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HomeMy WebLinkAbout006 - TWAS - Drainage Design Report TIDAL WAVE AUTO SPA DRAINAGE DESIGN REPORT Bozeman, Montana Prepared for: City of Bozeman Planning & Engineering Depts. 20 East Olive St. Suite 202 Bozeman, MT 59715 Prepared by: DJ&A, P.C. 220 W. Lamme Street Suite 1D Bozeman, MT 59715 August 24, 2023 TOC-1 Drainage Design Report Table of Contents 1. General .............................................................................................................................................. 1 2. Storm Water Calculations ................................................................................................................. 2 3. Summary .......................................................................................................................................... 4 References ................................................................................................................................................ 6 List of Figures Figure 1: Proposed Location .................................................................................................................... 1 List of Attachments Attachment A— Rainfall Intensity Data Attachment B— Retention Pond Location and Drainage Areas Attachment C— NRCS Soil Data/Geotechnical Report Attachment D—Mannings Equation Calculations Attachment E—Rational Method Calculations Drainage Design Report Tidal Wave Auto Spa, Bozeman MT Page 1 March 2023 Drainage Design Report 1. General This report presents a storm water design and management plan for the proposed Tidal Wave Auto Spa site, which includes a carwash structure, a small vacuum house structure, parking lot, sidewalk, and access driveway. The ~2.79-acre site is located on the northwest corner of the intersection of N 19th Ave and E Valley Center Rd in Bozeman, Montana, and is zoned B-2. The proposed storm water design aims to prevent flooding, erosion, and water quality issues for this site by retaining runoff on- site. Figure 1: Proposed Location This report uses rainfall intensity values obtained from the city of Bozeman Design Standards and Specifications Policy. The rainfall analysis findings include intensities of the site for a 10-year, 2-hour storm, this is summarized in Attachment A. This report and calculations are based on the findings of Drainage Design Report Tidal Wave Auto Spa, Bozeman MT Page 2 March 2023 a geotechnical report performed/written previously, as well as Natural Resources Conservation Service (NRCS) soils data. To manage storm water runoff on the Tidal Wave Auto Spa site, a combination of a drainage swale and 12-inch diameter HDPE corrugated storm water pipe will drain to a proposed retention pond at the north end of the site. The drainage swale will run along the west side of the site and will convey storm water runoff from the parking lot/drive aisles towards the retention pond to the north at a minimum 0.5% downward slope. It is expected that this drainage swale will experience infiltration of storm water runoff as it conveys to the retention pond. The 12-inch diameter HDPE corrugated pipe will collect six roof drain connections from the carwash structure and pipe roof runoff towards the retention pond to the north. The roof drain connections will be 3-inch HDPE pipe connecting in at a slope of approx. 4%. Once connected to the 12-inch pipe, it will run at a minimum 1% slope until it outfalls to the retention pond. The retention pond, located on the northeast end of the property, will store the storm water, and allow for it to infiltrate. The retention pond is designed to meet city of Bozeman’s storm water management standards, as specified in the Bozeman Design Standards and Specifications. The pond will be constructed from the natural ground, and the area surrounding the outlet pipe will be stabilized with rock riprap to prevent erosion. The outlet pipe will feature a rack feature to prevent rodent and trash from entering the pipe. This design is detailed in Attachment B and provides a visual of all storm water components. 2. Storm Water Calculations Stormwater calculations were conducted in accordance with the DSSP and based off the geotechnical report provided in Attachment C. The DSSP requires the following: 1. The stormwater conveyance system on site accommodates the 25-year event. 2. The stormwater retention pond accommodates the 10-year, 2-hour event. Site features will infiltrate into landscaping or drain to the onsite retention pond. The impervious area of 1.68 acres comprises the portion of the sidewalk, parking lot, and roof area that drain into the retention pond. A pervious area of 1.64 acres comprises the portion of landscaping that will percolate. Runoff coefficients of 0.95 and 0.25 were used for the impervious surfaces and landscaping, respectively, in accordance with DSSP Table I-1. The drainage area is detailed in Attachment B of this report. 2.1 Stormwater Conveyance System As mentioned above, the DSSP dictates that storm sewer systems in the city of Bozeman must accommodate the 25-year storm event. 2.1.1 Estimating Peak Flow on the Site The Rational Method assumes that peak flow occurs at the time of concentration, which was estimated at a conventional five minutes for this site. Rainfall intensity for the 25-year event, in accordance with DSSP Figure I-2, is 3.87 in/hr. The drainage areas for the site and their corresponding peak flows calculated via the Rational Method are provided in Attachment C. Drainage Design Report Tidal Wave Auto Spa, Bozeman MT Page 3 March 2023 2.1.2 Conveyance Pipe Sizing Storm sewer pipe was sized via the Manning’s equation as shown in Attachment D. The most downstream pipe at 12-inch diameter and 1% minimum slope is shown to accommodate the peak flow of 3.07 cubic feet per second (cfs). Thus, resulting in the necessary 3 fps for self-cleaning velocity. Additionally, the roof drains at 3-inch diameter and 4% minimum slope are shown to accommodate the peak flow of 0.15 cfs and maintain the necessary 3 fps for self-cleaning velocity. 2.2 Stormwater Retention Pond Retention Pond: Site features will either infiltrate into landscaping or drain to the onsite retention pond. The impervious area of ~1.68 acres was calculated for the portion of the sidewalk, parking lot, and roof area that will drain into the retention pond. A pervious area of ~1.64 acres was calculated for the portion of landscaping that will drain to the retention pond. The run-off coefficient of 0.95 was used for the impervious surfaces and a run-off coefficient of 0.25 for landscaping. The drainage area is detailed in Attachment B of this report. The proposed retention pond will have a volume of approximately 14,500 cubic feet (ft3) when full. The geotechnical boring log data for test holes OP-6 located on the north end of the site indicate that the native material is comprised of lean clay, sand, and poorly graded gravel. This observation pit is attached in Attachment C of this report. It is estimated that this soil type will have a long-term percolation rate of approximately one in/hr (Percolation rate is based on estimated percolation rates for the Geotech specified soil type). With a 2’ depth, it Is assumed that this pond, if maintained, should drain within 24 hrs, once and storm ends and the pond is max capacity. For the stormwater runoff calculations, the rational method was used. The rational method provides a estimate of storm water runoff for relatively small drainage areas (<200 acres). The rational method equation is: Vb = Cb * i *A Vb = Volume of run-off which will enter the sump (cubic feet). Cb = Run-off coefficient. This coefficient represents the ratio of runoff to rainfall based on the characteristics of ground surfaces within the drainage area. i = Average rainfall intensity. Values of i are based on rain fall intensities provided by the City of Bozeman Design Standards and Specifications Policy (inches per hour). A = Size of drainage area (square feet). 