Drainage ReportDrainage and Erosion Control
Report
for
Leah’s Landing
Yelm, WA
December 21, 2020
PO Box 12690 Olympia WA 98508 360.705.2474
www.olyeng.com
________________________________________________________________________________ December 2020 Drainage and Erosion Control Report 1
COVER SHEET
LEAH’S LANDING
Yelm, Washington December 18, 2020
Owner/Applicant
Prepared for: TCB Capital, LLC Contact: Mike Kempinski 201 Mosman Ave. SE Yelm, WA 98597 (360) 507-0868
Reviewing Agency
Jurisdiction: City of Yelm, Washington Project Number: 2020.0017 Project Contact: Tami Merriman (360) 458-8496
Contractor
Contact:
References
WSDOE Stormwater Management Manual for Western Washington (SWMMWW),
2014 ed.
Project Engineer
Prepared by: Olympic Engineering, Inc. PO Box 12690 Olympia, WA 98508 (360) 705-2474 Contact: Chris Merritt, PE Project Number: 19017 12/21/2020
"I hereby certify that this Drainage and Erosion Control Plan and Report and Construction SWPPP for the Leah’s Landing project has been prepared by me or under my supervision and meets the requirements of the City of Yelm Stormwater Standards and the standards of care and expertise which is usual and customary in this community for professional engineers. I understand that the City of Tumwater does not and will not assume liability for the sufficiency, suitability, or performance of drainage facilities prepared by me.”
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TABLE OF CONTENTS
COVER SHEET ........................................................................................................................ 1
TABLE OF CONTENTS ........................................................................................................... 2
SECTION 1 – PROPOSED PROJECT DESCRIPTION .......................................................... 3
Permit ................................................................................................................................................ 3
Project Location ................................................................................................................................. 3
Property Boundaries & Zoning ........................................................................................................... 3
Project Description ............................................................................................................................. 3
Minimum Requirements ..................................................................................................................... 3
Timing of the Project .......................................................................................................................... 5
SECTION 2 – EXISTING SITE CONDITIONS ......................................................................... 5
Topography ........................................................................................................................................ 5
Ground Cover .................................................................................................................................... 5
Drainage ............................................................................................................................................ 5
Soils ................................................................................................................................................... 6
Critical Areas ..................................................................................................................................... 6
Adjacent Areas .................................................................................................................................. 6
Precipitation Records ......................................................................................................................... 6
Reports and Studies .......................................................................................................................... 6
SECTION 3 – GEOTECHNICAL REPORT .............................................................................. 6
SECTION 4 – WELLS AND SEPTIC SYSTEMS ..................................................................... 6
SECTION 5 – FUEL TANKS .................................................................................................... 6
SECTION 6 – ANALYSIS OF THE 100-YEAR FLOOD .......................................................... 6
SECTION 7 – AESTHETIC CONSIDERATIONS FOR FACILITIES ....................................... 6
SECTION 8 – FACILITY SIZING AND OFF-SITE ANALYSIS ................................................ 7
Proposed Permanent BMP’s ............................................................................................................. 7
Off-Site Analysis ................................................................................................................................ 8
SECTION 9 – COVENANTS, DEDICATIONS, EASEMENTS ................................................ 9
SECTION 10 – PROPERTY OWNERS ASSOCIATION ARTICLES OF INCORPORATION 9 APPENDICES
Appendix 1 - Drainage Plans Appendix 2 - Drainage Calculations Appendix 3 - Soils Report
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SECTION 1 – PROPOSED PROJECT DESCRIPTION
Permit
The applicant is applying for permits to construct six single-family duplexes with associated public roadway, private/public utilities, grading, and storm drainage improvements. Project Location
See Vicinity Map on plans for reference. Site Address: 10548 Mill Rd. SE Yelm, WA 98594 Tax Parcel Number(s): 22730230600 Section, Township, Range: Section 30 Township 17 North Range 02 East, W.M. Property Boundaries & Zoning
The zoning is Low-Density Residential District (R-4). The parcel boundaries are shown on the drainage plans (see Appendix). Project Description
The proposal is to construct six single-family duplexes with associated public roadway, private/public utilities, grading, and storm drainage improvements. The project will be completed in one phase. It is anticipated that construction will begin in spring 2021 with substantial completion by fall 2021. See plans for additional information. Minimum Requirements
The Minimum Requirements for stormwater development and redevelopment sites are listed in Section I-2.4 of Volume I of the SWMMWW. The proposed project creates and/or replaces more than 5,000 square-feet of new hard surface area; therefore, the proposed project must address Minimum Requirements #1 through #9. This project will meet the LID Performance Standard and flow control standard as the majority of stormwater runoff from the new improvements will be infiltrated (see WWHM output in Appendix). The Minimum Requirements have been addressed as follows: Minimum Requirement #1 – Preparation of Stormwater Site Plans Drainage Plans have been prepared for this project (see Appendix). Minimum Requirement #2 – Construction Stormwater Pollution Prevention (SWPP) A Construction Stormwater Pollution Prevention (SWPP) Plan has been prepared.
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Minimum Requirement #3 – Source Control of Pollution A Permanent Source Control Plan will be provided with the storm drainage maintenance agreement prior to final project approval. Minimum Requirement #4 – Preservation of Natural Drainage Systems and Outfalls There are no existing natural drainage systems or outfalls located on or near the subject parcel; therefore, this Minimum Requirement is not applicable. Minimum Requirement #5 – On-Site Stormwater Management This project will meet the LID Performance Standard as the majority of hard surface areas are proposed to be infiltrated. The proposed BMP’s are as follows: Lawn and Landscape Areas:
• All disturbed and/or new lawn and landscape areas will contain soils meeting the Post-Construction Soil Quality and Depth (BMP T5.13) requirements. Roof Areas:
• It is anticipated that stormwater runoff from the future roof areas will be tightlined to individual lot Downspout Infiltration Trenches (BMP T5.10). This will be specified on the individual lot site plans at the building permit stage or on the face of the final plat map. Other Hard Surface Areas:
• Stormwater runoff from the new public on-site roadway, driveways, and sidewalks, along with the east half of Mill Rd. SE, will be collected and tightlined to a Type 2 catch basin containing two Baysaver Bayfilter™ cartridges for runoff treatment. Treated stormwater runoff will be conveyed to a below-grade infiltration trench (BMP T7.20) consisting of 44 StormTech chambers for storage and 100% infiltration.
• It is anticipated that stormwater runoff from the future lot driveway areas will be sheet flow dispersed per BMP T5.12. This will be specified on the individual lot site plans at the building permit stage or on the face of the
final plat map. See Section 8 and the drainage plans for additional information. Minimum Requirement #6 – Runoff Treatment This project will create/replace more than 5,000 square-feet of new total effective pollution-generating hard surface (PGHS) area; therefore, Runoff Treatment is required.
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See Minimum Requirement #5 above and Section 8 below for additional information along with the WWHM modeling results in the Appendix for the 15-minute water quality flow rate treatment requirement. Minimum Requirement #7 – Flow Control This project will have less than 10,000 square-feet of “effective” impervious surface area; will convert less than ¾-acre of vegetation to lawn/landscape; convert less than 2.5-acres of native vegetation to pasture; and cause less than a 0.15-cfs increase in the 100-year flow frequency; therefore, Flow Control is not required. Per WWHM, this project will meet the LID Performance Standard and flow control standard.
See Minimum Requirement #5 above and Section 8 below for additional information along with the WWHM modeling results in the Appendix for infiltration trench sizing. Minimum Requirement #8 – Wetlands Protection There are no known wetlands located on-site or within the immediate vicinity; therefore, this Minimum Requirement is not applicable. Minimum Requirement #9 – Operation and Maintenance A storm drainage maintenance agreement, including a pollution source control plan, will be prepared and recorded prior to final project approval. Optional Guidance #1 – Financial Liability A Financial Guarantee will be provided prior to final project approval, if required. Optional Guidance #2 – Off-Site Analysis and Mitigation See Section 8 below. No downstream impacts are anticipated as a result of this project. Timing of the Project
The project will be completed in one phase. It is anticipated that construction will begin in spring 2021 with substantial completion by fall 2021. SECTION 2 – EXISTING SITE CONDITIONS
Topography
Site topography is gentle and rolling, generally sloping down towards the west. Ground Cover
Site vegetation consists mainly of scattered trees (mainly deciduous), scotch broom, and field grass. Drainage
See drainage plan and Section 8 below.
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Soils
The Natural Resources Conservation Service (NRCS) Soil Survey of Thurston County classifies the on-site soils as Spanaway Gravelly/Stony Sandy Loam (HSG A) and Nisqually Loamy Fine Sand (HSG A). A Geotechnical Investigation and Engineering Report has been prepared by Materials Testing & Consulting, dated October 7, 2019 (see Appendix), and this report generally confirms the NRCS classifications.
Critical Areas
There are no known critical areas (i.e. wetlands, steep slopes, streams, etc.) located on-site or within the immediate vicinity of the site based on review of Thurston County critical areas maps and a site visit. Adjacent Areas
The project site is bounded by residential parcels to the north, south, and east and by Mill Road SE to the west. Precipitation Records
Precipitation data is included within the WWHM model. Reports and Studies
A Geotechnical Investigation and Engineering Report has been prepared by Materials Testing & Consulting, dated October 7, 2019 (see Appendix). SECTION 3 – GEOTECHNICAL REPORT
A Geotechnical Investigation report has been prepared by Materials Testing & Consulting, dated October 7, 2019 (see Appendix). SECTION 4 – WELLS AND SEPTIC SYSTEMS
The on-site well and septic system will be abandoned/decommissioned per Washington State and Thurston County requirements. There are no known off-site wells within 200-feet of this project’s boundaries. SECTION 5 – FUEL TANKS
No fuel tanks were located during a site inspection or during the soils evaluation work. Olympic Engineering reviewed the latest “LUST” list (Leaking Underground Storage Tank) and found no listing for the subject site. SECTION 6 – ANALYSIS OF THE 100-YEAR FLOOD
According to FEMA FIRM #53067C0365E dated October 16, 2012, the project site and surrounding area is located in Zone X (area outside the 0.2% annual chance floodplain). SECTION 7 – AESTHETIC CONSIDERATIONS FOR FACILITIES
All storm facilities will be located below-grade. All disturbed pervious areas will be vegetated and/or landscaped and will contain soils that meet the Post-Construction Soil Quality and Depth (BMP T5.13) requirements.
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SECTION 8 – FACILITY SIZING AND OFF-SITE ANALYSIS
Parcel Area: 83,135 sf (1.909 ac) Off-Site: 4,763 sf (0.109 ac) Project Area: 87,898 sf (2.018 ac) *Includes ±½ R/W area of Mill Rd. fronting the subject parcel as the half-street pavement area contributes stormwater runoff to the proposed on-site stormwater system. Existing Development Coverage
Land Coverage Table – Pre-Developed (Acres)
Roadway 0.065
Driveway (w/in R/W) 0.003
Driveway (on-site) 0.041
Misc. (patios/walkways) 0.002
Roof 0.041
Landscaping (w/in R/W) 0.039
Pasture (on-site) 1.687
Forest (on-site) 0.140
Total 2.018
Proposed Development Coverage
Land Coverage Table – Post-Developed (Acres)
Roadway 0.472
Sidewalk 0.038
Driveways (w/in R/W) 0.055
Driveways (on lots) 0.110
Misc. (patios/walkways on lots)* 0.041
Roof* 0.289
Landscaping (w/in R/W) 0.132
Landscaping (on lots) 0.279
Pasture (Open Space Tracts) 0.462
Forest (Open Space Tract A) 0.140
Total 2.018
*Assumes 2,100 sf roof area, 800 sf driveway area, and 300 sf misc. (patio/walkway) area per lot Proposed Permanent BMP’s
The following Permanent BMP’s have been incorporated into the design (see drainage plans): 1. BMP T5.10A Downspout Infiltration Trenches (future individual lot roof areas)
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2. BMP T5.12 Sheet Flow Dispersion (future individual lot driveway/patio/walkway areas) 3. BMP T5.13 Post-Construction Soil Quality and Depth (all disturbed, lawn/landscape, and stormwater dispersion areas) 4. BMP T7.20 Infiltration Trench (public roadway areas) 5. Baysaver Bayfilter™ Treatment System (public roadway areas) Flow Control & Runoff Treatment Facilities Two Baysaver Bayfilter™ cartridges (BFC 30 gpm) will provide treatment of stormwater runoff from all pollution generating hard surface (PGHS) areas (roadway & driveway areas within the public right-of-way). Per WWHM modeling results, this project is required to treat a 15-minute water quality flow rate of 0.091 cfs. 0.091 cfs / 0.067 cfs/cartridge = 1.36 (Use two 30 gpm cartridges)
The Washington State Department of Ecology issued a “General Use
Level Designation for Basic (TSS) Treatment” for this filter when
using a 30 gpm/cartridge design flow rate (see Appendix). Treated stormwater runoff will be conveyed to an underground infiltration trench system (BMP T7.20) consisting of 44 StormTech chambers. The Geotechnical Investigation Report prepared by Materials Testing & Consulting recommends a maximum design infiltration rate of 5.78”/hr be used; however, a 4”/hr rate has been used. The 4’ high infiltration trench will provide for 1.7’ of freeboard. At a maximum ponding depth of 2.3’, the facility will draw down in 3.4 hours (2.3’x12”)/4”/hr = 6.9 hours). See WWHM modeling results in the Appendix for infiltration trench sizing. Modeling & Assumptions
• Stormwater runoff from the public roadway, sidewalk, and driveway areas, along with the individual lot roof areas, will be infiltrated. These areas are considered “ineffective” and can be excluded from the impervious area threshold determination of Minimum Requirement #7.
• All infiltrated areas can be discounted from WWHM when comparing pre- to post-developed runoff rates.
• All lawn/landscape areas that meet the Post-Construction Soil Quality and Depth (BMP T5.13) requirements may be modeled as “pasture”.
• For the LID analysis, all areas to be disturbed were modeled as forest. Off-Site Analysis
The majority of stormwater runoff generated from the new on-site improvements, along with existing and new improvements associated with the east-half of Mill Rd., will be infiltrated on-site and the project will meet the LID Performance Standard. There does not appear to be any noticeable stormwater run-on from adjacent parcels.
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Stormwater from a complete failure of the on-site infiltration system would temporarily flood the on-site roadway. No downstream impacts, including impacts to structures, are anticipated as a result of this project. SECTION 9 – COVENANTS, DEDICATIONS, EASEMENTS
No easements are required for the storm drainage system components. SECTION 10 – PROPERTY OWNERS ASSOCIATION ARTICLES OF INCORPORATION
The property owner will be required to maintain the stormwater system components located outside of the public right-of-way. The City of Yelm will maintain the stormwater collection and conveyance components located within the right-of-way.
Appendix 1 Drainage Plans
PO Box 12690Olympia, WA 98508360.705.2474 officewww.olyeng.com CHRIM.M
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PO Box 12690Olympia, WA 98508360.705.2474 officewww.olyeng.com CHRIM.M
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RACCEPTABLE FILL MATERIALS: STORMTECH SC-740 CHAMBER SYSTEMS
PLEASE NOTE:
1. THE LISTED AASHTO DESIGNATIONS ARE FOR GRADATIONS ONLY. THE STONE MUST ALSO BE CLEAN, CRUSHED, ANGULAR. FOR EXAMPLE, A SPECIFICATION FOR #4 STONE WOULD STATE: "CLEAN, CRUSHED,
ANGULAR NO. 4 (AASHTO M43) STONE".
2. STORMTECH COMPACTION REQUIREMENTS ARE MET FOR 'A' LOCATION MATERIALS WHEN PLACED AND COMPACTED IN 6" (150 mm) (MAX) LIFTS USING TWO FULL COVERAGES WITH A VIBRATORY COMPACTOR.
