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APPROVED BLD RET WALL CALCS BLD2019-0026
Client SSS # Project Identification SOUND STRUCTURAL SOLUTIONS E N G I N E E R S Michel Construction Rob Michel 7305 Soundview Drive Edmonds WA 98026 206-930-2445 phone fax s1909026 546 Paradise Lane 4 Unit Townhouse Michel Design (206-930-2445) WAC 196-23-070 Section Engineering Calculations 1 Modular Retaining Wall Calculations 2 Modular Retaining Wall Evaluation Report 3 Geotech Report Structural calcs Approved 1 1 By L. Bjorback 7/27/2020 City of Edmonds Building Division 1 24113 56th Ave W - Mountlake Terrace, WA 98043 - Ph: 425-778-1023 - Fax: 206-260-7490 SSSOUND STRUCTURAL SOLUTIONS E N G T N E E R S MODULAR RETAINING WALL CALCULATIONS Site Retaining Wall 1: Maximum back slope = Level Soil Type = Silty Sands (Top 5ft) (Per attached Geotech Report) Maximum Allowed Height = 5'-0" (Fig.2, ESR-2113, page 9 of 11) Maximum Wall Height = 5'-0" OK Site Retaining Wall 2: Maximum back slope = Level Soil Type = Silty Sands (Top 5ft) (Per attached Geotech Report) Maximum Allowed Height = 5'-0" (Fig.2, ESR-2113, page 9 of 11) Maximum Wall Height = 4'-6" OK Site Retaining Wall 3: Maximum back slope = Level Soil Type = Silty Sands (Top 5ft) (Per attached Geotech Report) Maximum Allowed Height = 5'-0" (Fig.2, ESR-2113, page 9 of 11) Maximum Wall Height = 4'-3" OK 24113 56th Ave W - Mountlake Terrace, WA 98043 - Ph: 425-778-1023 - www.ssseng.com ICC-ES Evaluation Report ESR-2113 www.icc-es.ora 1 (800) 423-6587 1 (562) 699-0543 DIVISION: 32 00 00—EXTERIOR IMPROVEMENTS Section: 32 32 00—Retaining Walls Section: 32 32 23—Segmental Retaining Walls REPORT HOLDER: KEYSTONE RETAINING WALL SYSTEMS, LLC EVALUATION SUBJECT: KEYSTONE RETAINING WALL SYSTEMS ADDITIONAL LISTEE: RCP BLOCK AND BRICK, INC. 1.0 EVALUATION SCOPE Compliance with the following codes: ❑ 2015, 2012 and 2009 International Building Code°(IBC) ❑ 2015, 2012 and 2009 International Residential Codee (IRC) ❑ 2013 Abu Dhabi International Building Code (ADIBC)t tThe ADIBC is based on the 2009 IBC. 2009 IBC code sections referenced in this report are the same sections in the ADIBC. Properties evaluated: Physical properties 2.0 USES The Keystone Retaining Wall Systems (Keystone SRWs) consist of modular concrete units for the construction of conventional gravity- or geogrid-reinforced-soil retaining walls, respectively, with or without a mass of reinforced soil, stabilized by horizontal layers of geosynthetic reinforcement materials. 3.0 DESCRIPTION 3.1 Keystone Units: Keystone concrete units are available in four configurations: Standard III, Compac III, Compac II, Country Manor. See Figure 1 for dimensions and nominal weights. Standard III, Compac III, Compac II units and corresponding cap units have either a straight or three - plane split face. Country Manor units have a straight face. Cap units are half -height units without pin holes in the top surface. The nominal unit weights, noted in Figure 1, are to be used in design. Standard III, Compac III and Compac II units have four holes each for installation of two fiberglass connection Reissued August 2019 This report is subject to renewal August 2021. A Subsidiary of the International Code Council° pins. Country Manor units have six holes for installation of two fiberglass connection pins. The Small Country Manor Unit has three holes, for installation of one fiberglass connection pin. The underside of each unit has a slot to receive the connection pin. See Figure 1 for typical unit configurations. All units are made with normal -weight aggregates, and comply with ASTM C1372, including having a minimum 28- day compressive strength of 3,000 psi (21 MPa) [minimum of 24 MPA is required under ADIBC Appendix L, Section 5.1.1] on the net area. In areas where repeated freezing and thawing under saturated conditions occur, evidence of compliance with freeze -thaw durability requirements of ASTM C1372 must be submitted to the code official for approval prior to construction. 3.2 Fiberglass Pins: Pultruded fiberglass pins provide alignment of the units during placement, positive placement of the geogrid reinforcement, and inter -unit shear strength. The connection pins are 0.5 inch (12.7 mm) in diameter and 5.25 inches (133 mm) long, and have a minimum short beam shear strength of 6,400 psi (44 MPa). 3.3 Unit Core Drainage Fill: Unit core drainage fill must be inch to 3/4 inch (13 mm to 19 mm), clean, crushed -stone material that is placed between and behind the units. The unit core fill provides additional weight to the completed wall section for stability, local drainage at the face of the structure, and a filter zone to keep the backfill soils from filtering out through the space face between units. 3.4 Geogrid: The geogrid materials listed in Tables 1, 2A and 213 are proprietary materials used to increase the height of the Keystone Wall System above the height at which the wall is stable under its self -weight as a gravity system. Geogrids are synthetic materials specifically designed for use as soil reinforcement. 4.0 DESIGN AND INSTALLATION 4.1 Design: 4.1.1 General: Structural calculations must be submitted to the code official for each wall system installation. The system must be designed as a conventional gravity or reinforced -soil retaining wall that depends on the weight and geometry of the concrete units and soil to resist lateral earth pressures and other lateral forces. Lateral earth pressures are determined using either Coulomb or Rankine earth pressure theory. The design must include ICC-ES Evaluation Reports are not to be construed as representing aesthetics or any other attributes not specifically addressed, nor are they to be construed as an endorsement of the subject of the report or a recommendation for its use. There is no warranty by ICC Evaluation Service, LLC, express or implied, as i to any finding or other matter in this report, or as to any product covered by the report. Copyright © 2019 ICC Evaluation Service, LLC. All rights reserved. Page 1 of 11 ESR-2113 I Most Widely Accepted and Trusted Page 2 of 11 evaluation of both external and internal stability of the structure, and include consideration of external loads such as surcharges and seismic forces, as applicable. External stability analysis must be similar to that required for conventional retaining walls, and must consider base (lateral) sliding, overturning, bearing capacity (and excessive settlement), and overall (deep-seated) slope stability. Internal stability analysis of SRWs without geogrid-reinforced soil must consider movement between courses. Internal stability analysis of the SRWs with geogrid-reinforced soil must consider the maximum allowable reinforcement tension, pull-out resistance of reinforcement behind the active failure zone (excessive movement of geosynthetic material through the reinforced soil zone), and the connection strength of geosynthetic reinforcement material to the SRW concrete units or blocks, and movement between courses. Minimum safety factors used in design (for external stability check) for SRWs, with and without a geogrid- reinforced soil mass, must be 1.5 for deep-seated (global) stability and 2.0 for bearing capacity. The minimum safety factors must be 1.5 for lateral sliding and 2.0 for overturning for SRWs with a geogrid-reinforced soil mass. The minimum safety factors against lateral sliding and overturning must be 1.5 (IBC Section 1807.2.3, or IRC Section R404.4, as applicable), for SRWs without a reinforced soil mass. Minimum safety factors used in design (for internal stability) must be 1.5 for peak connection strength between the geosynthetic material and SRW units, and for peak shear strength between SRW units with or without geosynthetic material. Seismic safety factors for all limit states related to SRW design may be 75 percent of the corresponding minimum allowable static safety factors. A site -specific soils investigation report in accordance with IBC Section 1803, or IRC Section R401.4, as applicable, is required. The soils investigation report must provide a global slope stability analysis that considers the influence of site geometry, subsoil properties, groundwater conditions, and existing (or proposed) slopes above and below the proposed retaining wall. The soils investigation report must also specify the soil -reinforcement and interaction coefficients, including the coefficient of interaction for pullout and coefficient of direct sliding; and include derivation of the ultimate tensile strength of the geogrid material (according to ASTM D4595), and the applicable safety factors for the determination of the ultimate tensile strength, long-term design strength and allowable tensile strength of the geogrid. The soils investigation report must also specify safety factors for tensile rupture and pullout of the geogrid. Where the wall is assigned to Seismic Design Category (SDC) C, D, E or F, the site -specific soils report must include the information as required by IBC Section 1803.5.11. Where the wall is assigned to Seismic Design Category (SDC) D, E or F, the site -specific soils report must include the information as required by IBC Section 1803.5.12. The design of the Keystone wall is based on accepted geotechnical principles for gravity and soil -reinforced structures. Specifics of design recommended by the manufacturer are found in the Keystone Design Manual dated February 2011. 4.1.2 Conventional Gravity Retaining Walls: The gravity wall system relies on the weight and geometry of the Keystone units, without the contribution of geogrids, to resist lateral earth pressures. Gravity wall design is based on standard engineering principles for modular concrete retaining walls. The maximum height of retaining walls constructed using Keystone Standard III, Compac III, Compac II and Country Manor units is shown in Figure 2 for different soil and back slope combinations. Typical design heights are 2.5 to 3 times the depth of the unit being used. Inter -unit shear capacity equations are provided in Table 1. 4.1.3 Geogrid-reinforced Retaining Walls: 4,1.3.1 General: The geogrid reinforced soil system relies on the weight and geometry of the Keystone units and the reinforced soil mass to act as a coherent gravity mass to resist lateral earth pressures. The design of a reinforced soil structure is specific to the Keystone unit selected, soil reinforcement strength and soil interaction, soil strength properties, and structure geometry. Inter -unit shear capacity equations are provided in Table 1. Grid -to -block pullout resistance values/equations are provided in Tables 2A and 2B. The maximum practical height above the wall base is approximately 50 feet (15 m). Figure 3 shows typical component details. 4,1.32 Structural Analysis: Structural analysis must be based on accepted engineering principles, the Keystone Design Manual dated February 2011, and the IBC. The analysis must include all items noted in Sections 4.1.1, 4.1.3.2.1 and 4.1.3.2.2 of this report, and must follow the design methodology of the Keystone Design Manual dated February 2011. All contact surfaces of the units must be maintained in compression. 4,1.32.1 External Stability Analysis: 1. The minimum length of the reinforced mass is 0.6 times the height of the wall (as measured from the top of the leveling pad to the top of the wall) or as required to satisfy a safety factor of 1.5 on sliding at the base, whichever is greater. 2. The minimum safety factor for overturning the reinforced mass is 2.0, considering the mass as a rigid body rotating about the toe of the wall. 3. Global stability analysis must be provided for walls with slopes below the toe of the wall, walls on soft foundations, walls that will be designed for submerged conditions, or tiered walls. 