10-year: 2-hour Storm Drainage Design Report Tidal Wave Auto Spa, Bozeman MT Page 4 March 2023 Attachment A was obtained from the City of Bozeman Design Standards and Specifications Policy, which predicts the precipitation depth (in) for a 10-year, 2-hour storm. Entire Site: Volume of runoff entering sump during a 10-year, 2-hour storm event: Cr = 0.95 Cl = 0.25 A(improved) = 1.68 acres A(unimproved) = 1.64 acres A(total) = 3.32 acres CTotal = ((0.25*(1.64/3.32))+(0.95*(1.68/3.32)) = 0.6042 Intensity= 0.5 in/hr Time = 7200 sec V = (0.6042)(3.32)(0.5)(7200) = 7221.39 ft3 (Rounds to 7222) Percolation: Percolation rate = 1 in/hr Assume area of drainage basin to be 7660 ft2 Allowable runoff = (7660)(0.0833/60/60)(7200 sec) = (0.17731 ft3/sec)(7200 sec) = 1276.632 ft3 (Rounds to 1276) Storage required = 7221.39 ft3 – 1276.632 ft3 = 5944.758 ft3 (Rounds to 5945 ft3) Storage provided = ~14,500 ft3 The proposed retention pond will provide ample storage for the design event. Due to the ample storage of more than double what is required for the design event, it is assumed that this retention pond will drain within 24 hours after the design event. Thus, this retention pond will remain dry the majority of the time, unless it is not properly maintained. See Attachment E for the Excel spreadsheet calculations following this methodology. 3. Summary In conclusion, calculations were completed to evaluate the performance of the proposed retention pond when exposed to a 10-year, 2-hour storm event. This retention pond will store and pretreat site storm water and will collect runoff from the site, except for four roof drains which will surface drain and, in all likelihood, percolate through proposed landscaping before reaching the pond. In a large drainage event, the site drainage is designed to collect in the retention pond. The onsite retention pond has been conservatively sized based on assumptions. These assumptions include percolation rates and soil composition further than three feet in depth. When completing Drainage Design Report Tidal Wave Auto Spa, Bozeman MT Page 5 March 2023 calculations for a 10-year, 2-hour storm it was determined that the retention pond will have excess storage. This assumption is based on the amount of storage available, which is calculated from the rational method. This retention pond is designed to follow the Bozeman DSSP maximum water depth of 1.5’ with a maximum basin depth of 2.5’. With the excess storage and assumed percolation rate, this retention pond should no longer hold water 24 hours after the design storm event. In the event that the storm is greater than the design event and overtopping does occur, the finished grades and finish ground elevations have been designed to allow stormwater to run off the northern portion of the site and would infiltrate over natural surrounding grounds. The proposed storm water management system is expected to effectively address site drainage, storm water treatment and prevents flooding of adjacent private property. Drainage Design Report Tidal Wave Auto Spa, Bozeman MT Page 6 March 2023 References  City of Bozeman. “Design Standards and Specifications Policy.” City of Bozeman Engineering Division. 2004. Web accessed 2023.  Unknown. “Report of Geotechnical Exploration.” GEOS. 2021. PDF. Drainage Design Report Tidal Wave Auto Spa, Bozeman MT Attachment A— Rainfall Intensity Data Drainage Design Report Tidal Wave Auto Spa, Bozeman MT Attachment B—Retention Pond Location and Drainage Area * * * * * >>>>>>>>>>R/W R/W R/W R/W R/W R/W T T E E E E EE WV TV E E E E E TT T TT S S HY DIRR 12''IRR 12''IRR 12''>>>>>>>>>>>>& ENGINEERS PLANNERS SURVEYORS DESIGNER DRAWN CHECKED PROJ. NO. DATE SURVEYED DESCRIPTIONDATEREVISION SHEET OF 7/13/23 13:08 KYLE.DRUYVESTEIN F:\7350 TIDAL WAVE AUTO SPA, NORTH 19TH, BOZEMAN\DRAWINGS\DWG\CIVIL\5 SHEET PRODUCTION\STORM WATER\5 - UTILITY PLAN.DWG;--- DJ&A, P.C. 08/04/2023 7350 MR KD KD ATTACHMENT BBOZEMAN, MT TIDAL WAVE AUTO SPA SCALE IN FEET 0 30 60 DRAINAGE SWALE N12" Ø HDPE CORRUGATED STORMWATER PIPE TO FLOW AND DAYLIGHT AT DRAINAGE POND DOWNSPOUTS TO BE PIPED UNDERGROUND WITH 3" Ø HDPE PIPE TO TIE INTO MAIN 12" Ø PIPE AND DRAIN TO POND. 3" Ø HDPE PIPE WILL SLOPE A MINIMUM OF 4% TYING INTO THE 12" Ø PIPE WHICH WILL SLOPE AT A MINIMUM 1%. APPROX. 14,500 CUBIC FT DETENTION POND 53,4 6 5 . 0 6 s f 760.08 sf4,400.9 5 s f 5,216.06 sf 2,751.07 sf144,583.7 sf7,562. 8 8 sf SIDEWALK 800 SF SIDEWALK 430 SF BUILDING 4325 SF TOTAL SITE DRAINING TO RETENTION 144,583 SF CONCRETE DRIVEWAY AND PARKING LOT 52,537 SF DETENTION POND 7,658.23 SF 15,067.08 sf VALLEY CENTER ROAD 15,067 SF Drainage Design Report Tidal Wave Auto Spa, Bozeman MT Attachment C— NRCS Soil Data/Geotechnical Report United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Gallatin County Area, MontanaNatural Resources Conservation Service March 10, 2023 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map................................................................................................................9 Legend................................................................................................................10 Map Unit Legend................................................................................................11 Map Unit Descriptions.........................................................................................11 Gallatin County Area, Montana.......................................................................13 50B—Blackdog silt loam, 0 to 4 percent slopes..........................................13 References............................................................................................................15 4 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil 5 scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil-landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and Custom Soil Resource Report 6 identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. Custom Soil Resource Report 7 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8 9 Custom Soil Resource Report Soil Map 506201050620305062050506207050620905062110506213050621505062170506219050622105062230506201050620305062050506207050620905062110506213050621505062170506219050622105062230494780 494800 494820 494840 494860 494880 494900 494920 494940 494780 494800 494820 494840 494860 494880 494900 494920 494940 45° 42' 49'' N 111° 4' 1'' W45° 42' 49'' N111° 3' 53'' W45° 42' 41'' N 111° 4' 1'' W45° 42' 41'' N 111° 3' 53'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 12N WGS84 0 50 100 200 300 Feet 0 15 30 60 90 Meters Map Scale: 1:1,110 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Gallatin County Area, Montana Survey Area Data: Version 26, Aug 30, 2022 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 18, 2022—Aug 29, 2022 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 10 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 50B Blackdog silt loam, 0 to 4 percent slopes 3.3 100.0% Totals for Area of Interest 3.3 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. Custom Soil Resource Report 11 An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 12 Gallatin County Area, Montana 50B—Blackdog silt loam, 0 to 4 percent slopes Map Unit Setting National map unit symbol: 56vq Elevation: 4,350 to 5,500 feet Mean annual precipitation: 15 to 19 inches Mean annual air temperature: 37 to 43 degrees F Frost-free period: 90 to 110 days Farmland classification: All areas are prime farmland Map Unit Composition Blackdog and similar soils:90 percent Minor components:10 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Blackdog Setting Landform:Stream terraces Down-slope shape:Linear Across-slope shape:Linear Parent material:Calcareous loess Typical profile A - 0 to 10 inches: silt loam Bt - 10 to 19 inches: silty clay loam Bk - 19 to 60 inches: silt loam Properties and qualities Slope:0 to 4 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Capacity of the most limiting layer to transmit water (Ksat):Moderately high (0.20 to 0.57 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:30 percent Available water supply, 0 to 60 inches: High (about 10.9 inches) Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 3e Hydrologic Soil Group: C Ecological site: R044BB032MT - Loamy (Lo) LRU 01 Subset B Hydric soil rating: No Minor Components Meagher Percent of map unit:4 percent Landform:Stream terraces, alluvial fans Down-slope shape:Linear Across-slope shape:Linear Custom Soil Resource Report 13 Ecological site:R044BB032MT - Loamy (Lo) LRU 01 Subset B Hydric soil rating: No Bowery Percent of map unit:3 percent Landform:Stream terraces, alluvial fans Down-slope shape:Linear Across-slope shape:Linear Ecological site:R044BB032MT - Loamy (Lo) LRU 01 Subset B Hydric soil rating: No Quagle Percent of map unit:3 percent Landform:Stream terraces Down-slope shape:Linear Across-slope shape:Linear Ecological site:R044BB030MT - Limy (Ly) LRU 01 Subset B Hydric soil rating: No Custom Soil Resource Report 14 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/national/soils/?cid=nrcs142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 15 United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/? cid=nrcs142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf Custom Soil Resource Report 16     GEOServices, LLC | 2561 Willow Point Way, Knoxville, TN, 37931 | Phone (865) 539‐8242 Fax (865) 539‐8252 | www.geoservicesllc.com  October 20, 2021    New Potato Creek Holdings, LLC  124 East Thompson Street  Thomaston, Georgia 30286    ATTENTION:  Mr. John Lapointe, P.E.      