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HomeMy WebLinkAboutSW5210304_Report (Geotech)_20210617Report of Subsurface Investigation And Geotechnical Engineering Evaluation Youngsville Storage Expansion Youngsville, North Carolina prepared for C4-YS, LLC Prepared by TeffaTech Engineers, Inc. NC Engineering Corp. C-1356 I NC Geology Corp. C-560 4905 Professional Court Raleigh, NC 27609 919-876-9799 TFRRATECH July 17, 2020 Mr. Michael Isaac C4-YS, LLC misaacCd,',csere.com Report of Subsurface Investigation and Geotechnical Engineering Evaluation Youngsville Storage Expansion Youngsville, North Carolina Our Project Number 121-20-101820 Gentlemen: ENGIN EERS- INC GeotechnicafEngineen . ng Environmenta(Consufting Construction Xateriids Testing TerraTech Engineers, Inc. has completed the authorized subsurface investigation and engineering evaluation for the proposed construction in Youngsville, North Carolina. The enclosed report describes our investigative procedures and presents the results of our testing and evaluation, along with construction recommendations for this project. We appreciate the opportunity to work with you on this subsurface investigation and engineering evaluation, and are prepared to follow up with the recommended construction materials testing services. If you have any questions concerning this report, please contact us. Sincerely, TerraTech Engineers, Inc. (C-1356) — �14 k ell - *i— William D. Oakes Project Manager WDO/sk JU—C, . ---- Glen A. Malpass, Ph.D., P.E. Principal Engineer TerraTech Engineers, Inc. NC Engineering Corp. C-1356 I NC Geology Corp. C-560 4905 Professional Court, Raleigh, North Carolina 27609 (919) 876-9799 TFRRATECH Page 2 SCOPE OF SERVICES ENGINEERS - INC GeotechniadEngineering Environmentaf Consulting Construction 914ateriafs Testing The scope of this subsurface investigation was outlined in our proposal number 8254-N dated July 2, 2020. The primary objectives of this investigation were to evaluate the subsurface conditions at selected locations and to provide geotechnical recommendations related to site development and foundation support. More specifically, this investigation included the following objectives: (1) To evaluate the existing subsurface soil and ground water conditions within the area of proposed construction. (2) To recommend foundation types which can safety and economically support the proposed construction. (3) To evaluate the allowable bearing pressure of the foundation subsoils encountered within the proposed building area for support of shallow foundations. (4) To make recommendations concerning site preparation and site grading. (5) To provide a discussion of the depth to the seasonal high ground water table and in -situ ground water infiltration rates in the areas of the proposed storin water management ponds and/or ditches. (6) To make design recommendations for concrete slabs -on -grade. (7) To make recommendations concerning control of ground water during construction and on a permanent basis, if necessary. (8) To make recommendations for material types and thicknesses for the planned pavement systems in the driveways and parking areas. (9) To make recommendations for achieving high density structural fill capable of satisfactorily supporting the proposed construction. (10) To make pertinent recommendations concerning quality control measures during construction. TFRPATECH Page 3 INVESTIGATIVE PROCEDURES Field Invesdimflon E N G I N E E R S - I N C GeotechnicafEnyinetring Ent4ronmenta(Consuffing Construction Watefiafs Testing The subsurface investigation consisted of 12 soil test borings in the proposed construction areas. The test borings were performed to depths between 10 to 15 feet below the ground surface. The test boring and infiltration test locations are approximately shown on Figure I included in the Appendix. The test borings were located by measuring distances and angles from existing reference points by a representative of TerraTech Engineers, Inc. Ground surface elevations were not known at the time of this report. In general, the locations of the test borings should be considered approximate. Standard penetration testing, as described in ASTM D- 15 86, was performed at selected intervals in the soil test borings. The penetration resistance, in conjunction with soil classification, provides an indication of a soil's engineering characteristics. We used the inverse borehole method (similar to percolation tests) for our water infiltration testing procedure. Detailed descriptions of the soils encountered in the test borings are provided in the Test Boring Records included in the Appendix. Ground water conditions, penetration resistances, and other pertinent information are also included. Because our samples are taken at discrete locations and depths, variations in the materials could be present that are not identified by the industry standard procedures used for this project and cannot be delineated in the Test Boring Records. Laboratory Investigation The laboratory investigation consisted of a physical examination and classification of all samples obtained from the drilling operation. Classification of the soil samples was performed in general accordance with ASTM D-2488 (Visual -Manual Procedure for Description of Soils). Soil classifications include the use of the Unified Soil Classification System described in ASTM D-2487 (Classification of Soils for Engineering Purposes). The Visual -Manual procedure used for soil classification is a qualitative analysis performed in conjunction with the education, experience and professional judgment of our geotechnical engineer. Quantitative analysis of soil properties, such as those referenced in ASTM D-2487, could result