anticipated foundation bearing depths to range from one (1) to two (2) feet below grades which existed at the time of this exploration. This exploration was conducted to provide recommendations pertaining to the type and depth of foundation system, allowable soil bearing pressures, groundwater conditions, and to identify any complications that may be encountered during or after construction due to subsurface conditions. SITE INVESTIGATION The field investigation performed on June 11, 2020, consisted of drilling, logging, and sampling one (1) test boring within the approximate building envelope at the site. The boring was drilled to a depth of sixteen (16) feet. The location of the Test Hole is shown on Figure No. 1. The boring location was established by a representative of CDS Engineering Corporation based on locations provided by the Matt Lemke. A graphical log of the boring is shown on Figure No. 3. The descriptions of the soils and/or bedrock strata are based, primarily, on visual and tactual methods which are subject to interpretation. The test boring was advanced using a truck mounted, four (4) inch diameter, continuous flight auger drill rig. Laboratory samples were obtained by driving a two and one-half (21/2) inch diameter California Barrel Sampler twelve (12) inches (or as shown) into undisturbed soils with a 140 -pound hammer falling thirty (30) inches. Bag samples of auger cuttings may have also been collected. Laboratory tests performed were - Swell -Consolidation, Natural Moisture, Natural Dry Densities, Unconfined Compressive Strengths, and Atterberg Limits. All tests were conducted in accordance with ASTM standards. A Summary of the Swell -Consolidation Test Results is shown on Figure No. 4. A Summary of Test Results is shown on Table No. 1. 2 SITE LOCATION AND DESCRIPTION The site is located east of Severance, on the southeast corner of County Roads 74 and 25, Weld County, Colorado. The site is generally in a plains region with dirt roads and utilities, and vegetation consists primarily of an irrigated grass field. The site has a gentle slope to the west. No rock outcrops or water features were observed at this site. SUBSURFACE CONDITIONS Based on the boring drilled within the proposed building footprint, the subsurface conditions at the site consist of clay over weathered sandstone. Groundwater levels were recorded after completion of the drilling operations. During our field exploration groundwater was encountered in the test boring at a depth of five (5) feet. Follow- up measurements indicated groundwater at depths ranging from three and one-half (31/2) to four and one-half (41/2) feet. The water levels listed above are the stabilized levels of the free groundwater surface at the time of this exploration and may not properly define yearly groundwater levels. The groundwater table should be expected to fluctuate throughout the year depending on seasonal moisture variations. Refer to the Log of Borings, Figure No. 3, for additional details specific to each boring. FOUNDATION RECOMMENDATIONS The type of foundation best suited for a particular building site is dependent not only on the characteristics of the soil and rock but also depends on the type of structure, depth to groundwater, the proposed depth of excavation, and owner preference. The recommendations that follow are primarily based on the type of soil encountered. Based on the conditions observed in the field and laboratory tests, we recommend the foundation be a continuous spread footing and isolated pad foundation. Continuous Spread Footing and Isolated Pad Foundation The foundation should be a continuous spread footing and isolated pad foundation designed for a maximum allowable bearing capacity of 1000 pounds per square foot (dead load plus full live load). The bottom of the footings should be kept a minimum of two (2) feet above the 3 groundwater. The foundation is to bear on the native, undisturbed clays, and not on unapproved fill, topsoil, or frozen ground. The bottom of all foundation components should be kept at least thirty (30) inches (or per local code) below finished grade for frost protection. The open excavation should not be left open for an extended period of time or exposed to adverse weather conditions. Excessive wetting or drying of the excavation should be avoided during construction. Excavations that are inundated with water may soften and require re - compaction, or removal, of the exposed subgrade soils. The completed open excavation should be observed by a representative of CDS Engineering Corporation in order to verify the subsurface conditions from test -hole data. In the event that low strength soils are encountered in the excavation, we recommend a layer of washed gravel, or equivalent, be placed in the excavation to provide