JLapointe@brightworkre.com     Subject:             REPORT OF GEOTECHNICAL EXPLORATION   Proposed Tidal Wave Auto Spa  North Bozeman, MT 59718  GEOServices Project No. 21‐211043    Dear Mr. Lapointe:    We are submitting the results of the geotechnical exploration performed for the subject project. The  geotechnical exploration was performed in accordance with our Proposal No. 11‐21151M, dated August 12,  2021. The following report presents our findings and recommendations for the proposed project. Should you  have any questions regarding this report, or if we can be of any further assistance, please contact us at your  convenience.    Sincerely,  GEOServices, LLC                                    Joshua R. Watson, P.E., C.W.I.     Michael D. Kelso, E.I.  Geotechnical Project Manager     Geotechnical Project Manager  PE MT #      Submitted by:  GEOServices, LLC  2561 Willow Point Way  Knoxville, TN 37931  Phone (865) 539‐8242  Fax (865) 539‐8252  REPORT OF  GEOTECHNICAL EXPLORATION    Tidal Wave Auto Spa  4500 Valley Center Dr.  North Bozeman, MT 59718    GEOServices Project No. 21‐211043    Submitted to:  New Potato Creek Holdings, LLC  124 East Thompson Street  Thomaston, Georgia 30286                        TABLE OF CONTENTS  Contents Page  1.0 INTRODUCTION .............................................................................................................................. 1  1.1 PURPOSE .................................................................................................................................... 1  1.2 PROJECT INFORMATION AND SITE DESCRIPTION ...................................................................... 1  1.3 SCOPE OF STUDY ........................................................................................................................ 2  2.0 EXPLORATION AND TESTING PROGRAMS ....................................................................................... 2  2.1 FIELD EXPLORATION ................................................................................................................... 2  3.0 SUBSURFACE CONDITIONS ............................................................................................................. 2  3.1 GEOLOGIC CONDITIONS ............................................................................................................. 2  3.2 SOIL STRATIGRAPHY ................................................................................................................... 3  4.0 CONCLUSIONS AND RECOMMENDATIONS ...................................................................................... 4  4.1 SITE ASSESSMENT ...................................................................................................................... 4  4.2 SITE PREPARATION RECOMMENDATIONS ................................................................................. 5  4.2.1 Subgrade .................................................................................................................... 5  4.2.2 Structural Fill .............................................................................................................. 6  4.3 FOUNDATION RECOMMENDATIONS ......................................................................................... 7  4.3.1 Shallow Foundations .................................................................................................. 7  4.3.2 Slabs‐on‐Grade ........................................................................................................... 9  4.4 SEISMIC DESIGN CRITERIA.......................................................................................................... 9  4.5 PAVEMENT DESIGN RECOMMENDATIONS .............................................................................. 11  4.5.1 Flexible Pavement Design ........................................................................................ 11  4.5.2 Rigid Pavement Design ............................................................................................ 12  4.5.3 General ..................................................................................................................... 12  4.6 LATERAL EARTH PRESSURES .................................................................................................... 13  5.0 CONSTRUCTION CONSIDERATIONS ............................................................................................... 13  5.1 FOUNDATION CONSTRUCTION ................................................................................................ 13  5.2 EXCAVATIONS .......................................................................................................................... 13  5.4 MOISTURE SENSITIVE SOILS ..................................................................................................... 14  5.5 DRAINAGE AND SURFACE WATER CONCERNS ......................................................................... 15  6.0 LIMITATIONS ................................................................................................................................ 15    APPENDICES  APPENDIX A – FIGURES, GENERAL NOTES, AND OBSERVATION PIT LOGS           Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  1 | Page  1.0 INTRODUCTION  1.1 PURPOSE    The purpose of our geotechnical exploration was to explore the subsurface conditions for the proposed  Tidal Wave Auto Spa to be located in the northwest quadrant of the intersection of East Valley Center  Road and North 19th Avenue in North Bozeman, Montana and provide geotechnical recommendations for  site preparation and grading and for design and construction of the foundation system. Additionally,  recommendations for light and heavy‐duty pavements are included.    1.2 PROJECT INFORMATION AND SITE DESCRIPTION    Project information was provided via phone conversations and email correspondence in August of 2021.  We were provided a conceptual drawing which was undated as prepared by Brightworks Real Estate.     Based on the provided information, we understand the development will consist of a new car wash facility  which includes a 3,500 square foot structure, proposed canopy area, and dumpster pad along with  associated pavement areas. We anticipate the proposed structure will be steel framed supported on  shallow foundations with a slab on grade. We have assumed that maximum column and continuous  foundation loads will be on the order of 80 kips and 3 kips per linear foot, respectively.     Information concerning existing surface elevation and proposed grades has not been provided. However,  the site appears to be relatively flat; therefore, we anticipate minimal grading (cuts/fills less than 4 feet)  will be necessary for the majority of the proposed development.     The proposed development is immediately bordered by an off ramp for Highway 90 to North 19th Avenue  to the north, East Valley Center Road to the South, North 19th Avenue to the east, and a Residence Inn to  the west. At the time of our field activities, the site was mostly grass covered and contained some debris.  Based on aerial imagery (GoogleEarth) some grading activities occurred on site during the construction of  the nearby Residence Inn between 2004 and 2006. The site has remained relatively unchanged since.           Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  2 | Page  1.3 SCOPE OF STUDY     This geotechnical exploration involved a site reconnaissance, field exploration, and engineering analysis.  