3. WHERE INFILTRATION SURFACES MAY BE COMPROMISED BY COMPACTION, FOR STANDARD DESIGN LOAD CONDITIONS, A FLAT SURFACE MAY BE ACHIEVED BY RAKING OR DRAGGING WITHOUT COMPACTION
EQUIPMENT. FOR SPECIAL LOAD DESIGNS, CONTACT STORMTECH FOR COMPACTION REQUIREMENTS.
NOTES:
1. SC-740 CHAMBERS SHALL CONFORM TO THE REQUIREMENTS OF ASTM F2418 "STANDARD SPECIFICATION FOR POLYPROPYLENE (PP) CORRUGATED WALL STORMWATER COLLECTION CHAMBERS", OR ASTM F2922 "STANDARD SPECIFICATION FOR POLYETHYLENE (PE) CORRUGATED WALL STORMWATER COLLECTION CHAMBERS".
2. SC-740 CHAMBERS SHALL BE DESIGNED IN ACCORDANCE WITH ASTM F2787 "STANDARD PRACTICE FOR STRUCTURAL DESIGN OF THERMOPLASTIC CORRUGATED WALL STORMWATER
COLLECTION CHAMBERS".
3. "ACCEPTABLE FILL MATERIALS" TABLE ABOVE PROVIDES MATERIAL LOCATIONS, DESCRIPTIONS, GRADATIONS, AND COMPACTION REQUIREMENTS FOR FOUNDATION, EMBEDMENT, AND FILL
MATERIALS.
4. THE SITE DESIGN ENGINEER IS RESPONSIBLE FOR ASSESSING THE BEARING RESISTANCE (ALLOWABLE BEARING CAPACITY) OF THE SUBGRADE SOILS AND THE DEPTH OF FOUNDATION STONE
WITH CONSIDERATION FOR THE RANGE OF EXPECTED SOIL MOISTURE CONDITIONS.
5. PERIMETER STONE MUST BE EXTENDED HORIZONTALLY TO THE EXCAVATION WALL FOR BOTH VERTICAL AND SLOPED EXCAVATION WALLS.
6. ONCE LAYER 'C' IS PLACED, ANY SOIL/MATERIAL CAN BE PLACED IN LAYER 'D' UP TO THE FINISHED GRADE. MOST PAVEMENT SUBBASE SOILS CAN BE USED TO REPLACE THE MATERIAL
REQUIREMENTS OF LAYER 'C' OR 'D' AT THE SITE DESIGN ENGINEER'S DISCRETION.
MATERIAL LOCATION DESCRIPTION AASHTO MATERIAL
CLASSIFICATIONS
COMPACTION / DENSITY
REQUIREMENT
D
FINAL FILL: FILL MATERIAL FOR LAYER 'D' STARTS
FROM THE TOP OF THE 'C' LAYER TO THE BOTTOM OF FLEXIBLE PAVEMENT OR UNPAVED FINISHED
GRADE ABOVE. NOTE THAT PAVEMENT SUBBASE MAY BE PART OF THE 'D' LAYER
ANY SOIL/ROCK MATERIALS, NATIVE SOILS, OR PER
ENGINEER'S PLANS. CHECK PLANS FOR PAVEMENT
SUBGRADE REQUIREMENTS.
N/A
PREPARE PER SITE DESIGN ENGINEER'S PLANS.
PAVED INSTALLATIONS MAY HAVE STRINGENT
MATERIAL AND PREPARATION REQUIREMENTS.
C
INITIAL FILL: FILL MATERIAL FOR LAYER 'C'
STARTS FROM THE TOP OF THE EMBEDMENT
STONE ('B' LAYER) TO 18" (450 mm) ABOVE THE
TOP OF THE CHAMBER. NOTE THAT PAVEMENT
SUBBASE MAY BE A PART OF THE 'C' LAYER.
GRANULAR WELL-GRADED SOIL/AGGREGATE MIXTURES, <35%
FINES OR PROCESSED AGGREGATE.
MOST PAVEMENT SUBBASE MATERIALS CAN BE USED IN LIEU
OF THIS LAYER.
AASHTO M145¹
A-1, A-2-4, A-3
OR
AASHTO M43¹3, 357, 4, 467, 5, 56, 57, 6, 67, 68, 7, 78, 8, 89,
9, 10
BEGIN COMPACTIONS AFTER 12" (300 mm) OF
MATERIAL OVER THE CHAMBERS IS REACHED.
COMPACT ADDITIONAL LAYERS IN 6" (150 mm) MAX
LIFTS TO A MIN. 95% PROCTOR DENSITY FOR
WELL GRADED MATERIAL AND 95% RELATIVE
DENSITY FOR PROCESSED AGGREGATE
MATERIALS. ROLLER GROSS VEHICLE WEIGHT
NOT TO EXCEED 12,000 lbs (53 kN). DYNAMIC FORCE NOT TO EXCEED 20,000 lbs (89 kN).
B
EMBEDMENT STONE: FILL SURROUNDING THE
CHAMBERS FROM THE FOUNDATION STONE ('A'
LAYER) TO THE 'C' LAYER ABOVE.
CLEAN, CRUSHED, ANGULAR STONE, NOMINAL SIZE
DISTRIBUTION BETWEEN 3/4-2 INCH (20-50 mm)
AASHTO M43¹
3, 357, 4, 467, 5, 56, 57 NO COMPACTION REQUIRED.
A
FOUNDATION STONE: FILL BELOW CHAMBERS
FROM THE SUBGRADE UP TO THE FOOT (BOTTOM) OF THE CHAMBER.
CLEAN, CRUSHED, ANGULAR STONE, NOMINAL SIZE
DISTRIBUTION BETWEEN 3/4-2 INCH (20-50 mm)
AASHTO M43¹
3, 357, 4, 467, 5, 56, 57
PLATE COMPACT OR ROLL TO ACHIEVE A FLAT
SURFACE. ² ³
18"(450 mm) MIN*
8'
(2.4 m)MAX
SUBGRADE SOILS
(SEE NOTE 5)
PAVEMENT LAYER (DESIGNED
BY SITE DESIGN ENGINEER)
SC-740
END CAP
6" (150 mm) MIN
D
C
B
A
PERIMETER STONE
(SEE NOTE 6)
EXCAVATION WALL
(CAN BE SLOPED OR VERTICAL)
12" (300 mm) MIN
ADS GEOSYNTHETICS 601T NON-WOVEN GEOTEXTILE ALL
AROUND CLEAN, CRUSHED, ANGULAR STONE IN A & B LAYERS
12" (300 mm) TYP51" (1295 mm)6" (150 mm) MIN
30"
(760 mm)
12"
*TO BOTTOM OF FLEXIBLE PAVEMENT. FOR UNPAVED INSTALLATIONS WHERE RUTTING FROM VEHICLES MAY OCCUR, INCREASE COVER TO 24" (600 mm).
BOTTOM ELEV. = 363.00
NOTE:
SEE WSDOT STANDARD PLANS B-10.20-01 B-30.90-01 FOR ACCESS AND STEP/LADDER
LOCATION/ORIENTATION AND DETAILS.
BAYSAVER - BAYFILTER DETAIL (CB#9)
NTS
BAYFILTER
60-1 MANHOLE
PROJECT
LOCATION
WATER QUALITY FLOW 0.091 CFS
DRAINAGE AREA
CARTRIDGE DESIGN FLOW RATE 30 GPM
# BAYFILTER CARTRIDGES 2
TREATED SEDIMENT CAPACITY
CB#9
LEAH'S LANDING
INSPECTION PORT
12" X 12" ADS N-12 MANIFOLDWOVEN GEOTEXTILE OVER BEDDING STONE AND UNDERNEATH CHAMBER FEET FOR SCOUR PROTECTION AT ALL CHAMBER INLET
ROWS
STA. 22+91.77, 38.63' RT.
48"Ø TYPE 2CATCH BASIN #10
RIM=371.50IE=364.2 (24" W & 12"E)
FRAME AND COVER (MARKED "STORM" PER WSDOT STANDARD
PLAN B-30.70-03
12"Ø OUTLET
TO CB#10 12"Ø INLET
FROM CB#6
OVERFLOW STANDPIPETOP ELEV.=366.88
SECTION A-A
12"Ø PIPE - OUTLET - 364.21
RIM - ±371.50
12"Ø PIPE - INLET - 366.88
NOTES:1. INSPECTION PORTS MAY BE CONNECTED THROUGH ANY CHAMBER
CORRUGATION VALLEY2. ALL SCHEDULE 40 FITTINGS TO BE SOLVENT CEMENTED.
CONNECTION DETAIL
NTS
8"
(200 mm)
4" (100 mm)
SCHED 40 PVC
COUPLING
4" (100 mm)
SCHED 40 PVC
4" (100 mm)
SCHED 40 PVC
CORE 4.5" (114 mm) Ø
HOLE IN CHAMBER
(4.5" HOLE SAW REQ'D)
ANY VALLEY
LOCATION
STORMTECH CHAMBER
4" (100 mm) SCHED 40
SCREW-IN CAP
NYLOPLAST 12" (300 mm)
INLINE DRAIN BODY W/SOLID
HINGED COVER OR GRATE
CONCRETE COLLAR
PAVEMENT
18" (450 mm) MIN WIDTH
8" (200 mm)
MIN THICKNESS
INSPECTION PORT DETAIL
NTS
24" CORED END CAP
FROM CB#9
IE ELEV. = 364.00
36" FRAME & COVER
ELEV. = 367.00
INSPECTION PORT (SEE STORMTECH
SC-740 INSPECTION PORT DETAIL)
STORMTECH END CAP
2 LAYERS OF ADS 315ST WOVEN GEOTEXTILE (OR EQUAL)
BETWEEN FOUNDATION STONE AND CHAMBERS
SC-740: 5'-6" [1.7 m] WIDE STRIP
SC-310: 4'-0" [1.2 m] WIDE STRIP
COVER ENTIRE ROW WITH ADS 601 NON-WOVEN
GEOTEXTILE (OR EQUAL)
SC-740: 8' [2.4 m] WIDE STRIP
SC-310: 5' [1.5 m] WIDE STRIP
ISOLATOR ROW DETAIL
NTS
ISOLATOR ROW
Appendix 2 Drainage Calculations
Project:
Chamber Model - SC-740
Units -Imperial
Number of chambers -44Voids in the stone (porosity) - 40 %
Base of Stone Elevation -0.00 ft
Amount of Stone Above Chambers - 6 in
Amount of Stone Below Chambers -12 in
Area of system -1802 sf Min. Area -
Height of
System
Incremental Single
Chamber
Incremental
Total Chamber
Incremental
Stone
Incremental Ch
& St
Cumulative
Chamber Elevation
(inches)(cubic feet)(cubic feet)(cubic feet)(cubic feet)(cubic feet)(feet)
48 0.00 0.00 60.05 60.05 4095.69 4.00
47 0.00 0.00 60.05 60.05 4035.64 3.92
46 0.00 0.00 60.05 60.05 3975.59 3.83450.00 0.00 60.05 60.05 3915.53 3.75
44 0.00 0.00 60.05 60.05 3855.48 3.67
43 0.00 0.00 60.05 60.05 3795.42 3.58420.05 2.42 59.09 61.51 3735.37 3.50
41 0.16 7.17 57.19 64.36 3673.86 3.42
40 0.28 12.41 55.09 67.50 3609.51 3.33
39 0.60 26.57 49.42 76.00 3542.01 3.25
38 0.80 35.28 45.94 81.22 3466.01 3.17
37 0.95 41.83 43.32 85.15 3384.79 3.08
36 1.07 47.28 41.14 88.42 3299.64 3.00
35 1.18 51.94 39.28 91.22 3211.22 2.92
34 1.27 55.69 37.78 93.47 3120.00 2.83331.36 59.62 36.21 95.83 3026.53 2.75
32 1.45 63.98 34.46 98.44 2930.71 2.67
31 1.52 67.09 33.22 100.31 2832.27 2.58
30 1.58 69.62 32.21 101.83 2731.96 2.50
29 1.64 72.26 31.15 103.41 2630.13 2.42
28 1.70 74.78 30.14 104.92 2526.72 2.33
27 1.75 77.13 29.20 106.33 2421.80 2.25
26 1.80 79.32 28.32 107.65 2315.47 2.17251.85 81.62 27.41 109.03 2207.82 2.08
24 1.89 83.30 26.74 110.03 2098.80 2.00
23 1.93 85.10 26.02 111.11 1988.76 1.92
22 1.97 86.90 25.29 112.19 1877.65 1.83
21 2.01 88.44 24.68 113.12 1765.46 1.75
20 2.04 89.98 24.06 114.04 1652.34 1.67
19 2.07 91.30 23.53 114.83 1538.30 1.58
18 2.10 92.62 23.01 115.62 1423.47 1.50
17 2.13 93.80 22.53 116.33 1307.84 1.42162.15 94.77 22.15 116.92 1191.51 1.33
15 2.18 95.79 21.74 117.53 1074.59 1.25
14 2.20 96.73 21.36 118.09 957.07 1.17
13 2.21 97.12 21.21 118.33 838.98 1.08
12 0.00 0.00 60.05 60.05 720.65 1.00
StormTech SC-740 Cumulative Storage Volumes
Leah's Landing
1487 sf min. area
Include Perimeter Stone in Calculations
11 0.00 0.00 60.05 60.05 660.59 0.92
10 0.00 0.00 60.05 60.05 600.54 0.83
9 0.00 0.00 60.05 60.05 540.49 0.75
8 0.00 0.00 60.05 60.05 480.43 0.67
7 0.00 0.00 60.05 60.05 420.38 0.58
6 0.00 0.00 60.05 60.05 360.32 0.5050.00 0.00 60.05 60.05 300.27 0.42
4 0.00 0.00 60.05 60.05 240.22 0.33
3 0.00 0.00 60.05 60.05 180.16 0.25
2 0.00 0.00 60.05 60.05 120.11 0.17
1 0.00 0.00 60.05 60.05 60.05 0.08
Orifice 1 0 0
Orifice 2 0 0
Orifice 3 0 0
NOTE: If system height is greater than 15 ft
contact ADS Technical Services at (860) 257-2151
To Be Copied as SSD Table (copy to new spreadhseet and save as csv file)Stage
(ft)
Area
(acres)
Storage
(ac-ft)
Dis
(cfs)Infil
0.000 0.041360 0.000000 0.0000.083 0.041360 0.001379 0.000
0.167 0.041360 0.002757 0.000
0.250 0.041360 0.004136 0.0000.333 0.041360 0.005515 0.000
0.417 0.041360 0.006893 0.000
0.500 0.041360 0.008272 0.0000.583 0.041360 0.009651 0.000
0.667 0.041360 0.011029 0.000
0.750 0.041360 0.012408 0.000
0.833 0.041360 0.013787 0.000
0.917 0.041360 0.015165 0.000
1.000 0.041360 0.016544 0.000
1.083 0.041360 0.019260 0.000
1.167 0.041360 0.021971 0.000
1.250 0.041360 0.024669 0.0001.333 0.041360 0.027353 0.000
1.417 0.041360 0.030024 0.000
1.500 0.041360 0.032678 0.000
1.583 0.041360 0.035315 0.000
1.667 0.041360 0.037933 0.000
1.750 0.041360 0.040529 0.000
1.833 0.041360 0.043105 0.000
1.917 0.041360 0.045656 0.0002.000 0.041360 0.048182 0.000
2.083 0.041360 0.050685 0.000
2.167 0.041360 0.053156 0.000
2.250 0.041360 0.055597 0.000
2.333 0.041360 0.058006 0.000
2.417 0.041360 0.060380 0.000
2.500 0.041360 0.062717 0.000
2.583 0.041360 0.065020 0.000
2.667 0.041360 0.067280 0.0002.750 0.041360 0.069480 0.000
2.833 0.041360 0.071625 0.000
2.917 0.041360 0.073719 0.000
3.000 0.041360 0.075749 0.000
3.083 0.041360 0.077704 0.000
* Note use whole numbers -
Invert to be entered as height
from bottom of system in inches
Orifice
Diameter*
(in)
Invert*
(in)
Click here for MC-3500 and MC-4500 Chambers
3.167 0.041360 0.079569 0.000
3.250 0.041360 0.081313 0.000
3.333 0.041360 0.082863 0.000
3.417 0.041360 0.084340 0.000
3.500 0.041360 0.085752 0.000
3.583 0.041360 0.087 0.0003.667 0.041360 0.089 0.000
3.750 0.041360 0.090 0.000
3.833 0.041360 0.091 0.000
3.917 0.041360 0.093 0.000
4.000 0.041360 0.094 0.000
WWHM2012
PROJECT REPORT
19017_050620 5/14/2020 2:59:33 PM Page 2
General Model Information
Project Name: 19017_050620
Site Name: Leahs Landing
Site Address: 10548 Mill Rd. SE
City:Yelm
Report Date: 5/14/2020
Gage:Lake Lawrence
Data Start: 1955/10/01
Data End: 2008/09/30
Timestep: 15 Minute
Precip Scale: 0.857
Version Date: 2018/10/10
Version: 4.2.16
POC Thresholds
Low Flow Threshold for POC1: 50 Percent of the 2 Year
High Flow Threshold for POC1: 50 Year
Low Flow Threshold for POC2: 50 Percent of the 2 Year
High Flow Threshold for POC2: 50 Year
19017_050620 5/14/2020 2:59:33 PM Page 3
Landuse Basin Data
Predeveloped Land Use
Water Quality
Bypass:No
GroundWater:No
Pervious Land Use acre
Pervious Total 0
Impervious Land Use acre
ROADS FLAT 0.472
DRIVEWAYS FLAT 0.055
Impervious Total 0.527
Basin Total 0.527
Element Flows To:
Surface Interflow Groundwater
19017_050620 5/14/2020 2:59:33 PM Page 4
Pre-Developed
Bypass:No
GroundWater:No
Pervious Land Use acre
A B, Forest, Flat 1.491
A B, Pasture, Flat 0.462
Pervious Total 1.953
Impervious Land Use acre
ROADS FLAT 0.065
Impervious Total 0.065
Basin Total 2.018
Element Flows To:
Surface Interflow Groundwater
19017_050620 5/14/2020 2:59:33 PM Page 5
Mitigated Land Use
Public Roadway Areas
Bypass:No
GroundWater:No
Pervious Land Use acre
A B, Lawn, Flat 0.132
Pervious Total 0.132
Impervious Land Use acre
ROADS FLAT 0.472
DRIVEWAYS FLAT 0.055
SIDEWALKS FLAT 0.038
Impervious Total 0.565
Basin Total 0.697
Element Flows To:
Surface Interflow Groundwater
Infiltration Trench Infiltration Trench
19017_050620 5/14/2020 2:59:33 PM Page 6
Water Quality
Bypass:No
GroundWater:No
Pervious Land Use acre
Pervious Total 0
Impervious Land Use acre
ROADS FLAT 0.472
DRIVEWAYS FLAT 0.055
Impervious Total 0.527
Basin Total 0.527
Element Flows To:
Surface Interflow Groundwater
19017_050620 5/14/2020 2:59:33 PM Page 7
Lots & Open Space Tracts
Bypass:Yes
GroundWater:No
Pervious Land Use acre
A B, Lawn, Flat 0.151
A B, Forest, Flat 0.14
A B, Pasture, Flat 0.741
Pervious Total 1.032
Impervious Land Use acre
Impervious Total 0
Basin Total 1.032
Element Flows To:
Surface Interflow Groundwater
19017_050620 5/14/2020 2:59:33 PM Page 8
Routing Elements
Predeveloped Routing
19017_050620 5/14/2020 2:59:33 PM Page 9
Mitigated Routing
Infiltration Trench
Depth:4 ft.
