Loading...
HomeMy WebLinkAboutSTORMWATER SITE PLAN - 14-00054 - McDonalds Parking Lot Expansion - Site PlanSTORMWATER SITE PLAN MCDONALD'S DEVELOPMENT REXBURG, IDAHO FEBRUARY 20, 2013 02/20/20/3 PREPARED FOR: City of Rexburg 35 North 1 st East Rexburg, ID 83440 Mr. Keith Davidson PREPARED BY: 11711 SE 8th Street, Suite 303 Bellevue, Washington 98005 Phone (425) 453-9501 Fax (425) 453-8208 jtaflin@pacland.com Jenelle Taflin, P.E., LEED AP REVIEWED BY: Paul Manzer, P.E. TABLE OF CONTENTS SECTION PAGE PROJECTOVERVIEW...................................................................................................... 1 PROPOSEDIMPROVEMENTS............................................................................................. 1 DESIGNCRITERIA........................................................................................................... 1 PROJECTLOCATION....................................................................................................... 2 COREELEMENTS............................................................................................................ 3 EXISTINGCONDITIONS.................................................................................................5 DEVELOPEDCONDITIONS............................................................................................ 7 OFFSITEANALYSIS REPORT........................................................................................... 8 PERMANENT STORMWATER CONTROL PLAN.............................................................. 8 EXISTING SITE HYDROLOGY............................................................................................. 8 DEVELOPEDSITE HYDROLOGY......................................................................................... 8 HYDROLOGIC MODELING............................................................................................... 9 FLOWCONTROL SYSTEM................................................................................................ 9 WATERQUALITY SYSTEM.............................................................................................. 12 CONVEYANCE SYSTEM ANALYSIS AND DESIGN.................................................................. 14 CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN ........................... 17 SPECIAL REPORTS AND STUDIES................................................................................. 22 OTHERPERMITS...........................................................................................................22 OPERATION AND MAINTENANCE MANUAL.............................................................. 22 APPENDIX A GEOTECHNICAL ENGINEERING REPORT APPENDIX B OPERATION AND MAINTENANCE GUIDELINES 2/20/13 STORMWATER SITE PLAN PROJECT OVERVIEW PROPOSED IMPROVEMENTS The proposed development consists of the construction of a new McDonald's restaurant building totaling approximately 4,016 ± SF with approximately 31 parking stalls, stormwater management facilities, utilities and on-site landscaping on a 0.824 -acre site at the northeast corner of the intersection of University Boulevard and Yellowstone Highway in Rexburg, Idaho (parcel # RP06N40E314120). No off-site roadway improvements are proposed as part of the specific development. The property is located in the Commercial Business Center (CBC) zone. DESIGN CRITERIA The City of Rexburg utilizes the 2005 Idaho Department of Environmental Quality (IDEQ) Catalog of Stormwater Best Management Practices for drainage requirements. As confirmed by Keith Davidson, Assistant City Engineer, the City of Rexburg is located in Zone G, for which the design storm is prescribed as the Type 2 storm. Projects shall maintain the pre -developed 25 -year, 60 -minute flow rate (at 0.9"/hour) for flow control facility design. The 2 -year, 24-hour developed flow rate shall be used for water quality facility sizing. Jurisdictional Requirements Table 1 below summarizes the stormwater requirements. TABLE 1 Jurisdictional Requirements Duration Analysis: 25 -year: Match pre -developed Water Quali Volume: n/a Water Quality Flow Rate: Runoff flow rate of the developed condition from the 2 -year, 24-hour 2/20/13 STORMWATER SITE PLAN PAGE 1 PROJECT LOCATION Location: Northeast corner of the intersection of University Boulevard and Yellowstone Highway in Rexburg, ldaho Section, Township, Range: South half of Section 36, Township 6N, Range 39E, B.M. Tax Account Number: RP06N40E314120 Size: 0.824 AC City, County, State: Rexburg, Madison County, ID Governing Agency: City of Rexburg Design Criteria: 2005 Idaho Department of Environmental Quality (IDEQ) Catalog of Stormwater Best Management Practices Zoning: Commercial Business Center (CBC) 2/20/13 STORMWATER SITE PLAN PAGE 2 CORE ELEMENTS Redevelopment is defined as the replacement or improvement of impervious surfaces on a developed site. As the project proposes to replace greater than 5,000 SF of existing pollution generating impervious surface (PCIS), Core Elements 1 — 8 below apply. Core Element #1: Preparation of a Stormwater Site Plan Stormwater management is most successful when integrated into project planning and design. Projects are expected to demonstrate compliance with the applicable Core Elements through preparation of a Stormwater Site Plan. Response: A stormwater site plan has been prepared for the development. The stormwater site plan includes the design drawings and this report. Core Element #2: Construction Stormwater Pollution Prevention (SWPP) All projects are responsible for preventing erosion and discharge of sediment into surface waters and must consider each of the twelve elements of pollution prevention in order to determine which controls are appropriate for the project site. Each of the twelve elements must be considered and included in the Construction SWPP unless site conditions render the element unnecessary and the exemption from that element is clearly justified in the narrative of the SWPPP. Response: The 12 elements of a Construction SWPP are addressed in the Construction SWPP section of this report. Core Element #3: Source Control of Pollution The intent of Source Control Best Management Practices (BMPs) is to prevent pollutants from coming into contact with stormwater. All known, available and reasonable source control BMPs shall be applied to all projects. Source control BMPs shall be selected, designed, and maintained according to the manual. Response: Roof runoff will be kept separate from runoff from pollution -generating surfaces to the maximum extent possible. Core Element #4: Preservation of Natural Drainage Systems Natural drainage patterns shall be maintained, and discharges from the project site shall occur at the natural location, to the maximum extent practicable. The manner by which runoff is discharged from the project site must not cause a significant adverse impact to downstream receiving waters and downgradient properties. All outfalls require energy dissipation. Response: The runoff from the project site collects at a low area on-site, where it discharges by means of infiltration to the sub -soils below. There does not appear to be a tight -lined connection to an off-site conveyance system. Core Element #5: Runoff Treatment The purpose of runoff treatment is to reduce pollutant loads and concentrations in stormwater runoff using physical, biological, and chemical removal mechanisms to protect water quality so that beneficial uses of receiving waters are maintained and where applicable, restored. Response: Runoff treatment will be provided by means of a CONTECH CDS unit for water quality treatment prior to release to the proposed underground infiltration trench system. Core Element #6: Flow Control Projects must provide flow control to reduce the impacts of stormwater runoff from impervious surfaces and land cover conversions. Response: Flow control will be provided by means of an underground infiltration trench system. 2/20/13 STORMWATER SITE PLAN PAGE 3 Core Element #7: Operation and Maintenance An operation and maintenance manual that is consistent with the provisions in Volume V of this manual shall be provided for all proposed stormwater facilities and BMPs, and the party (or parties) responsible for maintenance and operation shall be identified. At private facilities, a copy of the manual shall be retained onsite or within reasonable access to the site, and shall be transferred with the property to the new owner. For public facilities, a copy of the manual shall be retained in the appropriate department. A log of maintenance activity that indicates what actions were taken shall be kept and be available for inspection by the local government. Response: See the Operation and Maintenance Manual provided in this report. Core Element #8: Local Requirements All projects, regardless of size, shall meet additional local requirements for flood control, discharges to wetlands, protection of sensitive areas, basin plans, aquifer protections, special water quality requirements based on Total Maximum Daily Load (TMDL) or Water Cleanup Plan, or for any other purpose. Response: The City of Rexburg utilizes the 2005 Idaho Department of Environmental Quality (IDEQ) Catalog of stormwater Best Management Practices for drainage requirements. As confirmed by Keith Davidson, Assistant City Engineer, the City of Rexburg is located in Zone G, for which the design storm is prescribed as the Type 2 storm. Projects shall maintain the pre -developed 25 -year, 60 -minute flow rate (at 0.9"/hour) for flow control facility design. The 2 -year, 24-hour developed flow rate shall be used for water quality facility sizing. 2/20/13 STORMWATER SITE PLAN PAGE 4 EXISTING CONDITIONS The existing site is comprised of 0.824 -AC of undeveloped parcel of land located at the northeast corner of the intersection of University Boulevard and Yellowstone Highway in Rexburg, Idaho. FIGURE 1: txtstmg Lonamons The runoff from the project site collects at a general low area at the center of the site, where it discharges by means of infiltration to the sub -soils below. There does not appear to be a tight -lined connection to an off- site conveyance system. Per the FEMA Flood Insurance Rate Map (FIRM) panel 16065CO020D excerpt below, the site falls within Zone X, areas determined to be outside the 500 -year flood plain. 2/20/13 STORMWATER SITE PLAN PAGE 5 DEVELOPED CONDITIONS The proposed development consists of the construction of a new McDonald's restaurant building totaling approximately 4,016 ± SF with approximately 31 parking stalls, stormwater management facilities, utilities and on-site landscaping. See Figure 3 below. FIGURE 3: Developed Conditions The developed site is considered a single drainage basin for purposes of sizing the proposed water quality and infiltration facilities. Stormwater runoff will be infiltrated on-site after undergoing water quality treatment. 2/20/13 STORMWATER SITE PLAN PAGE 7 OFFSITE ANALYSIS An offsite analysis was performed to identify and evaluate potential offsite water quality, erosion, slope stability, and drainage impacts that could result from the proposed project, and to determine measures to mitigate potential impacts or mitigate aggravating existing problems. Upstream Analysis There appears to be upstream run-on from the existing landscaped area along Yellowstone Highway (US 91) immediately adjacent to the project site. The total area of run-on is approximately 0.115 -acre, which will be accounted for in the design of the on-site stormwater management facilities. Downstream Analysis The runoff from the project site collects at a general low area at the center of the site, where it discharges by means of infiltration to the sub -soils below. There does not appear to be a tight -lined connection to an off- site conveyance system. PERMANENT STORMWATER CONTROL PLAN EXISTING SITE HYDROLOGY Please see Tables 2 and 3 below for a summary of the surface area make-up of the existing on-site and off-site areas. Table 2 Existing Conditions — On -Site Area (AC) Description CN 0.824 Opens aces, lawn, parks (> 75% grass) 80 Table 3 Existing Conditions — Offsite Area (AC) Description CN 0.115 Open spaces, lawn, parks (> 75% grass) 80 DEVELOPED SITE HYDROLOGY Please see Tables 4 and 5 below for a summary of the surface area make-up of the developed on-site and off- site areas. Table 4 Developed Conditions — On -Site Area (AC) Description CN 0.566 Impervious Surfaces (pavement, roofs, etc.) 98 0.258 Open spaces, lawn, parks (> 75%grass) 80 Table 5 Developed Conditions — Offsite Area (AC) Description CN 0.115 Open spaces, lawn, parks (> 75% grass) 80 2/20/13 STORMWATER SITE PLAN PAGE 8 HYDROLOGIC MODELING The City of Rexburg utilizes the 2005 Idaho Department of Environmental Quality (IDEQ) Catalog of Stormwater Best Management Practices for drainage requirements. As confirmed by Keith Davidson, Assistant City Engineer, the City of Rexburg is located in Zone G, for which the design storm is prescribed as the Type 2 storm. Projects shall maintain the pre -developed 25 -year, 60 -minute flow rate (at 0.9"/hour) for flow control facility design. StormShed 3G software by Engenious was utilized to perform the hydrologic modeling. FLOW CONTROL SYSTEM Flow control for the entire 0.824 -acre on-site area and 0.115 -acre off-site area is provided by means of an underground infiltration trench system that is sized to maintain the pre -developed 25 -year, 60 -minute flow rate (at 0.9"/hour). Per the StormShed 3G output below, the resultant underground infiltration trench system required is 120' L x 10'WxYID. LPOOLCOMPUTE [LEVEL POOL] SUMMARY using Puts, 24 hr Storm Event Start of live storage: 100 ft Event Match Q (cfs) Peak Q (cfs) Max EI (ft) Vol (cf) [Vol (acft) Time to Empty (hr) 25 -r24 hr F 0.6222 0.0556 � 105.4515 2158.7985 0.0496 r 5.7779 Summary Report of all Detention Pond Data Project Precips Event Precip (in) 25 year 60 min —0.90- 12 yr 24 hr 1.10 10 yr 24 hr 1.70 25 yr 24 hr 2.00 100 yr 24 hr 2.50 BASLIST2 [PREDEVELOPED] Using [TYPE2.RAC] As [25 yr 24 hr] [24.0] [DEVELOPED] Using [TYPE2.RAC] As [25 yr 24 hr] [24.0] LSTEND B P cfs Q Peak T Peak Vol Area r BasinID Event Method/Loss Raintype ( ) (hrs) (ac-cf) (ac PREDEVELOPED 25hr 24 1 0.6222 12.09 0.0441 0.939 I SCS TYPE2.RAC DEVELOPED 25 hr 24 1.5298 12.02 0.0904 0.939 SCS TYPE2.RAC 2/20/13 STORMWATER SITE PLAN PAGE 9 BASLIST [PREDEVELOPED][DEVELOPED] LSTEND Record Id: PREDEVELOPED Design Method SCS Rainfall type I TYPE2.RAC Hyd Intv F 10.00 min lPeaking Factor 484.00 Storm Duration F 24.00 hrs lAbstraction Coeff 0.20 Pervious Area Pervious CN Pervious TC 0.939 ac �I)CIA 80.00 DC CN 14.2095 min DC TC 0.00 ac 0.00 F- 0.00 min Pervious CN Pervious CN Calc 0.00 Description Open spaces, lawns,parks (>75% grass) F SubArea Sub en 0.939 ac 80.00 0.00 min Pervious Composited CN (AMC 2) F 80.00 Description Pervious TC Cale - Type Description Length rSlope Sheet Short prairie grass and lawns. 100.00 ft F3.0% - --- Coeff Misc TT 0.15 [ 1.10 in 14.2095 min 0.566 ac 98.00 Pervious TC 14.2095 min 0.373 ac 80.00 - Pervious Composited CN (AMC 2) Record Id: DEVELOPED Design Method F SCS Rainfall type I TYPE2.RAC Hyd Intv 10.00 min Peaking Factor 484.00 Storm Duration 24.00 hrs lAbstraction Coeff F 0.20 Pervious Area 0.939 ac DCIA 0.00 ac Pervious CN F 90.85 DC CN 0.00 Pervious Pervious TC 6.40 min -F TC 0.00 min Pervious CN Cale Description F SubArea r Sub en Impervious surfaces (pavements, roofs, etc) 0.566 ac 98.00 �- Open spaces, lawns,parks (>75% grass) 0.373 ac 80.00 - Pervious Composited CN (AMC 2) -- F 90.8498 Pervious TC Cale TypeFr Description F Length Slope Coeff F Mise TT Sheet MinTravel Time 20.00 ft r 5.0% . 6.4 ! 0.00 in 6.40 min -- Pervious TC - -- 6.40 min STORMWATER SITE PLAN HYDLIST SUMMARY [25 yr 24 hr out] LSTEND HydID Peak Q (cfs) Peak T (hrs) Peak Vol (ac -ft) Cont Area (ac) 125 yr 24 hr out 1 0.0556 1 11.27 1 0.0902 ( 0.939 STORLIST [IT2] LSTEND Record Id: IT2 Descrip: Underground Infiltration Trench Increment 0.10 ft Start El. 1100.00 ft Max El. 105.00 ft Void Ratio 133.001 10.00 ftt I Length 120.00 ft Width F-1 Consider Bottom Only Vault Type Node DISCHLIST [INFILTRATION] LSTEND Record Id: INFILTRATION Infiltration Descrip: IDischarge by means of infiltration Increment F 0.10 ft iStart El. 100.00 ft IMax El. 105.00 ft Infiltration rate I 2.00 in/hr WP Multiplier 1.00 STORMWATER SITE PLAN PAG 26 yr 24 hr WOHydropreph Fob 1.5 1.4 13 1.2 1.1 1 09 08 0] 06 05 04 03 02 01 0 Time in minutes WATER QUALITY SYSTEM ONSITE 1,Wd1 Hyo J — Inflow Hld J OVMow Hyd The 2 -year, 24-hour developed flow rate shall be used for water quality facility sizing. Per NOAA, Atlas 2, volume V, Figure 25, Isopluvials of 2 -YR, 24 -HR Precipitation in Tenths of an Inch for Idaho, the 2 -year, 24 hour precipitation value for Rexburg is 1.1 ". Please see the StormShed 3G output below for the 2 -year, 24-hour peak flow rate for the developed site. 