in different soil classifications. In these instances, adjustments to the design and construction may be necessary, depending on the actual conditions. The soil classifications also include our evaluation of the geologic origin of the soils. Evaluations of geologic origin arc based on our experience and interpretation and may be subject to some degree of error. TFRRATECH Page 4 GENERAL SITE AND SUBSURFACE CONDITIONS Site Location and Description E N G I N E E R S - I N C GeotechnicidEngmeenng Environmentaf Consulting Construction 94ateriafs Testing We understand that the subject site consists of two parcels (Parcel A and B) derived from a larger 20 acre parcel (Franklin County Pin 1853-31-3172) located north of the intersection of Park Avenue and Hillsboro Street in Youngsville, North Carolina. There is an existing residential home on the property with the majority of the site being used for agricultural purposes. Based on our review of the Franklin County GIS topographic map, it appears that the ground surface of the subject site has an overall relief of approximately 30 feet and generally slopes east and west from a ridge that traverses north and south through the approximate center of the property- Ret-donal Geolopry Based on a review of geologic maps, the site is located in the Raleigh Terrane of the Piedmont Physiographic Province of North Carolina. Soils in this area have been formed by the in -place weathering of the underlying crystalline rock, which accounts for their classification as "residual" soils. Residual soils near the ground surface, which have experienced advanced weathering, frequently consist of red brown clayey silt (ML) or silty clay (CL). The thickness of this surficial clayey zone may range up to roughly 6 feet. (For various reasons, such as erosion or local variation of mineralization, the upper clayey zone is not always present.) With increased depth, the soil becomes less weathered, coarser grained, and the structural character of the underlying parent rock becomes more evident. These residual soils are typically classified as sandy micaceous silt (ML) or silty micaceous sand (SM). With a further increase in depth, the soils eventually become quite hard and take on an increasing resemblance to the underlying parent rock. When these materials have a standard penetration resistance of 100 blows per foot or greater, they are referred to as partially weathered rock. The transition from soil to partially weathered rock is usually a gradual one, and may occur at a wide range of depths. Lenses or layers of partially weathered rock arc not unusual in the soil profile. Partially weathered rock represents the zone of transition between the soil and the indurated metamorphic rocks from which the soils are derived. The subsurface profile is, in fact, a history of the weathering process which the crystalline rock has undergone. The degree of weathering is most advanced at the ground surface, where fine grained soil may be present. The weathering process is in its early stages immediately above the surface of relatively sound rock, where partially weathered rock may be found. The thickness of the zone of partially weathered rock and the depth to the rock surface have both been found to vary considerably over relatively short distances. The depth to the rock surface may frequently range from the ground surface to 60 feet or more. The thickness of partially weathered rock, which overlies the rock surface, may vary from only a few inches to as much as 40 feet or more. Stream valleys in this area often contain alluvial (water deposited) soils, depending on ground surface topography, stream flow characteristics, and other factors. By nature, alluvial soils can be highly variable depending upon the energy regime at the time of deposition. Coarse materials such as sand or gravel are deposited in higher energy environments, while fine grained materials such as silt and clay are deposited in low energy environments. Alluvial soils may also contain significant amounts of organic materials, and are frequently in a loose, saturated condition. In many cases, fine grained alluvial soils will be highly compressible and have relatively low shear strength. TFRPATECH Page 5 Document Review ENGINEERS - INC Geotechn-dEngi— . ng Environmenta(Consulting Construction 911ateriafs Testing We have reviewed the USDA Web Soil Survey for information related to the expected soil conditions at the subject property. Based on our review, the soils at the site are expected to consist of Cecil series soils. The Cecil series soils typically consist of gently sloping to steep, well -drained, deep soils of the Piedmont uplands consisting of silty sands, clayey gravels, silts and clays. Some of the soils in the Cecil Series include elastic silts. The soils in this series are described as having a low to moderate potential for volume change. Rock is generally expected at depths of 5 to more than 15 feet below the ground surface. The depth to the expected seasonal high groundwater table is greater than 10 feet. These soils can be identified as CaB and CaC on Figure 2 in the Appendix. General Subsurface Conditions Each of the test borings encountered a surficial layer of topsoil that ranged in thickness from 2 to 3 inches. Based on our experience, the thickness of topsoil materials will be generally quite variable and could be significantly different at other locations on the site. Therefore, the reported topsoil thicknesses should not be used for detailed quantity estimates. Although not encountered in our test borings, our experience indicates that cultivated soils are often found in areas used for agricultural purposes. Beneath the topsoil, residual soils were encountered