Discharge Structure: 1
Riser Height:3 ft.
Riser Diameter:6 in.
Element Flows To:
Outlet 1 Outlet 2
SSD Table Hydraulic Table
Stage Area Volume Outlet Infilt
(feet) (ac.) (ac-ft.) Struct (cfs) NotUsed NotUsed NotUsed
0.000 0.041 0.000 0.000 0.167 0.000 0.000 0.000
0.083 0.041 0.001 0.000 0.167 0.000 0.000 0.000
0.167 0.041 0.003 0.000 0.167 0.000 0.000 0.000
0.250 0.041 0.004 0.000 0.167 0.000 0.000 0.000
0.333 0.041 0.006 0.000 0.167 0.000 0.000 0.000
0.417 0.041 0.007 0.000 0.167 0.000 0.000 0.000
0.500 0.041 0.008 0.000 0.167 0.000 0.000 0.000
0.583 0.041 0.010 0.000 0.167 0.000 0.000 0.000
0.667 0.041 0.011 0.000 0.167 0.000 0.000 0.000
0.750 0.041 0.012 0.000 0.167 0.000 0.000 0.000
0.833 0.041 0.014 0.000 0.167 0.000 0.000 0.000
0.917 0.041 0.015 0.000 0.167 0.000 0.000 0.000
1.000 0.041 0.017 0.000 0.167 0.000 0.000 0.000
1.083 0.041 0.019 0.000 0.167 0.000 0.000 0.000
1.167 0.041 0.022 0.000 0.167 0.000 0.000 0.000
1.250 0.041 0.025 0.000 0.167 0.000 0.000 0.000
1.333 0.041 0.027 0.000 0.167 0.000 0.000 0.000
1.417 0.041 0.030 0.000 0.167 0.000 0.000 0.000
1.500 0.041 0.033 0.000 0.167 0.000 0.000 0.000
1.583 0.041 0.035 0.000 0.167 0.000 0.000 0.000
1.667 0.041 0.038 0.000 0.167 0.000 0.000 0.000
1.750 0.041 0.041 0.000 0.167 0.000 0.000 0.000
1.833 0.041 0.043 0.000 0.167 0.000 0.000 0.000
1.917 0.041 0.046 0.000 0.167 0.000 0.000 0.000
2.000 0.041 0.048 0.000 0.167 0.000 0.000 0.000
2.083 0.041 0.051 0.000 0.167 0.000 0.000 0.000
2.167 0.041 0.053 0.000 0.167 0.000 0.000 0.000
2.250 0.041 0.056 0.000 0.167 0.000 0.000 0.000
2.333 0.041 0.058 0.000 0.167 0.000 0.000 0.000
2.417 0.041 0.060 0.000 0.167 0.000 0.000 0.000
2.500 0.041 0.063 0.000 0.167 0.000 0.000 0.000
2.583 0.041 0.065 0.000 0.167 0.000 0.000 0.000
2.667 0.041 0.067 0.000 0.167 0.000 0.000 0.000
2.750 0.041 0.069 0.000 0.167 0.000 0.000 0.000
2.833 0.041 0.072 0.000 0.167 0.000 0.000 0.000
2.917 0.041 0.074 0.000 0.167 0.000 0.000 0.000
3.000 0.041 0.076 0.000 0.167 0.000 0.000 0.000
3.083 0.041 0.078 0.124 0.167 0.000 0.000 0.000
3.167 0.041 0.080 0.298 0.167 0.000 0.000 0.000
3.250 0.041 0.081 0.389 0.167 0.000 0.000 0.000
3.333 0.041 0.083 0.455 0.167 0.000 0.000 0.000
3.417 0.041 0.084 0.508 0.167 0.000 0.000 0.000
19017_050620 5/14/2020 2:59:33 PM Page 10
3.500 0.041 0.086 0.557 0.167 0.000 0.000 0.000
3.583 0.041 0.087 0.601 0.167 0.000 0.000 0.000
3.667 0.041 0.089 0.643 0.167 0.000 0.000 0.000
3.750 0.041 0.090 0.682 0.167 0.000 0.000 0.000
3.833 0.041 0.091 0.719 0.167 0.000 0.000 0.000
3.917 0.041 0.093 0.754 0.167 0.000 0.000 0.000
4.000 0.041 0.094 0.787 0.167 0.000 0.000 0.000
19017_050620 5/14/2020 2:59:33 PM Page 11
Analysis Results
POC 1
+ Predeveloped x Mitigated
Predeveloped Landuse Totals for POC #1
Total Pervious Area: 1.953
Total Impervious Area: 0.065
Mitigated Landuse Totals for POC #1
Total Pervious Area: 1.164
Total Impervious Area: 0.565
Flow Frequency Method: Log Pearson Type III 17B
Flow Frequency Return Periods for Predeveloped. POC #1
Return Period Flow(cfs)
2 year 0.030766
5 year 0.04981
10 year 0.066487
25 year 0.093135
50 year 0.117701
100 year 0.14692
Flow Frequency Return Periods for Mitigated. POC #1
Return Period Flow(cfs)
2 year 0.007692
5 year 0.027115
10 year 0.052388
25 year 0.105742
50 year 0.16645
100 year 0.250332
Annual Peaks
19017_050620 5/14/2020 3:00:39 PM Page 12
Annual Peaks for Predeveloped and Mitigated. POC #1
Year Predeveloped Mitigated
1956 0.033 0.015
1957 0.044 0.036
1958 0.030 0.013
1959 0.028 0.011
1960 0.037 0.008
1961 0.022 0.010
1962 0.021 0.001
1963 0.044 0.028
1964 0.027 0.005
1965 0.031 0.016
1966 0.023 0.003
1967 0.025 0.009
1968 0.017 0.002
1969 0.018 0.001
1970 0.021 0.005
1971 0.023 0.015
1972 0.046 0.028
1973 0.021 0.002
1974 0.042 0.008
1975 0.028 0.003
1976 0.024 0.006
1977 0.034 0.001
1978 0.028 0.013
1979 0.036 0.001
1980 0.021 0.003
1981 0.035 0.020
1982 0.028 0.012
1983 0.050 0.005
1984 0.026 0.007
1985 0.024 0.001
1986 0.034 0.020
1987 0.031 0.017
1988 0.014 0.001
1989 0.018 0.001
1990 0.094 0.099
1991 0.043 0.028
1992 0.027 0.001
1993 0.017 0.001
1994 0.024 0.009
1995 0.036 0.018
1996 0.059 0.022
1997 0.043 0.026
1998 0.051 0.049
1999 0.024 0.001
2000 0.027 0.005
2001 0.025 0.001
2002 0.030 0.011
2003 0.020 0.004
2004 0.220 0.198
2005 0.123 0.140
2006 0.124 0.083
2007 0.070 0.048
2008 0.040 0.029
Ranked Annual Peaks
Ranked Annual Peaks for Predeveloped and Mitigated. POC #1
19017_050620 5/14/2020 3:00:39 PM Page 13
Rank Predeveloped Mitigated
1 0.2197 0.1979
2 0.1240 0.1404
3 0.1229 0.0992
4 0.0936 0.0827
5 0.0700 0.0494
6 0.0589 0.0477
7 0.0506 0.0358
8 0.0498 0.0293
9 0.0455 0.0284
10 0.0443 0.0282
11 0.0442 0.0281
12 0.0433 0.0261
13 0.0432 0.0224
14 0.0417 0.0203
15 0.0399 0.0201
16 0.0374 0.0176
17 0.0363 0.0169
18 0.0361 0.0162
19 0.0347 0.0150
20 0.0342 0.0146
21 0.0341 0.0131
22 0.0331 0.0130
23 0.0308 0.0116
24 0.0307 0.0111
25 0.0303 0.0106
26 0.0301 0.0097
27 0.0282 0.0091
28 0.0277 0.0090
29 0.0277 0.0077
30 0.0277 0.0076
31 0.0274 0.0072
32 0.0270 0.0055
33 0.0267 0.0055
34 0.0263 0.0050
35 0.0255 0.0050
36 0.0254 0.0045
37 0.0245 0.0039
38 0.0242 0.0034
39 0.0237 0.0030
40 0.0236 0.0029
41 0.0232 0.0024
42 0.0231 0.0022
43 0.0220 0.0015
44 0.0213 0.0015
45 0.0209 0.0012
46 0.0208 0.0008
47 0.0207 0.0008
48 0.0196 0.0007
49 0.0180 0.0007
50 0.0176 0.0007
51 0.0168 0.0007
52 0.0168 0.0007
53 0.0143 0.0006
19017_050620 5/14/2020 3:00:39 PM Page 14
LID Duration Flows
The Facility PASSED
Flow(cfs) Predev Mit Percentage Pass/Fail
0.0025 70046 512 0 Pass
0.0026 66198 494 0 Pass
0.0027 62482 476 0 Pass
0.0029 59081 458 0 Pass
0.0030 55940 441 0 Pass
0.0031 52948 424 0 Pass
0.0032 50104 404 0 Pass
0.0034 47428 385 0 Pass
0.0035 45049 372 0 Pass
0.0036 42838 357 0 Pass
0.0038 40682 350 0 Pass
0.0039 38582 342 0 Pass
0.0040 36723 330 0 Pass
0.0042 34958 320 0 Pass
0.0043 33267 310 0 Pass
0.0044 31631 303 0 Pass
0.0045 30219 296 0 Pass
0.0047 28825 286 0 Pass
0.0048 27524 277 1 Pass
0.0049 26316 273 1 Pass
0.0051 25126 262 1 Pass
0.0052 23974 256 1 Pass
0.0053 22896 252 1 Pass
0.0055 21856 248 1 Pass
0.0056 20871 237 1 Pass
0.0057 19997 232 1 Pass
0.0059 19124 224 1 Pass
0.0060 18246 214 1 Pass
0.0061 17440 210 1 Pass
0.0062 16683 205 1 Pass
0.0064 15996 197 1 Pass
0.0065 15336 193 1 Pass
0.0066 14738 188 1 Pass
0.0068 14122 182 1 Pass
0.0069 13554 181 1 Pass
0.0070 12980 177 1 Pass
0.0072 12481 175 1 Pass
0.0073 11980 168 1 Pass
0.0074 11508 165 1 Pass
0.0076 11041 161 1 Pass
0.0077 10588 157 1 Pass
0.0078 10170 156 1 Pass
0.0079 9776 152 1 Pass
0.0081 9383 149 1 Pass
0.0082 9028 143 1 Pass
0.0083 8681 137 1 Pass
0.0085 8348 136 1 Pass
0.0086 7999 136 1 Pass
0.0087 7675 134 1 Pass
0.0089 7374 131 1 Pass
0.0090 7114 128 1 Pass
0.0091 6873 127 1 Pass
0.0092 6598 125 1 Pass
19017_050620 5/14/2020 3:00:39 PM Page 15
0.0094 6321 124 1 Pass
0.0095 6038 124 2 Pass
0.0096 5819 122 2 Pass
0.0098 5598 117 2 Pass
0.0099 5352 114 2 Pass
0.0100 5141 113 2 Pass
0.0102 4947 108 2 Pass
0.0103 4750 108 2 Pass
0.0104 4559 106 2 Pass
0.0106 4406 105 2 Pass
0.0107 4232 102 2 Pass
0.0108 4085 101 2 Pass
0.0109 3910 99 2 Pass
0.0111 3776 97 2 Pass
0.0112 3654 95 2 Pass
0.0113 3544 93 2 Pass
0.0115 3418 91 2 Pass
0.0116 3293 89 2 Pass
0.0117 3169 86 2 Pass
0.0119 3029 85 2 Pass
0.0120 2922 82 2 Pass
0.0121 2812 81 2 Pass
0.0123 2711 81 2 Pass
0.0124 2611 81 3 Pass
0.0125 2529 80 3 Pass
0.0126 2436 80 3 Pass
0.0128 2355 79 3 Pass
0.0129 2260 79 3 Pass
0.0130 2189 78 3 Pass
0.0132 2130 77 3 Pass
0.0133 2063 76 3 Pass
0.0134 1985 76 3 Pass
0.0136 1925 76 3 Pass
0.0137 1866 75 4 Pass
0.0138 1797 75 4 Pass
0.0139 1738 74 4 Pass
0.0141 1684 74 4 Pass
0.0142 1632 72 4 Pass
0.0143 1576 72 4 Pass
0.0145 1530 72 4 Pass
0.0146 1482 70 4 Pass
0.0147 1419 69 4 Pass
0.0149 1372 69 5 Pass
0.0150 1324 68 5 Pass
0.0151 1287 66 5 Pass
0.0153 1255 64 5 Pass
0.0154 1221 63 5 Pass
19017_050620 5/14/2020 3:00:54 PM Page 16
Duration Flows
The Facility PASSED
Flow(cfs) Predev Mit Percentage Pass/Fail
0.0154 1221 63 5 Pass
0.0164 978 56 5 Pass
0.0175 783 53 6 Pass
0.0185 625 46 7 Pass
0.0195 499 43 8 Pass
0.0206 405 38 9 Pass
0.0216 340 36 10 Pass
0.0226 278 31 11 Pass
0.0237 217 29 13 Pass
0.0247 186 24 12 Pass
0.0257 164 22 13 Pass
0.0268 135 20 14 Pass
0.0278 111 19 17 Pass
0.0288 98 14 14 Pass
0.0299 85 13 15 Pass
0.0309 73 13 17 Pass
0.0319 64 13 20 Pass
0.0330 55 12 21 Pass
0.0340 47 12 25 Pass
0.0350 40 11 27 Pass
0.0361 37 9 24 Pass
0.0371 32 9 28 Pass
0.0381 30 9 30 Pass
0.0392 27 8 29 Pass
0.0402 24 8 33 Pass
0.0412 23 8 34 Pass
0.0423 20 8 40 Pass
0.0433 17 8 47 Pass
0.0443 14 8 57 Pass
0.0454 12 8 66 Pass
0.0464 11 8 72 Pass
0.0474 10 8 80 Pass
0.0485 10 7 70 Pass
0.0495 9 5 55 Pass
0.0505 8 5 62 Pass
0.0516 7 5 71 Pass
0.0526 7 5 71 Pass
0.0536 7 5 71 Pass
0.0547 7 5 71 Pass
0.0557 7 5 71 Pass
0.0567 7 5 71 Pass
0.0578 7 5 71 Pass
0.0588 7 5 71 Pass
0.0598 6 5 83 Pass
0.0609 6 5 83 Pass
0.0619 6 5 83 Pass
0.0629 6 5 83 Pass
0.0640 6 5 83 Pass
0.0650 5 5 100 Pass
0.0660 5 5 100 Pass
0.0671 5 4 80 Pass
0.0681 5 4 80 Pass
0.0691 5 4 80 Pass
19017_050620 5/14/2020 3:00:55 PM Page 17
0.0702 4 4 100 Pass
0.0712 4 4 100 Pass
0.0722 4 4 100 Pass
0.0733 4 4 100 Pass
0.0743 4 4 100 Pass
0.0753 4 4 100 Pass
0.0764 4 4 100 Pass
0.0774 4 4 100 Pass
0.0784 4 4 100 Pass
0.0795 4 4 100 Pass
0.0805 4 4 100 Pass
0.0815 4 4 100 Pass
0.0826 4 4 100 Pass
0.0836 4 3 75 Pass
0.0846 4 3 75 Pass
0.0857 4 3 75 Pass
0.0867 4 3 75 Pass
0.0877 4 3 75 Pass
0.0888 4 3 75 Pass
0.0898 4 3 75 Pass
0.0908 4 3 75 Pass
0.0919 4 3 75 Pass
0.0929 4 3 75 Pass
0.0939 3 3 100 Pass
0.0950 3 3 100 Pass
0.0960 3 3 100 Pass
0.0970 3 3 100 Pass
0.0981 3 3 100 Pass
0.0991 3 3 100 Pass
0.1001 3 2 66 Pass
0.1012 3 2 66 Pass
0.1022 3 2 66 Pass
0.1032 3 2 66 Pass
0.1043 3 2 66 Pass
0.1053 3 2 66 Pass
0.1063 3 2 66 Pass
0.1074 3 2 66 Pass
0.1084 3 2 66 Pass
0.1094 3 2 66 Pass
0.1105 3 2 66 Pass
0.1115 3 2 66 Pass
0.1125 3 2 66 Pass
0.1136 3 2 66 Pass
0.1146 3 2 66 Pass
0.1156 3 2 66 Pass
0.1167 3 2 66 Pass
0.1177 3 2 66 Pass
19017_050620 5/14/2020 3:00:55 PM Page 18
Water Quality
Water Quality BMP Flow and Volume for POC #1
On-line facility volume: 0 acre-feet
On-line facility target flow: 0 cfs.
