18-102138_1
8- 102138
GEORESOURCES
earth science & geotechnical engineering
5007 Pacific Hwy E., Suite 16 1 Fife, WA 98424 1 253.896.1011 1 www.georesources.rocks _A
Mr. Nate Soto
nataneal.soto302@gmail.com
do David L. Thorstad Architect
406 South 289th Street
Federal Way, Washington 98003
(253) 941-4850
dltarchitect@comcast.net
January 23, 2019
RESUBMITTED
FEB 0 5 2019
CITY OF FEDERAL WAY
COMMUNITY DEVELOPMENT
Geotechnical Engineering Report
Addendum #2: Dispersion Trenches
Proposed Single Family Residence
xxx - 6` Avenue SW
Federal Way, Washington
PN:3021049064
Doc ID: Soto. 6thAveSW. RGA(2)
This geotechnical report addendum addresses the comments by the City of Federal Way
regarding the location of the proposed dispersion trenches and vegetated flow paths. Specifically,
the City has interpreted the King County Stormwater Design Manual (KCSWDM) Section C.2.1 Full
Dispersion which states, no dispersion trench or flow path may be installed or designated in areas
steeper than 15 percent. However, it is stated in the manual that the "project proponent may still
opt to use dispersion as long as the geotechnical evaluation and approval requirement is met".
Section C.2.1.1 - Minimum Design Requirements for Dispersion indicates that segments of
the vegetated flow path "must be no steeper than 15% for any 20-foot reach of the flowpath." This
section of the manual also states that dispersion devices are not allowed on slopes steeper than
20 percent and dispersion devices on slopes steeper than 15 percent must be approved by a
geotechnical engineer or engineering geologist. As currently proposed, the dispersion devices are
located on slopes steeper than 15 percent, and the flow paths will cross slope areas of 15 to 35
percent.
As indicated in our April 30, 2018 report, the sloping portion of the site below the home
site, slopes down at about 25 to 35 percent. A revised site topographic survey used to create the
current site plan shows the slope to be between 20 and 35 percent. The sloping portion of the site
is covered with a moderate to dense stand of mixed forest with a well -established understory of
native and invasive shrubs. No evidence of seeps, springs, erosion or slope movement was
observed on the slope.
Our report indicated the sloping portion of the site is underlain by over -consolidated
glacial soils. Our subsurface explorations encountered what appeared to be more of an ice -
contact deposit (medium dense silty sand with gravel and cobbles) in a medium dense to dense
condition, and not actual glacial till. No groundwater seepage was encountered, but mottling in
the upper 11/2 feet of the explorations indicates that the site is prone to a shallow, seasonal
"perched" groundwater table.
PERMIT # : 18-102138-00-SE,
ADDRESS:
PROJECT: New Construction
SOTO
RE -SUB: 02/05/2019
MEMO
r
Soto.6thAveSW. RGA(2)
January 23, 2019
Page 2
To address the requirements of the manual that dispersion flow paths on slopes steeper
than 15 percent must be approved by a geotechnical engineering, we performed a slope stability
analysis. Our analysis included a trial with no groundwater and a trial with shallow groundwater
condition with a shallow seasonal perched groundwater condition. According to the project civil,
pre -developed runoff from the proposed developed area will increase from 0.067 cfs to 0.208 cfs.
Slope Stability
We analyzed the global and internal slope stability of the existing slope below the
proposed dispersion trenches. The geometry used in our stability analysis is shown as Section A -A'
on the attached excerpt of the Site Plan, attached as Figure 1, as proposed by AP Consulting
Engineers, provided to us on January 10, 2019.
GeoResources, LLC assigned soil unit weight and strength parameters based on our field
explorations, field explorations completed on this site, index laboratory testing on samples
obtained from the site, and experience in the general site area. We assigned both dry and
saturated unit weight, friction angle, and cohesion for the various soil types encountered in our
explorations. Table 1 summarizes our assigned soil strength properties.
TABLE 1
ESTIMATED PROPERTIES OF ON -SITE SOILS FOR STABILITY ANALYSIS
Dry Unit
Sat. Unit
Internal
Soil Type
Weight
Weight
Cohesion
Friction
(psf)
Angle
(pcf)
(pcf)
(degrees)
Weathered Ice -contact
125
130
0
32
Ice -contact
128
133
50
36
Table 2, above, summarizes index properties for various native soil types encountered in
the Puget Sound as outlined in the "Geotechnical Properties of Geologic Material' by Koloski,
Schwarz, and Tubbs, as presented in ENGINEERING GEOLOGY IN WASHINGTON, Volume 1
(Washington Division of Geology and Earth Resources Bulletin 78). Based on our review of the
published literature, and the table attached below for your convenience, the soils values assigned
by GeoResources are well within the range of tabulated values in the literature, and in some
instances, the values appear to be conservative.
TABLE 2
PROPERTIES OF ON -SITE SOILS FOR STABILITY ANALYSIS
Dry Unit
Sat. Unit
Internal
Soil Type
Weight
Weight
Cohesion
Friction
(Psf)
Angle
(pct)
(pcf)
(degrees)
Glacial Till
120-140
N/A
1,000-4,000
35-45
Glacial Outwash
115-130
N/A
0-1,000
30-40
We used the computer program SLIDE version 7.035, from RocScience to perform the
slope stability analyses. The computer program SLIDE uses a number of methods to estimate the
factor of safety (FS) of the stability of a slope by analyzing the shear and normal forces acting on a
series of vertical "slices" that comprise a failure surface. Each vertical slice is treated as a rigid
Soto.6thAveSW. RGA(2)
January 23, 2019
Page 3
body; therefore, the forces and/or moments acting on each slice are assumed to satisfy static
equilibrium (i.e., a limit equilibrium analysis). The FS is defined as the ratio of the forces available
to resist movement to the forces of the driving mass. An FS of 1.0 means that the driving and
resisting forces are equal; an FS less than 1.0 indicates that the driving forces are greater than the
resisting forces (indicating failure).
We used the Generalized Limit Equilibrium method using the Morgenstern -Price analysis,
which satisfies both moment and force equilibrium, to search for the location of the most critical
failure surfaces and their corresponding FS. The most critical surfaces are those with the lowest
FS for a given loading condition, and are therefore the most likely to move. Based on our analyses
the FS for the current slope configuration, during the wet winter months when a perched water
table is most likely to develop in the weathered ice -contact (upper 2 to 3 feet) atop the underlying
glacial till, is 2.1 for static conditions, which exceeds manual's requirement of 1.5. In our opinion,
based on the results of our slope stability analyses, the impact of the overflow flow -paths on the
slopes will be minimal. Details of the slope stability analyses are included in Appendix "A".
Maintenance of Dispersion Trench and Slope
We understand that no vegetation removal or grading will occur on the slope below the
dispersion trenches. The exiting, well established native vegetation will be left in place. The
dispersion trenches are proposed to be on a portion of the site where slopes are less than 20
percent. There is a subtle "break" in the slope where the slopes steepen to 20 to 30 percent about
15 to 20 feet below the dispersion trenches. We recommend placing a 2-foot wide berm of quarry
spalls or light loose rip rap at the break in slope. The rip rap will protect the upper portion of the
vegetated flow path and the "break" in slope from scour by reducing sheet flow velocities and to
further disperse runoff from the dispersion trench. If the rock armoring becomes clogged by
debris, the flow path below each trench may become altered.
LIMITATIONS
We have prepared this report for use by Mr. Nate Soto, AP Consulting, and other members
of the design team for use in the design of a portion of this project. The data used in preparing
this report and this report should be provided to prospective contractors for their building or
estimating purposes only. Our report, conclusions and interpretations are based on site
reconnaissance and subsurface explorations, and should not be construed as a warranty of the
subsurface conditions.
Variations in subsurface conditions are possible between the referenced explorations and
may also occur with time. A contingency for unanticipated conditions should be included in the
budget and schedule. Sufficient monitoring, testing and consultation should be provided by our
firm during construction to confirm that the conditions encountered are consistent with those
indicated by the explorations, to provide recommendations for design changes should the
conditions revealed during the work differ from those anticipated, and to evaluate whether
earthwork and foundation installation activities comply with contract plans and specifications.
The scope of our services does not include services related to environmental remediation
and construction safety precautions. Our recommendations are not intended to direct the
contractor's methods, techniques, sequences or procedures, except as specifically described in
our report for consideration in design.
If there are any changes in the loads, grades, locations, configurations or type of facilities
to be constructed, the conclusions and recommendations presented in this report may not be fully
Soto.6thAveSW. RGA(2)
January 23, 2019
Page 4
applicable. If such changes are made, we should be given the opportunity to review our
recommendations and provide written modifications or verifications, as appropriate.
We have appreciated working for you on this project. Please do not hesitate to call at your
earliest convenience if you have any questions or comments.