'lirel7IA i9:r17:411411111:90MMI Q Basins _ l o I[E I DEVELOPED I Pery CN I Pery TC I Directly Connected CN I Directly Connected TC Compute Select Design Event: 12yr24hr Compute r AMC for this Computation: r AMC1 r AMC2 r AMC3 Project AMC: 2 Peak Rate: 0.5858 cfs Time to Peak: 721.48 min/ (12.02 hrs) from start. Hyd Val: 1447.10 cf / 0.033221 acft Close As confirmed by the CONTECH calculation below, a 2015-4 CDS model is adequate to provide water quality treatment of the peak 2 -year, 24-hour flow of 0.586 cfs. 2/20/13 STORMWATER SITE PLAN PAGE 13 CONVEYANCE SYSTEM ANALYSIS AND DESIGN As shown in the StormShed 3G output below, the 100 -year, 24-hour peak flow rate for the entire developed 0.824 -ace on-site area and 0.115 -acre off-site area is 2.077 cfs. DEVELOPED Event Summary Event CDS ESTIMATED NET ANNUAL SOLIDS LOAD REDUCTION Peak T (hrs) Hyd Vol (aeft) Area (ac) BASED ON THE RATIONAL RAINFALL METHOD 25 year 60 min 0.3976 BASED ON AN AVERAGE PARTICLE SIZE OF 125 MICRONS 0.0224 04 NTECH' SCS 2 yr 24 hr MoDRexb rRexburg 12.0246-F-0.0332 j 0.939 F SCS 10 yr 24 hr CC) DS ENGINEERED SOLUTIONS 0.939 SCS 25 yr 24 hr 1.5298 Area 0.84 acres 0.939 Rainfall Station N 53 2.0765 Weighted C 0.92 0.1253 FI ----0.939 (select from Rainfall Data column D) Tc 6.4 minutes Particle size 125 microns CDS Model 20154 (select from pulldown) CDS Treatment Capacity 0.7 cis Diameter CDS Hydraulic Capacity 10.0 cis Rainfall Percent Cumulative Total Treated Removal Intensity Rainfall Rainfall Flowrate Flowrate Operating Efficiency Incremental Rate ° Removal I%1 in/hr Volume' V % 0.08 63.5% 63.5% 0.06 0.06 8.83 99.6 63.3 0.16 19.6% 83.1% 0.12 0.12 17.66 97.9 19.1 0.24 7.4% 90,5% 0.19 0.19 26.50 96.1 7.2 0.32 2.9% 93.5% 0.25 0.25 35.33 94.3 2.8 0.40 1.9% 95.3% 0.31 0.31 44.16 92.6 1.7 0.48 1.5% 96.8% 0.37 0.37 52.99 90.8 1.4 0.56 0.7% 97.5% 0.43 0.43 61.82 89.0 0.6 0.64 0.9% 98.3% 0.49 0.49 70.66 1 87.3 0.8 0.72 0.3% 98.6% 0.56 0.56 79.49 85.5 0.2 0.80 0.5% 99.1% 0.62 0.62 88.32 83.7 0.4 1.20 0.2% 99.3% 0.93 0.70 100.00 81.4 0.1 2.00 0.3% 99.6% 1.55 0.70 100.00 81.4 0.1 0.00 0.0% 99.6% 0.00 0.00 0.00 100.0 0.0 0.00 0.0% 99.6% 0.00 0.00 0.00 100.0 0.0 0.00 0.0% 99.6% 0.00 0.00 0.00 100.0 0.0 0.00 0.0% 99.6% 0.00 0.00 0.00 100.0 0.0 0.00 0.0% 99.6% 0.00 0.00 0.00 100.0 0.0 0.00 0.0 % 99.6 % 0.00 0.00 0.00 1202. 0.0 0.00 0.00%% INS`. 0.00 0.00 0.00 100.0!97.7%/ 0.00 0.0% 99.6% 0.00 0.00 0.00 100.0 Removal Efficiency Adjustment'= Predicted % Annual Rainfall Treated = Predicted Net Annual Load Removal Efficiency = 1 - Based on 13 years of 15 minute data from NCDC station 09303, Twin Falls County, ID 2 - Reduction due to use o160 -minute data for a site that has a time of concentration less than 30 -minutes. CONVEYANCE SYSTEM ANALYSIS AND DESIGN As shown in the StormShed 3G output below, the 100 -year, 24-hour peak flow rate for the entire developed 0.824 -ace on-site area and 0.115 -acre off-site area is 2.077 cfs. DEVELOPED Event Summary Event Peak Q (cfs) Peak T (hrs) Hyd Vol (aeft) Area (ac) FMethod 25 year 60 min 0.3976 12.0246 0.0224 - 0.939 SCS 2 yr 24 hr 0.5858 12.0246-F-0.0332 j 0.939 F SCS 10 yr 24 hr 1.2059 I 12.0171 0.0703 0.939 SCS 25 yr 24 hr 1.5298 12.0171 j - 0.0904 0.939 SCS 100 yr 24 hr 2.0765 12.0171 0.1253 FI ----0.939 SCS 2/20/13 STORMWATER SITE PLAN PAGE 14 All results based on storm duration of 24.0 hours. This is ok if all precipitations are appropriate for the storm duration. If some design event precipitations are for different duration storms, those results are incorrect Record Id: DEVELOPED Design Method SCS Rainfall type TYPE2.RAC Hyd Intv 10.00 min Peaking Factor 484.00 Storm Duration ( 24.00 hrs !Abstraction Coeff 0.20 Pervious Area F 0.939 ac iDCIA 0.00 ac Pervious CN r 90.85 IDC CN 0.00 Pervious TC 6.40 min DC TC 0.00 min Pervious CN Calc Description SubArea F Sub en F_ Impervious surfaces (pavements, roofs, etc) F 0.566 ac r 98.00 Open spaces, lawns,parks (>75% grass) T 0.373 ac 80.00 F__ Pervious Composited CN (AMC 2) 70.8498 Pervious TC Calc Type r Description Length Slope r Coeff -mise TT Sheet IMinTravel Time 20.00 ft 5.0% 6.4 FO.00 in F 6.40 min Pervious TC 6.40 min In the main conveyance system, the proposed 12 -inch diameter pipe at 1.0% minimum slope is the most restrictive element. As demonstrated in the Manning's calculation below, this element can provide conveyance capacity up to 3.8195 cfs flowing near full, which is more than enough capacity to handle the 100 -year, 24-hour peak flow from the 0.824 -acre on-site area and 0.115 -acre off-site area of 2.077 cfs. 2/20/13 STORMWATER SITE PLAN PAGE 15 Solve For i Flowrake Flowrate Slope Manning's n Depth of Flow Diameter Velocity Area Perimeter Wetted Area Wetted Perimeter Hydraulic Radius Percent Full cfs 3.8195 Rift 0.0100 Select 0.0130 Select in 111.5000 in 12.0000 Select Pipe Shape: Circular 100 -YEAR FLOOD/OVERFLOW CONDITION The stormwater conveyance system for this project has been designed to address storm events in accordance with common industry practices. In the event of a larger storm, the system may fail. In this case, the runoff from larger events will overflow onto the parking lot area. 3 STORMWATER SITE PLAN PAGE 16 Plot fps 4.9335 Output R2 0.7854 Critical in 37.6991 ft2 0.7742 Bating in 32.7655 OY. in 3.4025 Cancel 95.8333 Help 100 -YEAR FLOOD/OVERFLOW CONDITION The stormwater conveyance system for this project has been designed to address storm events in accordance with common industry practices. In the event of a larger storm, the system may fail. In this case, the runoff from larger events will overflow onto the parking lot area. 3 STORMWATER SITE PLAN PAGE 16 CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN All erosion and sediment control measures shall be governed by the requirements of the City of Rexburg. A temporary erosion and sedimentation control plan has been prepared to assist the contractor in complying with these requirements. The Erosion and Sediment Control (ESC) plan is included with the construction plans. Element 1: Mark Clearing Limits • Prior to beginning land disturbing activities, including clearing and grading, all clearing limits, sensitive areas and their buffers, and trees that are to be preserved within the construction area shall be clearly marked, both in the field and on the plans, to prevent damage and offsite impacts. • Plastic, metal, or stake wire fence may be used to mark the clearing limits. • The duff layer, native top soil, and natural vegetation shall be retained in an undisturbed state to the maximum extent practicable. If it is not practicable to retain the duff layer in place, it should be stockpiled on-site, covered to prevent erosion, and replaced immediately upon completion of the ground disturbing activities. Response: Clearing limits are identified on the Temporary Erosion and Sediment Control Plan of the Construction Plans. Element 2: Establish Construction Access • Construction vehicle access and exit shall be limited to one route, if possible, or two for linear projects such as roadways where more than one access is necessary for large equipment maneuvering. • Access points shall be stabilized with a pad of quarry spalls or crushed rock prior to traffic leaving the construction site to minimize the tracking of sediment onto public roads. • Wheel wash or tire baths should be located on-site, if applicable. • If sediment is tracked off site, public roads shall be cleaned thoroughly at the end of each day, or more frequently during wet weather, if necessary to prevent sediment from entering waters of the state. Sediment shall be removed from roads by shoveling or pickup sweeping and shall be transported to a controlled sediment disposal area. Street washing will be allowed only after sediment is removed in this manner. • Street wash wastewater shall be controlled by pumping back onsite, or otherwise be prevented from discharging into systems tributary to state surface waters. Response: A stabilized construction entrance is identified on the Temporary Erosion and Sediment Control Plan of the Construction Plans. Element 3: Control Flow Rates • Properties and waterways downstream from development sites shall be protected from erosion due to increases in the volume, velocity, and peak flow rate of stormwater runoff from the project site, as required by local plan approval authority. • Downstream analysis is necessary if changes in flows could impair or alter conveyance systems, stream banks, bed sediment or aquatic habitat. • Where necessary to comply with Minimum Requirement #7, stormwater retention/detention facilities shall be constructed as one of the first steps in grading. Detention facilities shall be functional prior to construction of site improvements (e.g. impervious surfaces). • The local permitting agency may require pond designs that provide additional or different stormwater flow control if necessary to address local conditions or to protect properties and • waterways downstream from erosion due to increases in the volume, velocity, and peak flow rate of stormwater runoff from the project site. • If permanent infiltration ponds are used for flow control during construction, these facilities should be protected from siltation during the construction phase. Response: Silt fence shall be installed at downstream property boundaries to contain and limit release of site runoff during construction. 2/20/13 STORMWATER SITE PLAN PAGE 17 Element 4: Install Sediment Controls Prior to leaving a construction site, or prior to discharge to an infiltration facility, stormwater runoff from disturbed areas shall pass through a sediment pond or other appropriate sediment removal BMP. Runoff from fully stabilized areas may be discharged without a sediment removal BMP, but must meet the flow control performance standard of Element #3, bullet #1. Full stabilization means concrete or asphalt paving; quarry spalls used as ditch lining; or the use of rolled erosion products, a bonded fiber matrix product, or vegetative cover in a manner that will fully prevent soil erosion. The Local Permitting Authority shall inspect and approve areas stabilized by means other than pavement or quarry spalls. Sediment ponds, vegetated buffer strips, sediment barriers or filters, dikes, and other BMPs intended to trap sediment on-site shall be constructed as one of the first steps in grading. These BMPs shall be functional before other land disturbing activities take place. Earthen structures such as dams, dikes, and diversions shall be seeded and mulched according to the timing indicated in Element #5. BMPs intended to trap sediment on site must be located in a manner to avoid interference with the movement of juvenile salmonids attempting to enter off -channel areas or drainages, often during non - storm events, in response to rain event changes in stream elevation or wetted area. Response: Silt fence shall be installed at downstream property boundaries to contain and limit release of site runoff during construction. In addition, inlet protection at existing and proposed catch basins will be provided. Element 5: Stabilize Soils • All exposed and unworked soils shall be stabilized by application of effective BMPs that protect the soil from the erosive forces of raindrop impact and flowing water, and wind erosion. • From October 1 through April 30, no soils shall remain exposed and unworked for more than 2 days. From May 1 to September 30, no soils shall remain exposed and unworked for more than 7 days. This condition applies to all soils on site, whether at final grade or not. These time limits may be adjusted by the local permitting authority if it can be shown that the average time between storm events justifies a different standard. • Soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on the weather forecast. • Applicable practices include, but are not limited to, temporary and permanent seeding, sodding, mulching, plastic covering, soil application of polyacrylamide (PAM), the early application of gravel base on areas to be paved, and dust control. • Soil stabilization measures selected should be appropriate for the time of year, site conditions, estimated duration of use, and potential water quality impacts that stabilization agents may have on downstream waters or ground water. • Soil stockpiles must be stabilized from erosion, protected with sediment trapping measures, and when possible, be located away from storm drain inlets, waterways and drainage channels. • Linear construction activities, including right-of-way and easement clearing, roadway development, pipelines, and trenching for utilities, shall be conducted to meet the soil stabilization requirement. Contractors shall install the bedding materials, roadbeds, structures, pipelines, or utilities and re -stabilize the disturbed soils so that: • from October 1 through April 30 no soils shall remain exposed and unworked for more than 2 days; and from May 1 to September 30, no soils shall remain exposed and unworked for more than 7 days. Response: Temporary and permanent seeding will be employed to limit soil exposure. Element 6: Protect Slopes • Cut and fill slopes shall be designed and constructed in a manner that will minimize erosion. • Consider soil type and its potential for erosion. • Reduce slope runoff velocities by reducing the continuous length of slope with terracing and diversions, reduce slope steepness, and roughen slope surface. • Off-site stormwater (run-on) shall be diverted away from slopes and disturbed areas with interceptor dikes and/or swales. Off-site stormwater should be managed separately from stormwater generated on the site. STORMWATER SITE PLAN PAG • At the top of slopes, collect drainage in pipe slope drains or protected channels to prevent erosion. Temporary pipe slope drains shall handle the peak flow from a 10 year, 24 hour event assuming a Type 1A rainfall distribution. Alternatively, the 10 -year and 25 -year, 1 -hour flow rates indicated by an approved continuous runoff model, increased by a factor of 1.6, may be used. Consult the local drainage requirements for sizing permanent pipe slope drains. • Provide drainage to remove ground water intersecting the slope surface of exposed soil areas. • Excavated material shall be placed on the uphill side of trenches, consistent with safety and space considerations. • Check dams shall be placed at regular intervals within channels that are cut down a slope. • Stabilize soils on slopes, as specified in Element #5. Response: Permanent seeding shall be employed to protect any sloped and /or exposed areas. Element 7: Protect Drain Inlets • All storm drain inlets made operable during construction shall be protected so that stormwater runoff shall not enter the conveyance system without first being filtered or treated to remove sediment. • All approach roads shall be kept clean. All sediment and street wash water shall not be allowed to enter storm drains without prior and adequate treatment unless treatment is provided before the storm drain discharges to waters of the State. • Inlets should be inspected weekly at a minimum and daily during storm events. Inlet protection devices should be cleaned or removed and replaced when sediment has filled one-third of the available storage (unless a different standard is specified by the product manufacturer). Response: Catch basin inlet protection is identified on the Temporary Erosion and Sediment Control Plan of the Construction Plans. Element 8: Stabilize Channels and Outlets • All temporary on-site conveyance channels shall be designed, constructed and stabilized to prevent erosion from the expected peak 10 minute velocity of flow from a Type 1A, 10- year, 24-hour frequency storm for the developed condition. Alternatively, the 10 -year, 1 -hour flow rate indicated by an approved continuous runoff model, increased by a factor of 1.6, may be used. • Stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes and downstream reaches shall be provided at the outlets of all conveyance systems. Response: Since the site is predominantly flat and pervious in the existing condition, temporary conveyance channels are not proposed. Element 9: Control Pollutants • All pollutants, including waste materials and demolition debris, that occur on-site shall be handled and disposed of in a manner that does not cause contamination of stormwater. Woody debris may be chopped and spread on site. • Cover, containment, and protection from vandalism shall be provided for all chemicals, liquid products, petroleum products, and non -inert wastes present on the site (see Chapter 173-304 WAC for the definition of inert waste). On-site fueling tanks shall include secondary containment. • Maintenance and repair of heavy equipment and vehicles involving oil changes, hydraulic system drain down, solvent and de -greasing cleaning operations, fuel tank drain down and removal, and other activities which may result in discharge or spillage of pollutants to the ground or into stormwater runoff must be conducted using spill prevention measures, such as drip pans. Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Emergency repairs may be performed on- site using temporary plastic placed beneath and, if raining, over the vehicle. • Wheel wash or tire bath wastewater, shall be discharged to a separate on-site treatment system or to the sanitary sewer. • Application of agricultural chemicals, including fertilizers and pesticides, shall be conducted in a manner and at application rates that will not result in loss of chemical to stormwater runoff. Manufacturers' recommendations for application rates and procedures shall be followed. STORMWATER SITE PLAN BMPs shall be used to prevent or treat contamination of stormwater runoff by pH modifying sources. These sources include, but are not limited to, bulk cement, cement kiln dust, fly ash, new concrete washing and curing waters, waste streams generated from concrete grinding and sawing, exposed aggregate processes, and concrete pumping and mixer washout waters. Stormwater discharges shall not cause or contribute to a violation of the water quality standard for pH in the receiving water. Construction sites with significant concrete work shall adjust the pH of stormwater if necessary to prevent violations of water quality standards. Response: Construction equipment shall be fueled off-site and any chemicals to be utilized during construction (i.e. paint, adhesives, etc) shall be stored in a secured area to avoid leakage. Element 10: Control De -Watering • Foundation, vault, and trench de -watering water, which has similar characteristics to stormwater runoff at the site, shall be discharged into a controlled conveyance system prior to discharge to a sediment trap or sediment pond. Channels must be stabilized, as specified in Element #8. • Clean, non -turbid de -watering water, such as well -point ground water, can be discharged to systems tributary to state surface waters, as specified in Element #8, provided the de -watering flow does not cause erosion or flooding of receiving waters. These clean waters should not be routed through a stormwater sediment pond. • Highly turbid or otherwise contaminated dewatering water, such as from construction equipment operation, clamshell digging, concrete tremie pour, or work inside a cofferdam, shall be handled separately from stormwater. • Other disposal options, depending on site constraints, may include: 1) infiltration, 2) transport off-site in a vehicle, such as a vacuum flush truck, for legal disposal in a manner that does not pollute state waters, 3) Ecology -approved on-site chemical treatment or other suitable treatment technologies, 4) sanitary sewer discharge with local sewer district approval, if there is no other option, or 5) use of a sedimentation bag with outfall to a ditch or swale for small volumes of localized dewatering. Response: Any dewatering water created during construction will be stored and infiltrated on-site. Element 11: Maintain BMPs • All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to assure continued performance of their intended function. All maintenance and repair shall be conducted in accordance with BMP specifications. • All temporary erosion and sediment control BMPs shall be removed within 30 days after final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be removed or stabilized on site. Disturbed soil areas resulting from removal of BMPs or vegetation shall be permanently stabilized. Response: Contractor is responsible for maintaining all BMPs during construction activities. Element 12: Manage The Project • Phasing of Construction - Development projects shall be phased where feasible in order to prevent soil erosion and, to the maximum extent practicable, the transport of sediment from the site during construction. Revegetation of exposed areas and maintenance of that vegetation shall be an integral part of the clearing activities for any phase. • Clearing and grading activities for developments shall be permitted only if conducted pursuant to an approved site development plan (e.g., subdivision approval) that establishes permitted areas of clearing, grading, cutting, and filling. When establishing these permitted clearing and grading areas, consideration should be given to minimizing removal of existing trees and minimizing disturbance/compact! on of native soils except as needed for building purposes. These permitted clearing and grading areas and any other areas required to preserve critical or sensitive areas, buffers, native growth protection easements, or tree retention areas as may be required by local jurisdictions, shall be delineated on the site plans and the development site. 2/20/13 STORMWATER SITE PLAN PAGE 20 • Seasonal Work Limitations - From October 1 through April 30, clearing, grading, and other soil J disturbing activities shall only be permitted if shown to the satisfaction of the local permitting authority that silt -laden runoff will be prevented from leaving the site through a combination of the following: • Site conditions including existing vegetative coverage, slope, soil type and proximity to receiving waters; and • Limitations on activities and the extent of disturbed areas; and • Proposed erosion and sediment control measures. • Based on the information provided and/or local weather conditions, the local permitting authority may expand or restrict the seasonal limitation on site disturbance. The local permitting authority shall take enforcement action - such as a notice of violation, administrative order, penalty, or stop -work order under the following circumstances: • If, during the course of any construction activity or soil disturbance during the seasonal limitation period, sediment leaves the construction site causing a violation of the surface water quality standard; or • If clearing and grading limits or erosion and sediment control measures shown in the approved plan are not maintained. • The following activities are exempt from the seasonal clearing and grading limitations: • Routine maintenance and necessary repair of erosion and sediment control BMPs; • Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil; and • Activities where there is one hundred percent infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. • Coordination with Utilities and Other Contractors - The primary project proponent shall evaluate, with input from utilities and other contractors, the stormwater management requirements for the entire project, including the utilities, when preparing the Construction SWPPP. • Inspection and Monitoring - All BMPs shall be inspected, maintained, and repaired as needed to assure continued performance of their intended function. Site inspections shall be conducted by a person who is knowledgeable in the principles and practices of erosion and sediment control. The person must have the skills to 1) assess the site conditions and construction activities that could impact the quality of stormwater, and 2) assess the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. • For construction sites one acre or larger that discharge stormwater to surface waters of the state, a Certified Erosion and Sediment Control Specialist shall be identified in the Construction SWPPP and shall be on-site or on-call at all times. Certification may be obtained through an approved training program that meets the erosion and sediment control training standards established by Ecology. • Whenever inspection and/or monitoring reveals that the BMPs identified in the Construction SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant amount of any pollutant, appropriate BMPs or design changes shall be implemented as soon as possible. • Maintaining an Updated Construction SWPPP - The Construction SWPPP shall be retained on-site or I within reasonable access to the site. i • The SWPPP shall be modified whenever there is a significant change in the design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state. • The SWPPP shall be modified, if during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The SWPPP shall be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP shall be completed within seven (7) calendar days following the inspection. Response: The contractor shall be responsible for managing the proper implementation of all Construction Stormwater Pollution Prevention measures as noted on the construction plans, this report, and as directed by the City inspector. STORMWATER SITE PLAN PAGE 21 SPECIAL REPORTS AND STUDIES Geotechnical Engineering Evaluation by GeoEngineers Inc., dated March 20, 2012 OTHER PERMITS Outside Agencies: I • Health Department Application City of Rexburg: • Commercial Building Permit Application • Sign Permit Application • All applicable Building Permit Applications (i.e. Plumbing, Mechanical, Electrical, Fire, etc.) OPERATION AND MAINTENANCE MANUAL The owner or operator of the project shall be responsible for maintaining the stormwater facilities in accordance with local requirements. Proper maintenance is important for adequate functioning of the stormwater facilities. Operations and Maintenance Guidelines have been provided in Appendix B. 2/20/13 STORMWATER SITE PLAN PAGE 22 APPENDIX TABLE OF CONTENTS APPENDIX A GEOTECHNICAL ENGINEERING IREPORT APPENDIX B OPERATION AND MAINTENANCE GUIDELINES 3/5/2010 Stormwater Site Plan Appendix APPENDIX A GEOTECHNICAL ENGINEERING REPORT . O • GEOENGINEERS /((( Earth Science +Technology �. Geotechnical Engineering Evaluation McDonald's Restaurant - Rexburg University Boulevard and Yellowstone Highway Rexburg, Idaho for McDonald's USA, LLC March 20, 2012 GEOENGINEERS 523 East Second Avenue Spokane, Washington 99202 509.363.3125 Geotechnical Engineering Evaluation McDonald's Restaurant - Rexburg University Boulevard and Yellowstone Highway Rexburg, Idaho File No. 1038.032-00 March 20, 2012 Prepared for: McDonald's USA, LLC 12131 113th Avenue NE, Suite #103 Kirkland, Washington 98034 Attention: Brian Mattson, Area Construction Manager Prepared by: GeoEngineers, Inc. 523 East Second Avenue t,i�rtf y. Spokane, Washington 99202 509.363.3125 SAN{y0' 3� Teresa A. Dugger, PE Senior Engineer `7 Paul asserr, PEE Ass ate TAD:PEVV:cie:mlh:Om 7 - Disclaimer. Disclaimer. Any electronic form, facsimile or hard copy of the original document (emall, text, table, and/or figure), if provided, and any attachments are only a copy of the original document. The original document Is stored by GeoEngl nears, Inc. and will serve as the official document of record. Copyright© 2012 by GeoEngineers, Inc. All rights reserved. GWENGINEERS� Table of Contents INTRODUCTION..............................................................................................................................................1 SCOPEOF SERVICES....................................................................................................................................1 SITE CONDITIONS General................................................................................................................................................... 2 SurfaceConditions.................................................................................................................................2 SoilConditions.......................................................................................................................................2 GroundwaterConditions........................................................................................................................3 CONCLUSIONS AND RECOMMENDATIONS................................................................................................3 General...................................................................................................................................................3 SitePreparation and Earthwork............................................................................................................3 General............................................................................................................................................3 Grading and Excavations................................................................................................................4 Subgrade and Foundation Bearing Soil Preparation....................................................................4 StructuralFill..........................................................................................................................................5 Construction Considerations.................................................................................................................5 Cutand Fill Slopes..........................................................................................................................5 SiteDrainage...................................................................................................................................6 WeatherConsiderations................................................................................................................. 6 FoundationSupport...............................................................................................................................7 LateralResistance.................................................................................................................................7 FloorSlab Support.................................................................................................................................8 Seismic Considerations.........................................................................................................................8 Stormwater Considerations...................................................................................................................9 Pavements.............................................................................................................................................. 9 SubgradePreparation.....................................................................................................................9 MaterialSpecifications.................................................................................................................10 Thickness Design - Flexible Pavements.....................................................................................10 Thickness Design - Rigid Pavements..........................................................................................10 LIMITATIONS...............................................................................................................................................10 LIST OF FIGURES Figure 1. Vicinity Map Figure 2. Site Plan APPENDICES Appendix A. Field Explorations and Laboratory Testing Figure A-1. Key to Exploration Logs Figure A -2..A-7. Logs of Borings Figure A-8. Sieve Analysis Results Appendix B. Report Limitations and Guidelines for Use GEOENGINEER� March 20, 2012 1 Page! File No. 1038032-00 MCDONALD'S RESTAURANT -UNIVERSITY BOULEVARD AND YELLOWSTONE HIGHWAY Rexburg, Idaho INTRODUCTION This report presents the results of our geotechnical engineering evaluation for the proposed McDonald's Restaurant in Rexburg, Idaho. We understand that McDonald's is currently evaluating the Tamana Fields Pad D site, located east of Yellowstone Highway (US 91) in the southern part of Rexburg, approximately as shown on the Vicinity Map, Figure 1. We understand that the proposed site is currently undeveloped and relatively flat. Based on our experience with similar McDonald's restaurant developments, we anticipate that the proposed structure will be supported on a series of continuous spread and isolated column footings. Building loads are estimated to range from about 1 to 2 kips per lineal foot for spread footings and up to about 50 kips for interior isolated column footings. Additional site improvements include driveway and parking areas and on-site management of stormwater. The approximate location of proposed site improvements relative to existing site features is shown on the Site Plan, Figure 2. As part of the development of the site, we also completed a Phase I Environmental Site Assessment (ESA). The results of our Phase I ESA will be provided under separate cover. SCOPE OF SERVICES The purpose of our geotechnical engineering evaluation was to provide recommendations for site preparation and earthwork activities, foundation and pavement design and construction, and on- site management of stormwater based on subsurface exploration, laboratory testing and engineering analysis. Specifically, our scope of services included: 1. Contacting the public "One -call" utility notification service. 2. Exploration of soil and groundwater conditions underlying the site by completing six hollow - stem auger borings. 3. Laboratory testing to assess pertinent physical and engineering properties of soil encountered relative to the proposed development. 4. Recommendations for site preparation and earthwork including: criteria for clearing, stripping and grubbing; an evaluation of the suitability of on-site soil for use as structural fill; gradation 4 criteria for imported fill, if required; guidance for preparation of subgrade soil, which will support slab -on -grade concrete floors and pavements; and criteria for structural fill placement and compaction. I 5. Recommendations for design and construction of conventional shallow foundations including: allowable soil bearing pressures; minimum width and depth criteria; coefficient of friction and equivalent fluid densities for the passive earth pressure state of stress to estimate resistance to lateral loads; estimates of frost penetration; and estimates of foundation settlement. We have also provided recommendations for treatment of unsuitable soil that might be encountered during construction at proposed foundation grade. 6. Recommendations for design and construction of concrete slab -on -grade floors including: thickness, gradation and compaction criteria for an under -slab capillary moisture break layer; modulus of vertical subgrade reaction that may be used for thickness design of the slab; and GEo ENGINEER Marsh 20, 20121 Pagel File No. 1038032-00 MCDONALD'S RESTAURANT -UNIVERSITY BOULEVARD AND YELLOWSTONE HIGHWAY Rexburg, Idaho guidance regarding the need for moisture vapor barrier and criteria for design and construction of such a barrier, if warranted. 