Adjusted for 15 min: 0 cfs.
Off-line facility target flow: 0 cfs.
Adjusted for 15 min: 0 cfs.
19017_050620 5/14/2020 3:00:55 PM Page 19
LID Report
19017_050620 5/14/2020 3:01:38 PM Page 20
POC 2
+ Predeveloped x Mitigated
Predeveloped Landuse Totals for POC #2
Total Pervious Area: 0
Total Impervious Area: 0.527
Mitigated Landuse Totals for POC #2
Total Pervious Area: 0
Total Impervious Area: 0.527
Flow Frequency Method: Log Pearson Type III 17B
Flow Frequency Return Periods for Predeveloped. POC #2
Return Period Flow(cfs)
2 year 0.219763
5 year 0.298565
10 year 0.356375
25 year 0.436087
50 year 0.500486
100 year 0.569334
Flow Frequency Return Periods for Mitigated. POC #2
Return Period Flow(cfs)
2 year 0.219763
5 year 0.298565
10 year 0.356375
25 year 0.436087
50 year 0.500486
100 year 0.569334
Annual Peaks
Annual Peaks for Predeveloped and Mitigated. POC #2
Year Predeveloped Mitigated
19017_050620 5/14/2020 3:02:34 PM Page 21
1956 0.171 0.171
1957 0.309 0.309
1958 0.222 0.222
1959 0.210 0.210
1960 0.303 0.303
1961 0.155 0.155
1962 0.169 0.169
1963 0.294 0.294
1964 0.213 0.213
1965 0.216 0.216
1966 0.182 0.182
1967 0.206 0.206
1968 0.136 0.136
1969 0.143 0.143
1970 0.169 0.169
1971 0.159 0.159
1972 0.197 0.197
1973 0.164 0.164
1974 0.332 0.332
1975 0.224 0.224
1976 0.192 0.192
1977 0.277 0.277
1978 0.224 0.224
1979 0.294 0.294
1980 0.167 0.167
1981 0.270 0.270
1982 0.225 0.225
1983 0.394 0.394
1984 0.212 0.212
1985 0.198 0.198
1986 0.276 0.276
1987 0.196 0.196
1988 0.115 0.115
1989 0.146 0.146
1990 0.532 0.532
1991 0.274 0.274
1992 0.216 0.216
1993 0.129 0.129
1994 0.192 0.192
1995 0.292 0.292
1996 0.256 0.256
1997 0.227 0.227
1998 0.339 0.339
1999 0.191 0.191
2000 0.221 0.221
2001 0.199 0.199
2002 0.224 0.224
2003 0.159 0.159
2004 0.502 0.502
2005 0.587 0.587
2006 0.305 0.305
2007 0.247 0.247
2008 0.308 0.308
Ranked Annual Peaks
Ranked Annual Peaks for Predeveloped and Mitigated. POC #2
Rank Predeveloped Mitigated
1 0.5865 0.5865
19017_050620 5/14/2020 3:02:34 PM Page 22
2 0.5321 0.5321
3 0.5024 0.5024
4 0.3944 0.3944
5 0.3392 0.3392
6 0.3323 0.3323
7 0.3090 0.3090
8 0.3076 0.3076
9 0.3050 0.3050
10 0.3028 0.3028
11 0.2944 0.2944
12 0.2942 0.2942
13 0.2923 0.2923
14 0.2769 0.2769
15 0.2755 0.2755
16 0.2735 0.2735
17 0.2699 0.2699
18 0.2557 0.2557
19 0.2468 0.2468
20 0.2266 0.2266
21 0.2247 0.2247
22 0.2244 0.2244
23 0.2243 0.2243
24 0.2239 0.2239
25 0.2224 0.2224
26 0.2209 0.2209
27 0.2163 0.2163
28 0.2158 0.2158
29 0.2128 0.2128
30 0.2116 0.2116
31 0.2096 0.2096
32 0.2062 0.2062
33 0.1987 0.1987
34 0.1985 0.1985
35 0.1973 0.1973
36 0.1964 0.1964
37 0.1921 0.1921
38 0.1918 0.1918
39 0.1913 0.1913
40 0.1823 0.1823
41 0.1709 0.1709
42 0.1691 0.1691
43 0.1686 0.1686
44 0.1668 0.1668
45 0.1644 0.1644
46 0.1587 0.1587
47 0.1587 0.1587
48 0.1551 0.1551
49 0.1456 0.1456
50 0.1427 0.1427
51 0.1360 0.1360
52 0.1287 0.1287
53 0.1149 0.1149
19017_050620 5/14/2020 3:02:34 PM Page 23
LID Duration Flows
The Facility PASSED
Flow(cfs) Predev Mit Percentage Pass/Fail
0.0176 76160 76160 100 Pass
0.0185 72183 72183 100 Pass
0.0194 68596 68596 100 Pass
0.0204 65083 65083 100 Pass
0.0213 61887 61887 100 Pass
0.0222 58820 58820 100 Pass
0.0232 55940 55940 100 Pass
0.0241 53264 53264 100 Pass
0.0250 50717 50717 100 Pass
0.0260 48227 48227 100 Pass
0.0269 45997 45997 100 Pass
0.0278 43860 43860 100 Pass
0.0288 41853 41853 100 Pass
0.0297 39920 39920 100 Pass
0.0306 38024 38024 100 Pass
0.0316 36296 36296 100 Pass
0.0325 34753 34753 100 Pass
0.0334 33211 33211 100 Pass
0.0344 31780 31780 100 Pass
0.0353 30423 30423 100 Pass
0.0362 29178 29178 100 Pass
0.0372 27988 27988 100 Pass
0.0381 26836 26836 100 Pass
0.0390 25758 25758 100 Pass
0.0400 24736 24736 100 Pass
0.0409 23714 23714 100 Pass
0.0418 22785 22785 100 Pass
0.0428 21818 21818 100 Pass
0.0437 20926 20926 100 Pass
0.0446 20071 20071 100 Pass
0.0456 19309 19309 100 Pass
0.0465 18570 18570 100 Pass
0.0474 17856 17856 100 Pass
0.0483 17087 17087 100 Pass
0.0493 16394 16394 100 Pass
0.0502 15760 15760 100 Pass
0.0511 15167 15167 100 Pass
0.0521 14645 14645 100 Pass
0.0530 14096 14096 100 Pass
0.0539 13630 13630 100 Pass
0.0549 13089 13089 100 Pass
0.0558 12602 12602 100 Pass
0.0567 12136 12136 100 Pass
0.0577 11718 11718 100 Pass
0.0586 11294 11294 100 Pass
0.0595 10920 10920 100 Pass
0.0605 10510 10510 100 Pass
0.0614 10121 10121 100 Pass
0.0623 9740 9740 100 Pass
0.0633 9398 9398 100 Pass
0.0642 9092 9092 100 Pass
0.0651 8779 8779 100 Pass
0.0661 8447 8447 100 Pass
19017_050620 5/14/2020 3:02:34 PM Page 24
0.0670 8144 8144 100 Pass
0.0679 7861 7861 100 Pass
0.0689 7601 7601 100 Pass
0.0698 7311 7311 100 Pass
0.0707 7058 7058 100 Pass
0.0717 6806 6806 100 Pass
0.0726 6592 6592 100 Pass
0.0735 6360 6360 100 Pass
0.0745 6120 6120 100 Pass
0.0754 5910 5910 100 Pass
0.0763 5676 5676 100 Pass
0.0773 5477 5477 100 Pass
0.0782 5293 5293 100 Pass
0.0791 5096 5096 100 Pass
0.0800 4888 4888 100 Pass
0.0810 4722 4722 100 Pass
0.0819 4574 4574 100 Pass
0.0828 4419 4419 100 Pass
0.0838 4261 4261 100 Pass
0.0847 4137 4137 100 Pass
0.0856 3983 3983 100 Pass
0.0866 3851 3851 100 Pass
0.0875 3721 3721 100 Pass
0.0884 3600 3600 100 Pass
0.0894 3494 3494 100 Pass
0.0903 3382 3382 100 Pass
0.0912 3276 3276 100 Pass
0.0922 3171 3171 100 Pass
0.0931 3065 3065 100 Pass
0.0940 2961 2961 100 Pass
0.0950 2860 2860 100 Pass
0.0959 2747 2747 100 Pass
0.0968 2665 2665 100 Pass
0.0978 2583 2583 100 Pass
0.0987 2490 2490 100 Pass
0.0996 2422 2422 100 Pass
0.1006 2347 2347 100 Pass
0.1015 2273 2273 100 Pass
0.1024 2187 2187 100 Pass
0.1034 2102 2102 100 Pass
0.1043 2055 2055 100 Pass
0.1052 1989 1989 100 Pass
0.1062 1944 1944 100 Pass
0.1071 1884 1884 100 Pass
0.1080 1823 1823 100 Pass
0.1089 1768 1768 100 Pass
0.1099 1722 1722 100 Pass
19017_050620 5/14/2020 3:02:50 PM Page 25
Duration Flows
The Facility PASSED
Flow(cfs) Predev Mit Percentage Pass/Fail
0.1099 1763 1763 100 Pass
0.1138 1528 1528 100 Pass
0.1178 1334 1334 100 Pass
0.1217 1189 1189 100 Pass
0.1257 1054 1054 100 Pass
0.1296 940 940 100 Pass
0.1336 841 841 100 Pass
0.1375 753 753 100 Pass
0.1414 681 681 100 Pass
0.1454 603 603 100 Pass
0.1493 528 528 100 Pass
0.1533 469 469 100 Pass
0.1572 426 426 100 Pass
0.1612 389 389 100 Pass
0.1651 351 351 100 Pass
0.1691 313 313 100 Pass
0.1730 280 280 100 Pass
0.1770 257 257 100 Pass
0.1809 233 233 100 Pass
0.1848 203 203 100 Pass
0.1888 188 188 100 Pass
0.1927 165 165 100 Pass
0.1967 150 150 100 Pass
0.2006 135 135 100 Pass
0.2046 126 126 100 Pass
0.2085 111 111 100 Pass
0.2125 104 104 100 Pass
0.2164 91 91 100 Pass
0.2204 81 81 100 Pass
0.2243 74 74 100 Pass
0.2282 66 66 100 Pass
0.2322 63 63 100 Pass
0.2361 58 58 100 Pass
0.2401 53 53 100 Pass
0.2440 48 48 100 Pass
0.2480 46 46 100 Pass
0.2519 42 42 100 Pass
0.2559 41 41 100 Pass
0.2598 35 35 100 Pass
0.2638 32 32 100 Pass
0.2677 32 32 100 Pass
0.2716 28 28 100 Pass
0.2756 25 25 100 Pass
0.2795 23 23 100 Pass
0.2835 22 22 100 Pass
0.2874 22 22 100 Pass
0.2914 21 21 100 Pass
0.2953 17 17 100 Pass
0.2993 15 15 100 Pass
0.3032 12 12 100 Pass
0.3072 10 10 100 Pass
0.3111 8 8 100 Pass
0.3150 7 7 100 Pass
19017_050620 5/14/2020 3:02:50 PM Page 26
0.3190 7 7 100 Pass
0.3229 7 7 100 Pass
0.3269 7 7 100 Pass
0.3308 7 7 100 Pass
0.3348 6 6 100 Pass
0.3387 6 6 100 Pass
0.3427 5 5 100 Pass
0.3466 5 5 100 Pass
0.3506 5 5 100 Pass
0.3545 5 5 100 Pass
0.3584 5 5 100 Pass
0.3624 4 4 100 Pass
0.3663 4 4 100 Pass
0.3703 4 4 100 Pass
0.3742 4 4 100 Pass
0.3782 4 4 100 Pass
0.3821 4 4 100 Pass
0.3861 4 4 100 Pass
0.3900 4 4 100 Pass
0.3940 4 4 100 Pass
0.3979 3 3 100 Pass
0.4018 3 3 100 Pass
0.4058 3 3 100 Pass
0.4097 3 3 100 Pass
0.4137 3 3 100 Pass
0.4176 3 3 100 Pass
0.4216 3 3 100 Pass
0.4255 3 3 100 Pass
0.4295 3 3 100 Pass
0.4334 3 3 100 Pass
0.4374 3 3 100 Pass
0.4413 3 3 100 Pass
0.4452 3 3 100 Pass
0.4492 3 3 100 Pass
0.4531 3 3 100 Pass
0.4571 3 3 100 Pass
0.4610 3 3 100 Pass
0.4650 3 3 100 Pass
0.4689 3 3 100 Pass
0.4729 3 3 100 Pass
0.4768 3 3 100 Pass
0.4808 3 3 100 Pass
0.4847 3 3 100 Pass
0.4886 3 3 100 Pass
0.4926 3 3 100 Pass
0.4965 3 3 100 Pass
0.5005 3 3 100 Pass
19017_050620 5/14/2020 3:02:50 PM Page 27
Water Quality
Water Quality BMP Flow and Volume for POC #2
On-line facility volume: 0.0765 acre-feet
On-line facility target flow: 0.0912 cfs.