Respectfully submitted,
GeoResources, LLC
Vdan Kovash, GIT
Staff Geologist in Training
E
Keith S. Schembs, LEG
Principal
J LK: KSS: DCB/kss
Doc ID: Soto. 6thAveSW. RGA
Attachments: Figure 1: Site Plan
Appendix A - Slope Stability Analyses
E BI�I
WM& '/1+
56931
" �IONAL Vti�,
Kyle E. Billingsley, PE
Project Geotechnical Engineer
Appendix A
Slope Stability Analyses
•'do- -
Soto.6thAveSW: Page 1 of 7
Slide Analysis Information
Soto.6thAveSW
Project Summary
File Name: Soto. 6thAveSW.Lowe rSlope.SS.slmd - With Water - Static
Slide Modeler Version: 7.018
Project Title: Soto.6thAveSW
Analysis: Static - With Water
Author: JLK
Company: GeoResources
Date Created: 1/11/2019, 12:54:20 PM
General Settings
Units of Measurement:
Imperial Units
Time Units:
days
Permeability Units:
feet/second
Failure Direction:
Left to Right
Data Output:
Standard
Maximum Material Properties:
20
Maximum Support Properties:
20
Analysis Options
Slices Type:
Vertical
Analysis Methods Used
GLE/Morgenstern-Price with interslice force function: Half Sine
Number of slices:
50
Tolerance:
0.005
Maximum number of iterations:
75
Check malpha < 0.2:
Yes
Create Interslice boundaries at intersections
with water tables and piezos:
Yes
Initial trial value of FS:
1
Steffensen Iteration:
Yes
Groundwater Analysis
Soto.6thAveSW.LowerSiope.SS.slmd GeoResources 1/11/2019, 12:54:20 PM
woenrrrnaaer �.o�a
Soto.6thAveSW: Page 2 of 7
Groundwater Method:
Water Surfaces
Pore Fluid Unit Weight [Ibs/ft3]:
62.4
Use negative pore pressure cutoff:
Yes
Maximum negative pore pressure [psf]:
0
Advanced Groundwater Method:
None
Random Numbers
Pseudo -random Seed: 10116
Random Number Generation Method: Park and Miller v.3
Surface Options
Surface Type:
Circular
Search Method:
Slope Search
Number of Surfaces:
5000
Upper Angle:
Not Defined
Lower Angle:
Not Defined
Composite Surfaces:
Disabled
Reverse Curvature:
Invalid Surfaces
Minimum Elevation:
Not Defined
Minimum Depth [ft]:
3
Minimum Area:
Not Defined
Minimum Weight:
Not Defined
Seismic
Advanced seismic analysis: No
Staged pseudostatic analysis: No
Material Properties
Property
Color
Strength Type
Unsaturated Unit Weight [Ibs/ft3]
Saturated Unit Weight [Ibs/ft3]
Cohesion [psf]
Friction Angle [deg]
Water Surface
Hu Value
Ru Value
Global Minimums
Weathered Ice Contact deposits
Ice Contact deposits
❑
❑
Mohr -Coulomb
Mohr -Coulomb
125
130
0
50
32
36
Water Table
None
1
0
Soto.6thAveSW.LowerSlope.SS.slmd GeoResources 1/11/2019, 12:54:20 PM
1 Jr
Soto.6thAveSW: Pace 3 of 7
Method: gle/morge nste rn -price
FS
2.046780
Center:
223.858, 551.146
Radius:
234.457
Left Slip Surface Endpoint:
124.708, 338.686
Right Slip Surface Endpoint:
187.640, 319.503
Resisting Moment:
2.34434e+006 lb-ft
Driving Moment:
1.14538e+006 lb-ft
Resisting Horizontal Force:
9584.47 lb
Driving Horizontal Force:
4682.7 lb
Total Slice Area:
132.803 ft2
Surface Horizontal Width:
62.9324ft
Surface Average Height:
2.11025 ft
Valid / Invalid Surfaces
Method: gle/mo rgenstern -price
Number of Valid Surfaces: 5000
Numberof Invalid Surfaces: 0
Slice Data
Global Minimum
- Safety Factor: 2.04678
Angle
Slice
Width
Weight
of Slice
Base
Number
[ft]
[lbs]
Base
Material
[degrees]
1
1.2182
17.078
-24.8535
Weathered Ice
Contact deposits
2
1.2182
50.5915
-24.5259
Weathered Ice
Contact deposits
3
1.2182
82.825
-24.1991
Weathered Ice
Contact deposits
4
1.2182
113.788
-23.8731
Weathered Ice
Contact deposits
5
1.2182
143.491
-23.548
Weathered Ice
Contact deposits
6
1.2182
171.943
-23.2236
Weathered Ice
Contact deposits
7
1.28249
211.068
-22.8915
Weathered Ice
Contact deposits
8
1.28249
241.128
-22.5518
Weathered Ice
Contact deposits
9
1.28249
269.702
-22.2128
Weathered Ice
Contact deposits
10
1.28249
296.803
-21.8747
Weathered Ice
Contact deposits
11
1.28249
322.44
-21.5374
Weathered Ice
Contact deposits
12
1.28249
346.623
-21.2008
Weathered Ice
Contact deposits
Base
Base
Effective
Base
Shear
Shear
pore
Friction
Normal
Normal
Cohesion
Stress
Strength
Pressure
[Psf]
Angle
[Psfl
[Psf)
Stress
[Psfl
Stress
[degrees]
[psf]
[Psf]
0
32
3.74299
7.66107
12.2602
0
12.2602
0
32
11.0839
22.6864
36.3057
0
36.3057
0
32
18.1382
37.1249
59.4122
0
59.4122
0
32
24.9129
50.9913
81.6029
0
81.6029
0
32
31,4152
64.3001
102.901
0
102.901
0
32
37.6518
77.065
123.33
0
123.33
0
32
42.0713
86.1106
144.465
6.65942
137.806
0
32
44.7013
91.4938
166.12
19.6993
146.421
0
32
47.1506
96.507
186.627
32.1835
154.444
0
32
49.4303
101.173
206.027
44.116
161.911
0
32
51.5512
105.514
224.358
55.5007
168.857
0
32
53.5226
109.549
241.657
66.3414
175.316
Soto.6thAveSW.LowerSlope.SS.slmd GeoResources 1/11/2019, 12:54:20 PM
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as
Soto.6thAveSW: Page 4 of 7
Weathered Ice
13
1.28249
369.363
-20.865
0
32
55.3552
113.3
257.96
76.642
181.318
Contact deposits
Weathered Ice
14
1.28249
390.67
-20.53
0
32
57.0564
116.782
273.296
86.406
186.89
Contact deposits
Weathered Ice
15
1.28249
410.552
-20.1957
0
32
58.6345
120.012
287.696
95.6369
192.059
Contact deposits
Weathered Ice
16
1.28249
429.02
-19.8621
0
32
60.0963
123.004
301.186
104.338
196.848
Contact deposits
Weathered Ice
17
1.28249
446.082
-19.5292
0
32
61.4472
125.769
313.787
112.514
201.273
Contact deposits
Weathered Ice
18
1.28249
461.746
-19.197
0
32
62.6931
128.319
325.519
120.166
205.353
Contact deposits
Weathered Ice
19
1.28249
476.022
-18.8655
0
32
63.8373
130.661
336.399
127.298
209.101
Contact deposits
Weathered Ice
20
1.28249
488.918
-18.5346
0
32
64.8824
132.8
346.438
133.914
212.524
Contact deposits
21
1.25434
489.268
-18.208
Ice Contact
50
36
147.314
301.52
346.188
0
346.188
deposits
Ice Contact
22
1.25434
498.867
-17.8856
50
36
150.432
307.901
354.97
0
354.97
deposits
Ice Contact
23
1.25434
507.216
-17.5638
50
36
153.227
313.622
362.844
0
362.844
deposits
24
1.25434
514.322
-17.2425
Ice Contact
50
36
155.693
318.67
369.793
0
369.793
deposits
Ice Contact
25
1.25434
520.191
-16.9218
50
36
157.825
323.033
375.798
0
375.798
deposits
Ice Contact
26
1.25434
524.829
-16.6017
50
36
159.615
326.696
380.84
0
380.84
deposits
27
1.25434
528.243
-16.2821
Ice Contact
50
36
161.057
329.648
384.902
0
384.902
deposits
Ice Contact
28
1.25434
530.439
-15.963
50
36
162.145
331.875
387.967
0
387.967
deposits
Ice Contact
29
1.25434
531.422
-15.6445
50
36
162.873
333.366
390.02
0
390.02
deposits
Ice Contact
30
1.25434
531.199
-15.3264
50
36
163.237
334.11
391.044
0
391.044
deposits
Ice Contact
31
1.25434
527.199
-15.0088
50
36
162.554
332.713
389.12
0
389.12
deposits
Ice Contact
32
1.25434
511.905
-14.6917
50
36
158.837
325.105
378.649
0
378.649
deposits
Ice Contact
33
1.25434
494.398
-14.375
50
36
154.459
316.143
366.314
0
366.314
deposits
Weathered Ice
34
1.24095
470.586
-14.0605
0
32
65.5019
134.068
358.512
143.958
214.554
Contact deposits
Weathered Ice
35
1.24095
450.847
-13.748
0
32
64.3064
131.621
344.393
133.755
210.638
Contact deposits
Weathered Ice
36
1.24095
429.952
-13.436
0
32
62.9481
128.841
329.294
123.105
206.189
Contact deposits
Weathered Ice
37
1.24095
407.906
-13.1244
0
32
61.4204
125.714
313.195
112.01
201.185
Contact deposits
Weathered Ice
38
1.24095
384.712
-12.8133
0
32
59.7197
122.233
296.085
100.472
195.613
Contact deposits
Weathered Ice
39
1.24095
360.375
-12.5024
0
32
57.8411
118.388
277.951
88.4906
189.46
Contact deposits
Weathered Ice
40
1.24095
334.9
-12.192
0
32
55.7813
114.172
258.783
76.0693
182.714
Contact deposits
Weathered Ice
41
1.24095
308.29
-11.8819
0
32
53.5382
109.581
238.576
63.209
175.367
Soto.6thAveSW.LowerSlope.SS.slmd
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1/11/2019,
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Soto.6thAveSW: Page 5 of 7
Contact deposits
Weathered Ice
42
1.24095
280.549
-11.5722
0
32
51.1105
104.612
217.326
49.9114
167.415
Contact deposits
Weathered Ice
43
1.24095
251.682
-11.2628
0
32
48.4974
99.2635
195.033
36.1778
158.855
Contact deposits
Weathered Ice
44
1.24095
221.691
-10.9538
0
32
45.6993
93.5365
171.7
22.0098
149.69
Contact deposits
Weathered Ice
45
1.24095
190.58
-10.645
0
32
42.7177
87.4337
147.332
7.40867
139.924
Contact deposits
Weathered Ice
46
1.29413
165.219
-10.33
0
32
37.3304
76.4072
122.277
0
122.277
Contact deposits
Weathered Ice
47
1.29413
130.583
-10.0087
0
32
29.4948
60.3694
96.6109
0
96.6109
Contact deposits
Weathered Ice
48
1.29413
94.7364
-9.68772
0
32
21.3859
43.7722
70.0501
0
70.0501
Contact deposits
Weathered Ice
49
1.29413
57.6838
-9.36704
0
32
13.0114
26.6314
42.6191
0
42.6191
Contact deposits
Weathered Ice
50
1.29413
19.4282
-9.04666
0
32
4.37882
8.96249
14.343
0
14.343
Contact deposits
Interslice Data
Soto.6thAveSW.LowerSlope.SS.slmd GeoResources 1/11/2019, 12:54:20 PM
mod.
Soto.6thAveSW: Page 6 of 7
X
Y
Interslice
Interslice
Interslice
Slice
coordinate
coordinate - Bottom
Normal Force
Shear Force
Force Angle
Number
[ft]
[ft]
[Ibs]
[Ibs]
[degrees]
1
124.708
338.686
0
0
0
2
125.926
338.122
2.35847
0.0305855
0.742991
3
127.144
337.566
9.03611
0.233934
1.48299
4
128.362
337.019
19.4662
0.753606
2.21702
5
129.58
336.48
33.114
1.7019
2.94214
6
130.799
335.949
49.4753
3.16081
3.65547
7
132.017
335.426
68.075
5.18338
4.35422
8
133.299
334.884
92.3511
8.19518
5.07111
9
134.582
334.352
123.496
12.4697
5.76576
10
135.864
333.828
160.765
18.1331
6.43534
11
137.147
333.313
203.455
25.2591
7.0771
12
138.429
332.807
250.902
33.8716
7.68841
13
139.712
332.31
302.477
43.9485
8.26696
14
140.994
331.821
357.586
55.4244
8.81051
15
142.277
331.341
415.669
68.1952
9.31702
16
143.559
330.869
476.194
82.1218
9.78467
17
144.842
330.405
538.66
97.0349
10.2118
18
146.124
329.951
602.594
112.739
10.5969
19
147.407
329.504
667.548
129.018
10.9388
20
148.689
329.066
733.1
145.639
11.2362
21
149.972
328.636
798.851
162.356
11.4881
22
151.226
328.223
756.909
156.61
11.69
23
152.48
327.818
711.909
149.335
11.847
24
153.735
327.421
663.773
140.59
11.9588
25
154.989
327.032
612.446
130.457
12.0248
26
156.243
326.651
557.896
119.045
12.0452
27
157.498
326.277
500.114
106.483
12.0198
28
158.752
325.91
439.114
92.9248
11.9486
29
160.006
325.551
374.936
78.5455
11.8318
30
161.261
325.2
307.643
63.5407
11.6698
31
162.515
324.856
237.321
48.1243
11.4631
32
163.769
324.52
164.29
32.5669
11.2123
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165.024
324.191
89.5866
17.281
10.9181
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166.278
323.87
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10.5814
35
167.519
323.559
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116.586
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List Of Coordinates
Water Table
X Y
0 368.5
41 360.5
58 356.5
120 338.5
163 327.5
192 316.5
237 302.5
External Boundary
X Y
0 250
237 250
237 301
237 304
192 318
163 328
120 340
58 358
41 362
0 370
0 367
0 267
Material Boundary
X Y
0 367
41 359
58 355
120 337
163 325
192 315
237 301
Soto.6thAveSW.LowerSlope.SS.slmd GeoResources 1/11/2019, 12:54:20 PM
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_ GEORESOURCES
dombirlbZ earth science & geotechnical engineering
5007 Pacific Hwy E., Suite 16 1 Fife, WA 98424 1 253.896.1011 1 www.georesources.rocks
Mr. Nate Soto
natanael.soto302@gmaii.com
c/o David L. Thorstad Architect
406 South 2891h Street
Federal Way, Washington 98003
(253) 941-4850
dltarchitect@comcast.net
PERMIT #:
18-102138-00-SF
ADDRESS:
PROJECT
New SFR
SOTO,
DATE:
5/18/18
April 30, 2018
RECEIVED
MAY 18 2018
CITY OF COMMUNITY DEVELOPMENT
Geotechnical Engineering Report
Proposed Single Family Residence
xxx - 6 1 h Avenue Southwest
Federal Way, Washington
PN:3021049064
Doc ID: Soto. 6thAveSW.RG
INTRODUCTION
This geotechnical engineering report summarizes our site observations, our subsurface
explorations, geotechnical data review and engineering analyses and provides geotechnical
recommendations and design criteria for the proposed single family residence to be constructed on
6`h Avenue SW in Federal Way, Washington. The approximate site location is shown on the Site
Location Map, included as Figure 1.