4. After completion of the internal stability analysis and geogrid layout, sliding along each respective geogrid layer must be checked, including shearing through the connection at the wall face. 4.1.322 Internal Stability Analysis: 1. Geogrid spacing must be based on local stability of the Keystone units during construction. Vertical spacing is typically limited to 2 times the depth of the unit. 2. Tension calculations for each respective layer of reinforcing must be provided. Tension is based on the earth pressure and surcharge load calculated from halfway to the layer below to halfway to the layer above. Calculated tensions must not exceed the allowable geogrid strength. 3. Connection capacity must be checked for each geogrid-to-Keystone connection (see Tables 2A and 2B). The calculated connection capacity must be equal to or greater than the calculated tension for each layer. 4. A calculation check must be made on pullout of the upper layers of geogrid from the soil zone beyond the theoretical Coulomb or Rankine failure plane. The pullout capacity must be equal to or greater than the calculated tension after applying the applicable ESR-2113 I Most Widely Accepted and Trusted Page 3 of 11 geogrid interaction and sliding coefficient adjustment factors. 4.2 Installation: The wall system units are assembled in a running bond pattern, except for the Country Manor units, which are assembled in a random bond pattern. The wall system units are assembled without mortar or grout, utilizing high - strength fiberglass pins for shear connections, mechanical connections of reinforcing geogrid, if applicable, and unit alignment. The system may include horizontal layers of structural geogrid reinforcement in the backfill soil mass. Requirements for installation of the Keystone Retaining Wall System are as follows: 1. Excavate for leveling pad and reinforced fill zone. 2. Inspect excavations for adequate bearing capacity of foundation soils and observation of groundwater conditions by a qualified geotechnical engineer. 3. Install a 6-inch-thick (152 mm) leveling pad of crushed stone, compacted to 75 percent relative density as determined by ASTM D4564. (An unreinforced concrete pad in accordance with IBC Section 1809.8, may be utilized in place of the crushed stone pad.) 4. Install the first course of Keystone units, ensuring units are level from side to side and front to back. Adjacent Keystone units are placed so pin holes are approximately 12 inches (305 mm) on center. 5. Install the fiberglass pins in the units to establish the angle of wall inclination (batter). The pin placement and resulting batter for given units are as follows: • Standard III, Compac III and Compac II Units: Placing the pin in the rear pin holes in every course provides a minimum wall inclination of 7.1 degrees from vertical toward the backfill [1 inch (25.4 mm) minimum setback per course]. Pin placement alternating between the front and rear pin holes on vertically adjacent rows provides a wall inclination of approximately 3.6 degrees from vertical toward the backfill [1/2 inch (13 mm) minimum setback per course]. The pin placement during assembly in the front pin hole provides a wall inclination of approximately 0.5 degree from vertical toward the backfill ['/s inch (3 mm) minimum setback per course]. • Country Manor Units: Placing the pin in the rear pin holes in every course provides a wall inclination of approximately 9.5 degrees from vertical toward the backfill [1 inch (25.4 mm) setback per course]. Placing the pin in the middle pin hole provides a wall inclination of approximately 0.5 degree from vertical toward the backfill [1/8 inch (3 mm) minimum setback per course]. 6. Fill the unit cores with unit core drainage fill described in Section 3.3 of this report. The unit core drainage fill is required for all installations and must extend back a minimum of 2 feet (610 mm) from the outside or front face of the wall. See Figure 3. 7. Clean the top surface of the units to remove loose aggregate. 8. At designated elevation per the design, install geogrid reinforcing. All geogrid reinforcement is installed by placing it over the fiberglass pin. Check to ensure the proper orientation of the geogrid reinforcement is used so the strong direction is perpendicular to the face. Adjacent rolls are placed side by side; no overlap is required. 9. Pull taut to remove slack from the geogrids before placing backfill. Pull the entire length taut to remove any folds or wrinkles. 10. Place and compact backfill over the geogrid reinforcing layer in appropriate lift thickness to ensure compaction. 11. Repeat placement of units, core fill, backfill, and geogrids, as shown on plans, to finished grade. 12. Backfill used in the reinforced fill mass must consist of suitable fine-grained or coarse -grained soil placed in lifts compacted to at least 90 percent of the maximum dry density as determined by ASTM D1557 (95 percent per ASTM D698). The backfill soil properties, lift thickness, and degree of compaction must be determined by the soils engineer based on site -specific conditions. In cut -wall applications, if the reinforced soil has poor drainage properties, a granular drainage layer of synthetic drainage composite should be installed to prevent buildup of hydrostatic pressures behind the reinforced soil mass. Provisions for adequate subsurface drainage must be determined by the soils engineer. 13. Stack and align units using the structural pin connection between vertically adjacent units at the design setback batter. The completed wall is built with alignment tolerances of 1.5 inches (40 mm) in 10 feet (3048 mm) in both the horizontal and vertical directions. 14. When required by the design, geogrid reinforcement is placed at the elevations specified in the design. The reinforced backfill must be placed and compacted no lower than the top unit -elevation to which geogrid placement is required. 4.3 Special Inspection: Special inspection must be provided in accordance with 2015 and 2012 IBC Sections 1705.1.1, 1705.4 and 1705.6 (2009 IBC Sections 1704.15, 1704.5 and 1704.7). The inspector's responsibilities include verifying the following: 1. The modular concrete unit type and dimensions. 2. Keystone unit identification compliance with ASTM C1372, including compressive strength and water absorption, as described in Section 3.1 of this report. 3. Product identification, including evaluation report number (ESR-2113). 4. Foundation preparation. 5. Keystone unit placement, including proper alignment and inclination. 6. Fiberglass pin connections, including installation locations, proper fit within the blocks, and installation sequence with respect to the geogrid placement. 7. Geosynthetic reinforcement type (manufacturer and model number), location and placement. 8. Backfill placement and compaction. 9. Drainage provisions. 5.0 CONDITIONS OF USE The Keystone Retaining Wall Systems described in this report comply with, or are suitable alternatives to what is specified in, those codes listed in Section 1.0 of this report, subject to the following conditions: 5.1 The systems are designed and installed in accordance with this report; the Keystone Design ESR-2113 I Most Widely Accepted and Trusted Page 4 of 11 Manual, dated February 2011; the manufacturer's published installation instructions; and accepted engineering principles. If there is a conflict between this report and the manufacturer's published installation instructions, this report governs. 5.2 The Keystone Design Manual, dated February 2011, is submitted to the code official upon request. 5.3 The wall design calculations are submitted to, and approved by, the code official. The calculations must be prepared by a registered design professional where required by the statutes of the jurisdiction in which the project is to be constructed. 5.4 A site -specific soils investigation in accordance with IBC Section 1803, or IRC Section R401.4, as applicable, as noted in Section 4.1.1 of this report, must be provided for each project site. 5.5 In areas where repeated freezing and thawing under saturated conditions occur, evidence of compliance with freeze -thaw durability requirements of ASTM C1372 must be furnished to the code official for approval prior to construction. 5.6 Special inspection must be provided for backfill placement and compaction, geogrid placement (when applicable), and block installation, in accordance with Section 4.3 of this report. 5.7 Details in this report are limited to areas outside of groundwater. For applications where free -flowing groundwater is encountered, or where wall systems are submerged, the installation and design of systems must comply with the recommendations of the soils engineer and the appropriate sections of the NCMA Design Manual for Segmental Retaining Walls, and must be approved by the code official. 5.8 Under the 2015 IBC, project specifications for soil and water conditions that include sulfate concentrations identified in ACI 318-14 Table 19.3.1.1 as severe (S2) or very severe (S3), must include mix designs for the concrete, masonry and grout that comply with the intent of ACI 318-14 Table 19.3.1.1. See 2015 IBC Section 1904. 5.9 Under the 2012 IBC, project specifications for soil and water conditions that include sulfate concentrations identified in ACI 318-11 Table 4.2.1 as severe (S2) or very severe (S3), must include mix designs for the concrete, masonry and grout that comply with the intent of ACI 318-11 Table 4.3.1. See 2012 IBC Section 1904. 5.10 Under the 2009 IBC, project specifications or soil and water conditions that have sulfate concentrations identified in ACI 318-08 Table 4.2.1 as severe (S2) or very severe (S3), shall include mix designs for concrete and masonry and grout that comply with the intent of ACI 318-08 Table 4.3.1. See 2009 IBC Section 1904.5. 5.11 As to the geogrid reinforcement material, this report evaluates only the connection strength of the geogrid material when attached to the concrete units. Physical properties of the geogrid material or its interaction with the soil have not been evaluated. 6.0 EVIDENCE SUBMITTED Data in accordance with the ICC-ES Acceptance Criteria for Segmental Retaining Walls (AC276), dated October 2004 (editorially revised May 2014). 7.0 IDENTIFICATION 7.1 Each pallet of concrete units is identified with the manufacturer's name (RCP Block and Brick) and address, the name of the product, the unit type, and the evaluation report number (ESR-2113). Fiberglass pins are provided with each shipment of blocks, with a letter of certification by Keystone. 7.2 The report holder's contact information is the following: KEYSTONE RETAINING WALL SYSTEMS, LLC 4444 WEST 78T" STREET MINNEAPOLIS, MINNESOTA 55435 www.keystonewalls.com 7.3 The Additional Listee's contact information is the following: RCP BLOCK AND BRICK, INC. 8240 BROADWAY LEMON GROVE, CALIFORNIA 91945 ESR-2113 I Most Widely Accepted and Trusted Page 5 of 11 TABLE 1-INTER-UNIT SHEAR RESISTANCE' PEAK CONNECTION SERVICEABILITY STRENGTH CONNECTION STRENGTH UNIT (pounds/linear foot) (pounds/linear foot) Equation Maximum Equation Maximum WITHOUT GEOGRID F = 1376 F = 1263 Compac II + 0.14 N 1783 + 0.12 N 1618 F = 92 + Country Manor F = 1536 1536 0.81 N 1124 Compac III F=1543 4138 F=649+ 3206 + 0.74 N 0.73 N Standard III F = 2437 5084 F = 1524 4528 +0.53N +0.6N WITH GEOGRID Miragrid P = 1711+ 4456 P = 1464 3614 3XT 0.55 N + 0.43 N Standard III Miragrid P = 2197+ P = 1977 8XT Miragrid 0.45 N P = 1271 4447 + 0.23 N P = 543 + 3133 3XT + 0.65 N 3539 0.69 N 2953 Compac III Miragrid P = 1282 P = 706 + 8XT + 0.56 N 3223 0.3N 1591 For SI: 1 lb/linear foot = 14.6 N/m. 'The inter -unit shear resistance, F [lb/linear foot (N/m)], of the Keystone units at any depth is a function of the pin strength and superimposed normal (applied) load, N [lb/linear foot (N/m)]. TABLE 2A-GEOGRID-TO-BLOCK PULLOUT RESISTANCE EQUATIONS GEOGRID PEAK CONNECTION STRENGTH (Ibs/ft) SERVICEABILITY CONNECTION STRENGTH (Ibs/ft) Equation Maximum Equation Maximum KEYSTONE COMPAC II UNIT Strata Systems Stratagrid SG150 P = 798 + 0.34 N 1576 P = 593 + 0.27 N 1184 Stratagrid SG200 P = 707 + 0.93 N 1754 P = 928 + 0.10 N 1250 Stratagrid SG500 P = 626 + 1.15 N 2000 P = 770 + 0.42 N 1705 TC Mirafi Miragrid 2XT P = 800 + 0.29 N 1452 P = 800 + 0.29 N 1452 Miragrid 3XT P = 811 + 0.36 N 1617 P = 571 + 0.45 N 1593 Miragrid 5XT P = 1200 + 0.38 N 2050 P = 691 + 0.55 N 1941 Miragrid 7XT P = 1173 + 0.40 N 2222 P = 622 + 0.47 N 1948 Miragrid 8XT P = 960 + 0.84 N 2490 P = 691 + 0.73 N 2280 KEYSTONE COUNTRY MANOR UNIT Strata Systems Stratagrid SG150 P = 377 + 0.47 N 950 P = 327 + 0.48 N 932 Stratagrid SG200 P = 550 + 0.43 N 1238 P = 311 + 0.38 N 903 Tensar BX1200 P = 474 + 0.42 N 1142 P = 494 + 0.36 N 1045 For SI: 1 lb/linear ft. = 14.6 N/m. 