The following sections of this report present discussions of the field exploration, site conditions,  conclusions, and recommendations. Following the text of this report, Appendix A presents figures and  observation pit logs.     The scope of our geotechnical engineering services did not include an environmental assessment for  determining the presence or absence of wetlands, or hazardous or toxic materials in the soil, bedrock,  surface water, groundwater, or air, on, or below, or around this site. Statements in this report or on the  observation pit logs regarding odors, colors, and unusual or suspicious items or conditions are strictly for  informational purposes.     2.0 EXPLORATION AND TESTING PROGRAMS    2.1 FIELD EXPLORATION    The site subsurface conditions were explored by excavating twelve (12) observation pits across the  proposed development. The observation pits were located in the field by a GEOServices personal using  the provided site plan and a hand‐held GPS unit. The observation pits were excavated on October 5, 2021,  using an excavator with a 24‐inch‐wide tooth bucket. The excavations were observed by a member of our  staff to document the materials encountered. Upon completion of excavations, the pits were backfilled  and tamped. The approximate locations of the observation pits are shown on Figure 2 of Appendix A of  this report. The depths in this report reference the ground surface that existed at the time of this  exploration. Detailed logs for observation pits can also be found in Appendix A.    3.0 SUBSURFACE CONDITIONS    3.1 GEOLOGIC CONDITIONS    Based on published information on the United States Geological Survey (USGS), the site lies Sixmile Creek  formation. This formation is comprised of variable deposits that range from pebble to boulder size and include      Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  3 | Page  sand, silt, and clay. These deposits are dominantly alluvial terrace, abandoned channel and floodplain,  remnant alluvial fan, and local glacial outwash materials. Well logs in the area generally indicate similar  gravels extending to depths of greater than 100 feet.  3.2 SOIL STRATIGRAPHY    The following subsurface description is of a generalized nature to highlight the subsurface stratification  features and material characteristics at the observation pit locations. The observation pit logs included in  Appendix A of this report should be reviewed for specific information at each observation pit location.  Information on actual subsurface conditions exists only at the specific observation pit locations and is  relevant only to the time that this exploration was performed. Variations may occur and should be  expected at the site.    Surficial   In general, each observation pit encountered surficial materials which included approximately ¼ to 18  inches of topsoil classified as organic laden lean (low plasticity) clay.     Alluvium   Underlying the surficial materials, alluvial soils were encountered in each of the observation pits to  termination depths. These materials typically consisted of gray‐brown poorly graded gravel with varying  amounts of sand and clay. Additionally, seven locations (OP‐1, OP‐6, and OP‐8 through OP‐12),  encountered a layer of dark brown lean clays with varying amounts of sand and gravel beneath the  surficial materials. These lean clay soils were visually observed to have a firm to stiff consistency increasing  with depth. Furthermore, one location (OP‐4) encountered a layer of dense poorly graded sand with gravel  beneath the surficial layer. Each observation pit was terminated in dense to very dense alluvium soil.     Excavation Refusal   Excavation refusal was not encountered prior to reaching terminations depths in the observation pits.  Termination was determined based on location and material properties; and ranged from approximately  2 to 6 feet below existing grade. Excavation refusal is a designation applied to any material that cannot  be readily penetrated by the equipment and is normally indicative of a very hard or very dense material,  such as large boulders or the upper surface of bedrock.      Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  4 | Page    Ground Water  Groundwater was not encountered in the observation pit locations at the time of excavating. Extended  water levels were not obtained because the observation pits were backfilled upon completion as a safety  precaution. Groundwater levels may fluctuate due to seasonal changes in precipitation amounts,  construction activities in the area, and/or other factors.     Please note, it is possible for groundwater to exist within the depths explored during other times of the  year depending upon climatic and rainfall conditions. Additionally, discontinuous zones of perched water  may exist within the overburden materials. The groundwater information presented in this report is the  information that was collected at the time of our field activities.     4.0 CONCLUSIONS AND RECOMMENDATIONS    4.1 SITE ASSESSMENT    Based on the results of our geotechnical exploration, it is our opinion that the site is generally adaptable  for the proposed development. However, certain challenges are present which will affect development of  the site.    While fill materials were not encountered within our test locations, we note some surficial debris was  observed during our site reconnaissance. Should debris laden fill or significant amounts deleterious  materials be encountered during grading or construction and/or between our excavation locations, we  recommend these materials be completely undercut and disposed off‐site or onsite outside of structural  areas. A budget contingency for additional undercutting and replacement of unsuitable materials that  may be encountered during construction should be included.    Although, equipment refusal was not encountered, each observation pit encountered materials which  were dense to very dense at depths ranging from 1 to 6 feet below existing ground surface. Where  excavations extend to the depths where the very dense materials were encountered, then excavation  difficulty should be anticipated. The removal of very dense material in confined excavations, such as for  foundations or utilities, can often be difficult. Should field conditions vary, GEOServices should be allowed      Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  5 | Page  to review and revise these recommendations if necessary.     Additionally, we recommend performing close construction observations during earthwork and  foundation excavations activities to observe the consistency and suitability to support the proposed  construction. Any areas observed to be unsuitable for use as foundation or subgrade support should be  remediated accordingly. Generally, remediation of these types of soils consists of undercutting and  replacing a minimum of 2 feet below foundation bearing elevation and pavement and slab subgrade with  properly compacted structural soil fill or compacted dense graded aggregate. The depth of undercutting  should be determined at the time of construction.     Subgrades for lightly loaded slabs and/or pavement areas can typically be supported on materials which  proofroll successfully. Proofrolling should be observed by a geotechnical engineer or by a qualified  representative in order to help identify areas requiring subgrade support correction. Where the subgrade  does not pass proofrolling, remediation should be anticipated.     Based on our exploration, we anticipate the majority of the soils, classified as lean clays or sands and free  of deleterious materials (organics), may be suitable for reuse as structural soil fill. The client should  understand that some variation should be expected between our widely spaced observation pits and  selective undercut and replacement may be necessary during construction activities.     4.2 SITE PREPARATION RECOMMENDATIONS    4.2.1 Subgrade  Site stripping within the proposed construction areas (building and pavement) should include the removal  of topsoil, rock fragments greater than 6 inches, and any other deleterious material (such as trash or  construction debris). The stripping operations should extend a minimum of 5 feet beyond the limits of  proposed pavement areas and 10 feet beyond building footprints. These areas should be observed by a  geotechnical engineer upon grading to confirm the recommendations in this report are followed.    