Our understanding of the project is based on our email and telephone correspondences
with your architect Mr. David Thorstad, our April 9, 2018 site visit, our understanding of the City of
Federal Way Critical Areas and Development Code, and our past experience in the area. We
understand that the site is currently undeveloped. As shown on the attached Site and Exploration
Plan, Figure 2, we further understand that you propose to construct a new single family residence in
the southwest corner of the parcel, with a new driveway and typical residential utilities. We
anticipate that the new residence will likely be a one or two story, wood framed structure with
conventional shallow foundations. A copy of the Site and Exploration Plan is included as Figure 2.
Because of the steep slopes in the vicinity of the site, we anticipate that the City of Federal
Way will require a geotec nica engineering report to a dress the City of Federal Way Critical Areas
Ordinance Chapter 19.145.
SCOPE
The purpose of our services is to evaluate the surface and subsurface conditions across the
site as a basis for providing geotechnical recommendations and conclusions for the proposed
development. Specifically, the scope of services for this project included the following:
1. Reviewing the available geologic, hydrogeologic_, and geotechnical data for the site area;
r=
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Soto. 6thAveSW.RG
April 30, 2018
Page 12
2. Observing subsurface conditions across the site by logging the open pert holes at the site
and performing 2 hand auger explorations along the steep slope;
3. Describing surface and subsurface conditions, including soil type, depth to groundwater, and
an estimate of seasonal high groundwater levels;
4. Addressing the appropriate criteria for geologic hazards per the current City of Federal Way
Critical Areas Ordinance;
5. Providing geotechnical conclusions and recommendations regarding site grading activities
including; site preparation, subgrade preparation, fill placement criteria, suitability of on -site
soils for use as structural fill, temporary and permanent cut and fill'slopes, drainage and
erosion control measures;
6. Providing recommendations for seismic design parameters, including 2015 IBC soil profile
type;
7. Providing geotechnical conclusions regarding foundations and floor slab support and design
criteria, including bearing capacity and subgrade modulus as appropriate;
8. Providing our opinion about the feasibility of onsite infiltration including a preliminary design
infiltration rate based on grain size data per the 2016 King County Stormwater Design
Manual, if applicable;
9. Providing recommendations for erosion and sediment control during wet weather grading
and construction; and,
10. Preparing this written Geotechnical Engineering Report summarizing our site observations and
conclusions, and our geotechnical recommendations and design criteria, along with the
supporting data.
The above scope of work was summarized in our Proposal for Geotechnical Engineering Services
dated March 14, 2018. We received written authorization to proceed from you on March 22, 2018.
Because we proposed to perform hand auger explorations along the steep slopes at the site, we
submitted a Request for Administrative Decision on March 27, 2018. Our request was approved by the
City of Federal Way on April 3, 2018.
SITE CONDITIONS
Surface Conditions
The site is located at xxx - 6th Avenue SW (parcel number 3021049064) in Federal Way,
Washington, within an area of existing residential development. The site is rectangular in shape,
measures approximately 165 feet wide (north to south) by 625 feet deep (east to west), and
encompasses about 2.36 acres. The site is bounded by residential development to the north and
south, 61h Avenue SW to the west, and Merit High School to the east.
From 61h Avenue SW, the site slopes down to the east at about 10 to 15 percent for
approximately 200 feet before sloping down at about 25 to 35 percent. Near the toe of the slope,
the site slopes down at about 40 percent. Total topographic relief across the site is on the order of
135 feet. The parcel is currently undeveloped. The proposed development is shown on the Site and
Exploration Plan, Figure 2, while the existing topography and site configuration is shown on the Site
Vicinity Map, Figure 3.
Vegetation across the site consists of a moderate to dense stand of deciduous and
coniferous trees with a moderate understory of ferns, blackberries, evergreen huckleberries, and
GEORESOURCES
{ y `Soto.6thAveSW.RG
April 30, 2018
page 13
other native and invasive shrubs. No evidence of erosion or slope movement Was observed at the
site at the time of our site visit. Sj�
Site Soils 4v)
The USDA Natural Resource -Conservation Survey (NRCS) W b _oil Survey maps the site as
being underlain by Alderwood gravelly sandy loam (AgB, AgC, AgD). The Alderwood soils are typically
derived from glacial till and form on slopes of 0 to 8 (AgB), 8 to 15 (AgC) and 15 to 30 (AgD) percent.
These soils are listed as having a "slight' (AgB), "moderate," (AgC), and "moderate to severe" (AgD)
erosion hazard when exposed, and are included in hydrologic soils group B. An excerpt from the NRCS
soils map for the site area is included as Figure 4.
Site Geology
The Geologic Map of the Poverty Bay 7.5-Minute Quadrangle, Washington (Booth, Waldron, and
Troost, 2003) maps the site and the adjacent areas as being underlain by ice -contact deposits (Qvi)
and glacial till (Qvt). These glacial soils were deposited during the Vashon Stade of the Frasier
Glaciation. The ice contact soils generally consist of a combination of glacial till and outwash
deposited along the margins of the prehistoric continental ice mass. The ice contact deposits may or
may not have been overridden by the continental ice mass and are considered normally
consolidated. The glacial till generally consists of a heterogeneous mixture of gravel, sand, silt, and
clay that was deposited at the base of the advancing continental ice mass, and was subsequently
overridden. As such, it is considered to be over consolidated, and generally has high strength and
low compressibility characteristics where undisturbed. No areas of landslide deposits or mass
wasting are mapped within the vicinity of the site. An excerpt of the above referenced map is
included as Figure 5.
Subsurface Explorations
On April 9, 2018, a field representative from GeoResources, LLC (GeoResources) visited the
site and logged the previously excavated and still open pert holes in the upper portion of the site,
and advanced two hand augers along the slope to depths of about 63/a to 7 feet below the existing
ground surface, logged the subsurface conditions encountered in each hand auger, and obtained
representative soil samples. Since the hand auger explorations were excavated on a potential
landslide hazard area, we submitted a Request for Administrative Decision to the City of Federal Way
to perform explorations within a potential critical area and/or its buffer. We received approval of
our request on April 3, 2018.
The specific number, locations, and depths of our explorations were selected based on
location of the proposed single family residence and were adjusted in the field based on our
understanding of the proposed development, consideration for underground utilities, site access
limitations, and existing site conditions. A field representative from our office excavated the two
hand auger explorations, maintained logs of the subsurface conditions encountered, obtained
representative soil samples, and observed pertinent site features. Representative soil samples
obtained from the explorations were placed in sealed plastic bags and taken to a laboratory for
further examination and testing as deemed necessary. Each hand auger hole was then backfilled
with the excavated soils. Table 1, below, summarizes the approximate functional locations, surface
elevations, and termination depths of our hand auger explorations and the observed pert holes.
GEORESOURCES
Soto. 6thAveSW. RG
April 30, 2018
page 14
TABLE 1:
APPROXIMATE LOCATIONS, ELEVATIONS, AND DEPTHS OF EXPLORATIONS
Surface Termination Termination
Exploration Functional Location Elevation' Depth Elevation'
Number (feet) (feet) (feet)
PH-1
Upper, NW portion of site
382
4
378
PH-2
Upper, SW portion of site
382
4
378
PH-3
Upper, Western portion of site
384
4
381
HA-1
Central portion of site, along slope
370
7
359
HA-2
Lower, central portion of site, along slope
335
63/4
328'/4
Notes: 1 = Elevation datum: from King County Public GIS
The subsurface explorations excavated as part of this evaluation indicate the subsurface
conditions at specific location only, as actual subsurface conditions can vary across the site.
Furthermore, the nature and extend of such variation would not become evident until additional
explorations are performed or until construction activities have begun. Based on our experience in
the area, it is our opinion that the site soils encountered in the explorations are generally
representative of the soils at the site. The soils encountered were visually classified in accordance
with the Unified Soil Classification System (USCS) and ASTM D: 2488. The USCS is included in
Appendix A as Figure A-1. The approximate locations of our hand auger explorations and open pert
holes are indicated on the attached Site and Exploration Plan, Figure 2, while the descriptive logs of
our hand auger explorations and observed pert holes are included in Appendix A.
Subsurface Conditions
We observed generally uniform subsurface conditions in the open pert holes located in the
upper portion ofthe site and in our hand augers that generally confirmed the mapped stratigraphy. In
general, we observed approximately 11/2 feet of dark brown to black topsoil/forest duff mantling about
1 to 1'/2 feet of orange stained brown silty sand with gravel and cobbles in a loose to medium dense
and moist to damp condition. We interpret these soils to be consistent with weathered ice -contact
deposits. Underlying the weathered soils, we observed grey brown silty sand with gravel in a medium
dense to dense, moist silty sand with gravel condition to the full depth observed. Because of the
relative density of the deeper, unweathered soils, we interpret these soils to be consistent with ice -
contact deposits.
Our hand auger explorations on the slope east of the proposed residence encountered similar
subsurface conditions. In general, our hand augers encountered 1'/2 feet of topsoil mantling about 1'/4
to 1'/2 feet of loose to medium dense weathered ice -contract deposits that were underlain by medium
dense ice contact deposits. Table 2, below, surnmarizes the approximate thicknesses, depths, and
elevations of selected soil layers.
GEORESOURCES
r�--1
Soto.6thAveSW. RG
April 30, 2018
page 15
TABLE 2:
APPROXIMATE THICKNESS, DEPTHS, AND ELEVATION OF SOIL TYPES ENCOUNTERED IN
EXPLORATIONS
Thickness of Thickness of Depth to Ice- Elevation' of Top of
Exploration Weathered Ice -Contact
Number Topsoil Deposit Contact Deposit Ice -Contact Deposit
(feet) (feet) (feet) — (feet)
PH-1
1 %2
1'/4
23/a
379'/a
PH-2
1'/2
1
2'/2
379%z
PH-3
1'/2
1
2%2
381'/2
HA-1
13/2
1 %2
3
367335-
HA-2
1 %2
1'/a
23/a
332'/a
Notes: 1 = Elevation datum: from King County Public GIS
Laboratory Testing
Geotechnical laboratory tests were performed on select samples retrieved from the hand
auger explorations to determine soil index and engineering properties encountered. Laboratory
testing included visual soil classification per ASTM D: 2488, moisture content determinations per
ASTM D: 2216, and grain size analyses per ASTM D: 422 standard procedures. The results of the
laboratory tests are included in Appendix B, and summarized below in Table 3.