7. Recommendations for design of light- and heavy-duty asphalt concrete (AC) pavements including: thickness, gradation and compaction criteria for crushed aggregate base course; and thickness and compaction criteria for asphalt concrete (AC) surfacing. 8. Geotechnical seismic design criteria based on the 2009 and 2011 International Building Code (IBC). We have also provided our opinion regarding the probability of earthquake -induced liquefaction at the site. 9. An evaluation of the feasibility of on-site disposal of stormwater and design criteria, as appropriate. Our assessment is based on conditions encountered during site exploration and results of our laboratory testing. SITE CONDITIONS General Soil and groundwater conditions at the McDonald's site were explored on March 1, 2012 by completing six borings (6-1 through B-6) at various locations throughout the proposed site. Borings B-1 and B-2 were advanced to a depth of about 161/2 feet below existing site grade in the proposed pavement areas. Borings B-3 through B-6 were advanced to a depth of about 211/2 feet below existing grade within the proposed building footprint. The approximate boring locations with respect to proposed site features are shown on Figure 2. Representative soil samples from the explorations were returned to our laboratory for further evaluation and testing. Detailed descriptions of our site exploration and laboratory testing programs along with the exploration logs and laboratory test results are presented in Appendix A. Surface Conditions The Tamana Fields Pad D site is located in the southern part of Rexburg, Idaho, east of both U.S. Highway 20 and the Yellowstone Highway. The site is bounded to the south by University Boulevard, to the west by Yellowstone Highway, to the north by an irrigation ditch, a vacant gravel covered lot and farmland, and to the west by agricultural fields. At the time of our explorations, the site was undeveloped, with the exception of a sidewalk along the southern boundary. Surface conditions at the site consisted of a plowed field with remnant wheat stubble. The irrigation ditch was dry at the time of our visit. Soil Conditions We encountered approximately 2 to 4 inches of topsoil described as silty fine sand with organics at each of our boring locations. Below the topsoil at each of the boring locations, we encountered very loose to loose, brown silty fine sand. The silty sand unit extended to depths ranging between about 21/2 to 5 feet below existing site grade. In addition, we encountered a lower silty sand unit between approximately 4 and 71/2 feet below existing site grade in boring B-1. We characterize the silty sand as having low to moderate strength, moderate compressibility, low permeability and high susceptibility to changes in moisture content. Page 2 1 March 20, 2012 1 GeoEngineers, Inc. File No. 1038032-00 MCDONALD'S RESTAURANT -UNIVERSITY BOULEVARD AND YELLOWSTONE HIGHWAY Rexburg. Idaho Between the silty sand layers in boring B-1, and below the silty sand at each of the boring locations, we encountered fine to medium/medium to coarse sand with gravel, and fine to coarse gravel with sand and variable silt content. We encountered the fine to medium/medium to coarse sand in a loose to medium dense condition, and the fine to coarse gravel with sand and variable silt content in a medium dense condition. Gradation analysis completed on representative samples of the sand and gravel unit indicates the fines (silt- and clay -sized soil particles passing the U.S. No. 200 sieve) content ranges between about 41/2 and 51/2 percent. We classify the sand and gravel unit as having low to moderate strength and susceptibility to changes in moisture content, low compressibility, and moderate to high permeability. Groundwater Conditions We encountered groundwater at the location of boring B-5, approximately 20 feet below existing site grade at the time of our explorations. Based on our experience in the project vicinity, it is our opinion that the depth to groundwater underlying the site varies seasonally, and from year to year depending on factors such as precipitation, irrigation or other means of recharge. Agricultural irrigation ditches near the site can impact the depth to groundwater. We estimate that groundwater levels will likely reflect the irrigation season, generally being highest in the mid- to late -summer and lowest in the winter and spring seasons. Based on a previous geotechnical engineering evaluation that was completed within an approximate 1/4 -mile of the subject site, groundwater levels during the fall of 2011 (October 2011) ranged from about 8 to 111/2 feet below the ground surface. CONCLUSIONS AND RECOMMENDATIONS General Based on our understanding of the conceptual design, and the results of our site exploration, laboratory testing and engineering analyses, it is our opinion that the proposed McDonald's restaurant may be supported on conventional shallow spread footings bearing on a minimum of 2 feet of structural fill overlying proof -compacted on-site soil. Specific recommendations for the proposed foundation design and construction are presented in the following sections of this report. Site Preparation and Earthwork General Initial site preparation and earthwork activities will include clearing and grubbing surficial vegetation at the site and stripping topsoil; and excavation to the proposed foundation grade. We recommend that proposed areas for improvements be cleared of surface and subsurface deleterious and organic matter. Based on our observations, we estimate that stripping depths to remove topsoil and remnant wheat roots and stubble will be minimal (generally ranging between about 2 to 4 inches) across the majority of the site. Materials which are stripped should be transported off site and properly disposed. If earthwork activities cause excessive subgrade disturbance, replacement of the native soil with imported structural fill may be necessary. Disturbance to a greater depth should be expected if GEOENGINEERS� March 20, 2012 1 Page 3 FlIe No. 1038 03200 MCDONALD'S RESTAURANT- UNIVERSITY BOULEVARDAND YELLOWSTONE HIGHWAY c Rexburg, Idaho site preparation work is conducted during periods of wet weather when the moisture content of the site soil could exceed optimum. Grading and Excavations Grading information was not available at the time we prepared this report. However, we expect that cutting and filling, generally on the order of +2 feet, will be required to establish proposed foundation grade and floor -slab, pavement and sidewalk subgrade elevations. We recommend that footings be supported by at least 2 feet of structural fill overlying proof -compacted indigenous on-site soil. We further recommend that the floor slab be supported by at least 12 inches of improved soil and a 6 -inch -thick capillary break layer. This recommendation might require partial overexcavtion of the upper portion of the on-site soil, depending on proposed finished floor elevation. In our opinion, on-site soil can be excavated using conventional excavation equipment and procedures. The on-site silty sand unit is moisture sensitive, and will be difficult to work if moisture contents are greater than or less than the optimum moisture content by about 2 to 4 percentage points. Accordingly, earthwork during wet weather should be avoided, if possible. In addition, it will be essential that the contractor control stormwater during construction to reduce potential runoff from the site. Subgrade and Foundation Bearing Soil Preparation The exposed soil at proposed slab and pavement subgrade and foundation grade should be improved after initial grading and prior to placement of structural fill, as required. We recommend proof -compacting the upper 12 inches of soil to provide an uniform supporting condition beneath the foundation and pavement areas. Proof -compacting consists of moisture conditioning the surficial soil to near optimum moisture and making several passes with a large (minimum 10 -ton) steel -drum vibrating compactor to densify existing soil to at least 95 percent of the maximum dry density (MDD) based on ASTM International (ASTM) D 1557. Beneath the proposed wall and column foundations, we recommend that soil within 2 feet of foundation grade be improved. This should be accomplished by excavation and removal of the upper 12 inches of soil; scarification, moisture conditioning and compaction of the remaining 12 inches of soil; and placing 12 inches of structural fill to re-establish footing grade. We recommend the improved zone extend at least 1 foot horizontally beyond the width of the footing and that the improved soil be compacted to at least 95 percent of the MDD based on ASTM D 1557. Evaluation of compaction should be accomplished through in-place density testing of the prepared areas. Alternatively, visual observations of proofrolling and probing may be used. The most appropriate method for evaluating soil compaction should be determined by the geotechnical engineer at the time the site work is performed. Soil which cannot be properly compacted should be excavated to firm bearing or a depth of 2 feet, whichever is less, and replaced with structural fill compacted as recommended in the following section. Additional structural fill required to establish proposed subgrade elevations may be placed directly on proof -compacted soil as recommended above and in the following section. Page 4 1 March 20, 2012 1 GeoEngineers, Inc. File No. 1038 032 00 MCDONALD'S RESTAURANT- UNIVERSITY BOULEVARD AND YELLOWSTONE HIGHWAY; Rexburg, Idaho Structural Fill We recommend backfill placed beneath and directly adjacent to foundations and permanent subsurface walls be placed as structural fill. The suitability of soil for use as structural fill depends on its gradation and moisture content. As the percentage of fines increases, soil becomes increasingly sensitive to changes in moisture content and adequate compaction becomes more difficult to achieve. We recommend imported structural fill at foundation grade generally meet the requirements for 3/4 inch (Type 1) or 2 inch (Type II) nominal maximum size aggregate as specified in Table 1 - Crushed Aggregate for Base Gradations, Section 802, 2.2, Division 800 of the Idaho Standards for Public Works Construction (ISPWC), or 1 inch 'A' nominal maximum size aggregate as specified in Section 703.04 Aggregate for Untreated Base, Treated Base and Road Mix, of the Idaho Transportation Department (ITD) Standard Specifications for Highway Construction (2004). Imported structural fill also should be free of debris, organic contaminants and frozen soil. The on-site silty sand soil has a high fines content and will be very difficult to work and compact if the moisture content is more than about 2 to 4 percentage points above or below optimum. For this reason, we do not recommend reusing the on-site soil as structural fill except for utility trench backfill beyond the foundation perimeter and pavement limits, and then only during extended periods of dry weather. Structural fill should be placed in loose lifts not exceeding 8 inches in thickness and mechanically compacted to a firm, non -yielding condition. Each lift should be conditioned to the proper moisture content and compacted to the specified density before placing subsequent lifts. We recommend all structural fill within the proposed footprint, regardless of depth below foundation grade, be compacted to at least 95 percent MDD based on ASTM D 1557. We further recommend that a representative from GeoEngineers be on site during earthwork operations to observe site preparation and fill placement. Soil conditions should be evaluated by in-place density tests, visual observation, probing and proof -rolling of the structural fill and recompacted on-site soil as it is prepared to check for compliance with the contract documents and recommendations of this report. Construction Considerations Cut and FIII Slopes Temporary cut slopes will be necessary during earthwork and utility installation operations. The contractor is responsible for construction site safety and should monitor slopes during earthwork in accordance with applicable Occupational Safety and Health Administration (OSHA) regulations. i Based on our exploration and laboratory testing information, we recommend temporary cut slopes be inclined no steeper than 1Y2H:1V (horizontal to vertical) where excavations encounter the silty sand unit. These recommendations are based on the provision that all surface loads are kept a minimum distance of at least one half the depth of the cut away from the top of the slope. Flatter slopes could be necessary if surface loads are imposed at the top of the cut slpoe a distance equal to or less than one half the depth of the cut or if saturated soil conditions are encountered. GEoENGINEER� March 20, 2012 1 Page 5 File No. 1038-03200 MCDONALD'SRESTAURANT - UNIVERSITY BOULEVARD AND YELLOWSTONE HIGHWAY I, Rexburg, Idaho Regardless of the soil type encountered in the excavation, shoring, trench boxes or sloped sidewalls will be required under OHSA guidelines for excavations deeper than 5 feet. While this report describes certain approaches to excavation, the contract documents should specify that the contractor is responsible for selecting excavation methods, monitoring the excavations and slopes for safety, and providing shoring, as required, to protect personnel. Site Drainage Based on the soil and groundwater conditions observed in our borings at the time of our field exploration, we do not expect that groundwater will be encountered during excavation activities for footings and shallow utilities. Site excavations should be provided with appropriate ditches and sumps to keep the exposed areas dry. Pumping from sumps may be necessary during periods of wet weather. Weather Considerations As stated previously, the on-site soil has varying amounts of fine-grained particles and will be moisture sensitive. When the moisture content of this soil is more than a few percent above optimum moisture content, it becomes soft and unstable. Operation of equipment in these conditions can be difficult and the required compaction criteria will be difficult to achieve. Additionally, disturbance of near -surface soil should be expected if earthwork is completed during periods of wet weather. During dry weather, the soil will be less susceptible to disturbance and should provide better support for construction equipment. If wet weather earthwork is unavoidable, we recommend that the following steps be taken: ■ The ground surface in and around the work area should be sloped so that surface water is directed away from the excavation. The ground surface should be graded so that ponding of water does not occur. Additionally, measures should be taken by the contractor to prevent surface water from collecting in the excavation and trenches, and to remove surface water from the work areas. Examples of such measures include, but are not limited to, sumps and pumps or routing stormwater to a designated disposal area. ■ Earthwork activities should not take place during periods of heavy precipitation or during freezing conditions. ■ Slopes with exposed soil should be covered with plastic sheeting ■ The contractor should take necessary measures to prevent on-site soil and structural fill from becoming wet or unstable. These measures may include the use of plastic sheeting, sumps and pumps, and grading. The site soil should not be left uncompacted and exposed to moisture. Sealing the surficial soil by rolling with a smooth -drum roller prior to periods of precipitation should reduce the extent to which the soil becomes wet or unstable. ■ Construction traffic should be restricted to specific areas of the site, preferably areas that are surfaced with working pad materials not susceptible to disturbance. ■ Construction activities should be scheduled so that the length of time that soil is exposed to moisture during wet weather is reduced to the extent practical. Page 6 March 20, 2012 1 GeoEngineers, Inc. File No. 103803200 MCDONALO'S RESTAURANT -UNIVERSITY BOULEVARD AND YELLOWSTONE HIGHWAY r Rexburg, Idaho Foundation Support Based on the results of our subsurface exploration and analysis, it is our opinion that the proposed McDonald's restaurant may be designed and supported on conventional spread foundations bearing on a minimum of 2 feet of structural fill over indigenous on-site soil prepared as recommended in the Subgrade and Foundation Bearing Soil Preparation section of this report. We recommend that structural fill adjacent to proposed foundations be placed and compacted as recommended in the Structural FIII section of this report. A representative of our firm should observe the preparation of foundation bearing surfaces before placement of structural fill, reinforcement steel and concrete. We recommend individual and continuous wall footings be designed with minimum dimensions of 24 inches and 16 inches, respectively. Minimum frost depth per Madison County Planning and Zoning is 36 inches. Therefore, we recommend that proposed foundations be constructed at a minimum depth of 36 inches below the nearest adjacent exterior finished grade. Individual footings bearing on structural fill overlying the native soil as recommended above