a stabilizing layer under the footings. The gravel shall have a minimum diameter of 3/4" and should have no more than 5% passing the #200 sieve. The gravel should be a minimum of twelve (12) inches thick. The gravel should be worked into the excavation with heavy equipment until stable. The placement operations should be observed by the engineer to help assure compliance with the recommendations. LATERAL EARTH PRESSURES Lateral earth pressures are forces exerted on earth retaining structures and foundation components, by the soil. The pressure exerted is influenced by wetting of the backfill soils, type and compaction of the backfill and the methods used to compact the backfill. For the soils, above the free groundwater surface at this site, we recommend the foundation components be designed using the following equivalent fluid pressures. • Active Pressure = 40 pcf • At Rest Pressure = 65 pcf These values assume that the positive drainage will be maintained throughout the life of the structure. It is our opinion that the on -site soils encountered could be used as backfill material against foundation walls. The soils shall be moisture conditioned and well pulverized so that all fragments are smaller than six (6) inches. Refer to Appendix 1 for additional backfill information. 4 If there is opportunity for the backfill soils to become saturated, we shall be notified to revise the minimum equivalent fluid density. These values do not include a factor of safety or take into account any surcharge loading. SLAB CONSTRUCTION Changes in the moisture contents may result in consolidation or swelling of the subsoil, resulting in differential slab movement. The soils encountered and tested at this site exhibit no to low swell potential as moisture contents are increased. According to the Guideline for Slab Performance Risk Evaluation and Residential Basement Floor System Recommendations, developed by the Colorado Association of Geotechnical Engineers, slab performance risk at this site would be considered low. Slabs placed on the native, unaltered soils at this site may experience slight heaving and cracking, but should not be excessive. If slabs -on -grade are chosen and the owner is willing to accept the risks of potential damage from slab movement, slabs should be constructed to be "free-floating" and isolated from all structural members of the foundation, utility lines, and partition walls. There should be a minimum two-inch (2") void constructed below partition walls located over slabs -on -grade. The void should be increased to four (4) inches for slabs placed on potentially expansive bedrock stratum. Eliminate under -slab plumbing where feasible. Where such plumbing is unavoidable, it should be pressure tested before and after slab construction to minimize leaks which would result in wetting of the subsoil. Failure to allow the slab to float independently could result in functional, structural, architectural, and utility line damage. All slabs should be scored into maximum 225 square foot areas or maximum dimensions of fifteen (15) feet with a minimum depth of one (1) inch to localize and control any cracking due to heaving. Any slabs less than thirty (30) square feet should be scored at least once in each direction. The minimum slab thickness should be four (4) inches, with four (4) inches of clean, washed gravel under the slab. Slabs should be reinforced with welded wire fabric, or equivalent, to help control cracking and separation. Fiber mesh shall not be considered an equivalent substitute for the welded wire fabric. Slab -on -grade areas should not be finished for at least two (2) years (preferably three (3) to five (5) years) from the time of substantial completion, to allow for initial movement. 5 FOUNDATION DRAIN SYSTEM A perimeter drain system shall be installed where below grade floors are constructed. The drain shall be constructed around the entire exterior perimeter of the foundation of any below grade living space. Providing an interior perimeter drain in lieu of, or in addition to, the exterior drain should be determined at the excavation observation. Perimeter drains around crawl space areas, in our opinion, would be considered optional; however, may be required by local jurisdictions. The drain system should contain a four (4) inch diameter perforated drainpipe surrounded by a minimum of twelve (12) inches of clean, washed rock. There should be a minimum of eight (8) inches of gravel over the top of the pipe, for the full width of the trench. The gravel shall be covered with untreated building paper or geotextile fabric to minimize clogging by backfill material. The drain should have a positive slope to a non -perforated sump pit or to daylight, well away from the foundation. The sump pit should be a minimum of