TABLE 3:
LABORATORY TEST RESULTS FOR ON -SITE SOILS
Gravel
Sand
Silt/Clay
D10
Sample
Soil Type
Lab ID
Content
Content
Content
Ratio
Number
(percent)
(percent)
(percent)
(mm)
HA-1, S-1, 1.5'
Weathered Ice -Contact
094184
46.1
40.7
13.2
ND
HA-1, S-2, 3-7'
Ice -Contact
094183
35.3
50.5
14.2
ND
ND = Not determined
Groundwater Conditions
Mottling and orange iron oxide staining was observed at about 1%2 feet below the existing
ground surface. These characteristics are generally indicative of a seasonal perched groundwater
table, which generally develops when a higher permeability soil is underlain by a lower permeability
soil. No groundwater seepage was observed in our explorations at the time of excavation. We
anticipate fluctuations in the local groundwater levels will occur in response to precipitation
patterns, off -site construction activities, and site utilization.
ENGINEERING CONCLUSIONS AND RECOMMENDATIONS
Based on the results of our data review, site reconnaissance, subsurface explorations and
our experience in the area, it is our opinion that the construction of a new single-family residence on
the flatter, upper, western portion of the site is feasible from a geotechnical standpoint. Provided
GEORESOURC.ES
Soto. 6thAveSW.RG
April 30, 2018
page 1 6
the geotechnical recommendations contained in this report are included in the project plans and
specifications, the construction of the residence will have minimal impact on the steeper slope to
the east and adjacent parcels. .
Erosion Hazard Areas per Federal Way Revised Code
The FWRC, Chapter 19.05.070.G(1) defines erosion hazard areas as "those areas identified by
the U.S. Department of Agriculture's (USDA) Natural Resource Conservation Service (NRCS) as having
a moderate to severe or severe to very severe rill and inter -rill erosion hazard due to natural agents
such as wind, rain, splash, frost action or stream flow; those areas containing the following group of
soils when they occur on slopes of 15 percent or greater: Alderwood-Kitsap ("AkF"), Alderwood
gravelly sandy loam ("AgD"), Kitsap silt loam ("KpD"), Everett ("EvD"), and I la ("InD"); and those
areas impacted by shore land and/or stream bank erosion"
As previously stated, the site soils are mapped as AgB, AgC, a Ag have a slight,
moderate, and moderate to severe erosion hazards when exposed. ❑ ntional onstruction
BMP's should be installed prior to beginning construction. This will provide adequ to erosion
control for the disturbed areas of the site. It is critical that the installed erosion control asures be
monitored and maintained, and if necessary modified based on changing site al
event that the site is not worked for 7 days or more, the disturbed areas should be adequately
erosion protected and maintained in the event of a significant storm event. This may include the
use of plastic sheeting or mulch. Erosion control should specifically include the installation of silt
fencing along the downslope and side slopes of the active construction area. Straw waddles and
berms may also be necessary.
We have not been provided with a copy of the proposed Temporary Erosion and Sediment
Control (TESC) plan at this time. However, provided standard BMP's are installed prior to beginning
construction, the potential for erosion or sediment leaving the site should be minimal.
Landslide Hazard Areas per Federal Way Revised Code
The FWRC, Chapter 19.05.070.G(2) defines landslide hazard areas as "those areas potentially
subject to episodic downslope movement of a mass of soil or rock including but not limited to the
following areas." These are typically characterized as having the following indicators:
a. Any area with a combination of.
i. Slopes greater than 15 percent,
ii. Permeable sediment overlying a relatively impermeable sediment or bedrock,•
iii. Springs orgroundwater seeps.
b. Any area which has shown movement during the Holocene epoch, from 10,000 years ago to the
present, or which is underlain by mass wastage debris of that epoch.
c. Any area potentially unstable as a result of rapid stream incision, stream bank erosion or
undercutting by wave action.
d. Any area located in a ravine or on an active alluvial fan, presently or potentially subject to
inundation by debris flows or flooding.
e. Those areas mapped as Class U (unstable), UOS (unstable old slides), and URS (unstable recent
slides) by the Department of Ecology's Coastal Zone Atlas.
f. Areas designated as quaternary slumps, earthflows, mudflows, lahars, or landslides on maps
published by the U.S. Geological Survey or Washington State Department of Natural Resources.
GEORESOURCESS
' +"Soto.6thAveSW.RG
April 30, 2018
Page 17
g. Slopes havinggradients greater than 80 percent subject to rockfoll during seismic shaking
h. Any area with a slope of 40 percent or steeper and with a vertical relief of 10 or more feet except
areas composed of consolidated rock. A slope is delineated by establishing its toe and top and is
measured by averaging the inclination over at least 10 feet of vertical relief.
The site has slopes steeper than 15 percent, but no adverse or intersecting contacts are
mapped on the site, nor were any seeps or springs commonly indicative and adverse contract were
observed on the slope below the proposed homesite. No areas of mapped landslide debris or
activity were noted on the published USGS geologic map or coastal zone atlas. Given the slope
angles and mapped stratigraphy, we would not anticipate the eastern portion of the site to be
mapped by the Coastal Atlas as unstable, unstable — old slide, or unstable — recent slide. The upper,
western portion would likely be stable, while the eastern sloping area would be stable to
intermediate.
No streams are mapped in the vicinity of the site and the site is not located along a
shoreline. No areas of alluvial fans are mapped nor were any alluvial fans noted in the vicinity of the
site at the time of our past site visits. The site slopes are not steeper than 80 percent with more
than 10 feet of vertical relief and are not subject to rock fall during seismic shaking. Slopes steeper
than 40 percent are mapped in the lower portion of the site, along the toe of the slope.
Based on our observations and literature review, the site a he above indicators,
sl s 4 eecent with 10 feet or more of vertical relief. However, we did not observe
any evi ence o an s i ac ivi at the site during our st 7si . erefore it is our opinion that no
buffe u e r e City of Federal Way.
Recommended Setback
The 2015 IBC requires a building setback from slopes that are steeper than 3H:1V
(Horizontal: Vertical) or 33 percent with greater than 10 feet in vertical height unless evaluated and
reduced, and/or a structural setback is provided, by a licensed geotechnical engineer. The setback
distance is calculated based on the vertical height of the slope. The typical 2015 IBC setback from
the top of the slope equals one third the height of the slope, with a maximum setback of 40 feet
from the top of the slope, while a setback from the toe of the slope equals one half the height of the
slope, with a maximum setback of 15 feet from the toe of the slope. If the setback from the top of
the slope cannot be met, a structural setback may be used. A structural setback consists of
deepening the foundation elements so that, when measured horizontally from the front of the
footing to the face of the slope, the minimum IBC setback is achieved.
As stated above, the slope below the proposed single family residence has inclination of
about 25 to 40 percent. The portion of this slope sloping at more than 33 percent has a vertical
height on the order of 85 feet. Per the 2015 IBC, the slope area should have a minimum setback of
29 feet from the top of the slope. According to the Preliminary Site Plan, the proposed residence will
be setback approximately 95 feet from the steep slopes at the site and satisfies the minimum
structural setback.
Seismic Design
Based on our observations and the subsurface units mapped at the site, we interpret the
structural site conditions to correspond to a seismic Site Class "D" in accordance with the 2015 IBC
(International Building Code) documents and ASCE 7-10 Chapter 20 Table 20.3-1. This is based on
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g I abed
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E)d'MSanygl9'OIOS
Soto.6thAveSW. RG
April 30, 2018
page 19
designed using an allowable soil bearing capacity of 2,000 psf (pounds per square foot) for
combined dead and long-term live loads. The weight of the footing and any overlying backfill may
be neglected. The allowable bearing value may be increased by one-third for transient loads such as
those induced by seismic events or wind loads.
Lateral loads may be resisted by friction on the base of footings and floor slabs and as
passive pressure on the sides of footings. We recommend that an allowable coefficient of friction of
0.35 be used to calculate friction between the concrete and the underlying soil. Passive pressure
may be determined using an allowable equivalent fluid density of 300 pcf (pounds per cubic foot).
Passive resistance from soil should be ignored in the upper 1 foot. Factors of safety have been
applied to these values.
We estimate that settlenments of footings designed and constructed as recommended will be
less than 1-inch, for the anticipated load conditions, with differential settlements between
comparably loaded footings of Yz-inch or less. Most of the settlements should occur essentially as
loads are being applied. However, disturbance of the foundation subgrade during construction
could result in larger settlements than predicted. We recommend that all foundations be provided
with footing drains.
Floor Slab Support
We anticipate that any garage areas will consist of slab -on -grade floors that should be
supported on the native soils or on structural fill prepared as described above. Although not
encountered in our explorations, any areas of old fill material should be evaluated during grading
activity for suitability of structural support. Areas of significant organic debris should be removed.
We recommend that floor slabs be directly underlain by a minimum 4-inch thick pea gravel
or clean crushed rock with less than 2 percent fines. This layer should be placed in one lift and
compacted to an unyielding condition.
A synthetic vapor retarder is recommended to control moisture migration through the slabs.
This is of particular importance where the slab is underlain by the dense glacial till, or where
moisture migration through the slab is an issue, such as where adhesives are used to anchor carpet
or tile to the slab.
A subgrade modulus of 350 kcf (kips per cubic foot) may be used for floor slab design. We
estimate that settlement of the floor slabs designed and constructed as recommended, will be Yz
inch or less over a span of 50 feet.
Temporary Excavations
All job site safety issues and precautions are the responsibility of the contractor providing
services/work. The following cut/fill slope guidelines are provided for planning purposes only.
Temporary cut slopes will likely be necessary during grading operations or utility installation.
All excavations at the site associated with confined spaces, such as utility trenches and
retaining walls, must be completed in accordance with local, state, or federal requirements. Based
on current Washington State Safety and Health Administration (WSHA) regulations, the weathered
ice -contact deposits and ice -contact deposits would be classified as Type C soils.
According to WSHA, for temporary excavations of less than 20 feet in depth, the side slopes
in Type C soils should be sloped at a maximum inclination of 1.5H:1V. All exposed slope faces
should be covered with a durable reinforced plastic membrane during construction to prevent slope
raveling and rutting during periods of precipitation. These guidelines assume that all surface loads
- �0�_ �-=tw
GEORESOURCES "
Soto.6thAveSW. RG
April 30, 2018
page 1 10
are kept at a minimum distance of at least one half the depth of the cut away from the top of the
slope and that significant seepage is not present on the slope face. Flatter cut slopes will be
necessary where significant raveling or seepage occurs, or if construction materials will be stockpiled
along the slope crest.
Where it is not feasible to slope the site soils back at these inclinations, a retaining structure
should be considered. Where retaining structures are greater than 4-feet in height (bottom of
footing to top of structure) or have slopes of greater than 15 percent above them, they should be
engineered per Washington Administrative Code (WAC 51-16-080 item 5).
This information is provided solely for the benefit of the owner and other design consultants,
and should not be construed to imply that GeoResources assumes responsibility for job site safety.
It is understood that job site safety is the sole responsibility of the project contractor.
Site Drainage
All ground surfaces, pavements and sidewalks at the site should be sloped away from the
structures. Surface water runoff should be controlled by a system of curbs, berms, drainage swales,
and or catch basins, and conveyed to an appropriate discharge point.
We recommend that footing drains are installed for the residences in accordance with 2015 IBC
1807.4.2, and basement walls (if utilized) have a wall drain as describe above. The roof drain should not
be connected to the footing drain.
Stormwater Infiltration
We understand that the City of Federal Way uses the 2016 King County Surface Water Design
Manual (KCSWDM) for stormwater management. In accordance with Section 5.2 of the 2016
KCSWDM, a minimum separation of 3 feet between the bottom of an infiltration facility and the top
of a seasonal high groundwater table or other impermeable layer is required. Per the 2016
KCSWDM, evidence of seasonal high groundwater includes mottling or iron oxide staining. Evidence
of seasonal high groundwater, iron staining, was observed at 1'/z feet below the existing ground
surface; therefore, vertical setbacks cannot be met and the onsite infiltration of stormwater runoff
generated by the proposed development is not feasible in accordance with the 2016 KCSWDM.
Alternative stormwater management methods should be considered for this project.