may be designed using an allowable net soil bearing pressure of 1,500 pounds per square foot (psf) for dead plus long-term live loads. Continuous wall footings bearing on structural fill overlying the indigenous soil, prepared as previously described, may be designed using an allowable net soil bearing pressure of 2,000 psf. These values may be increased by one-third to account for short- term live loads such as those induced by wind and seismic conditions. Based on the anticipated column and wall loads noted previously in this report, we estimate that the settlement of foundations bearing on properly prepared structural fill overlying the native soil, and designed and constructed as recommended herein, should be less than about 1 inch. Differential settlement between columns or along approximately 20 feet of continuous wall footings should be less than about 1/2 inch. Settlement should occur essentially as loads are applied. Post - construction settlement should be minor. Loose soil or rock not removed from footing excavations, or disturbance of soil at foundation grade during construction could result in larger settlement than estimated. Lateral Resistance The soil pressure available to resist lateral foundation loads is a function of the frictional resistance against the foundation base and the passive resistance which can develop on the face of below - grade elements of the structure as those elements move horizontally into the soil. For foundations bearing on structural fill prepared as recommended herein, the allowable frictional resistance may be computed using a coefficient of friction of 0.35 applied to vertical dead -load forces for the contact between concrete and compacted structural fill. The allowable passive resistance on the face of footings, or other embedded foundation elements may be estimated using an allowable equivalent fluid density of 200 pounds per cubic foot (pcf) (triangular distribution). This value is based on the foundation element being located above the water table and surrounded by structural fill for a distance equal to at least 2.5 times the height of the element. Both values include a factor of safety of about 1.5. GEOENGINEERS� March 20, 2012 1 Page 7 File ND. 1038 032 00 MCDONALD'S RESTAURANT- UNIVERSITY BOULEVARD AND YELLOWSTONE HIGHWAY i Rexburg, Idaho Floor Slab Support As noted previously, we recommend that the floor slab be supported on at least 12 inches of improved soil and a 6 -inch -thick capillary break layer. We recommend the slab be design using a modulus of vertical subgrade reaction (k) of 150 pounds per cubic inch (pci). To retard the upward wicking of moisture beneath the floor slab, we recommend that a capillary break be placed over the subgrade. Floor slabs and flat work should be underlain by at least 6 inches of free -draining crushed rock compacted to a minimum 95 percent of the MDD. We recommend the crushed rock generally meet the requirements for "Coarse Aggregate for Concrete, Sieve Size No. 1" as defined in Section 703.02 C. of the [TO Standard Specifications for Highway Construction, or the requirements for "Crushed Rock Aggregate for Base Gradations (Type II)" as defined in Section 802.2.2, Division 800 of the ISPWC. A vapor retarder consisting of durable plastic sheeting also may be used in areas where the prevention of moisture migration through the slab could adversely influence performance of adhesives used to anchor floor coverings to the slab. If a vapor retarder is used, a moisture absorption layer consisting of an approximate 2 -inch -thick layer of sand or crushed rock may be placed over the vapor retarder and immediately below the slab to protect the vapor retarder during steel and/or concrete placement. However, current American Concrete Institute criteria does not call for the moisture absorption layer. The architect, in conjunction with the structural engineer, should make the final determination regarding use of a vapor barrier and protective absorption layer. Seismic Considerations Spectral response acceleration is estimated by classifying the site based on soil and rock conditions to a depth of 100 feet below site grade. Based on subsurface conditions encountered in our explorations and our understanding of the geologic conditions in the site vicinity, it is our opinion that the site should be characterized as Class D. Liquefaction refers to the condition when vibration or ground shaking, usually from earthquake forces, results in the development of excess pore pressures in saturated soils with subsequent loss of strength in the soil deposit. In general, soils that are susceptible to liquefaction include very loose to medium dense clean to silty sand below the water table. Liquefaction usually results in ground settlement and loss of bearing capacity, resulting in settlement of structures that are supported on foundations within or above the liquefied soils. The "Liquefaction Susceptibility Map for the Rexburg Quadrangle, Madison County, Idaho"' maps the liquefaction susceptibility at and around the project site as "low". On the basis of existing liquefaction mapping, and the results of our field explorations and analysis, we conclude that no mitigation for liquefaction will be required at the site. I Phillips, William M., Welhan, John A., Breckenridge, Roay M., "Liquefaction Susceptibility Map for the Rexburg Quadrangle, Madison County, Idaho", Idaho Geological Survey, 2010. Page 8 1 March 20, 2012 GeoEngineers, Inc. M N.. 1038 032 00 MCDONALD'S RESTAURANT- UNIVERSITY BOULEVARD AND YELLOWSTONE HIGHWAY Rexburg, Idaho Stormwater Considerations We recommend that all surfaces be sloped to drain away from the proposed building area. Pavement surfaces and open spaces should be sloped such that surface runoff is collected and routed to suitable discharge points. Roof drains should be tightlined separately to a suitable stormwater disposal system. Based on the results of our site exploration, laboratory testing, and engineering analyses, it is our opinion that on-site infiltration of stormwater is generally feasible across the site with optimal opportunities along the south end. Based on the results of our explorations, the contact between the upper, less permeable silty sand and the lower, more permeable sand and gravel ranged between about 41/2 and 71/2 feet below existing site grade on the approximate northern half of the site. This contact ranged from about 21/2 to 41/2 feet below existing site grade on the approximate southern half of the site. As stated previously, the depth of groundwater at the time of our site exploration was on the order of about 20 feet below existing site grade. However, our experience in the vicinity of the site indicates that groundwater levels could rise to within the range of about 8 to 111/2 feet below existing site grade. For this reason, we recommend that on-site disposal of stormwater occur near the southern end of the site using an infiltration trench or other shallow infiltration system (such as a low -profile drywell) that is hydraulically connected to the sand and gravel soil unit. Based on the results of laboratory testing and correlations to hydraulic conductivity, we recommend that a long-term design infiltration rate of 2 inches per hour (in/hr) may be used for design of infiltration trenches or other shallow infiltration facilities that extend into the underlying sand and gravel unit encountered at the site. This includes a safety factor of about 2, which accounts for possible variations in infiltration rates at actual infiltration trench locations, and limited long-term maintenance of proposed infiltration trenches. This recommendation is based on the assumption that infiltration trenches or other shallow infiltration facilities extend at least 12 inches into, or are hydraulically connected into the free -draining portions of the sand and gravel unit, as described above. Based on results of our site exploration and the Natural Resource Conservation Services (NRCS) mapping of surficial soil in the project vicinity, the site is underlain by Labenzo gravelly loam. Furthermore, the NRCS classifies the Labenzo unit as Group B hydrologic soil. Typically Group B soils are characterized by surface infiltration rates in the range of about 0.15 to 0.30 inches per hour (in/hr). On this basis and considering results of our explorations and laboratory testing programs, we recommend an infiltration rate of 0.15 in/hr for design purposes for surface detention swales at the site. Pavements Subgrade Preparation As discussed previously, we recommend the upper 12 inches of soil exposed at pavement subgrade be thoroughly proof -compacted to at least 95 percent of the MOD in accordance with ASTM D 1557. Soft, wet or otherwise unsuitable soil identified during proof -rolling should be GEOENGINEER� March20,2012 Page9 File No. 1039-092-00 MCDONALD'S RESTAURANT- UNIVERSITY BOULEVARD AND YELLOWSTONE HIGHWAY I=- Rexburg, Idaho removed to a depth of 2 feet, or firm bearing, whichever is less, and replaced with structural fill as recommended in the Site Preparation and Earthwork section of this report. Material Specifications We recommend pavement materials for improvements at the proposed McDonald's restaurant conform to applicable sections of the Idaho Standards for Public Works Construction (2005 Edition with 2007, 2008 and 2010 supplemental revisions) as well as the ITD Standard Specifications for Highway Construction (2004), including the January 2012 supplements). Thickness Design - Flexible Pavements Provided subgrade soil in pavement areas is prepared as recommended herein, we estimate a California Bearing Ratio (CBR) of about 6 for the on-site silty sand and a corresponding resilient modulus (MR) on the order of about 6,500 pounds per square inch (psi). On this basis, we recommend that flexible light-duty pavements consist of at least 2.5 inches compacted thickness of HMA surfacing over 4 inches of crushed aggregate base course and 5 inches of granular subbase compacted to at least 95 percent MOD. Aggregate surfacing should meet the criteria for "Aggregate for Untreated Base, Treated Base and Road Mix" called for in Section 703.04 of the ITD Standard Specification for Highway Construction (2004). The untreated base aggregate should meet the requirements for "3/4 -inch B" nominal maximum size. Hot mix asphalt (HMA) should meet the requirements in Section 703.05 Aggregate for Superpave HMA Pavement and Section 405 Superpave Hot Mix Ashpalt of the ITD Standard Specifications for Highway Construction (2004). We recomment Superpave HMAMixture SP -1 for the flexible asphalt pavement. Thickness Design - Rigid Pavements Our recommendations for portland cement concrete (PCC) are based on a minimum 4,000 pounds per square inch (psi) compressive strength mix. Concrete pavement edges should be thickened and provided with nominal reinforcing. For standard -duty concrete pavement section, we recommend 4 inches of PCC over 6 inches of crushed aggregate base course compacted to at least 95 percent of the MDD. LIMITATIONS We have prepared this report for McDonald's USA. LLC, and their authorized agents and regulatory agencies for the proposed McDonald's - Tamana Fields Pad D in Rexburg, Idaho. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was prepared. The conclusions, recommendations, and opinions presented in this report are based on our professional knowledge, judgment and experience. No warranty or other conditions, express or implied, should be understood. Page 10 March 20, 2012 1 GecEngineers, Inc. File No. 1038.03200 MCDONALD'S RESTAURANT- UNIVERSITY BOULEVARD AND YELLOWSTONE HIGHWAY c Rexburg, Idaho Any electronic form, facsimile or hard copy of the original document (email, text, table and/or figure), if provided, and any attachments should be considered a copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official document of record. Please refer to the Appendix B titled "Report Limitations and Guidelines for Use" for additional information pertaining to use of this report. GEOENGINEERS� March 20, 2012 1 Page 11 Fle No. 1038-032-00 GEOENGINEERS�,, Earth Science +Technelegy �e ---------- X E Idaho ontana ming 3 o Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. 5 can not guarantee the accuracy and content of electronic files. The master i file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. 3. It is unlawful to copy or reproduce all or any part thereof, whether for personal use or resale, without permission. L Data Sources: ESRI Data & Maps, Street Maps 2008 US Topographic Map from ESRI ArcGIS Online U 1 Transverse Mercator, Zone 12 N North, North American Datum 1983 5 NOM arrow orienletl to grid north at SITE N WE s 2,000 0 2,000 Feet Vicinity Map McDonald's Restaurant-Tamana Fields Pad D Rexburg, Idaho GEOENGINEERFigure 1 10' UTIUTY- EASEMENT Al 10' FRONT YARD BUFFER PENDING 2T R.O.W. DEDICATION 1 �I N59'52'01'W 17.00���� N30 -07'59"E 13.31`7 4=9459'36 /r R=20.00 L=33.16 177.79' N90000'00"W NEW POLE SIGNS \ 1.5' UTILITY \ EASEMENT 101 ` YA C1 ' AL2 — .S6 es Data Source: Base drawing from PACLAND Conceptional Site Sketch, 2/14 Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. I GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. 5 Legend B Boring Number and Approximate Location 1 inch = 40 feet Site Plan McDonald's Restaurant Jamana Fields Pad Rexburg, Idaho GEOENGINEERFigure APPENDIX A Field Explorations and Laboratory Testing i s UNIVERSITY BOULEVARD AND YELLOWSTONE HIGHWAY, Rezburg,ldaho APPENDIX A Field Explorations and Laboratory Testing Subsurface Explorations Soil and groundwater conditions at the McDonald's Restaurant site were explored on March 1, 2012 by completing six borings (B-1 through B-6) at the approximate locations shown on Figure 2. The borings were advanced to depths ranging between about 16'/2 and 21'/2 feet below existing ground surface using a truck -mounted SIMCO 2500, hollow -stem auger drill rig subcontracted to GeoEngineers. The borings were continuously monitored by a representative from our firm who obtained representative samples, observed groundwater conditions and maintained a detailed log of each exploration showing stratigraphic changes and other pertinent information. Soil encountered in the explorations was classified in general accordance with ASTM D 2488 (visual -manual procedure) and the classification chart listed in Key to Exploration Logs, Figure A-1. A summary of each boring is presented in Log of Boring, Figures A-2 through A-7. The logs are based on interpretation of the field and laboratory data, and indicate the depth at which subsurface materials or their characteristics change, although these changes might actually be gradual. Samples of soil encountered in the borings were obtained at approximate 2'/2- to 5 -foot -depth intervals using either a 2 -inch, outside -diameter, standard split -spoon sampler, or a 2.4 -inch, inside -diameter, California -type, split -barrel sampler. The samplers were driven into the soil using a 140 -pound automatic hammer, free -falling 30 inches on each blow. The number of blows required to drive the samplers each of three, 6 -inch increments of penetration were recorded in the field along with visual -manual descriptions of the soil based on ASTM D 2488. The sum of the blow counts for the last two 6 -inch increments of penetration is reported on the boring logs. The blow counts for the standard sampler are reported as the ASTM D 1556 Standard Penetration Test (SPT) N -value. Blow counts for the California -style sampler were converted to equivalent N -values and are shown on the logs. The conversion of non-standard penetration resistance to SPT N -values was made using the Lacroix -Horn equation (ASTM SPT -523, 1973). The borings were located in the field by pacing and taping from existing site features such as existing manhole covers. Topographic data was not available at the time we prepared this report. Therefore, boring elevations could not be established. The exploration locations should be considered accurate to the degree implied by the method used. Laboratory Testing Soil samples obtained from the borings were returned to our laboratory for further examination and testing. Two sieve analyses (ASTM C 136) were completed on representative soil samples from the site. The results of these tests are presented on Particle Size Distribution Report, Figure A-8. Selected samples also were tested to estimate their natural moisture content in general accordance with ASTM D 2216. The results of these tests are presented on the exploration logs at the respective sample depths. GEOENGINEER� March 20,20121 Page A-1 File No. 1038032-00 SOIL CLASSIFICATION CHART NOTE: Multiple symbols are used to indicate borderline or dual soil classifications Sampler Symbol Descriptions ® SYMBOLS TYPICAL MAJOR DIVISIONS ■ GRAPH LETTER Piston DESCRIPTIONS Direct -Push ® CLEAN ob- GW WELL -GRADED GRAVELS, Measured free product In well or GRAVEL GRAVELS Crushed Rock/ Graphic Log Contact GRAVEL -SAND MIXTURES Quarry Spalls AND geologic units Topsoil/ location of soil strata TS Forest Duff/Sod GRAVELLY IUmeoaxormssl 0000 GP POORLY -GRADED GRAVELS, geologic units SOILS Approximate location of soil strata O O change within a geologic soil unit GRAVEL -SAND MIXTURES GRAVELS WITH MS Moderate Sheen HIS GM SILTY GRAVELS, GRAVEL -SAND COARSE GRAINED MORE THAN W% -SILT MIXTURES SOILS OF COARSE FRACTION FINES GC GRAVELS GRAVEL RETAINED ON N0, 4 SIEVE (AN`.ASLENN.HT OF Drvssl 0 SAND - SAND. CLAY MIXTURES Sw WELL -GRADED SANDS, CLEAN SANDS GRAVELLY SANDS MORE THAN W% SAND RETAINED ON NO. AND µITRE Cx xO fmf51 2WSIEVE POORLY -GRADED SANDS, SANDY Sp GRAVELLY SAND SOILS SANDS WITH CSM SILTY SANDS, SAND - SILT MORE THAN EO% Or COARSE FRACTN IO FINES MIXTURES PASSING N0.4 SIEVE (FPPRECIPELEAMWNTCLAYEY SC SANDS. SAND -CLAY Of FII MIXTURES INORGANIC SILTS, ROCK FLOUR, ML CLAYEY SILTS WITH SLIGHT PLASTICITY INORGANIC CLAYS OF LOW TO SILTS MEDIUM PLASTICITY, GRAVELLY FINE AND UOUID LIMIT CL CLAYS SAND S. SILTY CLAYS LESS THAN NO CLAYS. LEAN CLAYS GRAINED OL ORGANIC SILTS AND ORGANIC SOILS SILTY CLAYS OF LOW PLASTICITY MORESO% I INORGANIC ISATEOUS PASSING N0. 