twenty-four (24) inches in diameter by two (2) feet deep and should be surrounded by at least six (6) inches of clean gravel similar to that provided around the drain. The sump pit shall be capable of positive gravity or mechanical drainage to remove any accumulated water. The drainage system shall discharge a minimum of five (5) feet beyond the backfill zone. The discharge area should be placed so that it does not interfere with adjacent properties. Typical drain details are provided in Appendix 2 of this report. CONCLUSIONS The soils and rock encountered at this site exhibit no to low swell potential as moisture contents are increased. Future owners should be cautioned that there may be some risk of future damage caused by introduction of excess water to the soils and/or rock. All new and future owners should be directed to those items under "Post -Construction Site Preparation and Maintenance" in Appendix 1, included in this report. Our experience has shown that damage to foundations usually results from saturation of the foundation soils caused by improper drainage, excessive irrigation, poorly compacted backfills, and leaky water and sewer lines. The elimination of the potential sources of excessive water will greatly minimize the risks of movement at this site. It is recommended that a copy or summary of this report be provided to any new or future owners of 6 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 findings and recommendations of this report have been obtained in accordance with accepted professional engineering practices in the field of Geotechnical Engineering. However, standard Geotechnical Engineering practices and related government regulations are subject to change. The recommendations provided in this report are only valid as of the date of this report. If the construction is at a later date, we would be glad to review the information presented in this report with regard to updated governmental requirements or industry standards. There is no other warranty, either expressed or implied. 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 report applies only to the type of construction anticipated in the area tested. The current technology is not at a stage where a guarantee of "absolutely no damage" can be assured by design and construction practices. Client: Matt Lemke Project: Lot A, Recorded Exemption No. 0805-06-03 RECX17-0026, Weld County, Colorado LOCATION OF TEST BORINGS Approximate Scale: 1" = 200' Project No. 20-0401 CDS Engineering Corporation 165 2nd St. S.W. Loveland, CO 80537 Tele: (970) 667-8010 I Fig. No.: 1 . A, I r • f • • F. �• d ' '1 • .r • ... 1'-, /// /// 7 ..., ,./.<,/,:;:. \\ b., ..: .....„ 1 i i ...rr J „J„ 0_, �J„_,. s y mbols & Soil FIGURE HO. 2 Fill Gravel Sand Silt Silty Clay Clay Weathered Bedrock Sil tston e Claystone Sandstone Limestone Igneous & Metamorphic �a 3 I rtics N/12 CALIFORNIA N/12 SPLIT SPOON THIN WALLED (SHELBY) BAG SAMPLE PITCHER SAMPLE Penetration Resistance and Strength Classifications are Based on The Standard Penetration Test Number of Blows Per foot (N)* 0-4 4-10 10-30 30-50 50+ Relative Density Cohesionless Soils Very Loose Loose Medium Dense Very Dense * BLOWS PER FOOT - BLOWS OF 140 LB. HAMMER DROPPED 30 IN. TO DRIVE SPLIT SPOON OR CALIFORNIA SAMPLER 12" (IN.) (ASTM DL586-67) ** EQUIVALENT TO PP/2 AND Qu/2 Consistency Cohesive Soils Soft Firm Stiff Very Stiff Hard Approximate Cohesion ksf** Less than 0.5 0.5-1.0 1.0-2.0 2.0-4.0 Greater than 4.0 CDS Engineering Corporation 165 2nd St. S.W. Loveland, CO 80537 Tele: (970) 667-8010 t 0 0 X m = w r O 5 FT. 10 FT. 15 FT. 20 FT. 25 FT. 30 FT. 35 FT. 0 FT. TH-1 V V 8/12 0 FT. 9/12 50 /1 2 50/12 CLAY: tr. sand moist to v. moist, firm, dark brown Sandstone: weatherd, silty, moist, hard, gray/brown 0 0 N M 13 a= m GO m r O 5 FT. 10 FT. 15 FT. 20 FT. 25 FT. 30 FT. 35 FT. Borings drilled 06/11/20 using a 4" diameter, continuous flight truck mounted drilling rig. V V Groundwater © drilling Groundwater on 06/15/20 Groundwater by client 06/25/20 All soil and/or rock contacts shown on boring logs are approximate and represent subsurface conditions at time of drilling. Boring logs and information presented on logs are subject to discussion and limitations of this report. LOG OF BORINGS CLIENT: Matt Lemke PROJECT NO. 20-0401 PROJECT LOCATION Lot A, Recorded Exemption No. 0805-06-03 RECX17-0026, Weld County, Colorado Engineering Corporation Fig. No.: 3 I 165 2nd St. S.W. Loveland, CO 80537 Tele: (970) 667-8010 SWELL / CONSOLIDATION TEST CURVES Client: Matt Lemke Project: Lot A RE -0805-06-03, Recx. 17-0026, Weld Co. Project No.: 20-0401 Boring: TH-1 Depth, ft: 2' Swell (%):* 0.0 100 6 5 4 3 2 1 et V 0 Ca 0 -2 -3 -4 -5 -6 Description: Clay, dk. brown, v. moist, firm Water Content: 21.7% Dry Density, pcf: 106.0 Approximate