in each test boring location. These materials typically classified as fine to medium silty sands (SM), sandy clays (CL) and sandy silts (ML) with varying amounts of small mica flakes. Standard penetration resistances in the residual soils ranged from 9 to 33 blows per foot. Ground water was not encountered in our test borings at the time of drilling. However our test borings caved in at depths of 7.0 to 13.0 feet below the existing ground surface. Based on our experience and the soils present in our test borings, ground water is likely to be encountered at elevations just below the cave-in depth at the test borings. It should be noted that ground water levels will fluctuate depending on seasonal variations of precipitation and other factors and may occur at higher elevations at some time in the future. Detailed descriptions of the materials encountered in our borings are provided on the Test Boring Records included in the Appendix. TFRP4TECH Page 6 PROPOSED CONSTRUCTION ENGIN EERS- INC Geotechnica(Engineering Enviro nmen tal Consulting Construction Waterials Testing We understand the subject site is to be developed with a self -storage facility, associated parking and driveway areas and at least two ponds or trenches for the infiltration of storm water. We expect the buildings will be a single or two story , steel framed and/or load bearing masonry structures with a concrete slab -on -grade floor. Loading conditions for the planned building are not currently known. However, based on our experience, we estimate maximum wall and column loads of 3 kips per lineal foot and 50 kips, respectively. Site grading plans have not been provided to us. Traffic volumes in the planned pavement areas are not currently known. For purposes of this report and based on the planned building and parking lot size, we have estimated a maximum traffic volume of 200 cars per day and 25 moving trucks per week. If actual traffic volumes are greater than these assumed maximums, please contact us and we will review our recommendations for applicability to the actual traffic volumes. TERRATECH Page 7 EVALUATIONS AND RECOMMENDATIONS E N G I N E E R S - I N C GeotechdofEngineering Ensdronmenta(Consulting Construction Materiafs Testing The following preliminary evaluations and recommendations are based on the data obtained from our soil test borings, and our experience with soils and subsurface conditions similar to those encountered at this site. Because the test borings represent a very small statistical sampling of subsurface conditions, it is possible that conditions may be encountered during flirther investigation or construction that are substantially different from those indicated by the test borings. In these instances, adjustments to the design and construction may be necessary depending on actual conditions. General Site Preearation All topsoil, roots, trees, vegetation and other deleterious materials should be removed from the proposed construction areas. Site clearing and stripping should be performed only during dry weather conditions. Operation of heavy equipment on the site during wet conditions could result in excessive mixing of topsoil and organic debris with clean underlying soils. Topsoil containing greater than 3% organic matter by weight should be removed. Based on our observations at the site, a residential structure is currently present. Therefore, it is possible that water wells and/or septic tanks are located on the property. We recommend that all wells be filled in with concrete and closed in accordance with the Franklin County Health Department requirements. Concrete should be pumped or tremied into the wells to an elevation approximately 5 feet below the finished subgrade. Then, excavate and remove the well casings to a depth 5 feet below finished subgrade and backfill with well compacted ABC stone meeting the NCDOT Standard Specifications for gradation. The crushed stone should be placed in 6 inch loose lifts and compacted with "wacker-packers" or other suitable equipment to at least 95 percent of the standard Proctor (ASTM D-698) maximum dry density. The excavation should be backfilled to return to the originally planned finished subgrade. Septic tanks and associated drain fields should be removed backfilled with suitable compacted fill soils in accordance with the structural fill section of this report. After completion of site clearing, grubbing and stripping of topsoil relocation and removal of existing underground utilities, we recommend that proofrolling operations be performed. All areas of the site which are to receive fill should be proofrolled prior to placement of structural fill. Areas of proposed excavation should be proofrolled after rough finished subgrade is achieved. Proofrolling should be performed using a loaded dump truck weighing at least 25 tons. Proofrolling should be accomplished by performing at least 3 passes in each of two perpendicular directions within entire construction areas, and 10 feet beyond. Any unsuitable materials that may be present, and any low consistency soils that are encountered which cannot be adequately densified in place, should generally be removed and replaced with well compacted fill material placed in accordance with the Structural Fill section of this report. Proofrolling should facilitate the identification of soft surficial soils, but should not be expected to reveal soft conditions more than 2 feet below the ground surface at the time of proofrolling. The provided site plan indicates that driveway access will be provided to the property along Park Avenue. Based on our site observations, there are currently drainage ditches located along the edges of the existing road. Our experience with similar sites