Stormwater facilities should be designed and constructed in accordance with the 2016 KCSWDM. All
infeasibility criteria and minimum setbacks should be considered prior to the selection of a
stormwater management method.
EARTHWORK RECOMMENDATIONS
Site Preparation
All structural areas on the site to be graded should be stripped of vegetation, organic surface
soils, and other deleterious materials including existing structures, foundations or abandoned utility
lines. Organic topsoil is not suitable for use as structural fill, but may be used for limited depths in
non-structural areas. Stripping depths ranging from 12 to 18 inches should be expected to remove
these unsuitable soils. Areas of thicker topsoil or organic debris may be encountered in areas of
heavy vegetation or depressions.
Where placement of fill material is required, the stripped/exposed subgrade areas should be
compacted to a firm and unyielding surface prior to placement of any fill. Excavations for debris
00
GEORESOURCES
Soto. 6thAveSW.RG ,1
April 30, 2018
page 1 11
removal should be backfilled with structural fill compacted to the densities described in the
"Structural Fill" section of this report.
We recommend that a member of our staff evaluate the exposed subgrade conditions after
removal of vegetation and topsoil stripping is completed and prior to placement of structural fill.
The exposed subgrade soil should be proof -rolled with heavy rubber -tired equipment during dry
weather or probed with a 1 /2-inch-diameter steel rod during wet weather conditions.
Soft, loose or otherwise unsuitable areas delineated during proofrolling or probing should
be recompacted, if practical, or over -excavated and replaced with structural fill. The depth and
extent of over excavation should be evaluated by our field representative at the time of construction.
The areas of old fill material should be evaluated during grading operations to determine if they
need mitigation, recompaction, or removal.
Structural Fill
All material placed as fill associated with mass grading, as utility trench backfill, under
building areas, or under roadways should be placed as structural fill. The structural fill should be
placed in horizontal lifts of appropriate thickness to allow adequate and uniform compaction of each
lift. Structural fill should be compacted to at least 95 percent of MDD (maximum dry density as
determined in accordance with ASTM D-1557).
The appropriate lift thickness will depend on the structural fill characteristics and
compaction equipment used. We recommend that the appropriate lift thickness be evaluated by
our field representative during construction. We recommend that our representative be present
during site grading activities to observe the work and perform field density tests.
The suitability of material for use as structural fill will depend on the gradation and moisture
content of the soil. As the amount of fines (material passing US No.200 sieve) increases, soil
becomes increasingly sensitive to small changes in moisture content and adequate compaction
becomes more difficult to achieve. During wet weather, we recommend use of well -graded sand
and gravel with less than 5 percent (by weight) passing the US No. 200 sieve based on that fraction
passing the 3/4-inch sieve, such as Gravel Backfill for Walls (WSDOT 9-03.12(2)). If prolonged dry
weather prevails during the earthwork and foundation installation phase of construction, higher
fines content (up to 10 to 12 percent) may be acceptable.
Material placed for structural fill should be free of debris, organic matter, trash, and cobbles
greater than 6-inches in diameter. The moisture content of the fill material should be adjusted as
necessary for proper compaction.
Suitability of On -Site Materials as Fill
During dry weather construction, any nonorganic onsite soil may be considered for use as
structural fill, provided it meets the criteria described above in the "Structural Fill" section and can
be compacted as recommended. If the moisture content of the soil is over optimum when
excavated, it will be necessary to aerate or dry the soil prior to placement as structural fill.
The native weathered ice -contact and ice -contact soils generally consisted of silty sand with
gravel. These soils are generally comparable to common borrow (WSDOT 9-03.14(3)) and are
suitable for use as structural fill provided the moisture content is maintained within 2 percent of the
optimum moisture level. However, these soils may become difficult to adequately compact during
extended periods of wet weather or where seepage occurs.
GEORESOURCES 0
Soto. 6thAveSW.RG
April 30, 2018
page l 12
We recommend that completed graded areas be restricted from traffic or protected prior to
wet weather conditions. The graded areas may be protected by paving, placing asphalt -treated
base, a layer of free -draining material such as pit run sand and gravel or clean crushed rock material
containing less than 5 percent fines, or some combination of the above.
Erosion Control
Weathering, erosion and the resulting surficial sloughing and shallow land sliding are natural
processes. As noted, no evidence of surficial raveling or sloughing was observed at the site. To
manage and reduce the potential for these natural processes, we recommend erosion protection
measures will need to be in place prior to grading activity on the site. Erosion hazards can be
mitigated by applying BMPs outlined in the 2016 King County Surface Water Design Manual.
We understand that you propose to have a level backyard at the site. Permanent fill slopes
should not be any steeper than 2H:1 V in order to prevent erosion from runoff along the slope.
Wet Weather Earthwork Considerations
In the Puget Sound area, wet weather generally begins about mid -October and continues
through about May, although rainy periods could occur at any time of year. Therefore, it is strongly
encouraged that earthwork be scheduled during the dry weather months of June through
September. Most of the soil at the site contains sufficient fines to produce an unstable mixture
when wet. Such soil is highly susceptible to changes in water content and tends to become unstable
and impossible to proof -roll and compact if the moisture content exceeds the optimum.
In addition, during wet weather months, the groundwater levels could increase, resulting in
seepage into site excavations. Performing earthwork during dry weather would reduce these
problems and costs associated with rainwater, construction traffic, and handling of wet soil.
However, should wet weather/wet condition earthwork be unavoidable, the following
recommendations are provided:
• The ground surface in and surrounding the construction area should be sloped as much as
possible to promote runoff of precipitation away from work areas and to prevent ponding of
water.
• Work areas or slopes should be covered with plastic. The use of sloping, ditching, sumps,
dewatering, and other measures should be employed as necessary to permit proper
completion of the work.
• Earthwork should be accomplished in small sections to minimize exposure to wet conditions.
That is, each section should be small enough so that the removal of unsuitable soils and
placement and compaction of clean structural fill could be accomplished on the same day.
The size of construction equipment may have to be limited to prevent soil disturbance. It
may be necessary to excavate soils with a backhoe, or equivalent, and locate them so that
equipment does not pass over the excavated area. Thus, subgrade disturbance caused by
equipment traffic would be minimized.
■ Fill material should consist of clean, well -graded, sand and gravel, of which not more than 5
percent fines by dry weight passes the No. 200 mesh sieve, based on wet -sieving the fraction
passing the 3/4-inch mesh sieve. The gravel content should range from between 20 and 50
percent retained on a No. 4 mesh sieve. The fines should be non -plastic.
GEORESOURCES
' Soto. 6thAveSW. R G —
April 30, 2018
page 1 13
■ No exposed soil should be left uncompacted and exposed to moisture. A smooth -drum
vibratory roller, or equivalent, should roll the surface to seal out as much water as possible.
• In -place soil or fill soil that becomes wet and unstable and/or too wet to suitably compact
should be removed and replaced with clean, granular soil (see gradation requirements
above).
• Excavation and placement of structural fill material should be observed on a full-time basis
by a geotechnical engineer (or representative) experienced in wet weather/wet condition
earthwork to determine that all work is being accomplished in accordance with the project
specifications and our recommendations.
• Grading and earthwork should not be accomplished during periods of heavy, continuous
rainfall.
We recommend that the above requirements for wet weather/wet condition earthwork be
incorporated into the contract specifications.
LIMITATIONS
We have prepared this report for use by Nate Soto, David L. Thorstad Architect, and other
members of the design team, for use in the design of a portion of this project. The data used in
preparing this report and this report should be provided to prospective contractors for their bidding
or estimating purposes only. Our report, conclusions and interpretations are based on our
subsurface explorations, data from others and limited site reconnaissance, and should not be
construed as a warranty of the subsurface conditions.
Variations in subsurface conditions are possible between the explorations and may also occur
with time. A contingency for unanticipated conditions should be included in the budget and schedule.
Sufficient monitoring, testing and consultation should be provided by our firm during construction to
confirm that the conditions encountered are consistent with those indicated by the explorations, to
provide recommendations for design changes should the conditions revealed during the work differ
from those anticipated, and to evaluate whether earthwork and foundation installation activities
comply with contract plans and specifications.
The scope of our services does not include services related to environmental remediation and
construction safety precautions. Our recommendations are not intended to direct the contractor's
methods, techniques, sequences or procedures, except as specifically described in our report for
consideration in design.
If there are any changes in the loads, grades, locations, configurations or type of facilities to be
constructed, the conclusions and recommendations presented in this report may not be fully
applicable. If such changes are made, we should be given the opportunity to review our
recommendations and provide written modifications or verifications, as appropriate.
GEORESOURCES
Soto. 6thAveSW. RG
April 30, 2018
page 114
We have appreciated the opportunity to be of service to you on this project. If you have any
questions or comments, please do not hesitate to call at your earliest convenience.
Respectfully submitted,
GeoResources, LLC
Jordan L. Kovash, GIT
Staff Geologist in Training
o[ Was -Q
925
o�nsed Ge-0
KEITH SC9FT SCHEMBS
912
Keith S. Schembs, LEG
Principal
JLK:KSS:DCB/jlk
Doc ID: Soto.6thAveSW.RG
Attachments: Figure 1: Site Location Map
Figure 2: Site & Exploration Plan
Figure 3: Site Vicinity Map
Figure 4: NRCS Soils Map
Figure 5: Geologic Map
Appendix A -Subsurface Explorations
Appendix B - Laboratory Test Results
aF� �
a
Q Sao
Dana C. Biggerstaff, PE
Senior Geotechnical Engineer
�v
GEORESOURCES
4
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Particle Size Distribution Report
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tp N
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WIN
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ai
IUU I
�/, +3" % Gravel
r Coarse Fine
F
N
0.0 16.7 29.4
ca
N C ._U
Q3rV,%l I r a
°/ Sand % Fines
Coarse Medium Fine Silt
14.3 13.1 13.3 13.2
Test Results (ASTM D 422 & ASTM D 1140)
Opening
I Percent
Spec.' Pass?
Size
Finer
(Percent) (X=Fail)
1.25
I 100.0
1
I 97.4
.75
83.3
.5
73.8
.3125
69.3
#4
53.9
#10
39.6
#20
32.4
#40
26.5
#60
21.2
#100
16.9
#200
13.2
M (no specification provided)
f° a Location: 14A 1, S-1
E Sample Number: 0941940.
De
GeoResources, LLC
Fife, WA
Material Descri tp 1on
silty gravel with sand
Atterber Limits ASTM D 4318)
PL= NP LL= NV P1= ,tip
Classification
USCS (D 2487)= GM AASHTO (M 145)= A-1-a
Coefficients
D90= 21.8411 D85= 19.7212 D60= 5.8210
D50= 3-7484 D30= U395 D15= 0.1046
1390= Cu= Cc=
Remarks
Date Received: 4/9/18
Tested By: AL-S
Checked By: KSS
Title: PM
Date Tested: 4/11/18
Date Sampled: 4/9/18
Client: Nate Soto
Project: Soto.6thAveSW
Tested By: Checked By:
Appendix B
Laboratory Analyses
^� Perc Hole PH-3
Location: Western portion of the parcel
Approximate Elevation: 384'
Depth (ft) Soil Type Soil Description
0 - 1'/2 - Dark brown to black forest duff with abundant organics and roots (loose, moist)
1 %2 - 21/2 SM Brown with orange staining silty SAND with gravel and occasional cobbles (loose to
medium dense, moist to damp) (weathered ice -contacts?)
2% - 4 SM
Logged by: CC
Brown grey silty SAND with gravel (medium dense, moist to damp) (ice -contacts?)
Terminated at 4 feet below existing ground surface.
Mottling observed at 1 %2 feet below existing ground surface.
No caving observed.
No groundwater seepage observed at the time of site visit.