After the completion of stripping operations and excavation to reach the planned subgrade elevation, we  recommend that the subgrade be proofrolled with a fully‐loaded, tandem‐axle dump truck or other  pneumatic‐tired construction equipment of similar weight. Areas to receive structural soil fill should also be      Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  6 | Page  proofrolled prior to the placement of new fill.  The geotechnical engineer or his representative should observe  proofrolling. Areas judged to perform unsatisfactorily (e.g., pumping and/or rutting) by the engineer should  be undercut and replaced with structural soil fill or remediated at the geotechnical engineer’s  recommendation. Areas to receive structural soil fill should also be proofrolled prior to the placement of new  fill. Proofrolling operations should extend a minimum distance of 10 feet beyond the building perimeter and  5 feet beyond pavement areas.    If site preparation and construction is anticipated during cold weather, we recommend all foundations, slabs  and other improvements that may be affected by frost movements be insulated from frost penetration during  freezing temperatures. If filling is performed during freezing temperatures, all frozen soils, snow, and ice  should be removed from the areas to be filled prior to placing the new fill. The new fill should not be allowed  to freeze during transit, placement, and compaction. Concrete should not be placed on frozen subgrades.  Frost should not be allowed to penetrate below the footings. If floor slab subgrades freeze, we recommend  the frozen soils be removed and replaced, or completely thawed, prior to placement of the floor slab.    4.2.2 Structural Fill  Material considered suitable for use as structural fill should be clean soil free of organics, trash, and other  deleterious material, containing no rock fragments greater than 6 inches in dimension. Preferably, structural  soil fill material should have a standard Proctor maximum dry density of 90 pounds per cubic foot (pcf),  or greater, and a PI value of 35 percent, or less. The material to be used as structural fill should be tested  by the geotechnical engineer to confirm that it meets the project requirements before being placed.  Some  moisture conditioning may be required if a clay fill is used.    If granular fill materials are to be placed, we recommend a non‐expansive material a pit‐run or processed  sand or gravel having a maximum particle size of 3 inches with less than 15 percent by weight passing the  #200 sieve. The granular material can be placed in lifts of up to 1 foot in thickness. The material to be used as  structural fill should be tested by the geotechnical engineer. The maximum particle size and gradation may  relax during fill placement by the engineer of record depending on construction techniques, lift thicknesses,  and observations.     Based on the data from this exploration, we expect that the existing on‐site materials (classified as lean clays  or sandy lean clays) may be reused as structural fill, assuming the materials pass proof‐rolling activities. The      Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  7 | Page  client should anticipate some undercut and replacement may be necessary.     Structural fill should be placed in loose, horizontal lifts not exceeding 8 inches in thickness. Each lift should be  compacted to at least 98 percent of the soil’s maximum dry density per the standard Proctor method (ASTM  D 698) and within the range of minus (‐) 2 percent to plus (+) 3 percent of the optimum moisture content.  Each lift should be tested by geotechnical personnel to confirm that the contractors’ method is capable of  achieving the project requirements before placing subsequent lifts. Areas which have become soft or frozen  should be removed before additional structural fill is placed.    4.3 FOUNDATION RECOMMENDATIONS    4.3.1 Shallow Foundations   Upon completion of site preparation, as previously recommended and based on our assumptions of proposed  grades, it is our opinion the proposed building can be supported on conventional spread footing foundations  bearing on properly compacted structural granular fill or approved alluvium materials. If the surface of the  native gravels cannot be rolled smooth due to protruding cobbles or boulders, a thin leveling course of  granular fill should be considered between the concrete elements and the compacted native gravels to  prevent stress concentrations on the concrete. The use of road base materials conforming to Section 02235  of the Montana Public Works Standard Specifications (MPWSS) is recommended for this application. We  recommend that if soft or unstable soils are encountered during footing excavations, they be undercut and  backfilled with structural fill or lean concrete in the building area. Spread and continuous footings supported  on properly placed and compacted structural soil fill or suitable residual soils can be designed for an allowable  soil bearing pressure of 3,000 psf.    We recommend that continuous foundations be a minimum of 18 inches wide and isolated spread footings  be a minimum of 24 inches wide to reduce the possibility of a localized punching shear failure. Exterior  foundations should be designed to bear at least 48 inches below finished exterior grade to develop the design  bearing pressure and to protect against frost heave. Frost heave is the deformation of a building caused by  uplift due to the expansion of excessive soil water as it freezes; however, frost heave can also occur when  moist, frost susceptible soil freezes or adheres to the side of foundation members and ice lenses deform the  building by similar action. Soils used for backfilling above the frost line should not be susceptible to frost to      Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  8 | Page  prevent the side‐grip frost heave.  We expect that the existing on‐site materials classified as sands and  gravels may be used to satisfy this recommendation.    Alternatively, should the client wish to reduce foundation depths, Frost‐Protected Shallow Foundations (FPSF)  may be used in accordance with the design methods of ASCE 32 Design and Construction of Frost‐Protected  Shallow Foundations. This method utilizes foundation insulation and non‐frost‐susceptible materials in a  defined manner to utilize building and geothermal heat to reduce the depth required to protect from frost  heave. The design based on the building use characteristics (heated, unheated, or semi‐heated) and the air‐ freezing index (AFI), more specifically the design air‐freezing index (F100), which for Bozeman, MT is 2140 °F‐ days per NOAA.      The available lateral capacity of shallow foundations includes a soil lateral pressure and coefficient of friction  as described in the IBC, Section 1806. Footings will be embedded in material similar to those described as  Class 4 in Table 1806.2. Where footings are cast neat against the sides of excavations, an allowable lateral  bearing pressure of 150 psf per foot depth below natural grade may be used in computations. The lateral  sliding resistance may be evaluated considering a coefficient of friction of 0.25. An increase of one‐third in  the allowable lateral capacity may be considered for transient load combinations, including wind or  earthquake, unless otherwise restricted by design code provisions.    A geotechnical representative should be retained to perform foundation subgrade tests to confirm that the  recommendations provided in this report are consistent with the site conditions encountered. Some  undercutting of lower consistency residual soils, where encountered, in foundation excavations should be  anticipated. A dynamic cone penetrometer (DCP) is commonly utilized to provide information that is  compared to the data obtained in the geotechnical report. Where unacceptable materials are encountered,  the material should be excavated to stiff, suitable soils or remediated at the geotechnical engineer's direction.    