indicates that soft, wet soils are often present in road ditches, and that underground utility lines in these areas can complicate preparation of pavement subgrades. We recommend that all underground utility lines be located in the proposed driveway areas prior to performing site grading in the driveway areas, and that a series of hand auger borings or test pits be performed to TFRRATECH Page 8 E N G I N E E R S - I N C geotechnicafEngineering EnvironmentalConsulting Construction 9daterials Testing determine, on a preliminary basis, if remedial measures will likely be required. Obtaining this information prior to grading will allow development of a suitable approach for preparation of the pavement subgrades to facilitate timely construction in these areas. Based on our experience with similar soil conditions, some softening of the near surface and exposed soils should be expected during times of wet weather. The depth of soft soils caused by wet weather can be highly variable, and can be dependent on the slope of the ground surface, the presence of on -site or off -site sources of surface water, and other factors. Therefore, we recommend that site preparation operations be performed during times of dry weather. While wet weather can occur at any time during the year, the summer and early fall are times when drier weather is generally prevalent. Scheduling site grading during this time frame would reduce the probability of softening of the near surface soils from inclement weather conditions. Based on our experience on similar sites, there may also be buried foundations, bum pits or trash pits. On sites located near developed areas, this is not an unusual occurrence. All too frequently such buried material occurs in isolated areas which are not detected by the soil test borings. Any buried waste construction debris or trash which is found during the construction operation should be thoroughly excavated, and the waste material should be removed from the site prior to placement of fill soils. We recommend that the contract documents include a contingency cost for the removal of unsuitable materials. Excavation Characteristics The residual soils encountered in our test borings should generally be excavatable with conventional soil excavation equipment, such as scrapers, loaders, etc. However, residual soils having penetration resistances ranging from 50 to 100 blows per foot may prove to be difficult to excavate using scrapers. These hard soils may require the use of heavy dozers or loaders to effectively achieve excavation. It is possible that hard soils may require ripping in some instances. Ground Water Control Although groundwater was not encountered in our test borings, every boring caved in at depths of 7 feet to 13 feet below the existing ground surface, respectively, indicating that groundwater may have been previously present near these depths. Water levels will fluctuate depending upon seasonal variations in precipitation and may occur at other elevations in the future. In general, we expect that control of ground water in foundation excavations and utility trench excavations can be performed by pumping directly from the excavations. If pumping from the trench excavations proves ineffective, then the use of well points or other methods may be required. Pumping from dewatering trenches should be done with care to prevent loss of soil fines, boils or instability of slopes. In certain cases, gravity flow in a trench may be sufficient for effective dewatering. We note that test borings B-1 I and B-12 encountered layers of sand within the soil profile. Depending on final site grades, a perched ground water condition may be developed. This condition occurs when sandy soils are underlain by less permeable silts and clays. Finished grading should be designed to direct surface water runoff away from buildings and pavements, and roof drainage systems should discharge collected water into the storm drainage system. Depending upon conditions encountered during building construction, it may also be appropriate to install a perimeter drain around the building. The need for a perimeter foundation drain should be evaluated by our representative at the time of construction. TFRRATECH Page 9 E N G I N E E R S - I N C GeotechnicafEngineenng EnvironmentalConsuffing Construction 914atedafs Testing We must emphasize that dewatcring requirements will be dictated by ground water conditions at the time of construction. The contractor should use a technique or combination of techniques which achieves the desired result under actual field conditions. Storm Water Control Features We performed two test borings located in the areas of the proposed storm water management features (see Figure 1 in the Appendix for the test locations). We have also reviewed the USDA Web Soil Survey for this area. The soils in our test borings were generally sandy clays underlain by silty sands in test boring B-1 I and clays underlain by clayey sands and sandy silts in test boring B-12. Based on our review of the encountered soils and the recorded cave in depths, it is our opinion that a seasonal high ground water table may be present at approximately 8 feet below the existing ground surface. This is consistent with the notes from the USDA Web Soil Survey. It should be noted that layers of sand were encountered in the soil profile in test borings B-I I and B-12. Depending on final site grades, a perched ground water condition may occur under the current soil conditions. Therefore, it is possible that ground water elevations may be temporarily present at other elevations. In -situ infiltration testing was performed in the near surface soils within the proposed stormwater pond and/or ditches at the provided locations. The results of our testing in the area of 1-1 indicated that the average infiltration rate was approximately 0.9 inches per hour. The results of our testing in the area of 1-2 indicated that the average infiltration rate was approximately 0. 