'Where N = superimposed normal (applied) load (lb/linear foot). ESR-2113 I Most Widely Accepted and Trusted Page 6 of 11 TABLE 213- GEOGRID-TO-BLOCK PULLOUT RESISTANCE VALUES Peak Connection Strength (Ibs/ft) Serviceability Connection Strength (Ibs/ft) C E2 o C 7 od o C N oa C E2 o C oa o C N oa BX1202 E m N E M `� .. N 6 c a 5 '0 ri E- aai .- c U ns m o E- d .- c U 0 c a 5 f6 a E- d c u CU a E- avi c& m c as oc) `o c o C o c o C c oc) o c O C `o c O m U Z V U Z V U U Z V U Z V () KEYSTONE COMPAC III UNIT Strata Systems Stratagrid 1070.00 2493.00 2179.96 6000.00 2179.96 412.65 2493.00 1659.42 6000.00 1659.42 SG200 Stratagrid 1150.00 1700.00 2735.28 3502.00 3409.02 897.82 3502.00 1562.70 6000.00 1562.70 SG550 Tencate Mirafi Miragrid 3XT 1345.22 2500.00 2020.24 6000.00 2020.24 398.97 2500.00 1374.18 6000.00 1374.18 Miragrid 8XT 1226.00 2710.00 2919.40 6000.00 2919.40 750.46 3498.00 1659.67 6000.00 1659.67 Huesker Fortrac 35T 900.00 1500.00 1372.95 6000.00 1372.95 842.82 2493.00 892.86 6000.00 892.86 Fortrac 80T 856.00 1700.00 1798.33 3500.00 2006.59 844.00 3500.00 1524.33 6000.00 1524.33 KEYSTONE STANDARD III UNIT Strata Systems Stratagrid 1823.21 3002.00 1973.18 6000.00 1973.18 889.70 3002.00 1189.87 6000.00 1189.87 SG200 Stratagrid 2322.00 2000.00 4060.57 5002.00 4402.61 955.00 2000.00 1682.94 6000.00 1524.33 SG550 Tencate Mirafi Miragrid 3XT 1398.00 1100.00 2197.20 3000.00 2566.52 484.00 1200.00 1069.28 3000.00 1484.84 Miragrid 8XT 1911.00 1600.00 3161.06 5053.00 4556.16 843.00 3800.00 2614.97 6000.00 2614.97 Huesker Fortrac 35T 1082.00 1000.00 1204.78 6000.00 1204.78 636.00 1800.00 985.88 2956.00 1087.02 Fortrac 85T 1600.00 2000.00 2367.73 5022.00 2420.48 894.00 2000.00 1467.49 5022.00 1625.87 For SI: 1 lb/linear ft. = 14.6 N/m. 'Minimum Connection Capacity is the connection strength when the normal load is 0 Ibs. 21P-1 is the last point (in a linear relationship between the normal load (X-axis) and the Connection Strength (Y-axis)) before it changes its linear relationship of the normal load and connection strength. 2500 , 111 w a u 1500 IP-1 AM. IP-2 0 0 500 1000 1500 2000 2500 3000 3500 4000 Normal Force (plf) ESR-2113 I Most Widely Accepted and Trusted Page 7 of 11 (¢30 mm) ,4- (3ee mm) eo C20* mm) \ (206*MM) e' e' Ver7se by Manultr*Ursr (467 mm) \ (407 mm) \ / (303 mm) / Standard III Unit 92 Ib. (42 kg) Compac Il Unit Unit 82 Ib. (37 kg) Compac III Unit 72 lb. (33 kg) 1, (363 mm) 0- eo oeb (300 mmltr ee e ♦• 'ee (406 mm We.2 Ra4 MM) Count�Manor UnitUnit25-60 lbs. (12 - 27 kg) ^ mm) Figure 1 - Keystone Wall Units ESR-2113 I Most Widely Accepted and Trusted Page 8 of 11 Three Plane Cap Unit 45 Ib. (20 kg) Universal Cap Unit 51 Ib. (23 kg) Country Manor Cap Unit 24 lbs. (11 kg) 4- •<+02 mm) 4- •(+02 mm) H- (203 mm) 10" (2b4 mm Flgure 1 - Keystone Wall Units (Continued) ESR-2113 I Most Widely Accepted and Trusted Page 9 of 11 - Slope Slope T::�etWwrrled Sal Type I Retained Soil Type NEAR VERTICAL WALL (Minimum setback per unit) STANDARD III 21"/18" UNITS Max. HgL Backslope Soil Type Level 41-11V 3HA V 21-1:1 V Sand/Gravel 5_QA.3' 4.313.T 4.3/3.T 3.713.0' Silty Sand 4.313.T 3.7/3.0' 3.7/3.0' 3.0/3.0' Si1VLean Clay 3.713.T 3.7/3.0' 3.0/3.0' 2.3/17 COMPAC II/III UNITS Max. HgL Backslope Soil Type Level 4H:1 V 3HA V 2H:1V Sandr Ravel 3.C' 2.3' 2.3' 2.3' Silty Sand 2—T 2.3' 1.T 17 [;iWL-n pay 2.3' 17 17 1.0' COUNTRY MANOR UNITS Max. Hgt. Backslope Sod Type Level 3HA V SandlGravel 2.25' 1.76 Silty Sand 1.75' 12Y S I/Lean Clay 1.75 1.2Y ONE INCH SETBACK WALL (1" min setback per unit) STANDARD III 21'718" UNITS Max. Hgt. Backslope Sol Type Level 41-1:1 V 3Ft 1 V 21-1:1 V SandlGravel 6.315.T 5.7/5.0' 5.715.0' 5.0/4.3' ity Sand II 5. M-Y 5.0/4.3' 5.0A.3' 4.313.T Silt&ean Clay 5.OA.3' 4.313.7 3.713.0' _312.3. COMPAC II/III UNITS Max. Hgt. Backslope Soil Type Level 41-1:1 V 3H:1 V 2HA V Sand'Gravel IT 3.0' 3.C' IT Silty Sand 3.0' 3.0' 2.3' 2.3' SihlLean Clay 3 V 2.3' 2.3' 1 A' COUNTRY MANOR UNITS Max. Hgt. Backslope Soil Type Level 3HAV SandlGravel 3.25' 2.25' Silty Sand 2.25' 1.75' SiR4 Clay 1.75' 1.25' Notes: Calcrdations assume a moist unit weight of 120 Ibwd for all soils. Assumed 0 angles for earth pressure calculations are: Sand/Gravel = 34', Silty Sand = 30'. and SittlLean Clay = 263. Analysis for non -critical structures with FS 2 1.50. No additional surcharge loadings are included. Surcharges or special loading conditions will reduce ma)dmum wal heights. Sliding calculation assumes a 6" crushed stone leveling pad as compacted foundation material. For Sk 1 That = 304.8 mm FIGURE 2 - GRAVITY WALL CHARTS ESR-2113 I Most Widely Accepted and Trusted Page 10 of 11 Keysone Unr-s Setback,'Barer Tonal Wall Height inished Grade ETC?tlmE9t l Leveling Pad Keystone Units S.Fback'Batter- Total 'Nall-leigh- Finished Grade Embedment % Depth % Leveling Pad :::�V- Fnished Grade Backslope or Surcharge • y / Low Penneabiity Soil • / / Retained Soil Zone •,� •r / Unit Core FIL'Orainge Fill • • •1 • .� ,/ Limit of Excavation N {Rough Cut) •` s') Drainage Collection Pipe (when required) Keystone Gravity Wall Finished Backslope or Surcharge . : • �, r , Low Permeabiliy Soil ". .• r Reinforced Sal Zone r r 1 r ? ' • • f .' r Geosynthetic Reinforcement r Retained Sal Zone w ,;� •r ;l r �• • •�' . � Omit of Excavation .� ;� %ti- • r Unr* Coreill.-•Drainge Fill (Rough Cut) �-�- 'r--- --- - - - - -- Drainage Collection Pipe (;when required Keystone Wall with Soil Reinforcement FIGURE 3 - TYPICAL WALL SECTIONS ICC-ES Evaluation Report ESR-2113 CBC Supplement Reissued August 2019 This report is subject to renewal August 2021. www.icc-es.ora 1 (800) 423-6587 1 (562) 699-0543 A Subsidiary of the International Code Council° DIVISION: 32 00 00—EXTERIOR IMPROVEMENTS Section: 32 32 00—Retaining Walls Section: 32 32 23—Segmental Retaining Walls REPORT HOLDER: KEYSTONE RETAINING WALL SYSTEMS, LLC EVALUATION SUBJECT: KEYSTONE RETAINING WALL SYSTEMS 1.0 REPORT PURPOSE AND SCOPE Purpose: The purpose of this evaluation report supplement is to indicate that Keystone Retaining Wall Systems, recognized in ICC-ES master evaluation report ESR-2113, have also been evaluated for compliance with the code noted below. Applicable code edition: 2016 California Building Code° (CBC) 2.0 CONCLUSIONS The Keystone Retaining Wall Systems, described in Sections 2.0 through 7.0 of the master evaluation report ESR-2113, comply with CBC Chapters 18 and 18A, provided the design and installation are in accordance with the 2015 International Building Code° (2015 IBC) provisions noted in the master report and the additional requirements of the CBC Chapters 16, 16A, 17 and 17A, and Section 1807A.2, as applicable. This supplement expires concurrently with the master report, reissued August 2019. ]CC -ES Evaluation Reports are not to be construed as representing aesthetics or any other attributes not specifically addressed, nor are they to be construed JZ as an endorsement of the subject of the report or a recommendation for its use. There is no warranty by ICC Evaluation Service, LLC, express or implied, as �_ to any finding or other matter in this report, or as to any product covered by the report. m Copyright © 2019 ICC Evaluation Service, LLC. All rights reserved. Page 11 of 11 Earth Solutions NW LLC Geotechnical Engineering Geology Environmental Scientists Construction Monitoring At` r GEOTECHNICAL ENGINEERING STUDY PROPOSED MULTI -FAMILY RESIDENCES 546 PARADISE LANE 1' � A EDMONDS, WASHINGTON - ES-5839 y E. 1805 - 136th P1ac� N.Fi.,�Suite 201/ 'S►Bekle�'uy�; A'��0� :. i, - , ��, ` •-• (425 449-4704 Fa)t' 425) 449=4711 ) (_ ) .r:_.,� www.eartfisoluUopsVw.com, PREPARED FOR PARADISE HEIGHTS, LLC March 5, 2018 Samuel E. Suruda, G.I.T. Staff Geologist Henry T. Wright, P.E. Senior Project Engineer c. Kyle R. Campbell, P.E. Principal Engineer GEOTECHNICAL ENGINEERING STUDY PROPOSED MULTI -FAMILY RESIDENCES 546 PARADISE LANE EDMONDS, WASHINGTON ES-5839 Earth Solutions NW, LLC 1805 — 136t" Place Northeast, Suite 201 Bellevue, Washington 98005 Phone: 425-449-4704 1 Fax: 425-449-4711 www.earthsolutionsnw.com r- Geotechnical Engineering Report --� Geotechnical Services Are Performed for Specific Purposes, Persons, and Projects Geotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical engineering study conducted for a civil engi- neer may not fulfill the needs of a construction contractor or even another civil engineer. Because each geotechnical engineering study is unique, each geotechnical engineering report is unique, prepared solelyfor the client. No one except you should rely on your geotechnical engineering report without first conferring with the geotechnical engineer who prepared it. And no one — not even you —should apply the report for any purpose or project except the one originally contemplated. Read the Full Report Serious problems have occurred because those relying on a geotechnical engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only. A Geotechnical Engineering Report Is Based on A Unique Set of Project -Specific Factors Geotechnical engineers consider a number of unique, project -specific fac- tors when establishing the scope of a study. Typical factors include: the client's goals, objectives, and risk management preferences; the general nature of the structure involved, its size, and configuration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless the geotechnical engineer who conducted the study specifically indicates oth- erwise, do not rely on a geotechnical engineering report that 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. Typical changes that can erode the reliability of an existing geotechnical engineering report include those that affect: • the function of the proposed structure, as when it's changed from a parking garage to an office building, or from a light industrial plant to a refrigerated warehouse, • elevation, configuration, location, orientation, or weight of the proposed structure, • composition of the design team, or • project ownership. As a general rule, always inform your geotechnical engineer of project changes —even minor ones —and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed. Subsurface Conditions Can Change A geotechnical engineering report is based on conditions that existed at the time the study was performed. Do not rely on a geotechnical engineer- ing reportwhose adequacy may have been 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, or groundwater fluctua- tions. Always contact the geotechnical engineer before applying the report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems. Most Geotechnical Findings Are Professional Opinions Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engi- neers review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ —sometimes significantly — from those indicated in your report. Retaining the geotechnical engineer who developed your report to provide construction observation is the most effective method of managing the risks associated with unanticipated conditions. A Report's Recommendations Are Not Final Do not overrely on the construction recommendations included in your report. Those recommendations are not final, because geotechnical engi- neers develop them principally from judgment and opinion. Geotechnical engineers can finalize their recommendations only by observing actual subsurface conditions revealed during construction. The geotechnical engineer who developed your report cannot assume responsibility or liability for the report's recommendations if that engineer