Based on the known subsurface conditions, geology, and past experience, we estimate foundations  supported on the recommended structural soil fill or other approved soils should experience maximum total  and differential settlements of less than 1 inch and ½ of an inch, respectively. The settlement information  provided was with maximum column and continuous foundation loads on the order of 80 kips and 3 kips per  linear foot (kpf), respectively, and an allowable bearing pressure of 3,000 psf. Additionally, this information  assumes that the site is prepared in accordance with our recommendations provided in this report. If these      Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  9 | Page  parameters are determined to be incorrect, we should be notified to reevaluate the settlements for the  building.    4.3.2 Slabs‐on‐Grade   Following the recommended site preparation activities, it is our opinion that the floor slab can be grade  supported on structural soil fill materials or suitable residual soils. Observing proofrolling of the subgrade, as  discussed earlier in this report, should be accomplished to identify soft or unstable soils which should be  removed from the floor slab area prior to fill placement and/or floor slab construction.     We recommend that the subgrade be topped with a minimum 6‐inch layer of crushed stone to act as a  capillary moisture block. The subgrade should be proofrolled and approved prior to the placement of the  crushed stone. Based on the conditions encountered on this site, we recommend that the floor slabs be  designed using a subgrade modulus of 100 pounds per cubic inch (pci). This modulus is appropriate for small  diameter loads (i.e. a 1ft x 1ft plate) and should be adjusted for wider loads.     4.4 SEISMIC DESIGN CRITERIA    In accordance with the International Building Code (IBC), 2018, we are providing the following seismic  design information. After evaluating the soil consistencies from the observation pits, it was determined  that the subsurface conditions at the site most closely matched the description for “Seismic Site Class C”  or “ Very Dense Soil and Soft Rock”. Table 1 provides the spectral response accelerations for both short  and 1‐second periods, which may be used for design.     Table 1 – Seismic Design Parameters          The short and 1‐second period values indicate the structure should be assigned a Seismic Design Category  “D” using the published information. The provided values are based on the results of our field exploration  and the assumption that the structure will be designed utilizing a Risk Category I, II or III.  If these assumptions  are incorrect, we should be contacted to reevaluate the seismic design information.  Structure Ss S1 SDS SD1  g g g g  Tidal Wave Auto Spa – North Bozeman, MT 0.712 0.22 0.577 0.22      Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  10 | Page    For structures assigned a Seismic Design Category D, Sections 1803.5.12 of the 2018 IBC requires the  determination of seismic lateral earth pressures on foundation walls and retaining walls supporting more  than 6 feet of backfill height. If walls of more than 6 feet are included in the project design, GEOServices  should be retained to develop the seismic lateral earth pressures.    In accordance with IBC 2018 sections 1803.5.11 and 1803.5.12, we have provided a discussion on the  following geologic and seismic hazards: slope instability, liquefaction, total/differential settlement, and  surface displacement due to faulting or seismically induced lateral spread or lateral flow.    Liquefaction occurs when soil, primarily saturated cohesionless soils, undergo a loss in strength due to  monotonic, transient, or repeated disturbance that commonly occurs during a seismic event (Kramer 1996).  This loss of strength occurs due to increased pore water pressures caused by an undrained condition.  The  increase in pore water pressure decreases the effective stress in the soil, thus reducing the soil’s ability to  support any applied loads.  For liquefaction to occur, there must be an increase in pore pressure meaning the  soil must be saturated and be able to behave in an undrained condition.  According to the NHI 2011 Reference  Manual on LRFD Seismic Analysis and Design of Transportation Geotechnical Features and Structural  Foundations, if any of the following criteria are satisfied then a significant liquefaction hazard does not exist:     The geologic materials underlying the site are either bedrock or have very low liquefaction  susceptibility according to the relative susceptibility ratings shown in the Estimated Susceptibility of  Sedimentary Deposits to Liquefaction During Strong Ground Motion table presented by Youd and  Perkins in 1978.     The soils below the groundwater table at the site are one of the following:  o Clayey soils which have a clay content greater than 15%, liquid limit greater than 35%, or  natural water content less than 90% of the liquid limit.  o Sand with a minimum corrected SPT (N1)60 value of 30 blows/foot.  o The water table is deeper than 50 feet below the ground surface or proposed finished grade  at the site.        Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  11 | Page  Based on our experience in this geologic region and immediate vicinity of the site, it is our opinion that a  liquefaction hazard does not exist for the subject development. As such, we do not expect significant  additional total and differential settlement, lateral soil movement, reduction in bearing capacity or lateral soil  reaction, permanent increase in soil lateral pressure, or flotation of buried structures in accordance with  Sections 1803.5.11 and 1803.5.12 of the 2018 IBC.    4.5 PAVEMENT DESIGN RECOMMENDATIONS    Following site preparation as previously recommended, the pavement areas can likely be grade supported on  properly compacted structural soil fill or suitable residual soil materials. We recommend that if the client  elects to utilize the existing materials for support of the proposed pavements, proof‐rolling of the subgrade  be accomplished to identify any soft or unstable soils which should be removed from the pavement area prior  to fill placement and/or pavement construction. Unsuitable soils will likely pump and deflect during proof‐ rolling and will likely need to be removed and replaced prior to placement of the structural soil fill or the  design pavement section.  4.5.1 Flexible Pavement Design  AASHTO flexible pavement design methods have been utilized for pavement recommendations. Our  recommendations are based on the assumptions that the subgrade has been properly prepared as  described previously which will require subgrade stabilization to improve support conditions at this site.  Based on our experience with similar developments, we recommend the following light and heavy‐duty  flexible pavement sections:    Table 2 ‐ Flexible Pavement Recommendations  Pavement Materials Light‐Duty (inches) Heavy‐Duty (inches)  Bituminous Asphalt Surface Mix 3.0 4.0  Crushed Aggregate Base Course 4.0 4.0  6” Minus Pit Run Gravel 8.0 8.0    We recommend an aggregate base stone equivalent to Montana Department of Transportation (MDT)  Type B Grade 2 specifications. The bituminous asphalt pavement and compaction requirements for the  crushed aggregate base and the bituminous asphalt pavement should generally follow the Montana Public      Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  12 | Page  Works Standard Specification (MPWSS) and MDT Division 400 specifications.     4.5.2 Rigid Pavement Design  AASHTO rigid pavement design methods have been utilized for the rigid pavement recommendations. In  areas of trash dumpster pads or areas where large trucks will traverse, we recommend the use of a  concrete pavement section. Our recommendations are based on the assumptions that the subgrade has  been properly prepared. Based on our experience with similar developments, we recommend the  following rigid pavement section:    Table 3 ‐ Rigid Pavement Recommendations  Pavement Materials Light‐Duty (inches) Heavy‐Duty (inches)  4,000 psi Type I Concrete 6.0 8.0  Compacted Crushed Aggregate Base 4.0 6.0        The concrete pavement and compaction requirements for the crushed aggregate base and the bituminous  asphalt pavement should generally follow the MPWSS and MDT Division 500 specifications.     