5 inches per hour. It should be noted that the infiltration rate of soils can depend on several factors including soil type and density. Given the variation of the soil profile encountered in test borings B- 11 and B- 12, we recommend that additional onsite infiltration testing be performed after the elevations of the planned stormwater control measures have been determined. Earth Slopes Temporary construction slopes should be designed in strict compliance with the most recent OSHA regulations. The test borings indicate that most soils at the site are Type B (residual clayey and silty soils) as defined in the Occupational Safety and Health Standards for the Construction Industry (29 CFR, Part 1926, Subpart P), July 1, 2001. This dictates that temporary construction slopes in Type B soils be no steeper than 1 horizontal to 1 for excavation depths of up to 20 feet. In Type C soils, which may be present in low- lying areas or swales of the site, temporary slopes should be no steeper than 1.5 horizontal to I vertical for excavation depths of up to 20 feet. Flatter slopes may be required, depending upon conditions encountered at the time of construction. We recommend that a "competent person" as defined in the OSHA Regulations be present on site during excavations. Temporary construction slopes should be closely observed for signs of mass movement: tension cracks near the crest, bulging at the toe of the slope, etc. If potential stability problems are observed, the Geotechnical Engineer should be immediately contacted. The responsibility for excavation safety and stability of construction slopes should lie solely with the contractor. We recommend that permanent cut or fill slopes be no steeper than 2.5 (H) to I (V) to maintain long term stability and to provide ease of maintenance. Slopes constructed steeper than 2.5 (H) to I (V) could be highly susceptible to erosion, will be difficult to maintain, and could experience large scale slope failure in some TFRRATECH Page 10 E N G I N E E R S - I N C geowfinicafEnyineefing EmdronmentafConsulting Construction Wateri& Testing instances. The crest or toe of cut or fill slopes should be no closer than 15 feet to any building foundation. The crest or toe should be no closer than 5 feet to the edge of any pavements. Foundation DesiLyn After the above described site preparation is completed, it is our opinion that the proposed structures may be supported on conventional shallow foundations. We recommend that footings for the building be designed for an allowable bearing pressure of 2,000 pounds per square foot (psf). In addition, we recommend a minimum width of 18 inches for continuous wall footings to prevent localized shear failure. Footings should bear at a minimum depth of 18 inches below the prevailing exterior ground surface elevation to provide the recommended bearing capacity. Detailed footing examinations should be performed in each footing excavation prior to placement of reinforcing steel. These examinations should be performed by our representative to confirm that the design allowable soil bearing pressure is available. The footing examinations should be performed using a combination of visual observation, hand rod probing, and dynamic cone penetrometer testing. Dynamic cone penetrometer testing, as described in ASTM STP-399, should be performed in each column footing location and at no greater than 20 foot intervals in continuous wall footings. If the soil is found to have an unsatisfactory bearing capacity, our inspector will review the problem with our project geotechnical engineer. Recommendations will be developed to be immediately implemented in order to minimize construction delays. Loose sands were encountered near the ground surface in test boring B-2. Depending on final site grades and conditions encountered during the time of construction, remedial measures may be required to achieve the recommended foundation bearing pressure. If remedial measures are required, we recommend that any over -excavated footings be backfilled with either compacted #57 washed stone, or concrete. Exposure to the environment may weaken the soils at the foundation bearing surface, if they are exposed for extended periods of time. If the foundation bearing surface becomes softened due to exposure, the soft soils should be removed prior to placement of concrete. Concrete Slabs -On -Grade Based on our test boring results, the encountered subsurface conditions are generally suitable for support of lightly loaded concrete slabs -on -grade. On a preliminary basis, we recommend that a design modulus of subgrade reaction (k) value of 100 pounds per cubic inch (pci) be used for concrete slabs -on -grade. This recommended value assumes that the subgrade soils and fill soils will be compacted to a minimum of 98 percent of their standard Proctor (ASTM D-698) maximum dry density in the upper 12 inches. TFRP4TECH Page 11 Pavement Desien Recommendations E N G I N E E R S - I N C GeoterfinicafEngineen . ng Environmen taf Consuffing Construction 9Watedais Testing Based on the results of the soil test borings, we expect the subgrade soils within the proposed pavement areas to consist generally of sandy clays, silty sands and sandy silts. The California Bearing Ratio (CBR) for these soils may reasonably range from approximately 8 to 15, if the subgrade soils are uniformly compacted to a minimum of 100% of the standard Proctor maximum dry density in the top 8 inches. For