200 MH ORDATOMACEOUS SIL EVE SOILS INORGANIC CLAYS OF HIGH SILTS DOUIO LIMIT AND GREATERT iWW 50 CH PLASTICITY CLAYS OH ORGANIC CLAYS AND SILTS OF MEDIUM TO HIGH PLASTICITY HIGHLY ORGANIC SOILS R e 4w.v PTPEAT LS H WITH IGH ORGANIC CONTENTS NOTE: Multiple symbols are used to indicate borderline or dual soil classifications Sampler Symbol Descriptions ® 2.4 -inch I.D. split barrel GRAPH Standard Penetration Test (SPT) ■ Shelby tube ® Piston lu Direct -Push ® Bulk or grab Blowcount is recorded for driven samplers as the number of blows required to advance sampler 12 inches (or distance noted). See exploration log for hammer weight and drop. A "P" indicates sampler pushed using the weight of the drill rig. ADDITIONAL MATERIAL SYMBOLS SYMBOLS TYPICAL DESCRIPTIONS GRAPH LETTER _ AC Asphalt Concrete Groundwater observed at time of _ exploration DS CC Cement Concrete exploration MC Measured free product In well or _ CR Crushed Rock/ Graphic Log Contact PM Quarry Spalls PP geologic units Topsoil/ location of soil strata TS Forest Duff/Sod Laboratory / Field Tests %F Groundwater Contact TMeasured groundwater level in _ exploration, well, or piezometer CP Groundwater observed at time of _ exploration DS Perched water observed at time of HA exploration MC Measured free product In well or _ piezometer OC Graphic Log Contact PM Distinct contact between soil strata or PP geologic units /Approximate location of soil strata SA change within a geologic soil unit TX Material Description Contact UC Distinct contact between soil strata or VS geologic units ____ Approximate location of soil strata NS change within a geologic soil unit Laboratory / Field Tests %F Percent fines AL Atterberg limits CA Chemical analysis CP Laboratory compaction test CS Consolidation test DS Direct shear HA Hydrometer analysis MC Moisture content MD Moisture content and dry density OC Organic content PM Permeability or hydraulic conductivity PP Pocket penetrometer PPM Parts per million SA Sieve analysis TX Triaxial compression UC Unconfined compression VS Vane shear Sheen Classification NS No Visible Sheen SS Slight Sheen MS Moderate Sheen HIS Heavy Sheen NT Not Tested NOTE: The reader must refer to the discussion in the report text and the logs of explorations for a proper understanding of subsurface conditions. Descriptions on the logs apply only at the specific exploration locations and at the time the explorations were made: they are not warranted to be representative of subsurface conditions at other locations or times. � KEY TO EXPLORATION LOGS ► GEOENGINEERS FIGURE A-1 Sled Drilled 3/1/2012 91A 3/1/2012 Total Depth (H) i5 5 Logged By SPO Checked By TAD Driller A Cache Corp Drilling Hollow -Stem Auger Method g Surface Elevation (ft) Vertical Datum Undetermined Hammer Automatic Data Drilling Equipment Simco 2500 Easting (X) System Groundwater Northing (Y) Datum Measured Depth toDate Water (10 Elevat'on(ft Notes: Not encountered FIELD DATA E d m o MATERIAL s 5 3 DESCRIPTION e� N REMARKS zv 'a E d go ' d_ 1. w O= lY m y rnF ID 0U 02 0 o 0 SM Brown silty fine sand (loose, moist) 18 4 I 11 SP Brown fine sand (loose, moist) SM Brown silty fine to medium sand (loose, moist) 6 5 2 12 16 3 SP Brown medium to coarse sand with gravel (medium dense, moist) n u 20 4 5 5 Notes: Please refer to Figure A-1 for an explanation of symbols. Log of Boring B-1 Project: McDonald's Restaurant - Tamana Fields Pad D G EO E N G I NEE RS Project Location: Rexburg, Idaho Project Number: 1038-032-00 Shheete1 02 1 Start Drilled 3/112012 tsd 3/1/2012 Total Depth (N) i5 5 Logged By SPO Checked By TAD Driller A Cache Cor P Project Number: 1038-032-00 FSheet I o i3 it Dfith Hollow -Stem Auger Method Surface Elevation Vertical Datum (N) Undetermined Hammer Automatic Data Drilling Equipment Simco 2500 Easting (X) System Groundwater Northing (1) Datum Dale Measured Depth to WaterN Elay.tion (N1 Notes: Not encountered FIELD DATA d MATERIAL o = d _A B a o DESCRIPTION REMARKS n n Z ' s = o n 'Mm =v o 'm d v 0 o E m « m @ 2 2 — .o_ f$ o.y 0 SM Brown silty fine sand (loose, moist) Iv 7 5 2 SP Brown fine sand (medium dense, dry) 12 13 0 GP -GM Brown fine to coarse gravel with silt and sand 0 (medium dense, moist) 12 27 3 0 4 $A; %F = 5.5 0 0 0 GP Brown fine to coarse gravel with sand (medium 1U 8 II 4 o dense, moist) 0 0 0 0 5 12 14 5 0 0 0 Notes: Please refer to Figure A-1 for an explanation of symbols. Log of Boring B-2 Project: McDonald's Restaurant - Tamana Fields Pad D G W E N G I N E E RS/�, /. Project Location: Rexburg, Idaho Project Number: 1038-032-00 FSheet I o i3 Start Drilled 3/1/2012 End 3/1/2072 Total Depth (ft) 21 .5 Logged By SPO Checked By TAD Driller A Cache Corp p Project Number: 1038-032-00 Figure 1 ofA I Melthod Hollow Auger Surface Elevation (ft) Vertical Datum Undetermined Hammer Automatic Data Drilling Equipment Simco 2500 Easting (X) System Groundwater Northing (Y) Datum Depth to Date Measured Water In Elevationft Notes: Not encountered FIELD DATA E E d m a MATERIAL 9 Z d J DESCRIPTION x REMARKS a 2 a v d 0 w o N m E y rn 3 LO U u° P t7 (7 28 o 0 SM Brown silty fine sand (loose, moist) 14 4 1 19 aSP 2 Brown medium sand with gravel (medium dense, 9 12 moist) 3 o OP Brown fine to coarse gravel with sand (loose to 5 13 medium dense, moist) 0 0 9 4 0 0 0 0 0 0 0 15 SP Brown medium to coarse sand with gravel (loose 14 9 5 to medium dense, moist) 20 9 6 Notes: Please refer to Figure A-1 for an explanation of symbols. Log of Boring B-3 Project: McDonald's Restaurant - Tamana Fields Pad D G W E N G I N E E R Project Location: Rexburg, Idaho Project Number: 1038-032-00 Figure 1 ofA I Suers End Total 2i 5 Logged By SPO Driller A Cache Corp Project Number: 1038-032-00 Shheet 1 05 1 Drilling Hollow -Stem Auger Drilled 3/1/2012 3/1/2012 Deplh (R) Checked 8y TAD Melhod Surface Elevation (R) Undetermined Hammer Automatic Data Drilling Equipment Simco 2500 Vertical Datum Easting (X) System Groundwater Northing (V) Datum Depth to Date Measured Water Elevatk n in Notes: Not encountered FIELD DATA = E w MATERIAL o w 8 d DESCRIPTION REMARKS m `5 v d - o 0 _ o E« E w o tz f m 0 0 a._ 0 SM Brown silty fine sand (very loose, moist) 16 3 1 5 14 20 2 6 C GP Brown fine to coarse gravel with sand (medium ° 0 dense, moist) II 16 3 0 0 0 0 0 13 4 ° 0 0 0 0 0 5 2 20 5 0 0 0 0 0 20 0 SP Brown fine to medium sand (loose, moist) 8 6 Notes: Please refer to Figure A-1 for an explanation of symbols. Log of Boring B-4 Project: McDonald's Restaurant - Tamana Fields Pad D G EO E N G I N E E R Project Location: Rexburg, Idaho Project Number: 1038-032-00 Shheet 1 05 1 �Jtl Drilled 3/1/2012 EEWTotal 3/1/2012 pepth (N) 21 5 Logged By SPO Checked By TAD Driller A Cache Corp Drilling Method Hollow -Stem Auger Surface Elevation (ft) Vertical Datum Undetermined Hammer automatic Data Drilling Equipment Simco 2500 Easling (X) System Groundwater Northing (h Datum Depth to Date Measured Water fryl Elevaton lftl Notes: 3/1/2012 20.0 FIELD DATA E MATERIAL o = o r z DESCRIPTION r REMARKS m g v. 0 SM Brown silty fine sand (loose, moist) 12 16 1 -0 GP Brown fine gravel with sand (medium dense, 0 moist) 50 11 30 2 0 0 0 11 22 3 3 SA; %F = 4.5 SP Brown medium to coarse sand with gravel (medium dense, moist) 10 11 20 4 N(spt) = 8 5 11 25 5 20-1 w Notes: Please refer to Figure A-1 for an explanation of symbols. Log of Boring B-5 Project: McDonald's Restaurant - Tamana Fields Pad D G EO E N G I N E E R Project Location: Rexburg, Idaho Figure Project Number: 1038-032-00 h et1 eo6 12ad EDII Drilled 3/1/2012 3/1/2012 Total 21 5 Depth (ft) Logged By SPO Checked By TAD Driller A Cache Corp Drilling Hollow -Stem Auger Method g Surface Elevation (ft) Undetermined Vertical Datum Hammer Automatic Data Drilling Simco 2500 Equipment Easting (X) System Groundwater Northing (Y) Datum Depth to Date Measured Water fft Elevation (ftl Notes: Not encountered FIELD DATA e q E w g O `_ MATERIAL o S Z e DESCRIPTION REMARKS > n y m E y n o� F— w o S K m 6 0 inH 3 r7 (7U 208 0a 0 SM Brown silty fine sand (loose, moist) 10 16 I 5 SP Brown fine to medium sand with gravel (medium dense, moist) 6 9 18 2 II 22 3 10 10 16 4 American Geotechnics Sieve Analysis Results McDonald's Restaurant - Tamana Fields Pad D Rexburg, Idaho GEoENGINEERS Figure A-8 PARTICLE -SIZE DISTRIBUTION REPORT CLIENT: GeoEngineers PROJECT NAME: Rexburg .... FILE NUMBER: 10B -G2083.13 PROJECT LOCATION:Rexburg, Idaho "11■1■II III II���IYIIVIIYY W IYI IIIIYYIIIIII II■■II IIIII■■ .11■■I IIIIII■��II IIIII■■1111111■■1111111■■1111111■■ �1■■1111111.:.1111111■■1111111■■1111111■■1111111■■ . 1■■1111111■.,1111111..1111111.■1111111■■1111111■■ 11■■IIII�11■r'�111�11■■1111111■■111111■■111111.. 11■.111111■■.I►111■.1111111..1111111■■1111111.. ',11■■III�111■■Il11111■■1111111..1111111■.1111111.■ 11■■1111111■■IIIICII■.111111.■1111111■■111111■. 11..111 III■■I IIIII`■1111111■.1111111■■1111111■■ 1■■1!11111■■IIIII�I...1111111■.1111111■■1111111.■ 11■■I IIIII■■1111111■t�lllllll■.1111111■.1111111.. ,11■■111111.■111111.\SII►1111■■1111111■■1111111■■ 11■.111111..111111.■i1U!!11■■1111111■■111111.. ,11■.1111111■.1111111■.1111111'7■II�IIII■■1111111.. 11■.1111111..1111111..1111111►`�!I IIII■■1111111■■ .11■■1111111.■1111111■■1111111■■II1111■■1111111■. [.r1MrM17=,rMT,.1rrn1 Him . �m0®mmm American Geotechnics Sieve Analysis Results McDonald's Restaurant - Tamana Fields Pad D Rexburg, Idaho GEoENGINEERS Figure A-8 APPENDIX B Report Limitations and Guidelines for Use r�. r r�. MCDONALD'S RESTAURANT -UNIVERSITY BOULEVARD AND YELLOWSTONE HIGHWAY r Rexburg,ldaho APPENDIX B REPORT LIMITATIONS AND GUIDELINES FOR USE2 This appendix provides information to help you manage your risks with respect to the use of this report. Geotechnical Services Are Performed for Specific Purposes, Persons and Projects This report has been prepared for McDonald's USA, LLC and their authorized agents. The information contained herein is not applicable to other sites. GeoEngineers structures our services to meet the specific needs of our clients. No party other than McDonald's USA, LLC may rely on the product of our services unless we agree to such reliance in advance and in writing. This is to provide our firm with reasonable protection against open-ended liability claims by third parties with whom there would otherwise be no contractual limits to their actions. Within the limitations of scope, schedule and budget, our services have been executed in accordance with our Agreement with McDonald's USA, LLC dated March 27, 2012 and generally accepted geotechnical practices in this area at the time this report was prepared. Use of this report is not recommended for any purpose or project except the one originally contemplated. A Geotechnical Engineering or Geologic Report is Based on a Unique Set of Project - Specific Factors This report has been prepared for the McDonald's - Tamana Fields Pad D site in Rexburg, Idaho. GeoEngineers considered a number of unique, project -specific factors when establishing the scope of services for this project and report. Unless GeoEngineers specifically indicates otherwise, it is important not to rely on this report if it was: ■ not prepared for you, ■ not prepared for your project, ■ not prepared for the specific site explored, or ■ completed before important project changes were made. For example, changes that can affect the applicability of this report include those that affect: ■ the function of the proposed structure; ■ elevation, configuration, location, orientation or weight of the proposed structure; ■ composition of the design team; or ■ project ownership. If important changes are made after the date of this report, we recommend that GeoEngineers be given the opportunity to review our interpretations and recommendations. Based on that review, we can provide written modifications or confirmation, as appropriate. 2. Developed based on material provided by ASFE, Professional Firms Practicing in the Geosciences; www.asfe.org. G EOENGINEERS� March 20, 2012 1 Page B-1 File No. 1038-03200 MCDONALD'S RESTAURANT- UNIVERSITY BOULEVARD AND YELLOWSTONE HIGHWAY it Rexburg, Idaho Subsurface Conditions Can Change This geotechnical or geologic report is based on conditions that existed at the time the study was performed. The findings and conclusions of this report may be affected by the passage of time, by man-made events such as construction on or adjacent to the site, or by natural events such as floods, earthquakes, and slope instability or groundwater fluctuations. If more than a few months have passed since issuance of our report or work product, or if any of the described events may have occurred, please contact GeoEngineers before applying this report for its intended purpose so that we may evaluate whether changed conditions affect the continued reliability or applicability of our conclusions and recommendations. Most Geotechnical and Geologic Findings Are Professional Opinions Our interpretations of subsurface conditions are based on field observations from widely spaced sampling locations at the site. Site exploration identifies the specific subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoEngineers reviewed field and laboratory data and then applied our professional judgment to render an informed opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ, sometimes significantly, from those indicated in this report. Our report, conclusions and interpretations should not be construed as a warranty of the subsurface conditions. Geotechnical Engineering Report Recommendations Are Not Final The construction recommendations included in this report are preliminary and should not be considered final. GeoEngineers' recommendations can be finalized only by observing actual subsurface conditions revealed during construction. GeoEngineers is unable to assume responsibility for the recommendations in this report without performing construction observation. We recommend that you allow sufficient monitoring, testing and consultation during construction by GeoEngineers to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes if the conditions revealed during the work differ from those anticipated, and to evaluate whether earthwork activities are completed in accordance with our recommendations. Retaining GeoEngineers for construction observation for this project is the most effective method of managing the risks associated with unanticipated conditions. A Geotechnical Engineering or Geologic Report Could Be Subject to Misinterpretation Misinterpretation of this report by members of the design team or by contractors can result in costly problems. GeoEngineers can help reduce the risks of misinterpretation by conferring with appropriate members of the design team after submitting the report, reviewing pertinent elements of the design team's plans and specifications, participating in pre-bid and preconstruction conferences, and providing construction observation. Do Not Redraw the Exploration Logs Geotechnical engineers and geologists prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. The logs included in a geotechnical engineering or geologic report should never be redrawn for inclusion in architectural or other design drawings. Page B-2 I March 20, 2012 1 GeoEngineers, Inc. Me No. 1038 032 00 MCDONALD'S RESTAURANT -UNIVERSITY BOULEVARD AND YELLOWSTONE HIGHWAY L Rexburgjdaho Photographic or electronic reproduction is acceptable, but separating logs from the report can create a risk of misinterpretation. Give Contractors a Complete Report and Guidance To help prevent costly problems associated with unanticipated subsurface conditions, we recommend giving contractors the complete geotechnical engineering or geologic report, but preface it with a clearly written letter of transmittal. In that letter, advise contractors that the report's accuracy is limited. In addition, encourage them to confer with GeoEngineers and/or to conduct additional study to obtain the specific types of information they need or prefer. Contractors Are Responsible for Site Safety on Their Own Construction Projects Our geotechnical recommendations are not intended to direct the contractor's procedures, methods, schedule or management of the work site. The contractor is solely responsible for job site safety and for managing construction operations to minimize risks to on-site personnel and adjacent properties. Read These Provisions Closely It is important to recognize that the geoscience practices (geotechnical engineering, geology and environmental science) are less exact than other engineering and natural science disciplines. Without this understanding, there may be expectations that could lead to disappointments, claims and