Adjusted for 15 min: 0.0912 cfs.
Off-line facility target flow: 0.0517 cfs.
Adjusted for 15 min: 0.0517 cfs.
19017_050620 5/14/2020 3:02:50 PM Page 28
LID Report
19017_050620 5/14/2020 3:02:50 PM Page 29
Model Default Modifications
Total of 0 changes have been made.
PERLND Changes
No PERLND changes have been made.
IMPLND Changes
No IMPLND changes have been made.
19017_050620 5/14/2020 3:02:50 PM Page 30
Appendix
Predeveloped Schematic
19017_050620 5/14/2020 3:02:51 PM Page 31
Mitigated Schematic
April 2017 GENERAL USE LEVEL DESIGNATON FOR BASIC TREATMENT For
BaySaver Technologies, LLC BayFilter™ System using BayFilter Cartridge (BFC)
Ecology’s Decision: 1. Based on BaySaver Technologies’ application submissions, Ecology hereby issues a
Basic Treatment General Use Level Designation (GULD) for the BayFilter™.
As a stormwater treatment device for Basic treatment (TSS) removal.
The Basic Treatment GULD is for the BayFilter Cartridge (BFC) and is limited to the following maximum flow rate:
a. BFC Cartridge maximum flow rate of 0.70 gpm/sq ft
o 30 gpm (0.067 cfs) per cartridge (example dimensions: 28-inches in diameter, 29-inches tall (43 sq ft filter area))
Canisters that provide 0.70 gpm per sq ft filter area, regardless of
dimensions meet this requirement
o Media Blend of Silica Sand, Perlite, and Activated Alumina
2. Ecology approves use of BayFilter™ Cartridges for treatment at the above flow rate per cartridge. Designers shall calculate the water quality design flow rates using the following procedures:
Western Washington: For treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute flow rate as calculated using the latest version of the Western Washington Hydrology Model or other Ecology-
approved continuous runoff model.
Eastern Washington: For treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute flow rate as calculated using one of the three methods described in Chapter 2.2.5 of the Stormwater Management Manual for Eastern Washington (SWMMEW) or local manual.
Entire State: For treatment installed downstream of detention, the water quality design flow rate is the full 2-year release rate of the detention facility.
3. The GULD has no expiration date, but it may be amended or revoked by Ecology, and is subject to the conditions specified below. Ecology’s Conditions of Use: BayFilter™ units shall comply with these conditions: 1. Design, assemble, install, operate, and maintain BayFilter™ units in accordance with BaySaver Technologies’ applicable manuals and documents and the Ecology Decision. 2. Maintenance: The required inspection/maintenance interval for stormwater treatment devices is often dependent upon the efficiency of the device and the degree of pollutant loading from a particular drainage basin. Therefore, Ecology does not endorse or recommend a “one size fits all” maintenance cycle for a particular model/size of manufactured filter treatment device.
BaySaver recommends that the following be considered during the design application of the BayFilter Cartridge systems:
o Water Quality Flow Rate
o Anticipated Pollutant Load
o Maintenance Frequency
A BayFilter System tested adjacent to construction activity required maintenance after 4-months of operation. Monitoring personnel observed construction washout in the device during the testing period; the construction activity may have resulted
in a shorter maintenance interval.
Ecology has found that pre-treatment device prior to the BayFilter system can provide a reduction in pollutant loads on these systems, thereby extending the maintenance interval.
Test results provided to Ecology from other BayFilter Systems, including the above mentioned system that was evaluated again after construction activities had been completed, have indicated the BayFilter System typically has longer maintenance intervals, sometimes exceeding 12-months.
The BayFilter system contains filter fabric that is highly oleophilic (oil absorptive). When sufficient quantities of oils are present in the runoff, the oil and subsequent sediment particles may become attached to the fabric. As a result, it may compromise the maintenance interval of the BayFilter system. Oil control BMP’s should be installed upstream of BayFilter installations if warranted, and/or the BayFilter system should be inspected after any known oil spill or release.
Owners/operators must inspect BayFilter systems for a minimum of twelve months from the start of post-construction operation to determine site-specific inspection/maintenance schedules and requirements. Owners/operators must
conduct inspections monthly during the wet season, and every other month during the dry season. (According to the SWMMWW, the wet season in western Washington is October 1 to April 30. According to SWMMEW, the wet season in eastern Washington is October 1 to June 30.) After the first year of operation, owners/operators must conduct inspections based on the findings during the first year of inspections or the manufacturer’s anticipated maintenance interval, whichever is more frequent.
Conduct inspections by qualified personnel, follow manufacturer’s guidelines, and must use methods capable of determining either a decrease in treated effluent flowrate and/or a decrease in pollutant removal ability.
3. When inspections are performed, the following findings typically serve as maintenance triggers:
Accumulated vault sediment depths exceed an average of 2 inches, or
Accumulated sediment depths on the tops of the cartridges exceed an average of 0.5 inches, or
Standing water remains in the vault between rain events.
Bypass during storms smaller than the design storm.
Note: If excessive floatables (trash and debris) are present, perform minor maintenance consisting of gross solids removal, not cartridge replacement. 4. Discharges from the BayFilter™ units shall not cause or contribute to water quality standards violations in receiving waters. Applicant: Advanced Drainage Systems - BaySaver Applicant’s Address: 4640 Trueman Blvd
Hilliard, Ohio 43065 Application Documents:
Technical Evaluation Report BayFilter System, Grandview Place Apartments, Vancouver, Washington and Appendices A through O (May 18, 2011)
Washington State Department of Ecology Technology Assessment Protocol – Environmental BayFilter™ Conditional Use Designation Application (March 2007)
BaySaver Technologies, Inc. BayFilter™ System Washington State Technical and Design
Manual, Version 1.1 (December 2006)
Efficiency Assessment of BaySeparator and Bay filter Systems in the Richard Montgomery High School January 6.2009.
Evaluation of MASWRC Sample Collection, Sample Analysis, and Data Analysis, December 27, 2008
Letter from Mid-Atlantic Stormwater Research Center to BaySaver Technologies, In. dated October 22, 2009.
Letter from Mid-Atlantic Stormwater Research Center to BaySaver Technologies, In. dated November 5, 2009.
Maryland Department of the Environment letter to BaySaver Technologies dated Jan. 13, 2008 regarding approval of BayFilter as a standalone BMP for Stormwater treatment.
NJCAT letter to BaySaver Technologies dated June 18, 2009 regarding Interim Certification.
Applicant’s Use Level Request:
General use level designation as a basic treatment device in accordance with Ecology’s
Stormwater Management Manual for Western Washington. Applicant’s Performance Claims:
Removes and retains 80% of TSS based on laboratory testing using Sil-Co-Sil 106 as a
laboratory stimulant.
Removes 42% of dissolved Copper and 38% of dissolved Zinc.
Expected to remove 50% of the influent phosphorus load. Ecology’s Recommendations:
BaySaver Technologies, Inc. has shown Ecology, through laboratory and field testing, that the BayFilter™ System using BayFilter Cartridge (BFC) is capable of attaining Ecology’s Basic Treatment goals.
Findings of Fact:
Based on field testing in Vancouver, WA, at a flow rate less than or equal to 30 gpm per canister, the BayFilter™ system demonstrated a total suspended solids removal efficiency
of greater than 80% for influent concentrations between 100 and 200 mg/l and an effluent concentration < 20 mg/l for influent concentration < 100 mg/l.
Based on laboratory testing, at a flowrate of 30 GPM per filter, the BayFilter™ system demonstrated a total suspended solids removal efficiency of 81.5% using Sil-Co-Sil 106
with an average influent concentration of 268 mg/L and zero initial sediment loading.
Based on laboratory testing, at a flowrate of 30 GPM per filter, the BayFilter™ system demonstrated a dissolved phosphorus removal efficiency of 55% using data from the Richard Montgomery High School field-testing. The average influent concentration was
0.31 mg/L phosphorus and zero initial sediment loading.
Based on data from field-testing at Richard Montgomery High School in Rockville, MD
the BayFilter system demonstrated a Cu removal efficiency of 51% and 41% for total and dissolved Cu respectively. Average influent concentrations are 41.6 µg/l total and 17.5 µg/l dissolved.
Based on data from field-testing at Richard Montgomery High School in Rockville, MD
the BayFilter system demonstrated a Zn removal efficiency of 45% and 38% for total and dissolved Cu, respectively. Average influent concentrations are 354 µg/l total and 251 µg/l dissolved, respectively. Other BayFilter™ Related Issues to be Addressed By the Company: 1. BaySaver should continue monitoring the system for a longer period to help establish a maintenance period and to obtain data from additional qualified storms. Conduct testing to obtain information about maintenance requirements in order to come up with a maintenance cycle.
2. Conduct loading tests on the filter to determine maximum treatment life of the system.
3. Conduct testing to determine if oils and grease affect the treatment ability of the filter. This should include a determination of how oil and grease may affect the ion-exchange capacity of the system if BaySaver wishes to make claims for phosphorus removal.
4. BaySaver should develop easy-to-implement methods of determining when a BayFilter system
requires maintenance (cleaning and filter replacement).
5. BaySaver must update their O&M documents to include information and instructions on the
“24-hour draw-down” method to determine if cartridges need replacing.
Technology Description: Download at www.BaySaver.com
Contact Information: Applicant: Daniel Figola Advanced Drainage Systems - BaySaver 4640 Trueman Blvd
Hilliard, Ohio 43065 (614) 658-0265 dfigola@ads-pipe.com Applicant website: www.BaySaver.com
Ecology web link: http://www.ecy.wa.gov/programs/wq/stormwater/newtech/index.html Ecology: Douglas C. Howie, P.E. Department of Ecology
Water Quality Program (360) 407-6444 douglas.howie@ecy.wa.gov Revision History
Date Revision April 2008 Original use-level-designation document
February 2010 Revision
August 2011 GULD awarded for Basic Treatment
April 2012 Maintenance requirements updated. August 2012 Revised design storm criteria
December 2012 Revised contact information and document formatting
December 2013 Revised expiration and submittal dates December 2014 Revised Inspection/maintenance discussion, Updated cartridge descriptions January 2015 Revised discussion for flow rate controls
December 2015 Revised Expiration date
January 2016 Revised Manufacturer Contact Information and expiration date January 2017 Revised Expiration, QAPP and TER due dates
April 2017 Updated to create separate ULDs for the BayFilter™ using BayFilter Cartridge (BFC) and the BayFilter™ using Enhanced Media Cartridge (EMC)
Appendix 3 Soils Report
ii
REPORT OF GEOTECHNICAL
INVESTIGATION AND ENGINEERING
PROPOSED DEVELOPMENT – LEAH’S LANDING DUPLEXES
10548 MILL ROAD SOUTHEAST YELM, WA Prepared for: Topline Development
Mike Kempinski
P.O. BOX 52 Yelm, Washington 98557 Prepared by:
_____________________________ _____________________________ Luke McCann, G.I.T. Medhanie G. Tecle, P.E. Senior Geologist Engineering Manager
MATERIALS TESTING & CONSULTING, INC. (MTC) 2118 Black Lake Blvd SW
Olympia, WA 98512
Phone: (360) 534-9777 Fax: (360) 534-9779 October 7, 2019 MTC Project Number: 19S147 Copyright 2019 Materials Testing & Consulting, Inc. All Rights Reserved
10-07-2019
Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
iii
Table of Contents
1.0 INTRODUCTION ............................................................................................................... 4
1.1 GENERAL PROJECT DESCRIPTION ......................................................................................................... 4
1.2 PURPOSE AND SCOPE OF SERVICES ...................................................................................................... 4
2.0 SITE EXPLORATION ........................................................................................................ 5
2.1 SITE EXPLORATION ................................................................................................................................... 5 3.0 EXISTING SOIL CONDITIONS........................................................................................ 6
3.1 SITE SURFACE CONDITIONS .................................................................................................................... 6
3.2 AREA GEOLOGY ......................................................................................................................................... 6
3.3 SOIL CONDITIONS ...................................................................................................................................... 6
3.4 GROUNDWATER CONDITIONS ................................................................................................................ 6
4.0 GEOTECHNICAL DESIGN RECOMMENDATIONS ..................................................... 7
4.1 SEISMIC DESIGN PARAMETERS .............................................................................................................. 7
4.2 SUBGRADE PREPARATION: ...................................................................................................................... 7
4.3 FOUNDATIONS ............................................................................................................................................ 7
4.4 SLAB-ON-GRADE ........................................................................................................................................ 9
4.5 PAVEMENT DESIGN DISCUSSION ......................................................................................................... 10
4.5.1 Flexible Pavement ............................................................................................................................... 10 4.5.2 Rigid Pavements and Flatworks .......................................................................................................... 11
4.6 INFILTRATION RATE DETERMINATION .............................................................................................. 11
4.6.1 Gradation Analysis Method & Results ................................................................................................ 11 4.6.2 Treatment Potential ............................................................................................................................. 13
4.7 SITE DRAINAGE CONTROLS .................................................................................................................. 13
5.0 CONSTRUCTION RECOMMENDATIONS ................................................................... 14
5.1 EARTHWORK ............................................................................................................................................. 14
5.1.1 SCOPE OF SITE GRADING .............................................................................................................. 14 5.1.2 EXCAVATION ................................................................................................................................... 14 5.1.3 SUBGRADE EVALUATION AND PREPARATION ....................................................................... 14 5.1.4 SITE PREPARATION, EROSION CONTROL AND WET WEATHER CONSTRUCTION .......... 14
5.2 STRUCTURAL FILL MATERIALS, AND COMPACTION ..................................................................... 15
5.2.1 MATERIALS ...................................................................................................................................... 15 5.2.2 FILL PLACEMENT AND COMPACTION ....................................................................................... 16
5.3 TEMPORARY EXCAVATIONS AND SLOPES ........................................................................................ 16
5.4 PERMANENT SLOPES ............................................................................................................................... 17
5.5 UTILITY TRENCHES AND EXCAVATIONS .......................................................................................... 17 6.0 ADDITIONAL RECOMMENDED SERVICES .............................................................. 18
7.0 LIMITATIONS .................................................................................................................. 19
Appendix A. SITE VICINITY AND LOCATION ..................................................................... 20 Appendix B. SITE AERIAL MAP WITH EXPLORATION LOCATIONS ................................ 21 Appendix C. EXPLORATION LOGS ...................................................................................... 22 Appendix D. LABORATORY TEST RESULTS........................................................................ 33
Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
4
1.0 INTRODUCTION
1.1 GENERAL PROJECT DESCRIPTION
This report presents the findings and recommendations of Materials Testing & Consulting, Inc.’s (MTC)
geotechnical investigation and engineering conducted in support of the construction of a new 5-lot
residential plat, including infiltration features, a new access roadway, and duplex structures. A regional
vicinity and general site plan of the project site are shown in Figures 1 and 2 of Appendices A and B,
respectively.