purposes of pavement design, we have used a California Bearing Ratio of 5 for the pavement subgrade soils and the loading condition described previously in this report. Based on the AASHTO design method, a 20-year design life, and our past experience, we suggest the following design pavement sections: Light Dutv Areas 2 inches Bituminous Concrete Surface Course 8 inches Aggregate Base Course Heavy Duly Areas 2 inches Bituminous Concrete Surface Course 2.5 inches Bituminous Concrete Intermediate Course 8 inches Aggregate Base Course The bituminous concrete surface course should be a type SF9.5B in accordance with division 6 of the current NCDOT Standard Specifications. The bituminous concrete intermediate course should be a type 119.013 in accordance with division 6 of the current NCDOT Standard Specifications. Aggregate base course stone should be in accordance with Division 5 of the current NCDOT Standard Specifications. Proper subgrade compaction and adherence to the NCDOT and project specifications are critical to proper pavement performance. Based on our past experience, we recommend that a Portland cement concrete pavement be used in areas where heavy trucks are turning while traveling at slow speeds. We suggest the use of a 6-inch thick section of NCDOT type AA Portland cement concrete having a 28-day design compressive strength of 4,500 psi above a 6-inch thick section of compacted ABC stone. The concrete pavement may be designed as a "plain concrete pavement" with no reinforcing steel or reinforcing steel maybe used at joints. Construction joints and other design details should be in accordance with guidelines provided by the Portland Cement Association, the American Concrete Institute, and NCDOT. The recommended pavement sections are designed to support the traffic volumes expected after completion of the planned construction. If construction traffic is allowed to use the recommended pavement sections, some damage requiring repair should be expected. TFRPATECH Page 12 Structural Fill E N G I N E E R S - I N C geotechnicalEngineefing EnvimmentafConsulting Constmaion Wateyiafs Testing In order to achieve high density structural fill, the following preliminary recommendations are offered: (1) Materials selected for use as structural fill should be free of vegetable matter, waste construction debris, and other deleterious materials. The material should not contain rocks having a diameter over 3 inches. It is our opinion that the following soils represented by their USCS group symbols will typically be suitable for use as structural fill: (SM), (SQ, (ML), (CL), (SW), (SP), (SP-SM), and (SP-SQ. The following soil types are considered unsuitable in the top 3 feet: (M11) and (CH). The following soil types are considered unsuitable: (OL), (OH), and (Pt). (2) Laboratory Proctor compaction tests and classification tests should be performed on representative samples obtained from the proposed borrow material to provide data necessary to determine acceptability and for quality control. The moisture content of suitable borrow soils should generally not be more than 3 percentage points above or more than 3 percentage points below optimum at the time of compaction. Tighter moisture limits may be necessary with certain soils, including the micaceous silts present at the site. (3) Suitable fill material should be placed in thin lifts (lift thickness depends on type of compaction equipment, but in general, lifts of 8 inches loose measurement are recommended). The soil should be compacted by mechanical means such as steel drum or sheepsfoot rollers. Proofrolling with rubber tired, heavily loaded vehicles may be desirable at approximately every third lift to bind the lifts together and to seal the surface of the compacted area thus reducing potential for absorption of surface water following a rain. This sealing operation is particularly important at the end of the work day and at the end of the week. Within small excavations such as behind retaining walls or in footing excavations, we recommend the use of "wacker packers" or sled tamps to achieve the specified compaction. Loose lift thicknesses of 4 to 6 inches are recommended in small area fills. (4) We recommend that structural fill be compacted to a minimum of 95% of the standard Proctor maximum dry density (ASTM D-698). The in -place maximum dry density of structural fill should be no less than 90 pounds per cubic foot. The upper 12 inches of floor slab subgrades should be compacted to at least 98% of the standard Proctor maximum dry density. Fill placement in pavement areas should be performed in accordance with the NCDOT Standard Specifications. (5) An experienced soil engineering technician should take adequate density tests throughout the fill placement operation to verify that the specified compaction is achieved. It is particularly important that this be accomplished during the initial stages of the compaction operation to enable adjustments to the compaction operation, if necessary. TFRRATECH Page 13 ADDITIONAL SERVICES RECOMMENDED E N 0 1 N E E R S - I N C Geotechnw,dEngineedng Environmenta(Consulting Constniction 911aaiiafs Testing Additional foundation engineering, testing, and consulting services recommended are summarized below: (1) Site PLeRaration Observations: Site preparation should be observed on a full-time basis by our representative. (2) Quality Control of Fill Placement and CgMpaction: We recommend that an experienced engineering technician witness all required filling operations and take sufficient in -place density tests to verify that the specified degree of compaction has been achieved. Soil engineering judgments will be involved and should be made by our project geotechnical engineer