disputes. GeoEngineers includes these explanatory "limitations" provisions in our reports to help reduce such risks. Please confer with GeoEngineers if you need to know more about how these "Report Limitations and Guidelines for Use" apply to your project or site. Biological Pollutants GeoEngineers' Scope of Work specifically excludes the investigation, detection, prevention or assessment of the presence of Biological Pollutants. Accordingly, this report does not include any interpretations, recommendations, findings or conclusions regarding the detecting, assessing, preventing or abating of Biological Pollutants, and no conclusions or inferences should be drawn regarding Biological Pollutants as they may relate to this project. The term "Biological Pollutants" includes, but is not limited to, molds, fungi, spores, bacteria and viruses, and/or any of their byproducts. A Client that desires these specialized services is advised to obtain them from a consultant who offers services in this specialized field. GEOENGINEERS� March20,2012 Page B.3 File No, 103E 03200 U 1 \ P. • E'OE NE \` C . E F e dec of APPENDIX B OPERATION AND MAINTENANCE GUIDELINES Infiltration Trench M Description Infiltration facilities, such as trenches, seepage beds, and bioretention basins, are designed to intercept and reduce direct site surface runoff. They hold runoff long enough to allow it to enter the underlying soil. They can include layers of coarse gravel, sand, or other filtering media to filter the runoff before it infiltrates the soil. Infiltration trenches are shallow (3 to 12 feet deep) trenches in relatively permeable soils that are backfilled with a sand filter, coarse stone, and lined with filter fabric. The trench surface can be covered with grating and/or consist of stone, gabion, sand, or a grassed covered area with a surface inlet. Depending on the design, trenches allow for the partial or total infiltration on stormwater runoff into the underlying soil. One alternative design is to install a pipe in the trench and surround it with coarse stone; this will increase the temporary storage capacity of the trench. Applications An infiltration trench will generally be used in relatively small drainage areas (usually less than 10 acres), such as on residential lots. Trenches are one of the few BMPs that are relatively easy to fit into the margin, perimeter, and other less -utilized areas of developed sites, making them particularly suitable for retrofitting. Unlike infiltration basins installed at the surface, the land above a subsurface trench system can be reclaimed and used. A trench may also be installed under a drainage swale to increase the storage of the infiltration system. Appropriate soil conditions and the protection of ground water are the most important considerations limiting the use of this BMP. Infiltration rates should be 0.5 inches per hour or greater). Generally speaking, SCS Type A and B soils will convey water at this rate, but site-specific testing should be done to confirm the infiltration rate. Other soil conditions that will not support the use of infiltration trenches include the following: • Soils with more than 40% clay content (subject to frost heave) • Fill soils, unless the fill material is specially designed to accommodate the facility • Steep site slopes (greater than 25%) which can contribute to slope failures Infiltration facilities are not suitable in many areas of Idaho where the ground- water table is very shallow. Conditions should be observed at the site during the winter and early spring when the water table is at its highest. If the minimum depth to ground water at these times is 3 feet from the proposed bottom of the infiltration trench bed and the other noted soil conditions are right, infiltration can be used. If depth to the water table is shallower, there is an increased risk of ground -water contamination. One advantage to trenches is that they are less likely to become clogged with sediment than do other infiltration BMPs, such as basins, if properly DEQ Storm Water Best Management Practices Catalog 46 September 2005 maintained. However, clogging is still an issue. This BMP should typically be located "off-line" from the primary conveyance/detention system in order to effectively treat pollutants and protect the infiltration soils from clogging. Infiltration trenches should always be preceded by a pretreatment BMP to remove sediments that could clog the infiltration soils. Infiltration trenches are not suitable for sites with exposed chemical or toxic materials. If there is the potential for a toxic spill, a spill prevention and control plan should be in place. As with any type of infiltration facility, infiltration trenches should not be used in areas with shallow aquifers. An official inventory form should be submitted to the Idaho Department of Water Resources (IDWR). Contact the closest IDWR regional office for further information. Conservatively speaking, the longevity of trenches is expected to be about 2 years before partial or full clogging/sealing of the floor. The life span can be significantly increased given good permeable soils and pretreatment to prevent clogging. The relatively short life span of infiltration facilities can be significantly increased through proper design and maintenance. Limitations Drainage area —10 ac. Minimum bedrock depth — 4 ft NRCS soil type — A, B Drainage/flood control — N/A Targeted Sediment — 75% Pollutants Phosphorus — 55% Trace metals Bacteria Hydrocarbons Max slope — 20% Minimum water table — 3 It Freeze/thaw — fair Design The procedure for sizing infiltration trenches should follow a Darcy's Law Parameters approach, as described in BMP 4 (Sand Filters). Typical dimensions are 3 feet wide and 3 to 12 feet deep. Additional design parameters specific to infiltration trenches are given below. Soils Investigation A minimum of 1 soils log should be collected for every 50 feet of trench length, and in no case less than 2 soils logs for each proposed trench location. Each soils log should extend to a minimum depth of the high water table below the bottom of the trench, describe the NRCS series of the soil, the textural class of the soil horizon(s) through the depth of the log (soil and structures), and note any evidence of high ground water level, such as mottling. In addition, the location of impermeable soil layers or dissimilar soil layers should be determined. The design infiltration rate (fd) will be equal to one-half the infiltration rate found from the soil textural and structural analysis. Pretreatment It is recommended that all infiltration trenches be preceded by a pretreatment IDEQ Storm Water Best Management Practices Catalog 47 September 2005 BMP, such as a presettling basin, a vegetated swale or a simple sump. A vegetated filter strip at least 20 feet wide appears to work well. A level spreader may be used to spread out concentrated flows. Regular maintenance of the pretreatment device is critical. Drawdown Time Infiltration trenches should be designed to completely drain stored runoff within 24 hours. This will ensure that the necessary aerobic conditions exist in order to provide effective treatment of pollutants. If a presettling basin precedes the infiltration trench, the combined drawdown time for both BMPs should be 24 hours. Backfill Material The aggregate material for the infiltration trench should consist of a clean aggregate with a maximum diameter of 3 inches and a minimum diameter of 1.5 inches. The aggregate should be graded such that there will be few aggregates smaller than the selected size. Void space for these aggregates is assumed to be in the range of 30 to 40%. Geotextile Fabric The aggregate fill material should be completely surrounded with an engineering geotextile. In the case of an aggregate surface, the fabric should surround all of the aggregate fill material except for the top I foot. Overflow Channel In general, because of the small drainage areas controlled by an infiltration trench, an emergency spillway is not necessary. In all cases, the overland flow path of surface runoff exceeding the capacity of the trench should be evaluated to preclude the development of uncontrolled, erosive, concentrated flow. A nonerosive overflow channel leading to a stabilized watercourse should be provided. Seepage Analysis and Control An analysis should be made to determine any possible adverse effects of seepage zones when there are nearby building foundations, basements, roads, parking lots or sloping sites. Developments on sloping sites often require the use of extensive cut and fill operations. The use of infiltration trenches on fill sites is not permitted. Buildings Trenches should be a minimum of 100 feet upslope and 20 feet downslope from any building foundation or water supply well. Land Use Infiltration facilities are not recommended under surfaces that are expected to have traffic loads, such as driveways and parking lots. Soils become too compacted and access is difficult. IDEQ Storm Water Best Management Practices Catalog 48 September 2005 Observation Well An observation well should be installed for every 50 feet of infiltration trench length. The observation well will serve two primary functions: it will indicate how quickly the trench dewaters following a storm and it will provide a method of observing how quickly the trench fills up with sediments. The observation well should consist of perforated PVC pipe, 2 to 4 inches in diameter. It should be located in the center of the structure and be constructed flush with the ground elevation of the trench. The top of the well should be capped to discourage vandalism and tampering. More specific construction information can be obtained by contacting IDWR or DEQ. Construction Construction Timing Guidelines An infiltration trench should not be constructed or placed into service until all of the contributing drainage area has been stabilized and approved by the appropriate agency. Trench Preparation Excavate the trench to the design dimensions. Excavated materials should be placed away from the trench sides to enhance wall stability. Care should also be taken to keep this material away from slopes, neighboring property, sidewalks and streets. It is recommended that this material be covered with plastic if it is to be left in place for more than 30 days. Fabric Laydown The geotextile fabric (a fabric that is defined as "non -woven, spunbonded and needlepunched") should be cut to the proper width prior to installation. The cut width should include sufficient material to conform to the trench perimeter irregularities and for a 12 -inch minimum top overlap. Place the geotextile over the trench and unroll a sufficient length to allow placement of the fabric down into the trench. Stones or other anchoring objects should be placed on the geotextile at the edge of the trench to keep the lined trench open during windy periods. When overlaps are required between rolls, the upstream roll should overlap a minimum of 2 feet over the downstream roll in order to provide a shingled effect. The overlap insures geotextile continuity and allows the geotextile to conform to the excavated surface during aggregate placement and compaction. Stone Aggregate Placement and Compaction The stone aggregate should be placed in lifts and compacted using plate compactors. As a rule of thumb, a maximum loose lift thickness of 12 inches is recommended. The compaction process ensures geotextile conformity, to the excavation sides, thereby reducing potential soil piping, geotextile clogging, and settlement problems. Overlapping and Covering Following the stone aggregate placement, the geotextile fabric should be folded over the stone aggregate to form a 12 -inch minimum longitudinal overlap. The desired fill soil or stone aggregate should be placed over the lap IDEQ Storm Water Best Management Practices Catalog 49 September 2005 at sufficient intervals to maintain the lap during subsequent backfilling. Care should be exercised to prevent natural or fill soils from intermixing with the stone aggregate. All contaminated stone aggregate should be removed and replaced with uncontaminated stone aggregate. Voids Behind Geotextile Voids that may be created between the geotextile and excavation sides should be avoided. Native soils should be placed in these voids at the most convenient time during construction to ensure fabric conformity to the excavation sides. Utilizing this remedial process will minimize soil piping, fabric clogging, and possible surface subsidence. Unstable Excavation Sites Vertically excavated walls may be difficult to maintain in areas where the soil moisture is high or where soft or cohesionless soils predominate. These conditions require laying back of the side slopes to maintain stability; a trapezoidal rather than rectangular cross-sections may result. This is acceptable, but any change in the shape of the stone reservoir needs to be taken into consideration in size calculations. Traffic Control Heavy equipment and traffic should be restricted from traveling over the infiltration areas to minimize compaction of the soil. The trench should be flagged or marked to keep equipment away from the area. Maintenance Inspection Schedule The observation well should be monitored periodically for water level. For the first year after completion of construction, the well should be monitored after every large storm (greater than 1 inch in 24 hours), and during the period from October 15 to April 15, inspections should be conducted monthly. From April 16 through October 14, the facility should be monitored on a quarterly basis. A log book should be maintained by the responsible person designated by the local government indicating the rate at which the facility dewaters after large storms and the depth of the well for each observation. Once the performance characteristics of the structure have been verified, the monitoring schedule can be reduced to an annual basis unless the performance data indicate that a more frequent schedule is required. Sediment Removal Sediment buildup in the top foot of stone aggregate or the surface inlet should be monitored on the same schedule as the observation well. A monitoring well - in the top foot of stone aggregate should be required when the trench has a stone surface. Sediment deposits should not be allowed to build up to the point where it will reduce the rate of infiltration into the trench. Pretreatment BMPs BMPs used for pretreatment should be inspected regularly. Sediment deposits should be removed and grassy swales or filter strips should be mowed. Repair any erosion (e.g., rills) in pretreatment swales or filter strips that might IDEQ Storm Water Best Management Practices Catalog 50 September 2005 concentrate runoff flow and cause erosion prior to the infiltration trench. IDEQ Storm Water Best Management Practices Catalog 51 September 2005 Mn o• n a O 4) C '~ IL. tL v 0 • p 4 p a..•+. v�• ryry �y U V 0 < V �y 0 1< ry 0 ..• '� 9 4 8 6 Q b (} p �' • Mn o• n a O L C '~ IL. tL v 0 • p 4 p a..•+. v�• ryry �y U V 0 V ry V �y 0 ry 0 ..• '� 9 4 8 6 Q b (} p �' • � � r .a .♦ v V rt . o i 6 4 O • •..J V (Z) 0 0 0 Q V O f\ 4 9 4 0 0 0 0 0 0 0 0 010 0 0 0 0 0 0 0 0 0 0 1 O 0,0 O 0 0 O O O p O o 0 0 0 0 0 0 0 0 t �/ • + v Q . 0 0 0 b 0 4 0 0 0 . 0 0 4v ov as oa.aio ' D O Q 0 Q) 0 q 0 0 0 p 0 p 0 .. a i .. 4 .4 6a a Qp Q a d s a 0 . Q � 0 0 Q 0 © 0 Q V V Vre V 9 d 0 4 q '' (� qq /r.