does not perform construction observation. A Geotechnical Engineering Report Is Subject to Misinterpretation Other design team members' misinterpretation of geotechnical engineering reports has resulted in costly problems. Lower that risk by having your geo- technical engineer confer with appropriate members of the design team after submitting the report. Also retain your geotechnical engineer to review perti- nent elements of the design team's plans and specifications. Contractors can also misinterpret a geotechnical engineering report. Reduce that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing construction observation. Do Not Redraw the Engineer's Logs Geotechnical engineers prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical engineering report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separating logs from the report can elevate risk. Give Contractors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give con- tractors the complete geotechnical engineering report, but preface it with a clearly written letter of transmittal. In that letter, advise contractors that the report was not prepared for purposes of bid development and that the report's accuracy is limited; encourage them to confer with the geotechnical engineer who prepared the report (a modest fee may be required) and/or to conduct additional study to obtain the specific types of information they need or prefer. A prebid conference can also be valuable. Be sure contrac- tors have sufficient time to perform additional study. Only then might you be in a position to give contractors the best information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Read Responsibility Provisions Closely Some clients, design professionals, and contractors do not recognize that geotechnical engineering is far less exact than other engineering disci- plines. This lack of understanding has created unrealistic expectations that have led to disappointments, claims, and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of explanatory provisions in their reports. Sometimes labeled "limitations" many of these provisions indicate where geotechnical engineers' responsi- bilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly. Geoenvironmental Concerns Are Not Covered The equipment, techniques, and personnel used to perform a geoenviron- mental study differ significantly from those used to perform a geotechnical study. For that reason, a geotechnical engineering report does not usually relate any geoenvironmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated environmental problems have led to numerous project failures. If you have not yet obtained your own geoen- vironmental information, ask your geotechnical consultant for risk man- agement guidance. Do not rely on an environmental report prepared for someone else. Obtain Professional Assistance To Deal with Mold Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts of mold from growing on indoor surfaces. To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a com- prehensive plan, and executed with diligent oversight by a professional mold prevention consultant. Because just a small amount of water or moisture can lead to the development of severe mold infestations, a num- ber of mold prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of the geotechnical engineering study whose findings are conveyed in -this report, the geotechnical engineer in charge of this project is not a mold prevention consultant; none of the services per- formed in connection with the geotechnical engineer's study were designed or conducted for the purpose of mold preven- tion. Proper implementation of the recommendations conveyed in this report will not of itself be sufficient to prevent mold from growing in or on the structure involved. Rely, on Your ASFE-Member Geotechncial Engineer for Additional Assistance Membership in ASFE/The Best People on Earth exposes geotechnical engineers to a wide array of risk management techniques that can be of genuine benefit for everyone involved with a construction project. Confer with you ASFE-member geotechnical engineer for more information. ASFE The Best People on Earth 8811 Colesville Road/Suite G106, Silver Spring, MD 20910 Telephone:301/565-2733 Facsimile:301/589-2017 e-mail: info@asfe.org www.asfe.org Copyright 2004 by ASFE, Inc. Duplication, reproduction, or copying of this document, in whole or in part by any means whatsoever, is strictly prohibited, except with ASFE's specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of ASFE, and only for purposes of scholarly research or book review. Only members of ASFE may use this document as a complement to or as an element of a geotechnical engineering report. Any other firm, individual, or other entity that so uses this document without being an ASFE member could be committing negligent or intentional (fraudulent) misrepresentation. IGER06045.0M March 5, 2018 ES-5839 Paradise Heights, LLC 24144 East Greystone Lane Woodway, Washington 98020 Attention: Mr. John Rettenmier Dear Mr. Rettenmier. Earth I Solutions NWLLC Earth Solutions NW LLC • Geotechnical Engineering • Construction Monitoring • Environmental Sciences Earth Solutions NW, LLC (ESNW) is pleased to present this report titled "Geotechnical Engineering Study, Proposed Multi -Family Residences, 546 Paradise Lane, Edmonds, Washington". Based on the results of our study, construction of the proposed multi -family residential structures at the subject site is feasible from a geotechnical standpoint. The proposed residential structures can be supported on a conventional foundation system bearing on competent native soil, recompacted native soil, or structural fill. Competent native soils, suitable for support of foundations, should be encountered beginning at a depth of roughly two feet below existing grades across the majority of the site. Slab -on -grade floors should be supported on dense native soil, re -compacted native soil, or structural fill. Where loose, organic or other unsuitable materials are encountered at or below the footing subgrade elevation, the material should be removed and replaced with structural fill, as necessary. This report provides a geologically hazardous areas assessment, and recommendations for foundation subgrade preparation, foundation and retaining wall design parameters, drainage, the suitability of the on -site soils for use as structural fill, and other geotechnical recommendations. The opportunity to be of service to you is appreciated. If you have any questions regarding the content of this geotechnical engineering study, please call. Sincerely, EARTH SOLUTIONS NW, LLC Samuel E. Suruda, G.I.T. Staff Geologist '1805 - 136th Place N.E., Suite 201 0 Bellevue, WA 98005 • (425) 449-4704 9 FAX (425) 449-4711 Table of Contents ES-5839 PAGE INTRODUCTION....................................................................... General........................................................................ . ProjectDescription.......................................................... SITE CONDITIONS.................................................................... 2 Surface........................................................................... 2 Subsurface...................................................................... 2 Geologic Setting ..................................................... 2 Groundwater.......................................................... 3 Geological Hazards Assessment ........................................ 3 Slope Reconnaissance ............................................ 3 Erosion Hazard Areas ............................................... 3 Landslide Hazard Areas ........................................... 4 Mapping of Geologically Hazardous Areas ................ 5 Special Study and Report Requirements ................... 5 Development Standards (General Requirements)....... 7 Development Standards (Specific Hazards) ............... 7 Analysis of Proposal ............................................... 9 DISCUSSION AND RECOMMENDATIONS ..................................... 9 General........................................................................... 9 Site Preparation and Earthwork ......................................... 9 Temporary Erosion Control ............................................. 10 In -Situ Soils....................................................................... 10 StructuralFill..................................................................... 10 Excavations and Slopes ........................................... 11 Foundations.................................................................... 11 Seismic Considerations....................................................... 12 Slab -On -Grade Floors ....................................................... 12 Retaining Walls............................................................... 12 Drainage......................................................................... 13 Infiltration Evaluation .............................................. 13 Low Impact Development ......................................... 14 Utility Trench Support and Backfill.................................... 15 Pavement Sections........................................................... 15 LIMITATIONS........................................................................... . 15 Additional Services.......................................................... 15 Earth Solutions NW, LLC GRAPHICS Plate 1 Plate 2 Plate 3 Plate 4 APPENDICES Appendix A Appendix B Table of Contents Continued ES-5839 Vicinity Map Test Pit Location Plan Retaining Wall Drainage Detail Footing Drain Detail Subsurface Exploration Test Pit Logs Laboratory Test Results Earth Solutions NW, LLC GEOTECHNICAL ENGINEERING STUDY PROPOSED MULTI -FAMILY RESIDENCES 546 PARADISE LANE EDMONDS, WASHINGTON ES-5839 INTRODUCTION General This geotechnical engineering study was prepared for the three proposed multi -family residential structures to be constructed at 546 Paradise Lane in Edmonds, Washington. To complete the scope of services detailed in our proposal PES-5839 dated January 17, 2018 we performed the following: • Subsurface exploration and characterization of soil and groundwater conditions by way of test pits excavated at accessible areas of the site; • Laboratory testing of soil samples obtained during subsurface exploration; • An infiltration evaluation based on observed soil conditions and the results of a Small- scale Pilot Infiltration Test (PIT); • Geotechnical engineering analyses, and; • Preparation of this report. The following documents and resources were reviewed as part of our report preparation: • Preliminary Drainage and Plot Plan, prepared by Michel Construction, Inc., dated July 3, 2008; • Geologic Map of the Edmonds East and Part of the Edmonds West Quadrangle, Washington, prepared by James P. Minard, dated 1983; • Department of Ecology Stormwater Management Manual for Western Washington, Volume III Hydrologic Analysis and Flow Control BMPs, dated August 2012; • Edmonds City Code, Chapter 23.80 (Geologically Hazardous Areas), and; • Online Web Soil Survey (WSS) resource provided by United States Department of Agriculture (USDA), Natural Resources Conservation Services. Project Description Based on the site plan provided to us, the existing single-family residential structure and garage will be demolished and three new multi -family residential structures will be constructed. We anticipate grading activities will primarily include cuts to establish the planned building alignments and roadway improvements. Based on the existing grades, we estimate cuts to establish building pad and foundation subgrade elevations will be on the order of up to four feet. Site improvements will also include underground utility installations. Earth Solutions NW. LLC Paradise Heights, LLC ES-5839 March 5, 2018 Page 2 At the time this report was prepared, specific building load values were not available. However, we anticipate the