Concrete should be reinforced with welded wire fabric or reinforcing bars to assist in controlling cracking  from drying shrinkage and thermal changes. Sawed or formed control joints should be included for each  144 square feet of area or less (12 feet by 12 feet). Saw cuts should not cut through the welded wire fabric  or reinforcing steel and dowels should be utilized at formed and/or cold joints.    4.5.3 General  Our recommendations are based upon the assumption that the subgrade has been properly prepared as  described in previous sections and that if used, off‐site soil borrow to be used to backfill to the final  subgrade meets the requirements of  the structural fill section. The paved areas should be constructed  with positive drainage to direct water off‐site and to minimize surface water seeping into the pavement  subgrade. The subgrade should have a minimum slope of 1 percent. In down grade areas, the basestone  should extend through the slope to allow water entering the basestone to exit. For rigid pavements,      Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  13 | Page  water‐tight seals should also be provided at formed construction and expansion joints.    We note that the City of Bozeman has provided modifications to the MPWSS. We recommend that  sections 02234, 02235, 02502, 02504, and 02510 be reviewed for potential modifications.     We understand that budgetary considerations sometimes warrant thinner pavement sections than those  presented. However, the client, owner, and project designers should be aware that thinner pavement  sections may result in increased maintenance costs and lower than anticipated pavement life. If thinner  pavement sections are warranted, alternate reinforced pavement sections can be considered, including  the use of geogrid reinforcement.    4.6 LATERAL EARTH PRESSURES    GEOS is unaware of any planned retaining structures for the planned development. Lateral earth pressure  theory used for retaining wall design is specific to the design method, type of wall system, and soil  conditions present at the site. If earth retaining structures are planned or required, GEOS will provide  lateral earth pressure recommendations based on interaction with the wall design team in an addendum  to this report.     5.0 CONSTRUCTION CONSIDERATIONS    5.1 FOUNDATION CONSTRUCTION    Foundation excavations should be opened, the subgrade evaluated, remedial work performed (if required),  and concrete placed in an expeditious manner. Exposure to weather often reduces foundation support  capabilities, thus necessitating remedial measures prior to concrete placement. It is also important that  proper surface drainage be maintained both during construction (especially in terms of maintaining dry  footing trenches) and after construction. Soil backfill for footings should be placed in accordance with the  recommendations for structural fill presented herein.     5.2 EXCAVATIONS        Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  14 | Page  Excavation refusal was not encountered; however, dense to very dense materials were encountered in  each of the observation pits. Excavation refusal conditions generally correspond to materials which  require difficult excavation methods such as ripping, chipping (by track‐mounted hydraulic hammers) or  blasting for removal. However, excavation equipment varies, and field refusal conditions may vary. The  removal of very dense material in confined excavations, such as for foundations or utilities, can often be  difficult .     Based on our understanding of the project, we anticipate minimal grading (cuts/fills less than 4 feet) will be  necessary for the majority of the site. Therefore, at this time, we do not anticipate that the difficult  excavation techniques will be necessary during most grading activities and foundation excavations.  However, some of the very dense materials may require additional equipment to remove, especially in  confined areas, such as foundations and utilities.  Once grading plans become available, GEOServices should  be allowed to review and revise these recommendations, if necessary.     Excavations should be sloped or shored in accordance with local, state, and federal regulations, including  OSHA (29 CFR Part 1926) excavation trench safety standards. The contractor is usually solely responsible for  site safety. This information is provided only as a service, and under no circumstances should GEOServices be  assumed responsible for construction site safety.    5.4 MOISTURE SENSITIVE SOILS    The fine‐grained soils encountered at this site will be sensitive to disturbances caused by construction traffic  and changes in moisture content. During wet weather periods, increases in the moisture content of the soil  can cause significant reduction in the soil strength and support capabilities. Construction traffic patterns  should be varied to prevent the degradation of previously stable subgrade. In addition, plastic soils which  become wet may be slow to dry and thus significantly retard the progress of grading and compaction  activities.     We caution if site grading is performed during the wet weather season, methods such as discing and allowing  the material to dry will be required to meet the required compaction recommendations. It will, therefore, be  advantageous to perform earthwork and foundation construction activities during dry weather.  If grading  operations are performed during the wet weather season, the owner should anticipate difficulties in      Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  15 | Page  achieving the proper compaction of the soil fill as well as some remediation (undercut and replacement) of  subgrade soils if exposed to inclement weather conditions.     5.5 DRAINAGE AND SURFACE WATER CONCERNS    To reduce the potential for additional undercut and construction induced sinkholes, water should not be  allowed to collect in the foundation excavations, on floor slab areas, or on prepared subgrades of the  construction area either during or after construction. Undercut or excavated areas should be sloped toward  one corner to facilitate removal of collected rainwater, subsurface water, or surface runoff. Positive site  surface drainage should be provided to reduce infiltration of surface water around the perimeter of the  building and beneath the floor slab. The grades should be sloped away from the building and surface drainage  should be collected and discharged such that water is not permitted to infiltrate the backfill and floor slab  areas of the building.    Significant construction dewatering is not anticipated for site grading based on our limited understanding of  the proposed grading.  However, seasonal fluctuations and runoff from adjacent properties may occur once  construction begins. If seepage or runoff is encountered at shallow depths, it is anticipated that it can be  controlled by simple means such as pumping from sumps or the use of perimeter trenches to collect and  discharge the water away from the work area. We recommend all excavations where groundwater is  encountered be observed on an individual basis to determine if interior drain systems are required.    6.0 LIMITATIONS    This report has been prepared in accordance with generally accepted geotechnical engineering practice for  specific application to this project. This report is for our geotechnical work only, and no environmental  assessment efforts have been performed. The conclusions and recommendations contained in this report are  based upon applicable standards of our practice in this geographic area at the time this report was prepared.  No other warranty, express or implied, is made.    The analyses and recommendations submitted herein are based, in part, upon the data obtained from the  exploration. The nature and extent of variations between the observation pit will not become evident until  construction. We recommend that GEOServices be retained to observe the project construction in the field.      