Swell Pressure, psf: 500 Pressure, psf 1000 10000 Boring: TH-1 Depth, ft: 10' Swell (%):* -0.1 Volume Change, 6 5 4 3 2 I 0 -2 -3 -4 -5 -6 100 Description: Wx. Sandstone, brown, moist, v. stiff/hard Water Content: 22.3% Dry Density, pcf: 93.4 Approximate Swell Pressure, psf: Pressure, psf 1000 10000 CDS Engineering Corporation * negative values indicate consolidation Figure 4 SUMMARY OF TEST RESULTS TABLE NO. 1 Project No.: 20-0401 Boring No. Depth (ft) # of penetration blows/ Moisture Natural (%) Natural Density (pcf) Dry Swell* (%) Swell @ Surcharge Pressure 500 psf Swell @ Surcharge Pressure 1000 psf Atterberg Limits Unconfined (psf) Unconfined #4 Seive Passing / #200 (%) Description (%) LL (%) PI Compressive Strength Compressive Strength**(psf) 1 2 8/12 21.7 106.0 0.0 500 Clay 1 6 9/12 24.6 107.3 33 14 1,020 Clay 1 10 50/12 22.3 93.4 -0.1 Wx. Sandstone 1 16 50/12 23.1 Wx. Sandstone r *Swell due to wetting under a 500 psf or 1000 psf surcharge - Negative values indicate consolidation **Unconfined compressive strength estimated using a pocket penetrometer Sheet 1 of 1 APPENDIX 1 POST -CONSTRUCTION SITE PREPARATION AND MAINTENANCE Backfill When encountering potentially expansive or consolidating soils, measures should be taken to prevent the soil from being wetted during and after construction. Generally, this can be accomplished by ensuring only minimal settlement of the backfill placed around the foundation walls. It should be understood that some backfill settlement is normal and should be anticipated. Areas that do settle should be repaired immediately to prevent ponding around the foundation. Water may need to be added to backfill material to allow proper compaction -- do not puddle or saturate. Backfill should be mechanically compacted to at least 90% of Standard Proctor. Compaction requirements could be verified with field tests by the Engineer. It is the contractor's responsibility to contact the engineer for such tests. Surface Drainage The final grade should have a positive slope away from the foundation walls on all sides. At minimum, the slope shall meet the requirements of the governing Building Code. Where site grading allows, we recommend a minimum of six inches (6") in the first five feet (5'). Downspouts and sill cocks should discharge into splash blocks that extend beyond the limits of the backfill. Splash blocks should slope away from the foundation walls. The use of long downspout extensions in lieu of splash blocks is advisable. Surface drainage away from the foundation shall be maintained throughout the lifetime of the structure. Lawn Irrigation Do not install sprinkler systems next to foundation walls, porches, or patio slabs. If sprinkler systems are installed, the sprinkler heads should be placed so that the spray from the heads under full pressure does not fall within five feet (5') of foundation walls, porches, or patio slabs. Lawn irrigation must be carefully controlled. If the future owners desire to plant next to foundation walls, porches, or patio slabs, and are willing to assume the risk of structural damage, etc., then it is advisable to plant only flowers and shrubbery (no lawn) of varieties that require very little moisture. These flowers and shrubs should be hand watered only. Landscaping with a plastic covering around the foundation area is not recommended. Check with your local landscaper for fabrics which allow evaporation when inhibiting plant growth when a plastic landscape covering is desired. Experience shows that the majority of problems with foundations due to water conditions are generally due to the owner's negligence of maintaining proper drainage of water from the foundation area. The future owners should be directed to pertinent information in this report. REV 7/30/13 EXEHOR AID/OR FOOT N COMPACTED BACKFILL PER SOIL REPORT UNTREATED BUILDING PAPER OR GEOTEXTILE OVER TOP OF GRAVEL CLEAN WASHED ROCK. MINIMUM OF 8" OVER THE TOP OF THE PIPE 4" PERFORATED PIPE, RIGID OR FLEXIBLE. SLOPE TO SUMP PIT OR DAYLIGHT. IN T1 - PO OR PEHVHEH NDATION FDN WALL, TYP. REINFORCEMENT NOT SHOWN DRA N OPTIONAL MOISTURE BARRIER. 6 -MIL MINIMUM, GLUE TO FOUNDATION WALL A MINIMUM OF 6" ABOVE VOIDS OR GRAVEL (WHICHEVER IS GREATER). CONTINUE BELOW PIPE AND UP SIDE OF TRENCH AS SHOWN. FLOOR BY OTHERS ADDT'L LATERALS AS RECOMMENDED 10' TO 12' DRAIN TRENCH SHALL NOT CUT INTO 1:1 SLOPE AWAY FROM THE EDGE OF THE FOOTING EXHH OR A DR COMPACTED BACKFILL PER SOIL REPORT N UNTREATED BUILDING PAPER OR GEOTEXTILE OVER TOP OF GRAVEL CLEAN WASHED ROCK. MINIMUM OF 8" OVER THE TOP OF THE PIPE 4" PERFORATED PIPE, RIGID OR FLEXIBLE. SLOPE TO SUMP PIT OR DAYLIGHT. D/OH ILLED IN D TFHOH �R FOU PHHMF EH DATION FDN WALL, TYP. REINFORCEMENT NOT SHOWN RA N MOISTURE 3ARIER. 