MTC understands that the proposed new construction is anticipated to employ shallow foundation
elements if site conditions are suitable. It is anticipated that loads will be typical for the type and
materials of construction and that no unusually large or vibratory loads are expected.
MTC should be allowed to review the final plans and specifications for the project to ensure that the
recommendations presented herein are appropriate. Recommendations and conclusions presented by
this report will need to be re-evaluated in the event that changes to the proposed construction are made.
1.2 PURPOSE AND SCOPE OF SERVICES
The purpose of our study was to explore and document subsurface conditions at the site and to provide
geotechnical engineering recommendations for design and construction of the proposed development.
Our scope of services was consistent with that presented in our Proposal for Geotechnical Engineering
Services, dated March 29, 2019.
Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
5
2.0 SITE EXPLORATION
2.1 SITE EXPLORATION
Site exploration activities were performed on May 10, 2019. During the site visit, MTC completed the
advancement of six (6) geotechnical test pits (TP), and three (3) Wildcat dynamic cone penetrometer
tests (DCP). Exploration locations were selected by MTC (and agreed to by the client) with respect to
the proposed development features and representative coverage. Explorations were field-located by
MTC personnel. All explorations were advanced to maximum achievable depths resulting in practical
machine refusal due to caving gravel filling back in the holes. Exploration locations are shown in Figure
2 of Appendix B. Complete exploration logs are provided in Appendix C. Complete laboratory test
results are included as Appendix D.
Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
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3.0 EXISTING SOIL CONDITIONS
3.1 SITE SURFACE CONDITIONS
Existing site grade of the subject project area is generally flat and grassed, partly developed with an
existing residence on the western frontage that is anticipated to be demolished.
3.2 AREA GEOLOGY
The Washington Interactive Geologic Map, maintained by the Department of Natural Resources
Division of Geology and Earth Resources (DNR DGER), depicts mapped surface geology of 1:100,000-
scale detail. The project area is mapped as Quaternary Glacial Outwash (Qgo). Commonly containing
sand and gravel, locally containing silt and clay; also contains lacustrine deposits and ice-contact
stratified drift. Glacial outwash is typically dense to very dense or hard, stratified, poor to moderately
sorted, resistant to erosion, and can have variable low to high permeability.
The site is not known to comprise any geohazards.
3.3 SOIL CONDITIONS
The exploration logs in Appendix C present details of soils encountered at each exploration location.
Site soils were generally consistent, with a common overriding layer of grass topsoil over dark brown
weathered sandy outwash soils with significant organic content down to approximately 2 feet. Beneath
these cover soils, down to the maximum depths explored was a generally consistent layer of tan to
brown outwash sands and gravels. Cover soils were generally loose, with the unweathered lower
outwash becoming dense with depth.
3.4 GROUNDWATER CONDITIONS
No natural surface water features were present within the project area at the time of this study. The
closest major surface water feature is a small pond at Cochran Memorial Park approximately ¼ mile
away.
During exploration, no apparent groundwater table or seepage was encountered. Available Department
of Ecology well logs from nearby locations indicate the groundwater table exists between 18 and 50 feet
deep.
Given the topography of the site area, known geology, and relationship to major surface water features
in the vicinity, regional static groundwater level would be presumably below depths of concern for the
proposed development. MTC’s scope of investigation did not include observation and determination of
seasonal variations, conclusive measurement or monitoring of groundwater elevations at the time of
exploration, or determination of regional groundwater levels past the depths explored.
Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
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4.0 GEOTECHNICAL DESIGN RECOMMENDATIONS
4.1 SEISMIC DESIGN PARAMETERS
The USGS Seismic Design Map Tool was used to determine site-specific seismic design coefficients and
spectral response accelerations for the project site assuming design Site Class C to D, representing a
subsurface profile (upper 100 feet) of generally very dense soil conditions. Parameters in Table 1 below
were calculated using 2008 USGS hazard data and 2015 International Building Code standards:
Table 1. Seismic Design Parameters – Site Class D
Mapped Acceleration Parameters (MCE horizontal) SS 1.246 g
S1 0.497 g
Site Coefficient Values Fa 1.001
Fv 1.503
Calculated Peak SRA SMS 1.248 g
SM1 0.747 g
Design Peak SRA (2/3 of peak) SDS 0.832 g
SD1 0.498 g
Peak Ground Acceleration PGA(M) 0.516
Seismic Design Category – Short Period (0.2 Second) Acceleration D
Seismic Design Category – 1-Second Period Acceleration D
4.2 SUBGRADE PREPARATION:
Surfaces beneath all structural features shall be stripped free of loose and overriding organic soils down
to the underlying tan soils approximately 1.5 to 2.0 feet below present grade (BPG). Some localized
areas near Test Pit 5 may be found to have an underlying horizon of soft silty soils. If encountered,
these poor soil conditions can be overcome by overexcavating down to suitable sandy or gravelly native
soils and then backfilling with structural fill.
4.3 FOUNDATIONS
Two requirements must be fulfilled in the design of foundations. First, the loads must be limited to the
allowable bearing capacity of the foundation soils to maintain stability. And second, the differential
settlement must not exceed an amount that will produce adverse behavior of the structure. Allowable
bearing pressure is determined while addressing settlement considerations that include differential
settlement. Both shallow and deep soils must be considered because either can cause excess settlement.
MTC understands the project design will employ relatively shallow perimeter and spread footings as
needed.
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• Allowable Soil Bearing Capacity:
1,500 pounds per square foot (psf) for footings placed on compacted structural fill installed over
tan colored, organic free, native soils compacted in place, or on compacted structural fill
installed over these compacted native soils. The allowable bearing capacity may be increased by
1/3 for transient loading due to wind and seismic events
• Structural Fill Preparation:
For lateral and bearing support, structural fill placement below footings shall extend at minimum
a distance past each edge of the base of the footing equal to the depth of structural fill placed
below the footing [e.g., for a 2.0-foot wide footing, fills placed to approximately 1.5 feet below
footing grade will require a minimum backfill width of 5.0 feet (1.5 feet each side plus 2.0-foot
width of footing)].
• Minimum Footing Depth:
For a shallow perimeter and spread footing system, all exterior footings shall be embedded a
minimum of 18 inches and all interior footings shall be embedded a minimum of 12 inches
below the lowest adjacent finished grade, but not less than the depth required by design.
However, all footings must penetrate to the prescribed bearing stratum cited above and be
supported by the recommended base section, and no footings should be founded above organic
soils, soft or loose soils, or uncontrolled fills.
• Minimum Footing Width:
Footings should be proportioned to meet the stated bearing capacity and/or the IBC 2012 (or
current) minimum requirements. For a shallow perimeter and spread footing system, continuous
strip footings should be a minimum of 16 inches wide and interior or isolated column footings
should be a minimum of 24 inches wide.
• Lateral Load Resistance:
Lateral loads can be resisted by passive pressure against buried portions of foundation elements
and sliding resistance along its base. We recommend an allowable lateral pressure equal to that
generated by a fluid with an equivalent unit weight of 200 pcf EFW. This value assumes
foundations are backfilled with structural fill to a minimum horizontal thickness of 18 inches and
includes a factor of safety of two. The upper 18 inches of soil should be ignored unless the area
is paved or covered with concrete, due to soil softening associated with freeze/thaw.
Sliding resistance between footings and the foundation base pad may be factored in terms of
contribution to lateral resistance. Assuming imported structural fill is placed beneath footings,
an allowable coefficient of friction of 0.33 may be applied. This value assumes concrete placed
directly on the structural fill and includes a factor of safety of 1.5.
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4.4 SLAB-ON-GRADE
MTC understands concrete slab-on-grade pads are proposed. Based on typical construction practices,
we assume finished slab grade will be similar to or marginally above present grade for the below
recommendations. If grades are planned to be substantially raised or lowered from existing grade, MTC
should be contacted to provide revised or alternative recommendations.
MTC recommends the below activities and parameters for slab-on-grade design and construction.
• Subgrade Modulus:
Overriding organic-rich soils should be removed from beneath slab areas (approximately 3 to 5
feet of overburden).
A Subgrade Modulus (k) of 200 pci is recommended for use in design of slab-on-grade exterior
slabs constructed on a structural fill pad above native gravelly outwash soils of suitably firm and
unyielding quality.
• Proof Roll:
Prior to the placement of capillary break material and slab construction, as well as structural fills
if called for, the exposed subgrade shall be proof-rolled with a fully loaded dump truck to
confirm no soft or deflecting areas are present. This is to ensure the subgrade is evenly prepared
and adequate for support of the slab. MTC recommends that we be contacted for observation of
the proof roll and visual confirmation of prepared base suitability. Areas of excessive yielding
should be excavated to suitably firm conditions and backfilled with structural fill.
• Capillary Break:
A capillary break will be helpful to maintain a dry slab floor and reduce the potential for floor
damage resulting from shallow perched water inundation. To provide a capillary moisture break,
a 6-inch thick, properly compacted granular mat consisting of open-graded, free-draining angular
aggregate is recommended below floor slabs. To provide additional slab structural support, or to
substitute for a structural fill base pad where specified, MTC recommends the capillary break
should consist of crushed rock all passing the 1-inch sieve and no more than 3 percent (by
weight) passing the U.S. No. #4 sieve, compacted in accordance with Section 5.2.2 of this
report.
• Vapor Barrier:
A vapor retarding membrane such as 10 mil polyethylene film should be placed beneath all floor
slabs to prevent transmission of moisture where floor coverings may be affected. Care should be
taken during construction not to puncture or damage the membrane. To protect the membrane, a
layer of sand no more than 2 inches thick may be placed over the membrane if desired.
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• Structural Design Considerations:
MTC assumes design and specifications of slabs will be assessed and confirmed by the project
design engineer. We suggest a minimum reinforced concrete structural section of 6.0 inches be
considered to help protect against cracking and localized settlement, especially where larger
equipment or localized loads are anticipated.
4.5 PAVEMENT DESIGN DISCUSSION
4.5.1 Flexible Pavement
Washington Department of Transportation (WSDOT) Pavement Policy (2015) was used to provide the
pavement section recommendations for the proposed roadway developments. Based on the overall size
of the planned roadway, we assumed typically low traffic. Table 2 includes preliminary
recommendations for impervious hot-mix asphalt (HMA) pavement and base course thickness for the
new roadway. This recommendation assumes that the subgrade will be prepared following the
recommendations provided in this report and the traffic assumptions are valid.
Table 2: Preliminary Pavement Design Recommendations for Roadway
Pavement Layer Type Minimum Thickness, inches WSDOT Specifications
Hot-Mix Asphalt 3 Section 5.4.4
Base Course (Dense Graded) 12 Section 5.4.4
These calculated sections should be considered preliminary until verifying the parameters, traffic
loading, and assumed grading are applicable to the final project design. We recommend pavement
sections be reviewed by the project designer, who may apply an alternative section for final project use
based on the conditions reported herein and final design and construction preferences.
The main entrance/exit drive will likely experience different traffic volumes than the far end of the
pavement areas. As a result, consideration could be given to increasing the pavement section in the
main entrance/exit drive. Pavement sections presented in the above table should not be used for areas
which experience repeated truck traffic/parking, equipment or truck parking areas, entrances and exit
aprons, or contain trash dumpster loading zones. In these areas, a Portland Cement Concrete (PCC)
pavement should be used.
One of the important considerations in designing a high quality and durable pavement is providing
adequate drainage. Design of drainage for the proposed pavement section is outside of MTC’s scope of
work at this time. It is important that bird baths (leeching basins) and surface waves are not created
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during construction of the HMA layer. A proper slope should also be allowed, and drainage should be
provided along the edges of pavements and around catch basins to prevent accumulation of free water
within the base course, which otherwise may result in subgrade softening and pavement deterioration
under exposure and repeated traffic conditions.
All pavements require regular maintenance and repair in order to maintain the serviceability of the
pavement. These repairs and maintenance are due to normal wear and tear of the pavement surface and
are required in order to extend the serviceability life of the pavement. However, after 10 years of
service, a normal pavement structure is likely to deteriorate to a point where pavement rehabilitation
may be required to maintain the serviceability. The deterioration is more likely if the pavement is
constructed over poor subgrade soils or in area of higher traffic volumes.
4.5.2 Rigid Pavements and Flatworks
Rigid pavement components are commonly utilized for portions of accesses and ancillary exterior
improvements. The project civil designer may re-evaluate the below general recommendations for
pavement thicknesses and base sections, if necessary, to ensure proper application to a given structure
and use. MTC recommends that we be contacted for further consultation if the below sections are
proposed to be reduced.
Concrete driveway aprons and curb alignments, if utilized, should consist of a minimum 6-inch
thickness of unreinforced concrete pavement over structural base fill. Base thickness should correspond
to related location and anticipated traffic loading. For light traffic areas, a 12-inch minimum base
thickness (total 18-inch section) can be applied. For heavy traffic zones, we recommend allotting a 18-
inch minimum base section beneath the pavement, or the incorporation of reinforcing steel in the
concrete.
Concrete sidewalks, walkways and patios if present may consist of a minimum 4-inch section of plain
concrete (unreinforced) installed over a 6-inch minimum compacted base of crushed rock. At locations
where grade has been raised with structural fill, a 4-inch minimum crushed rock section may be used.
Flatworks should employ frequent joint controls to limit cracking potential.
4.6 INFILTRATION RATE DETERMINATION
MTC understands design of on-site stormwater controls are pending the results of this study to confirm
design parameters and interpreted depths to perched seasonal groundwater and restrictive soil features.
4.6.1 Gradation Analysis Method & Results
During test pit excavations for general site investigation, MTC additionally collected representative
samples of native soil deposits among potential infiltration strata and depths. We understand the project
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will be subject to infiltration design based on the City of Tumwater Drainage Design and Stormwater
Control Manual, and the Washington Department of Ecology Stormwater Management Manual for
Western Washington (DoE SMMWW). For initial site infiltration characterization within the scope of
this study, laboratory gradation analyses were completed including sieve and hydrometer tests for
stormwater design characterization and rate determination to supplement field observations. Results of
laboratory testing in terms of rate calculation are summarized below.
Laboratory results were interpreted to recommended design inputs in accordance with methods of the
2012 DoE SMMWW. Gradation results were applied to the Massmann (2003) equation (1) to calculate
Ksat representing the initial saturated hydraulic conductivity.
(1) log10(Ksat) = -1.57 + 1.90*D10 + 0.015*D60 - 0.013*D90 - 2.08*ff
Corrected Ksat values presented below are a product of the initial Ksat and correction factor CFT. For a
generalized site-wide design situation, we have applied a site variability factor of CFv = 1.0 along with
typical values of CFt = 0.4 (for the Grain Size Method) and CFm = 0.9 (assuming standard influent
control).
(2) CFT = CFv x CFt x CFm = 1.0 x 0.4 x 0.9 = 0.36
Results were cross-referenced with test pit logs to determine the validity and suitability of unique
materials as an infiltration receptor.
Table 3. Usable Results of Massmann Analysis
TP #
Sample Depth (BPG)
Unit Extent (ft) Soil Type D10 D60 D90 Fines(%) Ksat (in/hr)
Corrected Ksat (in/hr)
Cation Exchange Capacity (meq/100g)
Organic Content %
2 1.0 ~0.5 to 2 SM 0.042 0.356 1.337 17.8 19.59 7.0 8.8 6.6
2 4.5 ~2 to 5+ SP 0.177 1.651 24.053 4.4 34.54 12.4 NA NA
2 6.0 ~5 to 10+ SP-SM 0.072 1.487 24.336 10.5 16.06 5.78 NA NA
Beneath sod and cover soils, the lower existing tan outwash soils were observed to generally exhibit
lower fines content and minimal oxidation patterns. For any stormwater infiltration feature, we
recommend a maximum design rate of up to 5.78 inches/hour be considered for undisturbed soils.
MTC recommends the facility designer review these results and stated assumptions per reference
literature to ensure applicability with the proposed development, level of anticipated controls, and long-
term maintenance plan. The designer may make reasonable adjustments to correction factors and the
resulting design values based on these criteria to ensure design and operational intent is met. We
recommend that we be contacted if substantial changes to rate determination are considered.