GEORESOURCES
earth science & geotechnical engineering
5007 Pacific Hwy E., Suite 16 1 Fife, WA 98424 1 253.896.1011 1 www.georesources.rocks
observed on: April 9, 2018
Perc Hole Logs
Proposed Single Family Residence
xxx - 6`h Avenue Southwest
Federal Way, Washington
PN: 3021049064
Doc ID: Soto.6thAveSw.F I April 2018 I Figure A-4
Perc Hole PH-1
Location: Western portion of the parcel
Approximate Elevation: 382'
Depth (ft) Soil Type Soil Description
0 - 1 %2 - Dark brown to black forest duff with abundant organics and roots (loose, moist)
1 %2 - 23/4 GM Brown with orange staining silty SAND with gravel and occasional cobbles (loose to
medium dense, moist to damp) (weathered ice -contacts?)
23/4 - 4 SM Brown grey silty SAND with gravel (medium dense, moist to damp) (ice -contacts?)
Terminated at 4 feet below existing ground surface.
Mottling observed at 1 %2 feet below existing ground surface.
No caving observed.
No groundwater seepage observed at the time of site visit.
Perc Hole PH-2
Location: Western portion of the parcel
Approximate Elevation: 382'
Depth (ft) Soil Type Soil Description
0 - 1%2 - Dark brown to black forest duff with abundant organics and roots (loose, moist)
1 %2 - 2%2 SM Brown with orange staining silty SAND with gravel and occasional cobbles (loose to
medium dense, moist to damp) (weathered ice -contacts?)
2%2 - 4 SM Brown grey silty SAND with gravel (medium dense, moist to damp) (ice -contacts?)
Terminated at 4 feet below existing ground surface.
Mottling observed at 1 %2 feet below existing ground surface.
No caving observed.
No groundwater seepage observed at the time of site visit.
Logged by: CC Observed on: April 9, 2018
GEORESOURCES
earth science & geotechnical engineering
5007 Pacific Hwy E., Suite 16 1 Fife, WA 98424 1253.896.1011 1 www.georesources.rocks
Perc Hole Logs
Proposed Single FamilyResidence
xxx — 611i Avenue Southwest
Federal Way, Washington
PN: 3021049064
Doc ID: Soto.6thAveSW.F ' April 2018 1 Figure A-3
^� Hand Auger HA-1
Location: West central portion of the parcel
Approximate Elevation: 370'
Depth (ft) Soil Type Soil Description
0 - 1 %2 - Dark brown to black forest duff with abundant organics and roots (loose, moist)
1 %2 - 3 GM Brown with orange staining silty GRAVEL with sand and occasional cobbles (loose to
medium dense, moist to damp) (weathered ice -contacts)
3 - 7 SM Brown grey silty SAND with gravel (medium dense, moist to damp) (ice -contacts)
Terminated at 7 feet below existing ground surface.
Mottling observed at 1 Meet below existing ground surface.
Some caving observed at 1/2 feet below existing ground surface.
No groundwater seepage observed at the time of excavation.
Hand Auger HA-2
Location: Central portion of the parcel
Approximate Elevation: 335'
Depth (ft) Soil Type Soil Description
0 - 1 %2 Dark brown to black forest duff with abundant organics and roots (loose, moist)
11/2 - 23/4 SM Brown with orange staining silty SAND with gravel and cobbles (loose to medium dense,
moist to damp) (weathered ice -contacts)
23/4 - 63/4 SM Brown grey silty SAND with gravel (medium dense, moist to damp) (ice -contacts)
Terminated at 4 feet below ground surface.
Mottling observed at 11/2 feet below existing ground surface.
No caving observed at the time of excavation.
No groundwater seepage observed at the time of excavation.
Logged by: CC Excavated on: April 9, 2018
r
G EO RESO U RCES
earth science & geotechnical engineering
5007 Pacific Hwy E., Suite 16 1 Fife, WA 98424 1 253.896.1011 1 www.georesources.rocks
Hand Auger Logs
Proposed Single Family Residence
xxx - 6Ih Avenue Southwest
Federal Way, Washington
PN: 3021049064
Doc ID: Soto.6thAveSW.F I April 2018 I Figure A-2
SOIL CLASSIFICATION SYSTEM
MAJOR DIVISIONS
GROUP
GROUP NAME
SYMBOL
I
GRAVEL
CLEAN
GW
WELL -GRADED GRAVEL, FINE TO COARSE GRAVEL
GRAVEL
GP
POORLY -GRADED GRAVEL
COARSE
GRAINED More than 50%
GRAVEL
GM
SILTY GRAVEL
SOILS Of Coarse Fraction
WITH FINES
Retained on
GC
CLAYEY GRAVEL
No. 4 Sieve
SAND
CLEAN SAND
SW
WELL -GRADED SAND, FINE TO COARSE SAND
SP
POORLY -GRADED SAND
More than 50%
Retained on
No. 200 Sieve
More than 50%
SAND
SM
SILTY SAND
Of Coarse Fraction
WITH FINES
Passes
Sc
CLAYEY SAND
No. 4 Sieve
SILT AND CLAY
INORGANIC
ML
SILT
CL
CLAY
FINE
GRAINED
SOILS
Liquid Limit
ORGANIC
OL
ORGANIC SILT, ORGANIC CLAY
Less than 50
SILT AND CLAY
INORGANIC
MH
SILT OF HIGH PLASTICITY, ELASTIC SILT
CH
CLAY OF HIGH PLASTICITY, FAT CLAY
More than 50%
Passes
No. 200 Sieve
Liquid Limit
ORGANIC
OH
ORGANIC CLAY, ORGANIC SILT
50 or more
HIGHLY ORGANIC SOILS
PT
PEAT
NOTES:
1. Field classification is based on visual examination of soil
in general accordance with ASTM D2488-90.
2. Soil classification using laboratory tests is based on
ASTM D2487-90.
3. Description of soil density or consistency are based on
interpretation of blow count data, visual appearance of
soils, and or test data.
GEORESGURCES
earth science & geotechnical engineering
5007 Pacific Hwy E., Suite 16 1 Fife, WA 98424 1253.896.1011 1 www georesources.rocks
SOIL MOISTURE MODIFIERS:
Dry- Absence of moisture, dry to the touch
Moist- Damp, but no visible water
Wet- Visible free water or saturated, usually soil is
obtained from below water table
Unified Soils Classification System
Proposed Single Family Residence
xxx - 61h Avenue Southwest
Federal Way, Washington
PN: 3021049064
Doc ID: Soto.6thAveSW.F I April 2018 1 Figure A-1
Appendix A
Subsurface Explorations
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Approximate Site Location
An excerpt from the Geologic Map of the Poverty Bay 7.5-minute Quadrangle, Washington, Booth, D.B., Waldron, H.H., and
Troost, K.G., (2003)
Qvi Ice -contact deposits
Qvt Glacial till
Qva Advance outwash deposits
GEORESOURCES
earth science & geotechnical engineering
5007 Pacific Hwy E., Suite 16 1 Fife, WA 98424 1253.896.1011 1 www.georesources.roch
USGS Geologic Map
Proposed Single Famfly Residence
xxx - 6th Avenue Southwest
Federal Way, Washington
PN: 3021049064
Doc ID: Soto.6thAveSW.F April 2018
Not to Scale
Figure 5
I- FEtiCE IS SOUTH
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Lo
17
FENCE END Is 1_5'+j—
SOUTH OF PROPERTY LINE
_FEACE EI-10 IS
ON =4CPERTY LhE
North
Scale 1 "=50'
Site Plan prepared by David L. Thorstad Architect and underlying topo%boundary survey
By Holmvig, Deweitt, Gallion & Assoc, LLC dated 3.28.2018
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GEORESOURCES
earth science & geotechnical engineering
5007 Pacific Hwy E., Suite 16 1 Fife, WA 98424 1253.996.1011 I www.georesources.rocks
Site Location Map
Proposed Single Family Residence
xxx - 6" Avenue Southwest
Federal Way, Washington
PN:3021049064
Doc ID: Soto.6thAveSW.F I April 2018
Not to Scale
Figure 1
Approximate
Map created from Web Soil Survey (http://webso
Soil + Soil Name
AgB Alderwood gravelly sandy loam
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Parent Mater
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GEORESOURCES
earth science & geotechnical engineering
5007 Pacific Hwy E., Suite 16 1 Fife, WA 98424 1253.896.1011 I www.georesources.rocks
Site Location
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ial Slopes Erosion Hazard HydrologicSoils Grou
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NRCS Soils Map
Proposed Single-FamilyResidence
xxx - 6th Avenue Southwest
Federal Way, Washington
PN: 3021049064
Doc ID: Soto.6thAveSW.F April 2018 Figure 4
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GEORESOURCES
earth science & geotechnical engineering
5007 Pa6fic Hwy E„ Suite 16 1 Fike YIA 984Z4 1 253.06.1011 I www.g"resources.reeRs
Not to Scale
Site Vicinity Map
Proposed Single Family Residence
xxx - 6"' Avenue Southwest
Federal Way, Washington
PN:3021049064
Doc 10: S0to.6thAveSW.F I April 2478 1 Figure 3
CITY OF
Federal Way
Centered on Opportunity
May 6, 2019
AP Consulting Engineers PLLC
Attn: Adam Paul, P.E.
PO Box 162
Auburn, WA 98071
RE: SOTO Folder # 18-102138-000-00-SF
Dear Mr. Paul:
CITY HALL
33325 8th Avenue South
Federal Way, WA 98003-6325
(253) 835-7000
www.cityoffederalway.com
Jim Ferrell, Mayor
Development Services has reviewed the third submitted site plan, Technical Information Report (TIR)
and make the following comments:
Technical Information Report (TIR)
Page 3, Core Requirement #1 — your description states the slopes range from 7-33% but
previously submitted documentation states the slopes are between 7-percent and 35-percent. The
documentation must remain consistent.
2. Page 3, Core Requirement #8 — states that project is exempt from water quality because there is
less than 5,000 square feet of new or replacement pollution -generating impervious surfacing;
however the City of Federal Way Addendum 1.1.1.A states any site that adds or will result in
2,000 square feet or more of new impervious surface... Therefore water quality treatment is
required for your site.
3. Page 7, 5.0 Cvnve ante System Analysis and Desi - Please clarify why the conveyance system
down the steep hill has been designed as a 12-inch main. It would be easier and more economical
to design a single family conveyance down a 35-percent slope as a 6-inch or perhaps 4-inch
system.
Sheet C1
4. All text must be 1/8" nominal size per the City of Federal Way Development Standards. This
includes all notes (General Notes, Drainage Notes), details and schedules.
5. Detail 1 indicates a curb to be installed at the edge of the driveway. The curb will not be allowed
within City right-of-way. Correct detail accordingly.
6. How can an area disturbed by installation of storm drain lines and gravel ditches be called
"Native Growth Retention" areas? Clarify.
\\CFWFILE 1 \Applications\CSDC\PROD\docs\save\151645_79113_03110416.doc
7. Clarify why this design now captures any excess lawn runoff.
8. In lieu of a 12-inch main installation of a 6-inch or 4-inch diameter pipe down the slope would
appear to be more economical and less impact upon the steep slope.
9. Given the steep slope the proposed pipe is installed on, it appears that an energy dissipater will be
necessary at the outlet.
10. In lieu of a storm pond it appears more practical to install a dispersion trench at elevation 267.
This would minimize the impacts to the existing tree canopy. In addition there appears to be 50-
feet of native growth for the flows to disperse across before the property line.
11. The current plan indicates a 54-inch control structure in the pond while the clearing limits shown
on Sheet C2 indicate 10-feet or less of clearing. Please list what piece of construction equipment
the designer has found that can carry a 54-inch structure down a 35-percent grade and is less than
10-feet wide.