• �y Mn 1 t1 O L C '~ IL. tL v 0 v�• t cn Mn CONSTRUCTION PRODUCTS INC. CDS Guide Operation, Design, Performance and Maintenance :DS® sing patented continuous deflective separation technology, the )S system screens, separates and traps debris, sediment, and I and grease from stormwater runoff. The indirect screening ipability of the system allows for 100% removal of floatables id neutrally buoyant material without blinding. Flow and reening controls physically separate captured solids, and inimize the re -suspension and release of previously trapped Autants. Inline units can treat up to 6 cfs, and internally bypass )ws in excess of 50 cfs. Available precast or cast -in-place, offline fits can treat flows from 1 to 300 cfs. The pollutant removal ipacity of the CDS system has been proven in lab and field sting. operation Overview ormwater enters the diversion chamber where the diversion eir guides the flow into the unit's separation chamber and Autants are removed from the flow. All flows up to the stem's treatment design capacity enter the separation chamber id are treated. virl concentration and screen deflection force floatables and Aids to the center of the separation chamber where 100% of )atables and neutrally buoyant debris larger than the screen )ertures are trapped. ormwater then moves through the separation screen, under �e oil baffle and exits the system. The separation screen remains og free due to continuous deflection. firing the flow events exceeding the design capacity, the version weir bypasses excessive flows around the separation camber, so captured pollutants are retained in the separation finder. Design Basics There are three primary methods of sizing a CDS system. The Water Quality Flow Rate Method determines which model size provides the desired removal efficiency at a given flow rate for a defined particle size. The Rational Rainfall MethodTM and Probabalistic Method are used when a specific removal efficiency of the net annual sediment load is required. Typically in the Unites States, CDS systems are designed to achieve an 80% annual solids load reduction based on lab generated performance curves for a gradation with an average particle size (d50) of 125 -microns (um). For some regulatory environments, CDS systems can also be designed to achieve an 80% annual solids load reduction based on an average particle size (d50) of 75 -microns (um). Water Quality Flow Rate Method In many cases, regulations require that a specific flow rate, often referred to as the water quality design flow (WOO), be treated. This WOO represents the peak flow rate from either an event with a specific recurrence interval (i.e. the six-month storm) or a water quality depth (i.e. 1/2 -inch of rainfall). The CDS is designed to treat all flows up to the WQQ. At influent rates higher than the WQQ, the diversion weir will direct most flow exceeding the treatment flow rate around the separation chamber. This allows removal efficiency to remain relatively constant in the separation chamber and reduces the risk of washout during bypass flows regardless of influent flow rates. Treatment flow rates are defined as the rate at which the CDS will remove a specific gradation of sediment at a specific removal efficiency. Therefore they are variable based on the gradation and removal efficiency specified by the design engineer. Rational Rainfall Method" Differences in local climate, topography and scale make every site hydraulically unique. It is important to take these factors into consideration when estimating the long-term performance of any stormwater treatment system. The Rational Rainfall Method combines site-specific information with laboratory generated performance data, and local historical precipitation records to estimate removal efficiencies as accurately as possible. Short duration rain gauge records from across the United States and Canada were analyzed to determine the percent of the total annual rainfall that fell at a range of intensities. US stations' depths were totaled every 15 minutes, or hourly, and recorded in 0.01 -inch increments. Depths were recorded hourly with 1 -mm resolution at Canadian stations. One trend was consistent at all sites; the vast majority of precipitation fell at low intensities and high intensity storms contributed relatively little to the total annual depth. These intensities, along with the total drainage area and runoff coefficient for each specific site, are translated into flow rates using the Rational Rainfall Method. Since most sites are relatively small and highly impervious, the Rational Rainfall Method is appropriate. Based on the runoff flow rates calculated for each intensity, operating rates within a proposed CDS system are determined. Performance efficiency curve determined from full scale laboratory tests on defined sediment PSDB is applied to calculate solids removal efficiency. The relative removal efficiency at each operating rate is added to produce a net annual pollutant removal efficiency estimate. Probabalistic Rational Method The Probabalistic Rational Method is a sizing program CONTECH developed to estimate a net annual sediment load reduction for a particular CDS model based on site size, site runoff coefficient, regional rainfall intensity distribution, and anticipated pollutant characteristics. The Probabilistic rational method is an extension of the rational method used to estimate peak discharge rates generated by storm events of varying statistical return frequencies (i.e.: 2 -year storm event). Under this method, an adjustment factor is used to adjust the runoff coefficient estimated for the 10 -year event, correlating a known hydrologic parameter with the target storm event. The rainfall intensities vary depending on the return frequency of the storm event under consideration. In general, these two frequency dependent parameters increase as the return frequency increases while the drainage area remains constant. These intensities, along with the total drainage area and runoff coefficient for each specific site, are translated into flow rates using the Rational Method. Since most sites are relatively small and highly impervious, the Rational Method is appropriate. Based on the runoff flow rates calculated for each intensity, operating rates within a proposed CDS are determined. Performance efficiency curve on defined sediment PSDB is applied to calculate solids removal efficiency. The relative removal efficiency at each operating rate is added to produce a net annual pollutant removal efficiency estimate. Treatment Flow Rate The inlet throat area is sized to ensure that the WQQ passes through the separation chamber at a water surface elevation equal to the crest of the diversion weir. The diversion weir bypasses excessive flows around the separation chamber, thus helping to prevent re -suspension or re -entrainment of previously captured particles. Hydraulic Capacity CDS hydraulic capacity is determined by the length and height of the diversion weir and by the maximum allowable head in the system. Typical configurations allow hydraulic capacities of up to ten times the treatment flow rate. As needed, the crest of the diversion weir may be lowered and the inlet throat may be widened to increase the capacity of the system at a given water surface elevation. The unit is designed to meet project specific hydraulics. Performance Full -Scale Laboratory Test Results A full-scale CDS unit (Model CDS2020-513) was tested at the facility of University of Florida, Gainesville, FL. This full-scale CDS unit was evaluated under controlled laboratory conditions of pumped influent and the controlled addition of sediment. Two different gradations of silica sand material (UF Sediment & OK -110) were used in the CDS performance evaluation. The particle size distributions (PSD) of the test materials were analyzed using standard method "Gradation ASTM D-422 with Hydrometer" by a certified laboratory. OF Sediment is a mixture of three different U.S. Silica Sand products referred as: "Sil-Co-Sil 106", "#1 DRY" and "20/40 Oil Frac". Particle size distribution analysis shows that the OF Sediment has a very fine gradation (d50 = 20 to 30 Nm) covering a wide size range (uniform coefficient Cu averaged at 10.6). In comparison with the hypothetical TSS gradation specified in the NJDEP (New Jersey Department of Environmental Protection) and NJCAT (New Jersey Corporation for Advanced Technology) protocol for lab testing, the OF Sediment covers a similar range of particle size but with a finer d50 (d50 for NJDEP is approximately 50 Nm) (NJDEP, 2003), The OK -110 silica sand is a commercial product of U.S. Silica Sand. The particle size distribution analysis of this material, also included in Figure 1, shows that 99.9% of the OK -110 sand is finer than 250 microns, with a mean particle size (d50) of 106 microns. The PSDB for the test material are shown in Figure 1. 90.0 DF Sediment (Avg) r e0-0 - OK 110 (Avg) 70.0 -,- NJCAT 600 50.0 f 400 00 1 2001 +o o { 0 0 10 100 1000 aaa�Ue Saxe ppm) Figure 1. Particle size distributions for the test materials, as compared to the NKAT/NJDEP theoretical distribution. Tests were conducted to quantify the CDS unit (1.1 cfs (31.3 -Us) design capacity) performance at various flow rates, ranging from 1 % up to 125% of the design capacity of the unit, using the 2400 micron screen. All tests were conducted with controlled influent concentrations approximately 200 mg/L. Effluent samples were taken at equal time intervals across the entire duration of each test run. These samples were then processed with a Dekaport Cone sample splitter to obtain representative sub -samples for Suspended Sediment Concentration (SSC—ASTM Standard Method D3977-97) and particle size distribution analysis. Results and Modeling Based on the testing data from the University of Florida, a performance model was developed for the CDS system. A regression analysis was used to develop a fitting curve for the scattered data points at various design flow rates. This model, which demonstrated good agreement with the laboratory data, can then be used to predict CDS system performance with respect to SSC removal for any particle size gradation assuming sandy -silt type of inorganic components of SSC. Figure 2 shows CDS predictive performance for two typical particle size gradations (NJCAT gradation and OK -110 sand). 100 OD ,•�-——..-- - 600 40 I 40 OD 20 OD NJ AT OK 110 0% 20% 40% 66% 80% 100% 120% 140% `Ye Design Flow Rale gure 2. CDS stormwater treatment predictive performance for rious particle gradations as a function of operating rate, any regulatory jurisdictions set a performance standard for rdrodynamic devices by stating that the devices shall be capable achieving an 80% removal efficiency for particles having a can particle size (d50) of 125 microns (WADOE, 2008). The ode[ can be used to calculate the expected performance of such PSD (shown in Figure 3). Supported by the laboratory data, the odel indicates (Figure 4) that the CDS system with 2400 micron reen achieves approximately 80% removal at 100% of design )w rate, for this particle size distribution (d50 = 125 Nm). Par4dc See D6l11bk4'W 700 f 90 h. 60 i 70 60 ----- —.. --r-1 --- so 4030 l 2010 -- — 0 1 10 100 1000 10000 Putitle Sm lrmcronl ;jure 3. PSD with d50 = 125 microns, used to model �rformance for Ecology submittal. CDS lhil Performance fa Ecology PSD d>=125 1an 100 vw—#� ..-__.. 804. 60 i -- ...: .... ..... 40 20 y = A9.� 145x 100.92: . R- = 0.931 e% 20% 40% 60% ao% IWK 120% 140% % Design Flew Rene gure 4. Modeled performance for CDS unit with 2400 microns reen, using Ecology PSD. Maintenance The CDS system should be inspected at regular intervals and maintained when necessary to ensure optimum performance. The rate at which the system collects pollutants will depend more heavily on site activities than the size of the unit, e.g., unstable soils or heavy winter sanding will cause the grit chamber to fill more quickly but regular sweeping of paved surfaces will slow accumulation. Inspection Inspection is the key to effective maintenance and is easily performed. Pollutant deposition and transport may vary from year to year and regular inspections will help insure that the system is cleaned out at the appropriate time. At a minimum, inspections should be performed twice per year (i.e. spring and fall) however more frequent inspections may be necessary in climates where winter sanding operations may lead to rapid accumulations, or in equipment washdown areas. Additionally, installations should be inspected more frequently where excessive amounts of trash are expected. The visual inspection should ascertain that the system components are in working order and that there are no blockages or obstructions to inlet and/or separation screen. The inspection should also identify evidence of vector infestation and accumulations of hydrocarbons, trash, and sediment in the system. Measuring pollutant accumulation can be done with a calibrated dipstick, tape measure or other measuring instrument. If sorbent material is used for enhanced removal of hydrocarbons then the level of discoloration of the sorbent material should also be identified during inspection. It is useful and often required as part of a permit to keep a record of each inspection. A simple form for doing so is provided. Access to the CDS unit is typically achieved through two manhole access covers. One opening allows for inspection and cleanout of the separation chamber (screen/cylinder) and isolated sump. The other allows for inspection and cleanout of sediment captured and retained behind the screen. For units possessing a sizable depth below grade (depth to pipe), a single manhole access point would allow both sump cleanout and access behind the screen. The CDS system should be cleaned when the level of sediment has reached 75% of capacity in the isolated sump and/or when an appreciable level of hydrocarbons and trash has accumulated. If sorbent material is used, it should be replaced when significant discoloration has occurred. Performance will not be impacted until 100% of the sump capacity is exceeded however it is recommended that the system be cleaned prior to that for easier removal of sediment. The level of sediment is easily determined by measuring from finished grade down to the top of the sediment pile. To avoid underestimating the level of sediment in the chamber, the measuring device must be lowered to the top of the sediment pile carefully. Finer, silty particles at the top of the pile typically offer less resistance to the end of the rod than larger particles toward the bottom of the pile. Once this measurement is recorded, it should be compared to the as -built drawing for the unit to determine if the height of the sediment pile off the bottom of the sump floor exceeds 75% of the total height of isolated sump. Cleaning Cleaning of the CDS systems should be done during dry weather conditions when no flow is entering the system. Cleanout of the CDS with a vacuum truck is generally the most effective and convenient method of excavating pollutants from the system. Simply remove the manhole covers and insert the vacuum hose into the sump. The system should be completely drained down and the sump fully evacuated of sediment. The area outside the screen should be pumped out also if pollutant build-up exists in this area. In installations where the risk of petroleum spills is small, liquid contaminants may not accumulate as quickly as sediment. However, an oil or gasoline spill should be cleaned out immediately. Motor oil and other hydrocarbons that accumulate on a more routine basis should be removed when an appreciable layer has been captured. To remove these pollutants, it may be preferable to use adsorbent pads since they are usually less expensive to dispose than the oil/water emulsion that may be created by vacuuming the oily layer. Trash can be netted out if you wish to separate it from the other pollutants. The screen should be power washed to ensure it is free of trash and debris. Manhole covers should be securely seated following cleaning activities to prevent leakage of runoff into the system from above and also to ensure proper safety precautions. Confined Space Entry procedures need to be followed. Disposal of all material removed from the CDS system should be done is accordance with local regulations. In many locations, disposal of evacuated sediments may be handled in the same manner as disposal of sediments removed from catch basins or deep sump manholes. Check your local regulations for specific requirements on disposal. CDS2015-4 4 1.2 3.0 0.9 0.5 0.4 CDS2015 5 1.5 3.0 0.9 1.3 1.0 CDS2020 5 1.5 3.5 1.1 1.3 1.0 CDS2025 5 1.5 4.0 1.2 1.3 1.0 CDS3020 6 1.8 4.0 1.2 2.1 1.6 CDS3030 6 1.8 4.6 1.4 2.1 1.6 CDS3035 6 1.8 5.0 1.5 2.1 1.6 CDS4030 8 2.4 4.6 1.4 5.6 4.3 CDS4040 8 2.4 5.7 1.7 5.6 4.3 CDS4045 8 2.4 6.2 1.9 5.6 4.3 ble 1: CDS Maintenance Indicators and Sediment Storage Capacities ate: To avoid underestimating the volume of sediment in the chamber, carefully lower the easuring device to the top of the sediment pile. Finer silty particles at the top of the pile ay be more difficult to feel with a measuring stick. These finer particles typically offer less sistance to the end of the rod than larger particles toward the bottom of the pile. CDS Model CDS Inspection & Maintenance Log Location: Date Water depth to sediment' Heatable Layer Thickness' Describe Maintenance Performed Maintenance Personnel Comments The water depth to sediment is determined by taking two measurements with a stadia rod: one measurement from the manhole opening to the top of the sediment pile and the other from the manhole opening to the water surface. If the difference between these measurements is less than eighteen inches the system should be cleaned out. Note: To avoid underestimating the volume of sediment in the chamber, the measuring device must be carefully lowered to the top of the sediment pile. For optimum performance, the system should be cleaned out when the floating hydrocarbon layer accumulates to an appreciable thickness. In the event of an oil spill, the system should be cleaned immediately. ipport Drawings and specifications are available at www.contechstormwater.com Site-specific design support is available from our engineers. !008 CONTECH Stormwater Solutions G�kwg�%_ rK &V OW! CONSTRUCTION PRODUCTS INC. i 800.925.5240 contechstormwatec com iNTECH Construction Products Inc. provides site solutions for the civil engineering industry. CONTECH's portfolio includes bridges, drainage, litary sewer, stormwater and earth stabilization products. For information on other CONTECH division offerings, visit contech-cpi.com or call 0.338.1122 thing in this catalog should be construed as an expressed warranty or an implied warranty of merchantability or fitness for any particular rpose. See the CONTECH standard quotation or acknowledgement for applicable warranties and other terms and conditions of sale. product(s) described may be protected by one or more of the following US patents: 5,322,629; 5,624,576; 5,707,527; 5,759,415; 5,788,848; 5,985,157; 6,027,639; 6350,374; 6,406,218; 11,720; 6,511,595; 6,649,048; 6,991,114; 6,998,038; 7,186,058; 7,296,692; 7,297,266; related foreign patents or other patents pending. +� RECYCLED manual 10/08 3M `� PAPER CY