proposed residential structures will consist of relatively lightly loaded wood framing supported on conventional foundations. Based on our experience with similar developments, we estimate wall loads on the order of one to two kips per linear foot and slab -on - grade loading of 150 pounds per square foot (psf). If the above design assumptions are incorrect or change, ESNW should be contacted to review the recommendations in this report. ESNW should review the final design to verify the geotechnical recommendations provided in this report have been incorporated into the plans. SITE CONDITIONS Surface The subject site is located at 546 Paradise Lane in Edmonds, Washington, as illustrated on the Vicinity Map (Plate 1). The site consists of one residential tax parcel (Snohomish County parcel number 27032500302600) totaling approximately 0.91 acres of land area. The property is currently developed with a single-family residence and associated improvements. The majority of the site is relatively level with a steep slope descending on the north side of the property adjacent to Paradise Lane and gentle slope descending to the east for the driveway adjacent to Paradise Lane. Based on site observation and available topographic data, the steep slope descending to the north has a slope gradient in excess of 40 percent and elevation change of up to about 12 feet; the steep slope extends beyond the property. Vegetation within the steep slope area consists of large trees and ivy groundcover. The subject site is bordered to the west by an easement for Edmonds Way, to the east and north by Paradise Lane, and to the south by a residential property. The Test Pit Location Plan (Plate 2) illustrates the approximate limits of the property. Subsurface As part of the subsurface exploration, four test pits were excavated in accessible portions of the site for purposes of assessing soil and groundwater conditions. The test pits were advanced to a maximum depth of approximately nine feet below existing grade. Please refer to the test pit logs provided in Appendix A for a more detailed description of the subsurface conditions. Soil conditions observed at test pit locations consisted of medium dense poorly graded sand (Unified Soil Classification System: SP) outwash deposits. Overall soil relative density increased with depth. Approximately nine feet below ground surface (bgs), dense to very dense silty sand with gravel glacial till was observed (USCS: SM). The glacial till was observed to be weakly cemented and exhibited iron oxide staining. Geologic Setting According to the referenced geologic map, the subject site is underlain by advance outwash (Qva) deposits. Soil conditions observed at the test pit locations were generally consistent with outwash deposits. According to the referenced NRCS soil survey, the subject site consists of Everett series soils. Everett series soils are classified as outwash deposits and are consistent with observations made in the field. Earth Solutions NW. LLC Paradise Heights, LLC March 5, 2018 Groundwater ES-5839 Page 3 No groundwater seepage was observed during our fieldwork on January 7, 2018. Groundwater seepage rates and elevations fluctuate depending on many factors, including precipitation duration and intensity, the time of year, and soil conditions. In general, groundwater elevations and flow rates are higher during the winter, spring and early summer months. Geological Hazards Assessment As part of this geotechnical engineering study, the referenced chapter of the Edmonds City Code (ECC) was reviewed. Per the ECC requirements, the following topics related to development plans and site conditions are addressed. Slope Reconnaissance During our fieldwork, we performed a visual slope reconnaissance of the steep slope area. The main focus of our reconnaissance was to identify signs of instability or erosion hazards along the site slopes. The typical instability indicators include features such as head scarps, tension cracks, hummocky terrain, groundwater seeps along the surface and erosion features such as gulleys and rills. During the slope reconnaissance, no signs of erosion or slope instability were observed. The slope is vegetated with large trees and ivy groundcover. In general, based on the slope reconnaissance, stability of the sloped areas within and adjacent to the property can be characterized as good. Erosion Hazard Areas — ECC 23.80.020.A. With respect to erosion hazard areas, section 23.80.020 of the ECC defines erosion hazards as "at least those areas identified by the U.S. Department of Agriculture's Natural Resources Conservation Service as having a "moderate to severe", "severe", or "very severe" rill and inter - rill erosion hazard. Erosion hazard areas are also those areas impacted by shoreland and/or stream bank erosion. Within the city of Edmonds, erosion hazard areas include: 1. Those areas of the city of Edmonds containing soils that may experience severe to very severe erosion hazard. This group of soils includes, but is not limited to, the following when they occur on slopes of 15 percent or greater: a. Alderwood soils (15 to 25 percent slopes); b. Alderwood/Everett series (25 to 70 percent slopes), and; c. Everett series (15 to 25 percent slopes). 2. Coastal and stream erosion areas which are subject to the impacts from lateral erosion related to moving water such as stream channel migration and shoreline retreat; 3. Any area with slopes of 15 percent or greater and impermeable soils interbedded with granular soils and springs or ground water seepage, and; 4. Areas with significant visible evidence of ground water seepage, and which also include existing landslide deposits regardless of slope. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 ES-5839 Page 4 The on -site soils are generally consistent with Everett series soils. Based on the ECC definition, the steep slope areas within and adjacent to the property classify as erosion hazard areas. Construction of the proposed engineered retaining wall is expected to be sufficient for adequately managing and mitigating the erosion potential for this project. Landslide Hazard Areas — ECC 23.80.020.13. With respect to landslide hazard areas, section 23.80.020 of the ECC defines landslide hazard areas as "areas potentially subject to landslides based on a combination of geologic, topographic, and hydrologic factors. They include areas susceptible because of any combination of soil, slope (gradient), slope aspect, structure, hydrology, or other factors. Within the city of Edmonds, landslide hazard areas specifically include: 1. Areas of ancient or historic failures in Edmonds which include all areas within the earth subsidence and landslide hazard area as identified in the 1979 report of Robert Lowe Associates and amended by the 1985 report of GeoEngineers, Inc., and further discussed in the 2007 report by Landau Associates; 2. Coastal areas mapped as class U (unstable), UOS (unstable old slides) and URS (unstable recent slides) in the Department of Ecology Washington coastal atlas; 3. Areas designated as quaternary slumps, earthflows, mudflows, or landslides on maps published by the United States Geological Survey or Washington State Department of Natural Resources; 4. Any slope of 40 percent or steeper that exceeds a vertical height of 10 feet over a 25- foot horizontal run. Except for rockeries that have been engineered and approved by the engineer as having been built according to the engineered design, all other modified slopes (including slopes where there are breaks in slopes) meeting overall average steepness and height criteria should be considered potential landslide hazard areas; 5. Any slope with all three of the following characteristics: a. Slopes steeper than 15 percent; b. Hillsides intersecting geologic contacts with relatively permeable sediment overlying a relatively impermeable sediment, and; c. Springs or ground water seepage. 6. Any area potentially unstable as a result of rapid stream incision or stream bank erosion; 7. Any area located on an alluvial fan, presently subject to, or potentially subject to, inundation by debris flow or deposition of stream -transported sediments, and; 8. Any slopes that have been modified by past development activity that still meet the slope criteria. Earth Solutions NW, LLC Paradise Heights, LLC ES-5839 March 5, 2018 Page 5 Based on site observation and the referenced topographic survey, a north -descending steep slope with gradient in excess of 40 percent is located to north of the subject property; based on site observations, the steep slope area was likely over steepened by historic excavations made to construct Paradise Lane. Per the above definition of landslide hazard areas, the steep slope to the north of the subject property classifies as a potential landslide hazard area based on a slope gradient of 40 percent or steeper with a vertical relief of 10 feet or more. The overall stability of the site can be characterized as good and it is our opinion that the potential landslide hazard for the slope to the north of the site can be considered very low. Additionally, we understand grading for the proposed development will include construction of engineered retaining walls that will effectively eliminate the steep slope hazard. Mapping of Geologically Hazardous Areas — ECC 23.80.030 Review of available geologically hazardous areas mapping did not reveal geologically hazardous areas within or immediately adjacent to the subject site. Special Study and Report Requirements — ECC 23.80.050 A. This geotechnical engineering study and geological hazards assessment was completed by a professional engineer licensed in the state of Washington with experience analyzing geologic hazards throughout the Puget Sound region. B. 1. The project area includes the subject site as delineated in the referenced preliminary plans. 2. No further geologically hazardous areas are located within 200 feet of the property or will be affected by construction on the property. C. This geological hazards assessment included a field investigation and an assessment of geologic hazards. This geotechnical report has been prepared, stamped, and signed by a qualified professional. 1. It is our opinion the level of analysis completed for this geological hazards assessment is appropriate for the scale and scope of the project and scale of the geological hazard areas present. 2. A discussion of all geologically hazardous areas on the site and any geologically hazardous areas off site potentially impacted by the proposed project is provided in this report. 3. Based on the results of our study and on -site observations, the proposed project will not decrease slope stability or pose an unreasonable threat to persons or property either on or off site. These conclusions are based on the current conditions of the slope in question and proposed replacement of the slope with an engineered retaining wall. 4. This geological hazard assessment is provided as adequate information to comply with requirements of ECC geological hazards. 5. This geotechnical report generally follows the guidelines set forth in the Washington State Department of Licensing Guidelines for Preparing Engineering Geology Reports in Washington (2006). Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 ES-5839 Page 6 6. It is our opinion a landslide hazard minimum building setback is not necessary, and erosion hazard mitigation recommendations are provided in this report. D. We are not aware of a previous study completed for the subject site. E. The mitigation recommendations include permanent solutions, such as construction of engineered retaining walls within the slope area in question and erosion control recommendations. F. This geological hazards assessment and geotechnical engineering study should be reviewed as part of the overall submittal package. 