Sheet C2
12. Again, all text must be 1/8" nominal size per the City of Federal Way Development Standards.
This includes all notes (General Notes, Drainage Notes), details and schedules.
13. To lessen the impact on native growth and to avoid disturbance of greater than one acre it would
appear installation of a dispersion trench at the base of the slope would be more practical.
Sincerely,
Cole Elliott, P.E.
Development Services Manager
CE:ss
Enc: Plan set redlines
cc: Leila Willoughby -Oakes, Associate Planner
Natanael Soto, Owner
David Thorstad, Architect
Project File
Day File
Leila Willoughby -Oakes
From:
Leila Willoughby -Oakes
Sent:
Wednesday, June 12, 2019 10:15 AM
To:
Ann Dower; 'Adam E. Paul'
Cc:
Cole Elliott; 'Natanael soto'
Subject:
RE: Soto residence
Hi All,
Thank you for meeting yesterday. I think we've found a good solution moving forward with the pump to get Mr. Soto to
a conclusion.
Planning's requirements are below if you did opt for a pond in the very rear and the 10 ft. wide area for the piping we
would need the following as it's a 35%/30% slope.
1) Resubmit the geotechnical report for staff/city consultant review and payment of a peer review fee before this
work. Under our code above 15%, contains permeable sediment, predominately sand and gravel, overlying
relatively impermeable sediment or bedrock, typically silt and clay; and Springs or groundwater
seepage would trigger the geotech. to look at the slope area to determine if this is landslide versus erosion
hazard.
2) Provide information on how the pond would be maintained and access over time- understanding that properties
do change hands and future owners may not be able to access the rear on foot like Mr. Soto.
3) Provide more detailed information on the number and size trees removed to accommodate the pond and pipe -
ensuring we do not trigger a forest practices permit (one log truck of merchantable timber)
4) How will you ensure there are no geological impacts off -site on abutting properties in the rear. A bit more off -
site topo information would be required.
If you opt for work in the front yard no peer review would apply- Planning would simply need a memo from the geotech,
confirming that further encroachment into the 50 ft. into the GHA standard buffer would not lead to or create any
increased slide, seismic or erosion hazard. Telling us how much additional disturbance in sf would occur- revising the
engineering drawings.
If there are issues with the encroachment further into the 50 ft. standard GHA buffer —they city can grant a reduced
front yard setback to 10 ft. from 20 ft. as long as the proposal meets FWRC 19.120.110.6, 1 believe Mr. Soto has 20 feet
length of parking area (I think there's 120 ft.).
"(6) Front yard setbacks for single-family residential development on lots with a slope of 15 percent or greater may be applied in
a flexible manner where such application will protect slopes and natural features from development encroachments. However, a
minimum front yard setback of 10 feet must be maintained in all cases, and a minimum 20 foot setback shall apply to garages,
unless the garage and driveway are oriented in such a way as to provide minimum 20 feet length of parking area in
front of the garage within the property boundaries."
Let me know if you have any further questions,
Leila
L. Willoughby -Oakes
Associate Planner
Federal Way
From: Ann Dower
Sent: Wednesday, June 12, 2019 8:49 AM
To: 'Adam E. Paul'
Cc: Cole Elliott; Leila Willoughby -Oakes
Subject: Soto residence
Good Morning Adam
I discussed the situation with Cole . The City will approve the basin break and the pump situation since there are
critical areas downslope and the flow is small. We are actually surprised that about 11,000 square feet of impervious
area would generate 0.5-cfs of runoff (I believe this is what you stated in the meeting) and suggest that you recheck the
calculations.
In that scenario you will need to provide the following:
a minimum pump capacity for the 2-year discharge
incremental storage up to the 50-year storm
emergency overflow to the back . Dispersion trench is ok as an emergency overflow, but please keep it as far as you can
from the edge of slope.
a duplex system is not required.
Please note that maintenance is the responsibility of the owners. To aid in that, a pump alarm system is highly
recommended, and the emergency generator that Mr. Soto mentioned is recommended as well.
I hope this helps. Let me know if you have questions.
Ann Dower
Senior Engineering Plans Reviewer
017
_. Federal Way
Public Works Department
33325 8th Ave S, Federal Way, WA 98003
Desk:253.835.2732 1 Fx:253.835.2709
cityoffederalway.com
CITY OF
Ak Federal. Way
�_z7ultered on Op
February 20, 2019
AP Consulting Engineers PLLC
Attn: Adam Paul, P.E.
PO Box 162
Auburn, WA 98071
RE: SOTO Folder # 18-102138-000-00-SF; Stormwater Adjustment Request
Dear Mr. Paul:
CITY HALL
33325 8th Avenue South
Federal Way, WA 98003-6325
(253) 835-7000
www.cityoffederalway.com
Jim Ferrell, Mayor
This letter responds to your request for adjustment to the 2016 King County Surface Water Design Manual
(KCSWDM) Section C.2.1.1, Minimum Design Requirements for Full Dispersion associated with the development
of the above -referenced project. After evaluating your request, review of Federal Way Revised Code (FWRC)
Section 16.30.070, KCSWDM Section C.2.1.1 and direction provided by City Council, the Public Works
Department hereby provides the following response to your request:
In accordance with FWRC 16.30.040 adjustments may be granted provided that the adjustment will:
1. Produce a result comparable to that which would be achieved by satisfaction of the KCSWDM and Federal
Way Addendum requirements, and which is in the public interest; and
2. Meet the objectives of safety, function, appearance, environmental protection, and maintainability based on
sound engineering judgement.
The geotechnical report indicates that slopes down gradient of the proposed dispersion trench are between 20 and 35
percent while KCSWDM Section C.2.1.1.5 states:
Dispersion devices are not allowed in critical area buffers (unless approved by DPER (the City)) or on
slopes steeper than 20%.
The Public Works Department hereby denies your request for adjustment of the maximum slope allowed for a
dispersion trench. If you have any questions or concern, please contact Cole Elliott, P.E., Development Services
Manager, at (253) 835-2730.
Sincerely,
ValshEJ/, P.EP lic Works Director
cc: Leila Willoughby -Oakes, Associate Planner
Natanael Soto, Owner
David Thorstad, Architect
Project File
Day File
\\CFW FILE 1 \Applications\CSDC\PROD\docs\save\ 151645_78793_ 19163524.doc
18-102138��
A-P CONSULTING ENGINEERS PLLC
CIVIL ENGINEERING
February 5, 2019
Mr. Cole Elliot, PE
City of Federal Way
33325 8th Avenue South
Federal Way, WA 98003-6325
RESUBMITTED
FEB 0 5 2019
CITY OF FEDERAL WAY
COMMUNITY DEVELOPMENT
RE: Soto Residence (File #18-102138-000-00-SF)
Response to 1st Review Comments
Mr. Elliot:
This letter includes a response to the third set of review comments, dated October 3, 2019,
as follows:
1. The frontage improvement waiver is currently being reviewed under a separate
permit. A letter with the final determination will be sent separately.
Noted.
2. Again it appears that the submitted packet does not contain all of the details
required. Development Services would expect at a minimum a detail for the
proposed storm water system.
A detail for the dispersion trenches has been added to C1.
3. The submitted storm system proposes to use full dispersion, but the site plan
indicates that the average 26-percent slope is in excess of the 20-percent
maximum slope allowed (with Geotechnical Engineer/Geologist review and
approval) in accordance with King County Surface Water Design Manual
(KCSWDM) Section C.2.1.1.
An adjustment request supported by a geotechnical analysis is included with
this resubmittal.
4. The Geotechnical Report (GeoResources) included within the Technical
Information Report (TIR) also indicates that full infiltration is not feasible.
The City makes this observation, but has not indicated how this is relevant to
the revisions being requested.
5. Within the TIR there appears to be an assumption that any impervious surface
(roadway or roof) does not count as impervious if it is dispersed. This
assumption is incorrect. All post development modeling must be run including
all impervious surfaces.
Section 1.2.9.4 of the KCSWDM indicates that "any impervious surface served
by a flow control BMP that meets the design specifications for the BMP in
Appendix C may be modeled as indicated in Table 1.2.9.A." With the approval
of the adjustment, this project will be in compliance with these requirements
and will, therefore, qualify to model fully dispersed impervious surfaces as
forest.
APCE@APConsultingEngineers.com (253) 737-4173 PO Box 162, Auburn, WA 98071
6. Any storm treatment system proposed must be accompanied by back-up sizing
calculations and references to the applicable KCSWDM Sections used.
Projects with less than 5,000 square feet of PGIS, such as this one, are
exempted by the KCSWDM from providing water quality treatment systems.
This comment does not apply to this project.
If you have any question or require additional information please feel free to contact us at
(253) 737-4173.
Sincerely,
AP CONSULTING ENGINEERS PLLC
t. t),
Adam E. ul, PE
Principal Civil Engineer
CITY OF
� Federal Way
Centered on Op ortunity
October 3, 2018
Mr. David Thorstad
406 S. 289' Street
Federal Way, WA 98003
RE: SOTO; Folder # 18-102138-000-00-SF
Dear Mr. Thorstad:
CITY HALL
33325 8th Avenue South
Federal Way, WA 98003-6325
(253) 835-7000
www. cityoffederalway.. com
Jim Ferrell, Mayor
Development Services has reviewed the second submitted site plan, Technical information Report (TIR) along
with your response letter; we make the following comments:
1. The frontage improvement waiver is currently being reviewed under a separate permit. A letter with
the final determination will be sent separately.
2. Again it appears that the submitted packet does not contain all of the details required. Development
Services would expect at a minimum a detail for the proposed storm water system.
3. The submitted storm system proposes to use full dispersion, but the site plan indicates that the average
26-percent slope is in excess of the 20-percent maximum slope allowed (with Geotechnical
Engineer/Geologist review and approval) in accordance with King County Surface Water Design
Manual (KCSWDM) Section C.2.1.1.
4. The Geotechnical Report (GeoResources) included within the Technical Information Report (TIR)
also indicates that full infiltration is not feasible.
5. Within the TIR there appears to be an assumption that any impervious surface (roadway or roof) does
not count as impervious if it is dispersed. This assumption is incorrect. All post development
modeling must be run including all impervious surfaces.
6. Any storm treatment system proposed must be accompanied by back-up sizing calculations and
references to the applicable KCSWDM Sections used.
Please revise your Site Plan and TIR and resubmit.
Since f
Cole Ellio , P.E.
Development Services Manager
cc: Leila Willoughby -Oakes, Associate Planner
Adam Paul, P.E., AP Consulting Engineers PLLC, PO Box 162, Auburn, WA 98071
Project File (ce)
Day File
\\cfwGlel \applications\csdc\prod\docs\save\151645_78328_03085828.doc
FILE
CITY OF
Federal way
Centered on Opportunity
June 26, 2018
CITY HALL
33325 8th Avenue South
Federal Way, WA 98003-6325
(253) 835-7000
wwwcityoffederalway. com
Jim Ferrell, Mayor
David Thorstad Emailed: dltarchitect@7u,comcast.net
406 S. 289th Street
Federal Way, WA 98003
RE: File #18-102138-00-SF; PLANNING REVIEW COMMENTS
Soto, No Site Address, 61h Avenue SW, Parcel #3021049064, Federal Way
Dear Mr. Thorstad:
Planning staff has reviewed your single-family building permit for a proposed new house located at the
above -referenced address. A review of the submitted materials indicates the following issues that must be
addressed prior to building permit approval. GeoResources LLC (2018) states the subject property
contains geologically hazardous areas including a 30-foot +/- relief change and slopes greater than 40
percent with 10 feet or more of vertical relief (p. 7).