Report of Geotechnical Exploration            GEOServices Project No. 21‐211043  Tidal Wave Auto Spa – North Bozeman, MT October 20, 2021  16 | Page  GEOServices cannot accept responsibility for conditions which deviate from those described in this report if  not retained to perform construction observation and testing. If variations appear evident, then we will re‐ evaluate the recommendations of this report. In the event that any changes in the nature, design, or location  of the structures are planned, the conclusions and recommendations contained in this report will not be  considered valid unless the changes are reviewed, and conclusions modified or verified in writing. Also, if the  scope of the project should change significantly from that described herein, these recommendations may  need to be re‐evaluated. ATTACHMENTS Knoxville, Tennessee 379312561 Willow Point WayFax: 865-539-8252Office: 865-539-8242FIGUREKSRN.T.S.SITE VICINITY MAPMDK8/17/2121-211043N1.) BASE MAP: USGS QUADRANGLE (BOZEMAN, MONTANA)NOTES:TIDAL WAVE AUTO SPABOZEMAN, MONTANA 597184500 VALLEY CENTER DRIVE BOZEMAN, MONTANA 59718 OBSERVATION TEST PIT MDK KSR 10/20/21 1.) OBSERVATION PIT LOCATIONS ARE SHOWN IN GENERAL ARRANGEMENT ONLY. 2.) DO NOT USE OBSERVATION PIT LOCATIONS FOR DETERMINATIONS OF DISTANCES OR QUANTITIES. 3.) BASE MAP PROVIDED BY: Brightwork Real Estate NOTES: N.T.S. 21-211043 TIDAL WAVE AUTO SPA Knoxville, Tennessee 379312561 Willow Point Way Fax: 865-539-8252Office: 865-539-8242 LOCATION OF SOIL OBSERVATION TEST PIT 4500 VALLEY CENTER DRIVE NLOCATION PLAN Observation Pit Logs TWAS - Bozeman, MT Date: GEOS Project No. 21-211043 Personnel: Michael D. Kelso from to 0 1 Topsoil Lean CLAY (CL) - with organics - dark brown 1 2.5 Alluvium Lean CLAY (CL) - with sand - light gray - dry 2.5 6 Alluvium Poorly Graded Gravel (GP) - with sand and clay - gray brown - dry October 5, 2021 OP-1 Firm Dense to very dense, terminated at 6 feet Location Depth (ft.)Material Type Description Comments Observation Pit Logs TWAS - Bozeman, MT Date: GEOS Project No. 21-211043 Personnel: Michael D. Kelso from to 0 1 Topsoil Lean CLAY (CL) - with organics - dark brown 1 3 Alluvium Poorly Graded Gravel (GP) - with sand and clay - gray brown - dry Dense to very dense, terminated at 3 feet OP-2 October 5, 2021 Location Depth (ft.)Material Type Description Comments Observation Pit Logs TWAS - Bozeman, MT Date: GEOS Project No. 21-211043 Personnel: Michael D. Kelso from to 0 1.5 Topsoil Lean CLAY (CL) - with organics - dark brown 1.5 3 Alluvium Poorly Graded Gravel (GP) - with sand and clay - gray brown - dry October 5, 2021 OP-3 Dense to very dense, terminated at 3 feet Location Depth (ft.)Material Type Description Comments Observation Pit Logs TWAS - Bozeman, MT Date: GEOS Project No. 21-211043 Personnel: Michael D. Kelso from to 0 1.5 Topsoil Lean CLAY (CL) - with organics - dark brown 1.5 3 Alluvium Poorly Graded SAND (SP) - with gravel - light grayish brown 3 6 Alluvium Poorly Graded Gravel (GP) - with sand and clay - gray brown - dry OP-4 Dense October 5, 2021 Dense to very dense, terminated at 6 feet Location Depth (ft.)Material Type Description Comments Observation Pit Logs TWAS - Bozeman, MT Date: GEOS Project No. 21-211043 Personnel: Michael D. Kelso from to 0 1 Topsoil Lean CLAY (CL) - with organics - dark brown 1 3 Alluvium Poorly Graded Gravel (GP) - with sand and clay - gray brown - dry October 5, 2021 OP-5 Dense to very dense, terminated at 3 feet Location Depth (ft.)Material Type Description Comments Observation Pit Logs TWAS - Bozeman, MT Date: GEOS Project No. 21-211043 Personnel: Michael D. Kelso from to 0 0.5 Topsoil Lean CLAY (CL) - with organics - dark brown 0.5 1.5 Alluvium Lean CLAY (CL) - with sand, dried clay clods, and gravel - dark brown - dry 1.5 3 Alluvium Poorly Graded Gravel (GP) - with sand and clay - gray brown - dry OP-6 October 5, 2021 Firm to Stiff Dense to very dense, terminated at 3 feet Location Depth (ft.)Material Type Description Comments Observation Pit Logs TWAS - Bozeman, MT Date: GEOS Project No. 21-211043 Personnel: Michael D. Kelso from to 0 0.25 Topsoil Lean CLAY (CL) - with organics - dark brown 0.25 2 Alluvium Poorly Graded Gravel (GP) - with sand and clay - gray brown - dry OP-7 Dense to very dense, terminated at 2 feet October 5, 2021 Location Depth (ft.)Material Type Description Comments Observation Pit Logs TWAS - Bozeman, MT Date: GEOS Project No. 21-211043 Personnel: Michael D. Kelso from to 0 1 Topsoil Lean CLAY (CL) - with organics - dark brown 1 3 Alluvium Lean CLAY (CL) - with sand - light gray - dry 3 4 Alluvium Poorly Graded Gravel (GP) - with sand and clay - gray brown - dry OP-8 Firm Dense to very dense, terminated at 4 feet October 5, 2021 Location Depth (ft.)Material Type Description Comments Observation Pit Logs TWAS - Bozeman, MT Date: GEOS Project No. 21-211043 Personnel: Michael D. Kelso from to 0 0.5 Topsoil Lean CLAY (CL) - with organics - dark brown 0.5 3 Alluvium Lean CLAY (CL) - with sand - light gray - dry 3 5 Alluvium Lean CLAY (CL) - with sand and gravel - gray brown - dry 5 6 Alluvium Poorly Graded Gravel (GP) - with sand and clay - gray brown - dry Location Depth (ft.)Material Type Description Comments Dense to very dense, terminated at 6 feet OP-9 Stiff Firm October 5, 2021 Observation Pit Logs TWAS - Bozeman, MT Date: GEOS Project No. 21-211043 Personnel: Michael D. Kelso from to 0 0.5 Topsoil Lean CLAY (CL) - with organics - dark brown 0.5 2 Alluvium Lean CLAY (CL) - with sand - light gray - dry 2 3 Alluvium Lean CLAY (CL) - with sand and gravel - gray brown - dry 3 4.5 Alluvium Poorly Graded Gravel (GP) - with sand and clay - gray brown - dry Location Depth (ft.)Material Type Description Comments Firm Dense to very dense, terminated at 4.5 feet OP-10 Stiff October 5, 2021 Observation Pit Logs TWAS - Bozeman, MT Date: GEOS Project No. 21-211043 Personnel: Michael D. Kelso from to 0 0.5 Topsoil Lean CLAY (CL) - with organics - dark brown 0.5 2 Alluvium Lean CLAY (CL) - with sand - light gray - dry 2 3 Alluvium Lean CLAY (CL) - with sand and gravel - gray brown - dry 3 4 Alluvium Poorly Graded Gravel (GP) - with sand and clay - gray brown - dry OP-11 Firm Stiff Dense to very dense, terminated at 4 feet October 5, 2021 Location Depth (ft.)Material Type Description Comments Observation Pit Logs TWAS - Bozeman, MT Date: GEOS Project No. 21-211043 Personnel: Michael D. Kelso from to 0 0.5 Topsoil Lean CLAY (CL) - with organics - dark brown 0.5 3 Alluvium Lean CLAY (CL) - with sand - light gray - dry 3 3.5 Alluvium Lean CLAY (CL) - with sand and gravel - gray brown - dry 3.5 4.5 Alluvium Poorly Graded Gravel (GP) - with sand and clay - gray brown - dry OP-12 Firm Stiff Dense to very dense, terminated at 4.5 feet October 5, 2021 Location Depth (ft.)Material Type Description Comments Drainage Design Report Tidal Wave Auto Spa, Bozeman MT Attachment D—Mannings Equation Calculations Input ValuesInput Valuesd = 1.000 ft 1.00 Pipe Diameter [ft] d = 0.250 ft 0.25 Pipe Diameter [ft]y =0.150ft 0.71 y =0.170ft 0.18Calculated Values(Equations from Open-Channel Hydraulics by Chow)Calculated Values(Equations from Open-Channel Hydraulics by Chow)Theta (Θ)1.59 3.99 rad 2*arccos(1-y/(d/2))Theta (Θ)3.87812844 3.99 rad 2*arccos(1-y/(d/2))Area (A) 0.07 0.59ft2(1/8)*(Θ-sinΘ)d2Area (A) 0.04 0.04ft2(1/8)*(Θ-sinΘ)d2Wetted Perimeter (P) 0.79 1.99 ft 0.5Θd Wetted Perimeter (P) 0.48 0.50ft 0.5ΘdHydraulic Radius (R ) 0.09 0.30 ft (.25)*(1-(sinΘ)/Θ)d Hydraulic Radius (R ) 0.07 0.07 ft (.25)*(1-(sinΘ)/Θ)dTop Width (T) 0.71 0.91 ft (sin 0.5Θ)d Top Width (T) 0.23 0.23 ft (sin 0.5Θ)dMannings EquationMannings Equationn = 0.012 Manning's Rougness Coefficient for HDPE pipe n = 0.012 Manning's Rougness Coefficient for HDPE pipeS0 =0.01 ft/ftS0=0.04 ft/ftQ = 0.19 cfs1.49/n*A*R2/3*S00.5Q = 0.15 cfs1.49/n*A*R2/3*S00.584.16gpm Peak Flow69.40gpm Peak FlowQfull75% = 3.27 cfs occurs when y/d = 0.94*.75Qfull75% = 0.16 cfs occurs when y/d = 0.94*.751467.72gpm72.81gpmMain Line Roof Drains Drainage Design Report Tidal Wave Auto Spa, Bozeman MT Attachment E—Rational Method Calculations Area A Area Calculations Acrea Coefficents UNIMPROVED (Al):1.64 acres Cl :0.25 PAVED AND ROOF AREA (Ar):1.68 acres Cr :0.95 GRAVEL AREA (Ag):0.00 acres Cg : TOTAL AREA (A):3.32 acres TOTAL C:0.604217 Runoff Calculations Allowable Runoff (or percolation)*0.18 cfs 7660.00 :area (SF) of drainage system Time (min) CA (Acres) Intensity (in/hr) Time (sec) Cummulati ve Runoff (ft3) Infiltration (ft3) Storage (ft3) 10 2.01 2.568 600 3,091 106 2,984 15 2.01 2.12 900 3,827 160 3,668 30 2.01 1.428 1,800 5,156 319 4,837 60 2.01 0.884 3,600 6,384 638 5,746 120 2.01 0.50 7,200 7,222 1,276 5,945 180 2.01 0.363333 10,800 7,872 0 7,872 360 2.01 0.221667 21,600 9,605 0 9,605 720 2.01 0.1375 43,200 11,916 0 11,916 1440 2.01 0.07875 86,400 13,649 0 13,649 STORAGE REQUIRED : 13,649 STORAGE PROVIDED :97,060