1. Please refer to preliminary plans prepared by Michel Construction, Inc. for the site plan. a. The height of the slopes and slope gradients are discussed in this report and displayed within the preliminary plans. b. Springs, seeps, or other surface expressions of groundwater were not observed on or within 200 feet of the project area. c. No surface water runoff features were observed during our site visits. 2. a. Vegetative cover across the landslide hazard areas generally consists of non-native groundcover (i.e. ivy), shrubs, and large trees. b. Subsurface conditions are described in the Subsurface section of this report. c. Surface and groundwater conditions are discussed in previous sections of this report. Roughly two and one-half feet of fill was observed in TP-3. Based on current conditions and elevation changes present, it is evident that some degree of land modification has occurred within and adjacent to the potential landslide hazard areas. The potential landslide hazard areas were likely artificially steepened by excavations completed during construction of Paradise Lane. Local natural topography was likely more of a gradual consistent slope. d. The slopes within and adjacent to the subject site generally exhibit good overall stability. e. The slopes within and adjacent to the subject site are not characterized as bluffs and we do not anticipate a retreat of the slopes to occur. Based on the sand soils present on the site and no indications of groundwater, we would anticipate the run -out hazard of landslide debris to be confined to a distance of up to half the height of slope away from the toe. If such a landslide occurred, impacts of run -out on downslope properties or right-of-way would likely consist of a few feet of landslide debris covering the ground adjacent to the toe of the slope. Repair of the slide would likely require cleanup of debris and engineered reconstruction of the slope and/or construction of an engineered retaining wall at the toe of the slope; construction of the proposed engineered retaining wall will effectively mitigate this potential. It should be noted, based on the results of our study, likelihood of such a landslide event occurring adjacent to the subject site is very low and the proposed project will not increase the likelihood. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 ES-5839 Page 7 g. We believe this report meets the criteria of a critical areas report to a degree adequate with respect to the severity of the steep slope hazard. h. Recommendations for building siting limitations are provided in this report. Proposed surface and subsurface drainage includes collecting surface water from impermeable surfaces and directing them to infiltration systems located along the eastern side of the site. The proposed drainage design is engineered and located in a manner which utilizes the native sand soils and minimizes impacts to sloped areas. The site soils are susceptible to erosion if exposed to surface water runoff without the implementation of BMP measures. However, typical temporary and permanent BMP measures will effectively mitigate the erosion potential. 3. This geotechnical engineering study was prepared by a licensed engineer. a. Geotechnical design parameters are provided within this report. b. Drainage and subdrainage recommendations are provided within this report. c. Earthwork recommendations are provided within this report. d. Recommendations for mitigation of adverse site conditions are provided within this report, as necessary. G. It is our opinion the site erosion hazard areas should be considered stable. H. Based on the results of our study, the site does not contain any seismic hazard areas. Development Standards (General Requirements) — ECC 23.80.060 Based on the results of our geological hazards assessment, the proposed project will not increase the threat of the geological hazard to adjacent properties beyond predevelopment conditions, the proposed project will not adversely impact other critical areas, the proposed project is designed so that the hazard to the project is eliminated or mitigated to a level equal to or less than predevelopment conditions, and the project is certified as safe as designed under anticipated conditions. Development Standards (Specific Hazards) — ECC 23.80.070 A. 1. We believe that with the construction of the engineered retaining wall adjacent to Paradise Lane at the toe of the slope hazard area, any structure placed atop the wall will not be at risk for landslides for the design life of the structure. 2. Based on the results of our study, it is our opinion that a buffer is not necessary for the landslide hazard areas. The proposed project will include reducing the overall height of the landslide hazard area as well as construction of engineered retaining walls in the slope area. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 ES-5839 Page 8 3. The proposed project will include construction of engineered retaining walls within the slope hazard area, effectively removing any permanent hazard found on site. The alteration will include establishing permanent erosion control and drainage measures at the top of the landslide and erosion hazard areas. Provided the recommendations in this report and subsequent geotechnical recommendations are incorporated into the design and construction of the project, the proposed alteration will not increase surface water discharge or sedimentation to adjacent properties beyond predevelopment conditions, will not decrease slope stability on adjacent properties, and such alterations will not adversely impact other critical areas. 4. a. As part of this geological hazards assessment, we assessed the current slope conditions and consider them to be stable in their current condition and configuration. We do not feel it is necessary to perform full slope stability analysis within the landslide hazard, as construction of engineered retaining walls will mitigate the hazard area prior to foundation loading and construction; however, an ESNW representative should be on -site during wall construction to observe changes to the steep slope area. b. It is our opinion that the structures and improvements have been located and engineered in a manner which sufficiently mitigates impacts to geologically hazardous areas; ESNW should review any plan changes. c. Historic development of Paradise Lane likely altered the natural contour of the slopes. The proposed project will construct an engineered retaining wall within the slope area, effectively eliminating any slope hazard. d. The structures and improvements have been located and engineered in a manner that effectively eliminates the most critical portions of the site by proposing engineered retaining walls to replace the artificially steepened slopes. e. The proposed development will not result in greater risk or a need for increased buffers on neighboring properties. f. Based on our study, building setback are not necessary. 5. We did not observe vegetation within the subject site which should be retained to maintain site and slope stability. 6. It is our opinion that this site should not be restricted to seasonal clearing and grading work. This opinion is based on the relatively small scope of the project and predominantly sandy soils, which are not as moisture sensitive as glacial till, of the geological hazard areas. 7. We are not aware of proposed point discharges. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 Analysis of Proposal ES-5839 Page 9 The proposed development will involve demolition of the existing single-family residential structure and construction of three new multi -family residential structures. Based on the referenced site plans, the grading will involve minor cuts to establish level building pad areas; we understand that an engineered retaining wall will be constructed at the base of the slope hazard area adjacent to Paradise Lane at the north edge of the site. The proposed project will eliminate the slope hazard area without creating any new geological hazards adjacent to the property. These determinations are based on the relatively small extent of the previously modified steeply sloped areas, stable nature of the site soils, and the construction of an engineered wall to retain the site grades. DISCUSSION AND RECOMMENDATIONS General Based on the results of our study, construction of the proposed residential structures at the subject site is feasible from a geotechnical standpoint. The primary geotechnical considerations associated with the proposed development include foundation support, temporary excavations, retaining walls, infiltration and drainage, and the suitability of the on -site soils for use as structural fill. The proposed residential structures can be supported on a conventional foundation system bearing on competent native soil, recompacted native soil, or structural fill. Competent soils suitable for support of foundations should be encountered beginning at a depth of roughly two feet below existing grades across the majority of the site. Slab -on -grade floors should be supported on dense native soil, re -compacted native soil, or structural fill. Where loose, organic or other unsuitable materials are encountered at or below the footing subgrade elevation, the material should be removed and replaced with structural fill, as necessary. This study has been prepared for the exclusive use of Paradise Heights, LLC and their representatives. No warranty, expressed or implied, is made. This study has been prepared in a manner consistent with the level of care and skill ordinarily exercised by other members of the profession currently practicing under similar conditions in this area. Site Preparation and Earthwork Based on the referenced site plans and given the existing topography, we anticipate grading for the project will involve cuts of up to about four feet to establish building pad and foundation subgrade alignments. Silt fencing and temporary erosion control measures should be placed along the perimeter of the site prior to beginning grading activities. Earth Solutions NK LLC Paradise Heights, LLC March 5, 2018 Temporary Erosion Control ES-5839 Page 10 Temporary construction entrances, consisting of at least six inches of quarry spalls, can be considered in order to minimize off -site soil tracking and to provide a temporary road surface. Silt fences should be placed along the margins of the property. Interceptor swales and a temporary sediment pond may be necessary for control of surface water during construction. Erosion control measures should conform to the Washington State Department of Ecology (DOE) and City of Edmonds standards. In -Situ Soils From a geotechnical standpoint, the soils encountered at the test pit locations are generally suitable for use as structural fill. However, successful use of the on -site soils will largely be dictated by the moisture content of the soils at the time of placement and compaction. The site soils were generally in a damp condition at the time of the exploration on January 7, 2018. Based on the conditions encountered during our fieldwork, the site soils generally have a low sensitivity to moisture. During periods of dry weather, the on -site soils should generally be suitable for use as structural fill, provided the moisture content is at or near the optimum level at the time of placement. If the on -site soils cannot be successfully compacted, the use of an imported soil may be necessary. Imported soil intended for use as structural fill should consist of a well -graded granular soil with a moisture content that is at or near the optimum level. During wet weather conditions, imported soil intended for use as structural fill should consist of a well - graded granular soil with a fines content of 5 percent or less defined as the percent passing the Number 200 sieve, based on the minus three-quarter inch fraction. Structural Fill Structural fill is defined as compacted soil placed in foundation, slab -on -grade, and roadway areas. Fills placed to construct permanent slopes and throughout retaining wall and utility trench backfill areas are also considered structural fill. Soils placed in structural areas should be placed in loose lifts of 12 inches or less and compacted to a relative compaction of 95 percent, based on the laboratory maximum dry density as determined by the Modified Proctor Method (ASTM D- 1557). For soil placed in utility trenches underlying structural areas, compaction requirements are dictated by the local city, county, or utility district, and in general are specified as 95 percent relative compaction. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 Excavations and Slopes ES-5839 Page 11 The native soils encountered in the upper approximately nine feet of the test pit locations consist of poorly graded sands in a dense condition. Temporary slopes within this layer should maintain a gradient of no steeper than 1 H:1 V. If groundwater is present within acute the minimum gradient of a slope should be increased to 1.5HA V. The presence of perched groundwater may cause caving of the temporary slopes due to hydrostatic pressure. ESNW should observe site excavations to confirm the soil type and allowable slope inclination are appropriate for the soil exposed by the excavation. If the recommended temporary slope inclination cannot be achieved, temporary shoring may be necessary to support excavations. Permanent slopes should maintain a gradient of 2H:1V, or flatter, and should be planted with vegetation to enhance stability and to minimize erosion. A representative of ESNW should observe temporary and permanent slopes to confirm the slope inclinations are suitable for the exposed soil conditions, and to provide additional excavation and slope recommendations, as necessary. Foundations The proposed residential structures can be supported on a conventional foundation system bearing on competent native soil, recompacted native soil, or structural fill. Competent soils suitable for support of foundations should be encountered beginning at a depth of roughly two feet below existing grades across the majority of the site. Where loose, organic or other unsuitable materials are encountered at or below the footing subgrade elevation, the material should be removed and replaced with structural fill, as necessary. Provided the structures will be supported as described above, the following parameters can be used for design of the new foundations: • Allowable soil bearing capacity 2,500 psf • Passive earth pressure 300 pcf (equivalent fluid) • Coefficient of friction 0.40 A one-third increase in the allowable soil bearing capacity can be assumed for short-term wind and seismic loading conditions. With structural loading as expected, total settlement in the range of one inch is anticipated, with differential settlement of about one-half inch. The majority of the settlements should occur during construction, as dead loads are applied. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 Seismic Considerations ES-5839 Page 12 The 2015 IBC recognizes ASCE for seismic site class definitions. If the project will be permitted under the 2015 IBC, in accordance with Table 20.3-1 of ASCE, Minimum Design Loads for Buildings and Other Structures, Site Class D, should be used for design. In our opinion, the site is not susceptible to liquefaction. The soil relative density and the absence of an established shallow groundwater table are the primary bases for this opinion. Slab -On -Grade Floors Slab -on -grade floors should be supported on a firm and unyielding subgrade consisting of competent native soil or at least 12 inches of structural fill. Unstable or yielding areas of the subgrade should be recompacted or overexcavated and replaced with suitable structural fill prior to construction of the slab. A capillary break consisting of a minimum of four inches of free - draining crushed rock or gravel should be placed below the slab. The free -draining material should have a fines content of 5 percent or less defined as the percent passing the Number 200 sieve, based on the minus three-quarters inch fraction. In areas where slab moisture is undesirable, installation of a vapor barrier below the slab should be considered. If used, the vapor barrier should consist of a material specifically designed to function as a vapor barrier and should be installed in accordance with the manufacturer's specifications. Retaining Walls Engineered retaining walls are proposed to eliminate the slope within the slope hazard area. The following parameters can be used for retaining wall design: • Active earth pressure (yielding condition) • At -rest earth pressure (restrained condition) • Traffic surcharge (passenger vehicles) • Passive earth pressure • Coefficient of friction • Seismic surcharge *Where H equals retained height 35 pcf 55 pcf 70 psf (rectangular distribution) 300 pcf 0.40 6H* Where sloping or other surcharge conditions will be present, supplement recommendations and design earth pressure values should be provided by ESNW. Drainage should be provided behind retaining walls such that hydrostatic pressures do not develop. If drainage is not provided, hydrostatic pressures should be included in the wall design. Earth Solutions NW, LLC Paradise Heights, LLC ES-5839 March 5, 2018 Page 13 Retaining walls should be backfilled with free -draining material that extends along the height of the wall, and a distance of at least 18 inches behind the wall. The upper one foot of the wall backfill can consist of a less permeable soil, if desired. A perforated drain pipe should be placed along the base of the wall, and should be connected to an approved discharge location. A typical retaining wall drainage detail is provided as Plate 3. Drainage Groundwater seepage was not observed during our fieldwork on January 7, 2018. Groundwater seepage is possible in site excavations, particularly in the winter, spring and early summer months. Temporary measures to control groundwater seepage and surface water runoff during construction will likely involve passive elements such as interceptor trenches and sumps, as necessary. Surface water should not be allowed to runoff over sloped areas and should not be allowed to pond near the top of sloped areas or retaining structures. Surface grades must be designed to direct water away from buildings. The grade adjacent to buildings should be sloped away from the buildings at a gradient of at least 2 percent for a horizontal distance of four feet or more as setbacks allow. In our opinion, perimeter footing drains should be installed at or below the invert of the building footings. A typical footing drain detail is provided on Plate 4 of this report. Infiltration Evaluation We understand drywells, trenches or other methods will be utilized for on -site infiltration. For design, the long-term infiltration rate was evaluated using a Small-scale Pilot Infiltration Test (PIT) completed at a depth of three feet in TP-3. Based on consistent nature of the upper outwash soils, it is our opinion one PIT is sufficient; once infiltration depths and locations are determined, we should reevaluate the need for additional testing. Table 3.3.1 of the referenced DOE Manual provides criteria for estimating the long-term infiltration rate based on measured rates and applicable correction factors. The following long term infiltration rate was calculated using the following equation and correction factors: K design rate = K measured rate X CFT • Measured infiltration rate Kmeasured = 120 in/hr • Site variability; number of locations tested CF„ = 0.33 • Test method CFt = 0.50 • Degree of influent control to prevent siltation Urn = 0.90 • Total correction factor CFT = 0.15 Calculated Long Term Infiltration Rate* TP-3 = 18 in/hr *Per Stormwater Management Manual for Western Washington, August, 2012. Chapter 3.3.4 Earth Solutions NK LLC Paradise Heights, LLC March 5, 2018 ES-5839 Page 14 We recommend the proposed infiltration systems be located with a setback of at least 25 feet from the top of slope hazard area (and proposed retaining wall upon completion) to the north of the subject site. The geotechnical engineer should observe the excavations for the proposed infiltration systems to confirm soil conditions at the time of construction. We recommend an emergency overflow provision be included in the infiltration system design. If an overflow is not incorporated, we recommend reducing the design infiltration rate by half. Low Impact Development The following table provides our evaluation and recommendations regarding low impact development BMPs for the proposed project: Limitations or ' BMP Viable? Infeasibility Criteria Lawns and Landscaped Areas T5.13: Post -construction soil quality Considered infeasible on slopes of 33 percent or and depth (Volume V, Chapter 5) I Yes I greater. Roofs T5.30: Dispersion is not recommended near the T5.30: Full dispersion (Volume V, Yes* slope hazard area/proposed retaining wall of the Chapter 5) site. T5.10A: A design infiltration of 18 inches per T5.10A: Downspout full infiltration hour should be used for preliminary design. Yes systems (Volume III, Chapter 3) Must be setback at least 25 feet from proposed retaining wall. A design infiltration of 18 inches per hour should Bioretention (Volume V, Chapter 7) Yes be used for design. Must be setback at least 25 feet from proposed retaininq wall. T5.1OR Downspout dispersion systems (Volume III, Chapter 3) T5.10C: Perforated stub -out connections (Volume III, Chapter 3 T5.30: Full dispersion (Volume V, Chapter 5) T5.15: Permeable pavement (Volume V, Chapter 5) Bioretention (Volume V, Chapter 7) Yes* Dispersion is not recommended near the slope hazard area/proposed retaining wall of the site. Yes No limitations. I Yes* Dispersion is not recommended near the slope hazard area/proposed retaining wall of the site. Near -surface soils generally have a higher fines content and a design infiltration rate of 4.5 inch Yes per hour should be used for design of permeable pavement. Must be setback at least 25 feet from proposed retaining wall. A design infiltration of 18 inches per hour should Yes be used for design. Must be setback at least 25 feet from proposed retaininq wall. T5.12: Sheet flow dispersion I Dispersion is not recommended near the slope T5.11: Concentrated flow dispersion Yes* hazard area/proposed retaining wall of the site. (Volume V, Chapter 5) 1 If dispersion is utilized all downspout areas should maintain at least a 25-foot buffer from the proposed retaining wall area. Dispersion is recommended to lead south or east boundaries of the site property where site topography is relatively level. Earth Solutions NW, LLC Paradise Heights, LLC March 5, 2018 Utility Trench Support and Backfill ES-5839 Page 15 In our opinion, the soils observed at the test pit locations are generally suitable for support of utilities. In general, the soils observed at the test pit locations may not be suitable for use as structural backfill in the utility trench excavations, unless the soil is at or near the optimum moisture content at the time of placement and compaction. Moisture conditioning of the soils may be necessary at some locations prior to use as structural fill. Utility trench backfill should be placed and compacted to the specifications of structural fill provided in this report, or to the applicable requirements of the City of Edmonds. Pavement Sections The performance of site pavements is largely related to the condition of the underlying subgrade. To ensure adequate pavement performance, the subgrade should be in a firm and unyielding condition when subjected to proofrolling with a loaded dump truck. Structural fill in pavement areas should be compacted to the specifications detailed in the Site Preparation and Earthwork section of this report. It is possible that soft, wet, or otherwise unsuitable subgrade areas may still exist after base grading activities. Areas of unsuitable or yielding subgrade conditions may require remedial measures such as overexcavation and replacement with structural fill or thicker crushed rock sections prior to pavement. For relatively lightly loaded pavements subjected to automobiles and occasional truck traffic, the following sections can be considered for preliminary design: Two inches of hot mix asphalt (HMA) placed over four inches of crushed rock base (CRB), or; • Two inches of HMA placed over three inches of asphalt treated base (ATB). The HMA, CRIB and ATB materials should conform to WSDOT specifications. LIMITATIONS The recommendations and conclusions provided in this geotechnical engineering study are professional opinions consistent with the level of care and skill that is typical of other members in the profession currently practicing under similar conditions in this area. A warranty is not expressed or implied. Variations in the soil and groundwater conditions observed at the test locations may exist, and may not become evident until construction. ESNW should reevaluate the conclusions in this geotechnical engineering study if variations are encountered. Additional Services ESNW should have an opportunity to review the final design with respect to the geotechnical recommendations provided in this report. ESNW should also be retained to provide testing and consultation services during construction. Earth Solutions NW, LLC %7 i (ftWt Z� TWO t1t 1 Ktif NT RK cw 1 , A0 arm tIM t- ItRN at YA TM _ R = t tl _OL �lr�Mi 1 Iltri• IMTNLai TV AA R -. Si 19'�r :^i' N Ip 10IISt r►�ro� �7 r s iR mftAt i=may► • IM Wf iQtM Wf B !