with information provided by our engineering technician. (3) Foundation and Floor Slab Evaluations: Specific recommendations for appropriate construction -phase evaluations and testing of foundation and floor slab construction should be contained in the recommended additional geotechnical evaluation reports and should be performed by the geotechnical engineer's representative at the time of construction. (4) Pavement ComRonents Testing and InsRection: Pavement components should be tested and inspected during and following construction to verify compliance with project plans and specifications. The attached Appendix completes this report. Sincerely, TeffaTech Engineers, Inc. (C-1356) 1. William D. Oakes Project Manager WDO/sk Enclosures CA /to 46 Date: 202 S 16J 1:43.0 SEAL Glen A. Malpass, Ph.D., P.E 030988 Principal Geotechnical Engind';_�Q A. M TFRRATECH E N G I N E E R S - I N C APPENDIX OIL Base Map obtained from Franklin County GIS and client Not to Scale Franklin County taxp-arcell PIN #1853-31-3172 Figure 1: Boring Plan TFRPATECH ENGINEE RS- INC 411111 Pi t A . T -�C% IW-Mw F i IL61 TerraTech Engineers, Inc. (C-1356) 4905 Professional Court Project: Youngsville Storage Expansion Raleigh, NC 27609 Youngsville, North Carolina 919-876-9799 Our Project Number: 121-20-101820 TERRAT H E N G I N E E k S - I N C CaC J CaB 6-9 B-5 B-6 B-1 1 B-3 CaC B-2 B-1 B-12 1-2 -Ts WeC OM Base Map obtained from N client and USDA Web SoilSurvey Figure 2: Site Soil Map Not to Scale TerraTech Engineers, Inc. (C-1356) Project: Youngsville Storage Expansion 4905 Professional Court Youngsville, North Carolina Raleigh, NC 27609 Our Project Number 121-20-101820 919-876-9799 Symbols and Nomenclature TERRATECH ENGINEERS - INC Undisturbed Sample (UD) Standard penetration resistance (ASTM D- 1586) 100/2" Number of blows (100) to drive the spoon a number of inches (2) W-0-H, R Weight of Hammer, Weight of Rods AX, BX, NX Core barrel sizes for rock cores 65% Percentage of rock core recovered RQD Rock quality designation - % of core 4 or more inches long M Water table at least 24 hours after drilling M Water table one hour or less after drilling A Loss of drilling water A Atterberg Limits test performed C Consolidation test perfonned GS Grain size test performed T Triaxial shear test performed P Proctor compaction test performed 18 Natural moisture content (percent) Penetration Resistance Results Sands Silts and Clays Number of Blows, N 0-4 5-10 11-20 21-30 31-50 over 50 Number of Blows, N 0-1 2-4 5-8 9-15 16-30 31-50 over 50 Drilling Procedures Relative Density very loose loose firm very firm dense very dense Approx. Consistency very soft soft firm stiff very stiff hard very hard Soil sampling and standard penetration testing performed in accordance with ASTM D-1586. The standard penetration resistance is the number of blows of a 140 pound hammer falling 30 inches to drive a 2 inch O.D., 1.4 inch I.D. split spoon sampler one foot. Core drilling performed in accordance with ASTM D-2113. Undisturbed sampling performed in accordance with ASTM D-1587, TEST BORING RECORD Water Level 24 hr.: Boring Backfilled Upon Completion Water Level I hr.: Caved @ 8.0' TerraTech Engineers, Inc. 4905 Professional Court Raleigh, NC 27609 TERRATECH F N G I N 6 E A S - I N C Boring Number: B-1 Project Number: 121-20-101820 Date Drilled: 7/8/20 TEST BORING RECORD Depth Description \Topsoil (Approximately 2 inches) Very stiff orange tan fine sandy clay (CL) 2— (RESIDUUM) 4 Hard tan orange fine sandy micaceous silt (ML) 6] Very stiff tan fine to medium sandy micaceous silt (ML) El. 10�Very stiff gray fine to medium sandy silt (ML) 12 ] Hard tan fine to medium sandy micaceous silt 14 � (ML) BORING TERMINATED IV 18 TERRATECH E N G I N E E R S - I N C Standard Penetration Test Elev. Water Blow Blows per Foot Level I Counts 20 40 60 80 3.0 1 1 7-13-12 5.5 1 � 7-15-17 8.0 11-13-17 6-12-13 12.0 15.0 0 16-16-17 1 1 0 1 201 1 W-t- Level 24 hr.: Boring Backfilled Upon Completion TerraTech Engineers, Inc. Boring Number: B-2 4905 Professional Court I FW.te' Level I hr.: Caved @ 12.0' Raleigh, NC 27609 Project Number: 121-20-101820 Date Drilled: 7/8/20 TEST BORING RECORD TERRATECH E N G I N E f R S , I N C Standard Penetration Test Depth Description Elev. Water Blow Blows per Foot Level Counts 20 40 60 80 L I I I \Topsoil (Approximately 3 inches) 2 7-10-11 4- Very stiff orange fine sandy micaceous clay (CL) (RESIDUUM) 7-11-12 6- C 8.0 5-7-12 8 Stiff orange fine to medium sandy micaceous silt (ML) 10.0 4-5-5 -Al�-- BORING TERMINATED 12- 14- 16- 18-: 20- Water Level 24 hr.: Boring Backfilled Upon Completion Water Level 1 hr.: Caved @ 7.0' TerraTech Engineers, Inc. 4905 Professional Court Raleigh, NC 27609 Boring Number: B-3 Project Number: 121-20-101820 Date Drilled: 7/8/20 TEST BORING RECORD Water Level 24 hr.: Boring Backfilled Upon Completion Water Level I hr.: Caved @ 8.0' TerraTech Engineers, Inc. 4905 Professional Court Raleigh, NC 27609 TERRATECH 6 N G I N E E R S - I N C Boring Number: B-4 Project Number: 121-20-101820 Date Drilled: 7/8/20 TEST BORING RECORD Depth Description \Topsoil (Approximately 2 inches) 2 Very stiff orange fine sandy clay (CL) (RESIDUUM) 4 6] Stiff orange fine sandy micaceous silt (ML) 8 Stiff gray red fine to medium sandy micaceous silt (ML) 10— BORING TERMINATED 12 14 IRA 18 201 Elev. Water Blow � Level Counts 6-10-12 5.5 1 5-7-1 �. �O � 5-8-6 10.0 Water Level 24 hr.: Boring Backfilled Upon Completion TerraTech Engineers, Inc. Water Level 1 hr.: Caved @ 8. 