6 -MIL MINIMUM, GLUE TO FOUNDATION WALL A v1INIvUM OF 6" ABOVE VOIDS OR GRAVEL (WHICHEVER IS GREATER). CONTINUE BELOW PIPE AND UP SIDE OF 1RENCH AS SHOWN. FLOOR BY OTHERS ADDT'L LATERALS AS RECOMMENDED 10' TO 12' Engineering Corporation 165 2nd St. S.W. Loveland, CO 80537 Tele: (970) 667-8010 TY HECO VVEN CALP DA MI- TER DRAH TIONS SITE CONDITIONS MAY WARRANT REVISIONS TO TYPICAL DETAILS Scale: N.T.S. APPENDIX 2 APPENDIX 3 GENERAL SPECIFICATIONS FOR THE PLACEMENT OF COMPACTED FILL MATERIAL PLACED BELOW A STRUCTURE Moisture -Density Determination Representative samples of the materials to be used for fill shall be furnished by the contractor at least seventy two (72) hours prior to compaction testing. Samples with higher moisture contents will require extra time for test results due to the required drying for sample preparation. Tests to determine the optimum moisture and density of the given material will be made using methods conforming to the most recent procedures of ASTM D698 (standard Proctor) or other approved methods, whichever may apply. 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. Materials The soils used for compacted fill shall be selected or approved by the Engineer. The material shall be free of vegetation, topsoil or any other deleterious materials. The material should be relatively impervious and non -swelling for the depth specified in the soils report with no material greater than six (6) inches in diameter. Site Preparation All timber, logs, trees, brush and rubbish shall be removed from the area and disposed in a manner approved by the local governing agency. All vegetation and a substantial amount of topsoil shall be removed from the surface upon which the fill is to be placed. Where applicable, the surface shall then be scarified to a depth of at least six (6) inches, moistened or dried as necessary to allow for uniform compaction by the equipment being used. The scarified surface shall be compacted to not less than 95% of maximum dry density based on ASTM D698, or to such other density as may be determined appropriate for the materials and conditions and acceptable to the Engineer. Fill shall not be placed on frozen or muddy ground. Moisture The fill material, while being compacted should contain, as nearly as practical (typically +/- 2%), the optimum amount of moisture as determined by the Standard Proctor Test ASTM D698, or other approved method. The moisture shall be uniform throughout the fill material. The effort required for optimum compaction will be minimized by keeping soils near optimum moisture contents. Freezing temperatures and/or inclement weather conditions may impede moisture control and compaction operations. Placement of Fill The Geotechnical Engineer shall be retained to supervise the place ment p ment of fill material. The fill material shall be placed in uniform layers and be compacted to not less than 95% ma ximum of maximum dry density based on ASTM D698, or to such other density as may be determined appropriate appropriate for the materials and conditions and acceptable to the Engineer. Prior to compacting, each layer shall have a maximum loose layer height of twelve as (12) inches dictated by the compaction equipment and/or soil conditions) with the surface relatively level. Test areas are e recommended to determine the optimum layer thickness. Thinner lifts may be necessary in order to achieve the required compaction. Compacted layer thickness shall not exceed six(6)inches. . Each twelve (12) inches of compacted fill shall be approved by the Engineerprior to placing succeeding g ucceeding lifts. Fill shall be compacted with machinery appropriate for the type of earthen material al being installed. Granular materials shall be compacted with vibratory type machinery. Clay and silt Yp y silt material shall be compacted with a sheepsfoot or other segmentedpad type compaction equipment. Yp p qulpment. "Wheel rolling" is not considered an appropriate method to achieve the recommended compaction compaction specifications. "Wheel rolling" is not recommended for extensive areas or depths p and cannot be relied upon to give uniform results. Moisture and Density Testing It is the contractor's responsibility to contact the Engineer with a minimum g of 24 -hours notice to schedule compaction testing. The density and moisture content of each lay er of compacted fill will be determined by the Engineer, or qualified technician, in accordance with ASTM D693 8 (nuclear method), or other approved method. If the tests show inadequate density, 1ty, that layer, or portion thereof, shall be reworked until the required conditions are obtained. Additional tional layers shall not be placed until each underlying lift has been approved. The results is of all density tests will be furnished to both the owner and the contractor by the Engineer. g Hello