��� VI•�10 NY is � R$ ■ PER ,.• Is3 :F T . 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Iw n ut` SiN Avg I' F it r4 rl:x t s �y t vft lM runt 1d�; b 3tpz ■ N s; �Rb I`w i7 i ..� s utIT 11� , 's 30 ; s :: 5 Z '''' _ M1 '� r Pots a ' A. p ! � � � ,• c n ^ s1i'• n rA NORTH ' ' Reference: Solutions IVWVLLU Snohomish County, Washington NW I-I-C LGeotechnical Engineering, Construction Monitoring Map 454 By The Thomas Guide Rand McNally Vicinity Map 32nd Edition 546 Paradise Lane Edmonds, Washington NOTE: This plate may contain areas of color. ESNW cannot be responsible for any subsequent misinterpretation of the information Drwn. CAM Date 02/13/2018 Proj. No. 5839 resulting from black & white reproductions of this plate. Checked SES Date Feb. 2018 Plate 1 -,54- 252,r 256 254' _ �258 \ ` 2F- 2' 26 262--'- - - `i 262 264—r Building A TP-1� 268 LEGEND TP-1 Approximate Location of — ■ — ESNW Test Pit, Proj. No. NORTH ES-5839, Feb. 2018 Subject Site Proposed Building Existing Building (To be Removed) NOT - TO -SCALE NOTE: The graphics shown on this plate are not intended for design purposes or precise scale measurements, but only to illustrate the approximate test locations relative to the approximate locations of existing and / or proposed site features. The information illustrated is largely based on data provided by the client at the time of our study. ESNW cannot be responsible for subsequent design changes or interpretation of the data by others. NOTE: This plate may contain areas of color. ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black & white reproductions of this plate. IsolutionS a.a■ a■■ vv•a�•.•v■•v NW LLC eotechnical Engineering, Construction Moni and Environmental Sciences Test Pit LocationPlan 4• ParLane adise Edmonds, Washington -• Date Feb.2018 r NOTES: 18" Min. 0 o ° o o ° o o- 0 Cr �0 o° �po°o°o°o0o °oO�p� C 0 0�0� o0o oo o ° oo o o oo 00 o� oo o-° o° o o o o n O o 0 0 o O �° o 0o0op oo 0o 0 0. C � o O o 0 0 00° o 0 o o O o o 0 0 0 0 0 ° b o 00 o° o O 0 o �o O O °o ° Oo O b o o o b 0 Cp 00 o -o 05� �� O 000°o 0 0 00 o V O a 000o o�000 0 O o 0 0 o g o'—o oo o o �o o a o° O ° O o °�� O o 0 0 0 oa0oo 00 0o ° o Do 0 8 o ° °0o o0 O .0 o 0 • Free -draining Backfill should consist of soil having less than 5 percent fines. Percent passing No. 4 sieve should be 25 to 75 percent. • Sheet Drain may be feasible in lieu of Free -draining Backfill, per ESNW recommendations. • Drain Pipe should consist of perforated, rigid PVC Pipe surrounded with 1-inch Drain Rock. LEGEND: °o' o 0 o00 00 Free -draining Structural Backfill .f.l.r.f. ,rtirtirtirti 1-inch Drain Rock Structural Fill Perforated Rigid Drain Pipe (Surround in Drain Rock) SCHEMATIC ONLY - NOT TO SCALE NOT A CONSTRUCTION DRAWING RETAINING WALL DRAINAGE DETAIL 546 Paradise Lane Edmonds, Washington Drwn. CAM Date 02/13/2018 Proj. No. 5839 Checked SES Date Feb. 2018 Plate 3 Perforated Rigid Drain Pipe (Surround in Drain Rock) NOTES: • Do NOT tie roof downspouts to Footing Drain. Surface Seal to consist of 12" of less permeable, suitable soil. Slope away from building. LEGEND: Surface Seal: native soil or other low -permeability material. 1-inch Drain Rock SCHEMATIC ONLY - NOT TO SCALE NOT A CONSTRUCTION DRAWING Drwn. CAM Date 02/13/2018 Proj. No. 5839 Checked SES Date Feb. 2018 Plate 4 Appendix A Subsurface Exploration ES-5839 The subsurface conditions at the site were explored by excavating two test pits at the approximate locations illustrated on Plate 2 of this report. The test pit logs are provided in this Appendix. The subsurface exploration was completed on February 7, 2018. The test pits were excavated to a maximum depth of nine feet below existing grades. Logs of the test pits advanced by ESNW are presented in Appendix A. The final logs represent the interpretations of the field logs and the results of laboratory analyses. The stratification lines on the logs represent the approximate boundaries between soil types. In actuality, the transitions may be more gradual. Earth Solutions NW, LLC Earth Solutions NWLLC SOIL CLASSIFICATION CHART MAJOR DIVISIONS SYMBOLS TYPICAL DESCRIPTIONS GRAPH LETTER GRAVEL AND CLEAN GRAVELS ��•�� ' GW WELL GRADED GRAVELS, GRAVEL - FINES ND MIXTURES, LITTLE OR NO °O° oQ° o ODo 0 Q Q °Q GP POORLY -GRADED GRAVELS, GRAVEL- SAND MIXTURES, LITTLE OR NO FINES GRAVELLY SOILS (LITTLE OR NO FINES) COARSE GRAINED SOILS MORE THAN 50% OF COARSE GRAVELS WITH FINES °� Q ° °° ° ° D GM SILTY GRAVELS, GRAVEL -SAND - SILT MIXTURES FRACTION GC CLAYEY GRAVELS, GRAVEL - SAND - CLAY MIXTURES RETAINED ON NO. 4 SIEVE (APPRECIABLE AMOUNT OF FINES) MORE THAN 50% OF MATERIAL IS SAND AND CLEAN SANDS SW WELL -GRADED SANDS, GRAVELLY SANDS, LITTLE OR NO FINES SP POORLY -GRADED SANDS, GRAVELLY SAND, LITTLE OR NO FINES LARGER THAN NO. 200 SIEVE SIZE SANDY SOILS (LITTLE OR NO FINES) SANDS WITH FINES `SM SILTY SANDS, SAND - SILT MIXTURES MORE THAN 50% OF COARSE FRACTION S`+ PASSING ON NO. 4 SIEVE (APPRECIABLE AMOUNT OF FINES) CLAYEY SANDS, SAND - CLAY MIXTURES INORGANIC SILTS AND VERY FINE ML SANDS, ROCK FLOUR, SILTY OR CLAYEY FINE SANDS OR CLAYEY SILTS WITH SLIGHT PLASTICITY FINE GRAINED SOILS SILTS LIQUID LIMIT AND LESS THAN 50 CLAYS CL INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, GRAVELLY CLAYS, SANDY CLAYS, SILTY CLAYS, LEAN CLAYS — — __ OL ORGANIC SILTS AND ORGANIC SILTY CLAYS OF LOW PLASTICITY MORE THAN 50% OF MATERIAL IS MH INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS FINE SAND OR SMALLER THAN NO.200 SIEVE SILTY SOILS SIZE SILTS LIQUID LIMIT AND CLAYS GREATER THAN 50 CH INORGANIC CLAYS OF HIGH PLASTICITY OH ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY. ORGANIC SILTS HIGHLY ORGANIC SOILS ' ' ' ' ' ' ' PT PEAT, HUMUS, SWAMP SOILS WITH HIGH ORGANIC CONTENTS DUAL SYMBOLS are used to indicate borderline soil classifications. The discussion in the text of this report is necessary for a proper understanding of the nature of the material presented in the attached logs. Earth Solutions NW TEST PIT NUMBER TP-1 1805 - 136th Place N.E., Suite 201 Bellevue, Washington 98005 PAGE 1 OF 1 Telephone: 425-449-4704 Fax: 425-449-4711 PROJECT NUMBER ES-5839 PROJECT NAME 546 Paradise Lane DATE STARTED 217/18 COMPLETED 2/7/18 GROUND ELEVATION 265 ft TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION --- LOGGED BY SES CHECKED BY HTW AT END OF EXCAVATION --- NOTES Depth of Topsoil & Sod 6" AFTER EXCAVATION --- w _ a. W w U = as � g TESTS U a p MATERIAL DESCRIPTION QW (L Q Z (7 0 TPSL = TOPSOIL 0.5 264 5 Brown poorly graded SAND with gravel, medium dense, damp MC = 4.20% -becomes gray -caving from 2' to BOH MC = 3.60% MC = 4.00% SP - -becomes dense 9.0 -becomes moist 256.0 - MC = 9.20% Test pit terminated at 9.0 feet below existinggrade. No groundwater encountered during excavation. Caving observed from 2.0 feet to BOH. Bottom of test pit at 9.0 feet. Earth Solutions NW TEST PIT NUMBER TP-2 1805 - 136th Place N.E., Suite 201 Bellevue, Washington 98005 PAGE 1 OF 1 VAX Telephone: 425-449-4704 Fax: 425-449-4711 PROJECT NUMBER ES-5839 PROJECT NAME 546 Paradise Lane DATE STARTED 2/7/18 COMPLETED 2/7/18 GROUND ELEVATION 265 ft TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION --- LOGGED BY SES CHECKED BY HTW AT END OF EXCAVATION — NOTES Depth of Topsoil & Sod 3": grass AFTER EXCAVATION — a. }w f— W C6 U wg TESTS J MATERIAL DESCRIPTION 0_ z Qz � rn 0 0.3 _TOPSOIL ,�64� Brown poorly graded SAND with silt and gravel, medium dense, damp MC = 8.60% Fines = 5.00% [USDA Classification: very gravelly coarse SAND] SP- MC = 3.50% SM -becomes gray 5.5 259.5 MC = 3.40% _lit Test pit terminated at 5.5 feet below existing grade. No groundwater encountered during excavation. No caving observed. Bottom of test pit at 5.5 feet. Earth Solutions NW TEST PIT NUMBER TP-3 1805 - 136th Place N.E., Suite 201 Bellevue, Washington 98005 PAGE 1 OF 1 Telephone: 425-449-4704 Fax: 425-449-4711 PROJECT NUMBER ES-5839 PROJECT NAME 546 Paradise Lane DATE STARTED 2/7118 COMPLETED _ 217/18 GROUND ELEVATION 265 ft TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION -- LOGGED BY SES CHECKED BY HTW AT END OF EXCAVATION --- NOTES Surface Conditions: grass AFTER EXCAVATION -- w a - of �w U _ a g TESTS U a p MATERIAL DESCRIPTION Qz U) 0 Brown poorly graded SAND, medium dense, damp (Fill) SP - MC = 3.60% 2.5 -caving to 8' 262.5 _ Gray poorly graded SAND with gravel, medium dense, damp -infiltration test at 3' SP MC = 10.60% Fines = 3.70% [USDA Classification: very gravelly coarse SAND] 8.0 -water from infiltration test mounding on till layer, groundwater seepage at 8' 257.0 SM g 5 Gray silty SAND with gravel, dense, damp (Unweathered Till) 258.5 ° MC = 11.20 /o -moderately cemented Test pit terminated at 8.5 feet below existing grade. Groundwater seepage encountered at 8.0 feet during excavation. Caving observed from 2.0 to 8.0 feet. Bottom of test pit at 8.5 feet. Earth Solutions NW TEST PIT NUMBER TP-4 1805 - 136th Place N.E., Suite 201 Bellevue, Washington 98005 PAGE 1 OF 1 WAIN Telephone: 425-449-4704 Fax: 425-449-4711 PROJECT NUMBER ES-5839 PROJECT NAME 546 Paradise Lane DATE STARTED 2/7/18 COMPLETED 2/7/18 GROUND ELEVATION 265 ft TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION -- LOGGED BY SES CHECKED BY HTW AT END OF EXCAVATION — NOTES Depth of Topsoil & Sod 12": duff AFTER EXCAVATION — w rw U a- � TESTS MATERIAL DESCRIPTION Q Z n C9 0 — Dark brown TOPSOIL, roots to 2' PS ,, — 1.0 264.0 Brown poorly graded SAND with gravel, medium dense, damp MC = 3.90% -caving to 8' -becomes gray MC = 3.90% SP 8.0 257.0 _ Gray silty SAND with gravel, dense to very dense, damp (Unweathered Till) SM MC = 11.20% 9 0 -moderately cemented 2560 Fines = 18.50% (USDA Classification: gravelly loamy SAND) Test it terminated at 9.0 feet below existing grade. No groundwater encountered during excavation. Caving observed from 2.0 to 8.0 feet. Bottom of test pit at 9.0 feet. Appendix B Laboratory Test Results ES-5839 Earth Solutions NW, LLC z W 0 Q cn W S"q NINE liiii lmmiiiiii IN 11111 INEIIIIIII NUNN liiiiiimmiiiiii iiii inmiiiiiii IN 0 liiiiiiomiiiiiii NO INNIS liiiii iiiiiiinmiiiiiilmmiiiilli IN iiiiiiin 11 11 11 lismi liimmiiiiiii ON lllin 111 Ell 11111111111101111 11 1ills �ill 11110,11111 I lismil 11 INNER I I in 1110 Im-l'Zon 11 lowl NINE NUNN kill III I I Ills 1111111. Us Ml I ILINEIIIIII MEN lool NO ME liiiin 111111101 1 1 1 ME lmmiiiiiiimm lllin H is I milli I I inmiiiiii NINE III ELVIII M I liiiinmii lool III In III 111110 111111L, immi IN ilillillin IN M.- 0MAP Report Distribution ES-5839 EMAIL ONLY Paradise Heights, LLC 24144 East Greystone Lane Woodway, Washington 98020 Attention: Mr. John Rettenmier Earth Solutions NW, LLC