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4.6.2 Treatment Potential
Depending on stormwater and runoff sources, some stormwater features, such as rain gardens or
pervious pavements may require treatment. Stormwater facilities utilizing native soils as treatment
media typically require Cation Exchange Capacities (CEC) of greater than 5 milliequivalents per
100grams (meq/100g) and organic contents greater than 1% (this may vary depending on local code).
soils at likely shallow treatment depths were found to have a Cation Exchange Capacity of 8.8 meq/100g
and an organic content of 6.6%.
4.7 SITE DRAINAGE CONTROLS
MTC recommends exterior drainage improvements be implemented with site development to limit the
adverse effects of piping and influx on site in the winter months. Pavement or flatwork stormwater
catchments should all be tightlined to the project designed stormwater management features or outfalls.
This will limit the amount of transient water within proximity to the building during its vertical
migration.
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5.0 CONSTRUCTION RECOMMENDATIONS
5.1 EARTHWORK
5.1.1 SCOPE OF SITE GRADING
A grading plan was not available to MTC at the time of this report. Based on discussions with the client
and provided conceptual plans, this study assumes finished site grade will approximate current grade.
Therefore, depths referred to in this report are considered roughly equivalent to final depths.
5.1.2 EXCAVATION
Excavations can generally be performed with conventional earthmoving equipment such as bulldozers,
scrapers, and excavators.
5.1.3 SUBGRADE EVALUATION AND PREPARATION
After excavations have been completed to the planned subgrade elevations, but before placing fill or
structural elements, the exposed subgrade should be evaluated under the full-time observation and
guidance of an MTC representative. Where appropriate, the subgrade should be proof-rolled with a
minimum of two passes with a fully loaded dump truck, water truck or scraper. In circumstances where
this seems unfeasible, an MTC representative may use alternative methods for subgrade evaluation.
Any loose soil should be compacted to a firm and unyielding condition and at least to 95 percent of the
modified Proctor maximum dry density per ASTM D1557. Any areas that are identified as being soft or
yielding during subgrade evaluation should be overexcavated to a firm and unyielding condition or to
the depth determined by the geotechnical engineer. Where overexcavation is performed below a
structure, the overexcavation area should extend beyond the outside of the footing a distance equal to the
depth of the overexcavation below the footing. The overexcavated areas should be backfilled with
properly compacted structural fill, with the fill extending outside from the structure footprint at a
minimum 1H:1V down to native soils.
5.1.4 SITE PREPARATION, EROSION CONTROL AND WET WEATHER CONSTRUCTION
Any silty or organic rich native cover soils may be moisture-sensitive and become soft and difficult to
traverse with construction equipment when wet. During wet weather, the contractor should take
measures to protect any exposed soil subgrades, limit construction traffic during earthwork activities,
and limit machine use only to areas undergoing active preparation.
Once the geotechnical engineer has approved a subgrade, further measures should be implemented to
prevent degradation or disturbance of the subgrade. These measures could include, but are not limited
to, placing a layer of crushed rock or lean concrete on the exposed subgrade, or covering the exposed
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subgrade with a plastic tarp and keeping construction traffic off the subgrade. Once subgrade has been
approved, any disturbance because the subgrade was not protected should be repaired by the contractor
at no cost to the owner.
During wet weather, earthen berms or other methods should be used to prevent runoff from draining into
excavations. All runoff should be collected and disposed of properly. Measures may also be required to
reduce the moisture content of on-site soils in the event of wet weather. These measures can include,
but are not limited to, air drying and soil amendment, etc.
MTC recommends earthwork activities take place during the summer dry season.
5.2 STRUCTURAL FILL MATERIALS, AND COMPACTION
5.2.1 MATERIALS
All material placed below structures or pavement areas should be considered structural fill. Structural
fill material shall be free of deleterious materials, have a maximum particle size of 4 inches, and be
compactable to the required compaction level.
Excavated surface soils containing organics and high fines content are not considered suitable for reuse
as structural fill. These may be reused for landscaping purposes where appropriate. Reuse of
underlying clean native gravelly outwash soils may be considered suitable for re-use as structural fill on
a case-by-case basis, determined by adequate follow-up laboratory testing of soils subject to reuse. Soils
with fines content near or greater than 10% increased fines content may likely be moisture sensitive, and
become difficult to use during wet weather. Care should be taken by the earthwork contractor during
grading to avoid contaminating stockpiled soils that are planned for reuse as structural fill with native
organic materials.
Imported material can be used as structural fill. Imported structural fill material should conform to
Section 9-03.14(1), Gravel Borrow, of the most recent edition (at the time of construction) of the State
of Washington Department of Transportation Standard Specifications for Road, Bridge, and Municipal
Construction (WSDOT Standard Specifications).
Controlled-density fill (CDF) or lean mix concrete can be used as an alternative to structural fill
materials, except in areas where free-draining materials are required or specified.
Frozen soil is not suitable for use as structural fill. Fill material may not be placed on frozen soil.
The contractor should submit samples of each of the required earthwork materials to the geotechnical
engineer for evaluation and approval prior to delivery to the site. The samples should be submitted at
least 5 days prior to their delivery and sufficiently in advance of the work to allow the contractor to
identify alternative sources if the material proves unsatisfactory.
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5.2.2 FILL PLACEMENT AND COMPACTION
Prior to placement and compaction, structural fill should be moisture conditioned to within 3 percentage
points of its optimum moisture content for coarse-grained soils and 3 percentage points of its optimum
moisture content for fine-grained and mixed soils. Individual lifts of structural fill shall not exceed 6
inches, in loose state, for compactive efforts using a walk-behind or hand operated compaction
equipment, 8 inches using light to medium-duty rollers, and 12 inches using heavy-duty compaction
equipment.
All structural fill shall be compacted to a firm and unyielding condition and to a minimum percent
compaction based on its modified Proctor maximum dry density as determined per ASTM D1557.
Structural fill placed beneath each of the following shall be compacted to the indicated percent
compaction:
Foundation and Floor Slab Subgrades: 95 Percent
Pavement Subgrades (upper 2 feet): 95 Percent
Pavement Subgrades (below 2 feet): 90 Percent
Utility Trenches (upper 4 feet): 95 Percent
Utility Trenches (below 4 feet): 90 Percent
Note: For lateral and bearing support, structural fill placement below footings shall extend at minimum
a distance past each edge of the base of the footing equal to the depth of structural fill placed below the
footing [e.g., for a 2.0-foot wide footing, fills placed to approximately 1.5 feet below footing grade will
require a minimum backfill width of 5.0 feet (1.5 feet each side plus 2.0-foot width of footing)].
If reused native gravels contain greater than 30% oversized material, MTC recommends that the
placement and compaction be evaluated by proof rolling with a fully loaded dump truck or water truck
under the observation of MTC personnel.
We recommend structural fill placement and compaction be observed on a full-time basis by an MTC
representative. A sufficient number of tests should be performed to verify compaction of each lift. The
number of tests required will vary depending on the fill material, its moisture condition and the
equipment being used. Initially, more frequent tests will be required while the contractor establishes the
means and methods required to achieve proper compaction.
5.3 TEMPORARY EXCAVATIONS AND SLOPES
All excavations and slopes must comply with applicable local, state, and federal safety regulations.
Construction site safety is the sole responsibility of the Contractor, who shall also be solely responsible
for the means, methods, and sequencing of construction operations. We are providing soil type
information solely as a service to our client for planning purposes. Under no circumstances should the
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information be interpreted to mean that MTC is assuming responsibility for construction site safety or
the Contractor’s activities; such responsibility is not being implied and should not be inferred.
Temporary excavations in the existing upper weathered native soils should be inclined no steeper than
2H:1V, although applying lesser grades may be necessary depending on actual conditions encountered
and the potential presence of water seepage. Heavy construction equipment, building materials,
excavated soil, and vehicular traffic should not be allowed near the top of any excavation.
Temporary excavations and slopes should be protected from the elements by covering with plastic
sheeting or some other similar impermeable material. Sheeting sections should overlap by at least 12
inches and be tightly secured with sandbags, tires, staking, or other means to prevent wind from
exposing the soils under the sheeting.
5.4 PERMANENT SLOPES
MTC recommends that new areas of permanent slopes be inclined no greater than 3H:1V. Permanent
slopes should be planted with a deep-rooted, rapid-growth vegetative cover as soon as possible after
completion of slope construction. Alternatively, the slope should be covered with plastic, straw, etc.
until it can be landscaped.
5.5 UTILITY TRENCHES AND EXCAVATIONS
The contractor shall be responsible for the safety of personnel working in utility trenches. Given that
steep excavations in native soils may be prone to caving, we recommend all utility trenches, but
particularly those greater than 4 feet in depth, be supported in accordance with state and federal safety
regulations.
Pipe bedding material should conform to the manufacturer’s recommendations and be worked around
the pipe to provide uniform support. Cobbles exposed in the bottom of utility excavations should be
covered with pipe bedding or removed to avoid inducing concentrated stresses on the pipe.
Trench backfill should be placed and compacted as structural fill as recommended in Section 5.2.
Particular care should be taken to insure bedding or fill material is properly compacted to provide
adequate support to the pipe. Jetting or flooding is not a substitute for mechanical compaction and
should not be allowed.
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6.0 ADDITIONAL RECOMMENDED SERVICES
The recommendations made in this report are based on the assumption that an adequate program of tests
and observations will be made during construction to verify compliance with these recommendations.
Testing and observations performed during construction should include, but not necessarily be limited
to, the following:
• Geotechnical plan review and engineering consultation as needed prior to construction phase,
• Observations and testing during site preparation, earthwork, structural fill, and pavement section
placement,
• Consultation on temporary excavation cutslopes and shoring if needed,
• Testing and inspection of any concrete or masonry included in the final construction plans, and
• Consultation as may be required during construction.
We strongly recommend that MTC be retained for the construction of this project to provide these and
other services. Our knowledge of the project site and the design recommendations contained herein will
be of benefit in the event that difficulties arise and either modifications or additional geotechnical
engineering recommendations are required or desired. We can also, in a timely fashion observe the
actual soil conditions encountered during construction, evaluate the applicability of the
recommendations presented in this report to the soil conditions encountered, and recommend
appropriate changes in design or construction procedures if conditions differ from those described
herein.
We further recommend that project plans and specifications be reviewed by us to verify compatibility
with our conclusions and recommendations.
Also, MTC retains fully accredited, WABO-certified laboratory and inspection personnel, and is
available for this project’s testing, observation and inspection needs. Information concerning the scope
and cost for these services can be obtained from our office.
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7.0 LIMITATIONS
Recommendations contained in this report are based on our understanding of the proposed development
and construction activities, our field observations and exploration and our laboratory test results. It is
possible that soil and groundwater conditions could vary and differ between or beyond the points
explored. If soil or groundwater conditions are encountered during construction that vary or differ from
those described herein, we should be notified immediately in order to review and provide supplemental
recommendations. If the scope of the proposed construction, including the proposed loads or structural
locations, changes from that described in this report, we should be notified to review and provide
supplemental recommendations.
We have prepared this report in substantial accordance with the generally accepted geotechnical
engineering practice as it exists in the site area at the time of our study. No warranty, expressed or
implied, is made. The recommendations provided in this report are based on the assumption that an
adequate program of tests and observations will be conducted by MTC during the construction phase in
order to evaluate compliance with our recommendations.
This report may be used only by the Client and their design consultants and only for the purposes stated
within a reasonable time from its issuance, but in no event later than 18 months from the date of the
report. It is the Client's responsibility to ensure that the Designer, Contractor, Subcontractors, etc. are
made aware of this report in its entirety. Note that if another firm assumes Geotechnical Engineer of
Record responsibilities, they need to review this report and either concur with the findings, conclusions,
and recommendations or provide alternate findings, conclusions and recommendation under the
guidance of a professional engineer registered in the State of Washington.
Land or facility use, on- and off-site conditions, regulations, or other factors may change over time, and
additional work may be required. Based on the intended use of the report, MTC may recommend that
additional work be performed and that an updated report be issued. Non-compliance with any of these
requirements by the Client or anyone else will release MTC from any liability resulting from the use of
this report. The Client, the design consultants, and any unauthorized party agree to defend, indemnify,
and hold harmless MTC from any claim or liability associated with such unauthorized use or non-
compliance. We recommend that MTC be given the opportunity to review the final project plans and
specifications to evaluate if our recommendations have been properly interpreted. We assume no
responsibility for misinterpretation of our recommendations.
The scope of work for this subsurface exploration and geotechnical report did not include environmental
assessments or evaluations regarding the presence or absence of wetlands or hazardous substances in the
soil, surface water, or groundwater at this site.
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Appendix A. SITE VICINITY AND LOCATION
Materials Testing & Consulting, Inc. 2118 Black Lake Blvd SW Olympia, WA 98512
Site Vicinity & Location Maps 10548 Mill Road Southeast Yelm, WA
FIGURE 1
Site Vicinity
Site Location
Map Source: Google Imagery 2019
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Appendix B. SITE AERIAL MAP WITH EXPLORATION LOCATIONS
Materials Testing & Consulting, Inc. 2118 Black Lake Blvd SW Olympia, WA 98512
Site Aerial Map with Exploration Locations 10548 Mill Road Southeast Yelm, WA
FIGURE 2
SCALE IS APPROXIMATE * Not for Construction *
Map Source:
Client Provided Survey
TP-2
TP-3 TP-1
0 80
SCALE (FEET)
TP-4 & DCP-1
TP-5 & DCP-2 TP-6 & DCP-3
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Appendix C. EXPLORATION LOGS
Exploration logs are shown in full in this appendix for DCP tests and test pits. The explorations were
monitored by MTC personnel who examined and visually classified the materials encountered in
accordance with the Unified Soil Classification System (USCS), obtained representative soil samples,
and recorded pertinent information including soil sample depths, stratigraphy, soil engineering
characteristics, and groundwater occurrence. All samples were placed in plastic bags to limit moisture
loss, labeled, and returned to our laboratory for further examination and testing. Upon completion, test
pits were backfilled with excavated soils.
The stratification lines shown on the individual logs represent the approximate boundaries between soil
types; actual transitions may be either more gradual or more severe. The conditions depicted are for the
date and location indicated only, and it should not necessarily be expected that they are representative of
conditions at other locations and times.
Dynamic Cone Penetrometer (DCP) tests were conducted at representative locations within the proposed
development. DCP test locations were correlated with adjacent or nearby soil explorations to most
accurately assess results in terms of observed stratigraphy per location. During DCP advancement, blow
counts were recorded in 10-centimeter (4-inch) increments as a thirty-five-pound weight was dropped a
distance of 15 inches. Blow counts were then converted to resistance (kg/cm2), standard penetration
blow counts (N-values) and corresponding soil consistency.
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Materials Testing & Consulting, Inc. 2118 Black Lake Blvd SW
Olympia, WA 98512
Exploration Log Key
FIGURE 3
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WILDCAT DYNAMIC CONE LOG Page 1 of 1
Materials Testing and Consulting
2118 Black Lake Blvd SW PROJECT NUMBER:19S147
Olympia, WA 98512 DATE STARTED:05-10-2019
DATE COMPLETED:05-10-2019
HOLE #:DCP-1
CREW:LM, RG SURFACE ELEVATION:Existing Grade
PROJECT:Leahs Landing WATER ON COMPLETION:None Encountered
ADDRESS:10549 Mill Rd, Yelm, WA HAMMER WEIGHT:35 lbs.