0' 4905 Professional Court Raleigh, NC 27609 am TERRATECH ENGIN EER$, INC Standard Penetration Test Blows per Foot 20 40 60 80 11 Boring Number: B-5 Project Number: 121-20-101820 Date Drilled: 7/8/20 TEST BORING RECORD Depth Description \\Topsoil (Approximately 2 inches) 2- Very stiff orange fine sandy micaceous clay (CL) (RESIDUUM) 4- 'I Very stiff orange tan fine sandy micaceous silt (ML) 8 I 0�Stiff brown gray fine to coarse sandy micaceous silt (ML) 12 14J Stiff orange fine sandy micaceous silt (ML) BORING TERMINATED 16 18 20 TERRATECH E N G I N E E R S - I N C Standard Penetration Test Elev. Water Blow Blows per Foot Level Counts 20 40 60 80 6-7-12 5.5 5-7-10 8.0 � 7-9-13 4-5-6 12.0 C i�--N 5-6-8 1 0 iter Level 24 hr.: Boring Backfilled Upon Completion TerraTech Engineers, Inc. Boring Number: B-6 iter Level I hr.: Caved @ 13.0' 4905 Professional Court Project Number: 121-20-101820 Raleigh, NC 27609 Date Drilled: 7/8/20 TEST BORING RECORD el 24 hr.: Boring Backfilled Upon Completion el 1 hr.: Caved @ 8.0' TerraTech Engineers, Inc. 4905 Professional Court Raleigh, NC 27609 TFRRATECH E N G I N E E R S - I N C Boring Number: B-7 Project Number: 121-20-101820 Date Drilled: 7/8/20 TEST BORING RECORD TERRATECH E N G 1 N E E It S - I N C Water Level 24 hr.: Boring Backfilled Upon Completion TerraTech Engineers, Inc. Boring Number: B-8 Water Level I hr.: Caved @ 8.0' 4905 Professional Court Project Number: 121-20-101820 Raleigh, NC 27609 Date Drilled: 7/8/20 TEST BORING RECORD Water Level 24 hr.: Boring Backfilled Upon Completion Water Level I hr.: Caved @ 12.0' TerraTech Engineers, Inc. 4905 Professional Court Raleigh, NC 27609 TERRATECH F N G I N e F R S - I N C Boring Number: B-9 Project Number: 121-20-101820 Date Drilled: 7/8/20 TEST BORING RECORD Water Level 24 hr.: Boring Backfilled Upon Completion Water Level 1 hr.: Caved @ 8.0' TerraTech Engineers, Inc. 4905 Professional Court Raleigh, NC 27609 TERRATECH ENGINEERS - INC Boring Number: B- 10 Project Number: 121-20-101820 Date Drilled: 7/8/20 TEST BORING RECORD TERRATECH E N G I N E E R S - I N C Depth Description Elev. Water Level Blow Counts Standard Penetration Test Blows per Foot 20 40 60 80 \Topsoil (Approximately 2 inches) Very stiff orange fine sandy micaceous clay 2- (CL) (RESIDUUM) 3.0 6-8-9 4- Very stiff gray orange fine to coarse sand (SQ with quartz fragments - 5.5 7-10-12 19 6 Very stiff orange gray fine to coarse sandy silt (ML) 8- 8.0 5-7-10 Stiff orange gray fine to coarse sandy silt (ML) 10 BORING TERMINATED 10.0 3-5-7 12- 14- 16- 18- 20- Water Level 24 hr.: Boring Backfilled Upon Completion Water Level I hr.: Caved @ 8.0' TerraTech Engineers, Inc 4905 Professional Court Raleigh, NC 27609 Boring Number: B-1 I Project Number: 121-20-101820 Date Drilled: 7/8/20 TEST BORING RECORD Depth Description ,,\Topsoil (Approximately 2 inches) Hard gray orange fine to medium sandy clay 2� (CL) with quartz fragments (RESIDUUM) 4 � Very firm orange silty fine to medium sand (SM) 1 Firm tan silty fine to medium sand (SM) 8 Very firm gray silty fine sand (SM) 10— BORING TERMINATED 12 14 16 18 1 201 TERRATECH E N G I N E E R S * I N C Standard Penetration Test Elev. Water Blow Blows per Foot Level Counts 20 40 60 80 3.0 1 � 7-12-21 � � 0 5.5 � 1 11-15-13 1 � 0 0�6-7-10 C � 10.0 Water Level 24 hr.: Boring Backfilled Upon Completion TerraTech Engineers, Inc. Water Level 1 hr.: Caved @ 8.0' 4905 Professional Court Raleigh, NC 27609 7-8-13 Boring Number: B- 12 Project Number: 121-20-101820 Date Drilled: 7/8/20 February 24, 2021 C4 YS, LLC Attn: Mr. Michael Isaac misaaccaesere.com Summary of Infiltration Testing Youngsville Storage Facility Phase 2 Youngsville, North Carolina Our Project Number 121-21-101822 Gentlemen: N V 5 As requested, a representative of NV5 Engineers and Consultants, Inc. was present at the above referenced site on February 17, 2021 to perform in -situ infiltration testing in the proposed stormwater pond area. Our scope of services did not include surveying of the planned construction areas. Our test location is approximately shown on the attached Figure 1. In general, the location of the infiltration testing should be considered approximate. The double ring infiltrometer (ASTM D3385) method was used to determine the infiltration rates. Prior to performing the infiltration testing, the area was excavated down to approximate final soil subgrade for the proposed stormwater pond. The results of our testing in the area of I- I indicated that the average infiltration rate was approximately 0.5 inches per hour. It should be noted that the infiltration rate of soils can depend on several factors including soil type and density. The encountered soils generally consisted of sandy clays and sandy silts. We have also reviewed the USDA Web Soil Survey for this area. Based on our review of the encountered soils and review of the USDA Web Soil Survey it is our opinion that a seasonal high ground water table may be present at a depth of 8 feet or greater in the location of the planned pond. We have appreciated the opportunity to provide these observations for the Youngsville Storage Expansion Phase 2. If you have any questions concerning this information, or if we may be of additional service, please do not hesitate to contact us. Sincerely, NV5 Engineers and Consultants, Inc. (F-1333) __� 9;�6n�. William D. Oakes, P.G. Project Manager WDO/sk Enclosures Sal, Date'. 20 1� 1 .1 rN.L 13:43:3 05 0' SEAL 030988 Glen A. Malpass, Ph.D., P.1 Principal Geotechnical Engi NV5 Engineers and Consultants, Inc. NC Engineering Corporation F-1333 4905 Professional Court, Raleigh, North Carolina 27609 (919) 876-9799 A. N V 5 R AG AREA N A -- -------- 2W iv F� A" J"� Base Map obtained from client Figure 1: Infiltration Map Not to Scale NV5 Engineers and Consultants, Inc. (F-1333) Project: Youngsville Storage Expansion Phase 2 4905 Professional Court Youngsville, North Carolina Raleigh, NC 27609 Our Project Number 121-21-101822 919-876-9799