LOCATION:Near Test Pits 6 CONE AREA:10 sq. cm
BLOWS RESISTANCE GRAPH OF CONE RESISTANCE TESTED CONSISTENCY
DEPTH PER 10 cm Kg/cm² 0 50 100 150 N'SAND & SILT CLAY
-3 13.3 •••3 VERY LOOSE SOFT
-9 40.0 •••••••••••11 MEDIUM DENSE STIFF
- 1 ft 8 35.5 ••••••••••10 LOOSE STIFF
-6 26.6 •••••••7 LOOSE MEDIUM STIFF
-6 26.6 •••••••7 LOOSE MEDIUM STIFF
- 2 ft 7 31.1 •••••••••8 LOOSE MEDIUM STIFF
-7 31.1 •••••••••8 LOOSE MEDIUM STIFF
-10 44.4 ••••••••••••12 MEDIUM DENSE STIFF
- 3 ft 11 48.8 ••••••••••••••13 MEDIUM DENSE STIFF
- 1 m 11 48.8 ••••••••••••••13 MEDIUM DENSE STIFF
-12 46.3 •••••••••••••13 MEDIUM DENSE STIFF
- 4 ft 21 81.1 •••••••••••••••••••••••23 MEDIUM DENSE VERY STIFF
-28 108.1 •••••••••••••••••••••••••••••••-MEDIUM DENSE VERY STIFF
-33 127.4 ••••••••••••••••••••••••••••••••••••-DENSE HARD
- 5 ft 38 146.7 ••••••••••••••••••••••••••••••••••••••••••-DENSE HARD
-
-
- 6 ft
-
- 2 m
- 7 ft
-
-
- 8 ft
-
-
- 9 ft
-
-
- 3 m 10 ft
-
-
-
- 11 ft
-
-
- 12 ft
-
-
- 4 m 13 ft
WILDCAT.XLS
Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
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WILDCAT DYNAMIC CONE LOG Page 1 of 1
Materials Testing and Consulting
2118 Black Lake Blvd SW PROJECT NUMBER:19S147
Olympia, WA 98512 DATE STARTED:05-10-2019
DATE COMPLETED:05-10-2019
HOLE #:DCP-2
CREW:LM, RG SURFACE ELEVATION:Existing Grade
PROJECT:Leahs Landing WATER ON COMPLETION:None Encountered
ADDRESS:10549 Mill Rd, Yelm, WA HAMMER WEIGHT:35 lbs.
LOCATION:Near Test Pit 5 CONE AREA:10 sq. cm
BLOWS RESISTANCE GRAPH OF CONE RESISTANCE TESTED CONSISTENCY
DEPTH PER 10 cm Kg/cm² 0 50 100 150 N'SAND & SILT CLAY
-4 17.8 •••••5 LOOSE MEDIUM STIFF
-9 40.0 •••••••••••11 MEDIUM DENSE STIFF
- 1 ft 9 40.0 •••••••••••11 MEDIUM DENSE STIFF
-7 31.1 •••••••••8 LOOSE MEDIUM STIFF
-6 26.6 •••••••7 LOOSE MEDIUM STIFF
- 2 ft 4 17.8 •••••5 LOOSE MEDIUM STIFF
-4 17.8 •••••5 LOOSE MEDIUM STIFF
-6 26.6 •••••••7 LOOSE MEDIUM STIFF
- 3 ft 7 31.1 •••••••••8 LOOSE MEDIUM STIFF
- 1 m 6 26.6 •••••••7 LOOSE MEDIUM STIFF
-7 27.0 •••••••7 LOOSE MEDIUM STIFF
- 4 ft 6 23.2 ••••••6 LOOSE MEDIUM STIFF
-10 38.6 •••••••••••11 MEDIUM DENSE STIFF
-40 154.4 ••••••••••••••••••••••••••••••••••••••••••••-DENSE HARD
- 5 ft 50 193.0 •••••••••••••••••••••••••••••••••••••••••••••••-VERY DENSE HARD
-
-
- 6 ft
-
- 2 m
- 7 ft
-
-
- 8 ft
-
-
- 9 ft
-
-
- 3 m 10 ft
-
-
-
- 11 ft
-
-
- 12 ft
-
-
- 4 m 13 ft
WILDCAT.XLS
Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
26
WILDCAT DYNAMIC CONE LOG Page 1 of 1
Materials Testing and Consulting
2118 Black Lake Blvd SW PROJECT NUMBER:19S147
Olympia, WA 98512 DATE STARTED:05-10-2019
DATE COMPLETED:05-10-2019
HOLE #:DCP-1
CREW:LM, RG SURFACE ELEVATION:Existing Grade
PROJECT:Leahs Landing WATER ON COMPLETION:None Encountered
ADDRESS:10549 Mill Rd, Yelm, WA HAMMER WEIGHT:35 lbs.
LOCATION:Near Test Pits 4 CONE AREA:10 sq. cm
BLOWS RESISTANCE GRAPH OF CONE RESISTANCE TESTED CONSISTENCY
DEPTH PER 10 cm Kg/cm² 0 50 100 150 N'SAND & SILT CLAY
-5 22.2 ••••••6 LOOSE MEDIUM STIFF
-9 40.0 •••••••••••11 MEDIUM DENSE STIFF
- 1 ft 8 35.5 ••••••••••10 LOOSE STIFF
-7 31.1 •••••••••8 LOOSE MEDIUM STIFF
-9 40.0 •••••••••••11 MEDIUM DENSE STIFF
- 2 ft 15 66.6 •••••••••••••••••••19 MEDIUM DENSE VERY STIFF
-16 71.0 ••••••••••••••••••••20 MEDIUM DENSE VERY STIFF
-12 53.3 •••••••••••••••15 MEDIUM DENSE STIFF
- 3 ft 21 93.2 •••••••••••••••••••••••••••-MEDIUM DENSE VERY STIFF
- 1 m 20 88.8 •••••••••••••••••••••••••25 MEDIUM DENSE VERY STIFF
-17 65.6 •••••••••••••••••••18 MEDIUM DENSE VERY STIFF
- 4 ft 22 84.9 ••••••••••••••••••••••••24 MEDIUM DENSE VERY STIFF
-21 81.1 •••••••••••••••••••••••23 MEDIUM DENSE VERY STIFF
-26 100.4 •••••••••••••••••••••••••••••-MEDIUM DENSE VERY STIFF
- 5 ft 26 100.4 •••••••••••••••••••••••••••••-MEDIUM DENSE VERY STIFF
-
-
- 6 ft
-
- 2 m
- 7 ft
-
-
- 8 ft
-
-
- 9 ft
-
-
- 3 m 10 ft
-
-
-
- 11 ft
-
-
- 12 ft
-
-
- 4 m 13 ft
WILDCAT.XLS
Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
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Materials Testing & Consulting Inc.Olympia, WA
Geotechnical Consulting
MTC Job # 19S147
Yelm, WALeah's Landing
Log of Test Pit TP-1
Date Started : 5/10/19
Date Completed : 5/10/19
Sampling Method : Grab Samples
Location : See Map
Logged By : RG
Depth in Feet0
1
2
3
4
5
6
7
8
9
10
11
12
13
14 USCSTS
SM
SP GRAPHICDESCRIPTION
SOD & TOPSOIL, dark brown, lighty moist, loose, minor gravel up to 1", moderate to heavy organics (thin roots). TOPSOIL
SILTY SAND, dark brown, lightly moist, medium dense, minor gravel up to 2", medium-grained sand. Approximately 5% gravel, 80% sand, 15% fines
WEATHERED OUTWASH
POORLY GRADED SAND WITH GRAVEL, tan, lightly moist, gravel up to 8", medium dense, course-grained sand. Approximately 30% gravel, 65% sand, 5% fines
GLACIAL OUTWASH
Total Depth 6.0' BPGTerminated due to caving.No seepage or groundwater observed.Water LevelSample% Finer than #200% Moisture
Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
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Materials Testing & Consulting Inc.Olympia, WA
Geotechnical Consulting
MTC Job # 19S147
Yelm, WALeah's Landing
Log of Test Pit TP-2
Date Started : 5/10/19
Date Completed : 5/10/19
Sampling Method : Grab Samples
Location : See Map
Logged By : RG
Depth in Feet0
1
2
3
4
5
6
7
8
9
10
11
12
13
14 USCSTS
SM
SP
SP-SM GRAPHICDESCRIPTION
SOD & TOPSOIL, dark brown, lighty moist, loose, minor gravel up to 1", moderate to heavy organics (thin roots). TOPSOIL
SILTY SAND, dark brown, lightly moist, medium dense, minor gravel up to 2", medium-grained sand. Approximately 5% gravel, 80% sand, 15% fines
WEATHERED OUTWASH
POORLY GRADED SAND WITH GRAVEL, tan, lightly moist, gravel up to 8", medium dense, course-grained sand. Approximately 30% gravel, 65% sand, 5% fines
GLACIAL OUTWASH
POORLY GRADED SAND WITH SILT AND GRAVEL, tan, very moist, gravel up to 8", medium dense, course-grained sand. Approximately 30% gravel, 60% sand, 10% fines
GLACIAL OUTWASH
Total Depth 10' BPGTerminated due to caving.No seepage or groundwater observed.Water LevelSample% Finer than #200% Moisture
Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
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Materials Testing & Consulting Inc.Olympia, WA
Geotechnical Consulting
MTC Job # 19S147
Yelm, WALeah's Landing
Log of Test Pit TP-3
Date Started : 5/10/19
Date Completed : 5/10/19
Sampling Method : Grab Samples
Location : See Map
Logged By : RG
Depth in Feet0
1
2
3
4
5
6
7
8
9
10
11
12
13
14 USCSTS
SM
SP
SP-SM GRAPHICDESCRIPTION
SOD & TOPSOIL, dark brown, lighty moist, loose, minor gravel up to 1", moderate to heavy organics (thin roots). TOPSOIL
SILTY SAND, dark brown, lightly moist, medium dense, minor gravel up to 2", medium-grained sand. Approximately 5% gravel, 80% sand, 15% fines
WEATHERED OUTWASH
POORLY GRADED SAND WITH GRAVEL, tan, lightly moist, gravel up to 8", medium dense, course-grained sand. Approximately 30% gravel, 65% sand, 5% fines
GLACIAL OUTWASH
POORLY GRADED SAND WITH SILT AND GRAVEL, tan, very moist, gravel up to 8", medium dense, course-grained sand. Approximately 30% gravel, 60% sand, 10% fines
GLACIAL OUTWASH
Total Depth 6' BPGTerminated due to caving.No seepage or groundwater observed.Water LevelSample% Finer than #200% Moisture
Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
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Materials Testing & Consulting Inc.Olympia, WA
Geotechnical Consulting
MTC Job # 19S147
Yelm, WALeah's Landing
Log of Test Pit TP-4
Date Started : 5/10/19
Date Completed : 5/10/19
Sampling Method : Grab Samples
Location : See Map
Logged By : RG
Depth in Feet0
1
2
3
4
5
6
7
8
9
10
11
12
13
14 USCSTS
SM
SP
SP-SM GRAPHICDESCRIPTION
SOD & TOPSOIL, dark brown, lighty moist, loose, minor gravel up to 1", moderate to heavy organics (thin roots). TOPSOIL
SILTY SAND, dark brown, lightly moist, medium dense, minor gravel up to 2" Approximately 5% gravel, 80% sand, 15% fines
lense of gravel from 1.5 to 2.0 feet
WEATHERED OUTWASH
POORLY GRADED SAND WITH GRAVEL, tan, lightly moist, gravel up to 8", medium dense, course-grained sand. Approximately 30% gravel, 65% sand, 5% fines
GLACIAL OUTWASH
POORLY GRADED SAND WITH SILT AND GRAVEL, tan, very moist, gravel up to 8", medium dense, course-grained sand. Approximately 30% gravel, 60% sand, 10% fines
GLACIAL OUTWASH
Total Depth 6' BPGTerminated due to caving.No seepage or groundwater observed.Water LevelSample% Finer than #200% Moisture
Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
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Materials Testing & Consulting Inc.Olympia, WA
Geotechnical Consulting
MTC Job # 19S147
Yelm, WALeah's Landing
Log of Test Pit TP-5
Date Started : 5/10/19
Date Completed : 5/10/19
Sampling Method : Grab Samples
Location : See Map
Logged By : RG
Depth in Feet0
1
2
3
4
5
6
7
8
9
10
11
12
13
14 USCSTS
SM
SP
SP-SM GRAPHICDESCRIPTION
SOD & TOPSOIL, dark brown, lighty moist, loose, minor gravel up to 1", moderate to heavy organics (thin roots). TOPSOIL
SILTY SAND, dark brown, lightly moist, medium dense, minor gravel up to 2" Approximately 5% gravel, 80% sand, 15% fines
WEATHERED OUTWASH
POORLY GRADED SAND WITH GRAVEL, tan, very moist, gravel up to 8", medium dense, course-grained sand. Approximately 30% gravel, 65% sand, 5% fines
Lense of silty sand, +30% fines, from 3.5 to 4.5 feet
GLACIAL OUTWASH
POORLY GRADED SAND WITH SILT AND GRAVEL, tan, very moist, gravel up to 8", medium dense, course-grained sand. Approximately 30% gravel, 60% sand, 10% fines
GLACIAL OUTWASH
Total Depth 7' BPGTerminated due to caving.No seepage or groundwater observed.Water LevelSample% Finer than #200% Moisture
Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
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Materials Testing & Consulting Inc.Olympia, WA
Geotechnical Consulting
MTC Job # 19S147
Yelm, WALeah's Landing
Log of Test Pit TP-6
Date Started : 5/10/19
Date Completed : 5/10/19
Sampling Method : Grab Samples
Location : See Map
Logged By : RG
Depth in Feet0
1
2
3
4
5
6
7
8
9
10
11
12
13
14 USCSTS
SM
SP
SP-SM GRAPHICDESCRIPTION
SOD & TOPSOIL, dark brown, lighty moist, loose, minor gravel up to 1", moderate to heavy organics (thin roots). TOPSOIL
SILTY SAND, dark brown, lightly moist, medium dense, minor gravel up to 2", medium-grained sand. Approximately 5% gravel, 80% sand, 15% fines
WEATHERED OUTWASH
POORLY GRADED SAND WITH GRAVEL, tan, lightly moist, gravel up to 8", medium dense, course-grained sand. Approximately 30% gravel, 65% sand, 5% fines
GLACIAL OUTWASH
POORLY GRADED SAND WITH SILT AND GRAVEL, tan, very moist, gravel up to 8", medium dense, course-grained sand. Approximately 30% gravel, 60% sand, 10% fines
GLACIAL OUTWASH
Total Depth 7' BPGTerminated due to caving.No seepage or groundwater observed.Water LevelSample% Finer than #200% Moisture
Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
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Appendix D. LABORATORY TEST RESULTS
Laboratory tests were conducted on several representative soil samples to better identify the soil
classification of the units encountered and to evaluate the material's general physical properties and
engineering characteristics. A brief description of the tests performed for this study is provided below.
The results of laboratory tests performed on specific samples are provided at the appropriate sample
depths on the individual boring logs. However, it is important to note that these test results may not
accurately represent in situ soil conditions. All of our recommendations are based on our interpretation
of these test results and their use in guiding our engineering judgment. MTC cannot be responsible for
the interpretation of these data by others.
Soil samples for this project will be retained for a period of 3 months following completion of this
report, unless we are otherwise directed in writing.
SOIL CLASSIFICATION
Soil samples were visually examined in the field by our representative at the time they were obtained.
They were subsequently packaged and returned to our laboratory where they were reexamined, and the
original description checked and verified or modified. With the help of information obtained from the
other classification tests, described below, the samples were described in general accordance with
ASTM Standard D2487. The resulting descriptions are provided at the appropriate locations on the
individual exploration logs, located in Appendix C, and are qualitative only.
GRAIN-SIZE DISTRIBUTION
Grain-size distribution analyses were conducted in general accordance with ASTM Standard D422 on
representative soil samples to determine the grain-size distribution of the on-site soil. In addition, soil
liquid and plastic limits and plasticity index were determined with ASTM Standard D4318 on
representative fine-grained samples. The information gained from these analyses allows us to provide a
description and classification of the in-place materials. In turn, this information helps us to understand
engineering properties of the soil and thus how the in-place materials will react to conditions such as
heavy seepage, traffic action, loading, potential liquefaction, and so forth. The results are presented in
this Appendix.
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Leah’s Landing - Geotechnical Engineering Report Materials Testing & Consulting, Inc. October 7, 2019 Project No.: 19S147
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