SITE PLAN/ TREE REMOVAL & REPLACEMENT PLAN
Provide the following on Sheet 1 of 6:
a. Total lot coverage.
b. A tree/vegetation removal and replacement plan (trees to be removed, to be retained and tree
protection measures/no disturbance zone).
i. Pursuant to FWRC 19.120.080 the applicant shall define the clearing and grading and land
disturbance limits, establishing the permitted areas for clearing, grading, cutting and filling on
the site plan. Permitted clearing and grading areas should minimize the removal of existing
trees, except as needed for building purposes.
ii. A no disturbance area shall be established for each tree to be protected. The no disturbance
zone shall be equal to the critical root zone which is defined as 12 inches radius for every one
inch of tree diameter measured at four and one-half feet above ground. Any other no
disturbance area proposed by the applicant shall be determined by a qualified arborist and
subject to review and approval by the director.
DRIVEWAY
Please note a driveway may only flare at the front property line to a maximum width of 30 feet if the
proposal:
• Serves a three -car garage;
• The subject property is at least 60 feet in width; and
The garage is located no more than 40 feet from the front property line.
It appears the flare is 60 feet within the public right-of-way; please reduce.
HEIGHT
Please provide the average building elevation (AABE) calculation, including the proposed and existing
contours. The site is sloped, and the grade change in the area where the building footprint is proposed as
10 feet. The proposed residence is limited to 30 ft. AABE.
Mr. Thorstad
June 26, 2018
Page 2 of 2
Be advised that as a condition of building permit approval, if the proposed height is greater than 27 feet
AABE it is likely that a height survey, prepared by a professional surveyor, will be required to be
submitted prior to the framing inspection to verify compliance with the height limitation.
GEOLOGICALLY HAZARDOUS AREAS
Please depict the extents of geologically hazardous areas on the site plan. FWRC 19.145.220 regulates all
development activities on or within 50 feet of a geologically hazardous area. It appears that the proposed
house will be located more than 50 feet from the erosion hazard area identified on the city's critical area
inventory. However, the April 30, 2018, geotechnical report prepared by GeoResources LLC does not
state if the subject property contains or does not contain erosion hazard areas, their location, nor their
extents. Please revise the report and classify the areas of the site containing erosion hazard areas (if
applicable).
CRITICAL AREAS -NOTICE ON TITLE
Prior to final occupancy, the applicant shall record the final site plan depicting geologically hazardous
areas (erosion hazard areas) and a critical area restrictive covenant on title with King County. FWRC
19.14.170 requires:
"The owner of any property containing critical areas or buffers on which a development proposal is
submitted or any property on which mitigation is established as a result of development, except a public
right-of-way or the site of a permanent public facility, shall file a notice approved by the city with the
King County recorder's office. The required contents and form of the notice shall be determined by the
director. The notice shall inform the public of the presence of critical areas, buffers or mitigation sites on
the property, and that limitations on actions in or affecting such critical areas or buffers may exist. The
notice shall run with the land. "
CLOSING
Please submit three copies of requested plans with the enclosed resubmittal form. Be advised that other
City departments are or will be reviewing these plans, and additional comments may be forthcoming. If
you have any questions regarding this letter, please contact me at leila.willoughby-
oakes@cityoffederalway.com, or 253-835-2644.
Sincerely,
Leiia Willoughby -Oakes
Associate Planner
enc: Resubmittal Form
Tree Unit Calculation Sheet
Critical Area Restrictive Covenant
Bulletin No. 151 Height Measurement
c: Riley Bushnell, Planning Intern, email
Cole Elliott, Development Services Manager
Kathy Mathena, Engineering Technician, email
Keith Schembs, GeoResources, Keith$ c georesources.us
18- 10213 8-00-SF Doc. I.D. 77912
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King County
Department of Permitting
and Environmental Review
35030 SE Douglas Street, Suite 210
Snoqualmie, WA 98065-9266
206-296-6600 TTY Relay: 711
www.kingcounty.gov
_ _ S30 Web Date: 11/20/201�
_ _
Surface Water Design Manual
FEa 0 5 zul Requirements / Standards
CITY OF FEDERAL WAY Adiustment* Reauest
COMMUNITY DEVELOPMErY
Project Name: � "Ucr
Project Address: �6C&&MAig
Applicant/Agent": Phone:
S %W- ASl��L.
Signature of ApplicantlA ent: I Date:
Address:
City, State, ZIP:
For alternate formats, call 206-296-6600*
Permitting Project File No:
Permitting Engineer/Planner Name:
De ign Engineer:
Z�
Address:
?D B014 l
Name:
Or
lone:
r14
City, State, ZIP:
INSTRUCTIONS TO APPLICANT/DESIGN ENGINEER: '
Please be sure to include all materials (Level One Downstream Analysis, Certification of Applicant Status form, sketches,
photos, and maps) that may assist in complete review and consideration of this adjustment request. Failure to provide all
pertinent information may result in delayed processing or denial of request. Please submit two complete copies of this request,
aopiicaiion form, and applicable fee to the Department of Permitting and Environmental Review, 35030 SE Douglas Street, Suite
210 in Snoqualmie, WA 98065-9266. For more information, call 206-296-6600.
"Applicant/Agent is the individual financially responsible for all fees
REFER TO CHAPTER 1, SECTION 1.4 OF THE SURFACE WATER DESIGN MANUAL FOR ADJUSTMENTS
DESCRIPTION OF ADJUSTMENT REQUEST: X Standard [:]complex ❑ Experimental ❑ Blanket ❑ Pre -application
APPLICABLE VERSION KCSWDM: ❑ 1990 (11/95)* ❑ 1998 (9/98) �2005 (1/05)
*(Note: the term "variance" replaced by "adjustment') 2014
APPLICABLE SECTION(S) OF STANDARDS:
JUSTIFICATION PER KCSWDM SECTION 1.4.2: dSee attachment: PERMIT #:
ADDRESS:
PROJECT:
AUTHORIZATION SIGNATURES
DETERMINATION: ❑ Approval
❑ DNRP/WLRD Approval Signed:
Permitting Staff Recommendation
Signed:
Conditions of
❑ See attached memo dated:
RE -SUB
18-102138-00-S-
New Construction
SOTO
02/05/2019
❑ Conditional Approval (see below) ❑ Denial
Date: (Experimental & Blanket only)
Permitting DIRECTOR / DESIGNEE:
Permitting, Engineering Review Supervisor:
Signed: Date:
Date:
Permitting, Site Engineering & Planning Supervisor
Signed: Date:
Check out the Permitting Web site at www.kingcounty.clovlpermi_fs
SurfWaterDesManRegStdsAdjRegFORM.doc le-info-surwa-adj.pdf S30 11/20/2012 Page 1 of 1
AP CONSULTING ENGINEERS PLLC
CIVIL ENGINEERING
February 1, 2019
Mr. Cole Elliot
City of Federal Way
33325 8th Avenue South
Federal Way, WA 98003
RE: SOTO RESIDENCE
ADJUSTMENT JUSTIFICATION LETTER
(APCE Project #2018044)
Cole:
This letter provides a justification for approving an adjustment to Section C.2.1.1 of the
2016 KCSWDM for the Soto Residence. Specifically, the request is for an adjustment of the
provisions that only allows full dispersion flow paths to be placed on slopes that have
slopes of less than 20%. Approval of this adjustment is necessary to ensure that this project
remains feasible for the property owner since the flow control credits that are available
for fully -dispersing runoff are the only feasible alternative that this project would have to
a detention system other than severely decreasing the size of the house and access.
The primary concern about placing dispersion trenches in areas where the slopes exceed
20% is the stability of those slopes when stormwater runoff is introduced into those areas.
GeoResources, a geotechnical engineering consulting firm, reviewed the slopes on this
property and performed a slope stability analysis and determined that the slopes were
stable and that the overflow flow paths would have a minimal impact on the slopes. The
geotechnical report is included with this letter.
The stormwater increase for this project is limited to an increase of 0.150 cfs for the 100-
year,15-minute peak flow rate. When including the credit for fully dispersing as much of
the impervious surface as it was feasible to collect and convey to the proposed dispersion
trenches, the peak flow increase is calculated to be 0.141 cfs. Losing the credit from the
dispersion areas would force the project to significantly decrease the size of the residence
and driveway that is proposed or to significantly increase the amount of money spent on
stormwater detention and water quality treatment that can safely and adequately be
handled by dispersing the water through native vegetation on this property.
APCE@APConsultingEngineers.com (253) 737-4173 PO Box 162, Auburn, WA 98071
Please let us know if we can provide you with any additional information to support
your review. If you have any questions, I can be reached at (253) 737-4173 or via email at
AEPaul@APConsultingEngineers.com.
Sincerely,
AP CONSULTING ENGINEERS PLLC
Adam E. Paul, PE
Principal Civil Engineer
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ABBREVIATIONS-
N.T.S.
A.B.
ANCHOR BOLT
LAV
LAVATORY
A.F.F.
ABOVE FINISHED FLOOR
LIN.
LINEAR
A.F.G.
ABOVE FINISHED GRADE
LINO.
LINOLEUM
A/C
AIR CONDITIONING
LT.
LIGHT
ABV.
ABOVE
LTG.
LIGHTING
AG
ABOVE GRADE
LVL
LAMINATED VENEER LUMBER
ALUM.
AVG
ALUMINUM
AVERAGE
MAT'L
MATERIAL
MAX.
MAXIMUM
AWG
AMERICAN WIRE GAUGE
MECH.
MECHANICAL
BLDG
BUILDING
MED.
MEDIUM
BLKG.
BLOCKING
MFG.
MANUFACTURING
C.O.
CLEAN OUT
MIN.
MINIMUM
C.T.
CERAMIC TILE
MISC.
MISCELLANEOUS
CFM
CUBIC FEET PER MINUTE
N.T.S.
NOT TO SCALE
CL
CENTERLINE
O.C.
ON CENTER
CLG.
CEILING
O.D.
OUTSIDE DIAMETER
CONC.
CONCRETE
OH
OVER HEAD
CONST.
CONSTRUCTION
P.C.
PRECAST CONCRETE
CONT.
CONTINUOUS
PERF.
PERFORATED
CONTR.
CONTRACTOR
PLUMB.
PLUMBING
D/W
DISHWASHER
PLYWD.
PLYWOOD
DBL.
DOUBLE
PORC.
PORCELAIN
DIA
DIAMETER
PREFAB.
PREFABRICATED
DIM.
DIMENSION
PSF
POUNDS PER SQUARE FOOT
DN.
DOWN
PSI
POUNDS PER SQUARE INCH
EQ.
EQUAL
PVC
POLYVINYLCLORIDE
EQUIP.
EQUIPMENT
PWR.
POWER
EST.
ESTIMATE
QTY.
QUANTITY
EXC
EXCAVATE
R
RADIUS
EXH.
EXHAUST
R.O.
ROUGH OPENING
EXIST
EXISTING
R.O.W.
RIGHT OF WAY
EXT.
EXTERIOR
REFR
REFRIG'EiATOR
F.A.
FIRE ALARM
REF.
REFERENCE
F.D.
FLOOR DRAIN
REINF.
REINFORCED
F.E.
FIRE EXTINGUISHER
REQ'D.
REQUIRED
F/G
FIBERGLASS
REV.
REVISION
FAB,
FABRICATE
S.D.
SMOKE DETECTOR
FDN.
FOUNDATION
SCHED.
SCHEDULE
FIN.
FINISH
SECT.
SECTION
FTG.
FOOTING
SHT'G.
SHEATHING
GALV.
GALVANIZED
SPECS
SPECIFICATIONS
GAR.
GARAGE
SO. FT.
SQUARE FEET
GFI
GROUND FAULT INTERRUPTER
SQ. IN.
SQUARE INCHES
GL
GLASS
STD.
STANDARD
GLB
GLUE LAMINATED BEAM
T & G
TONGUE AND GROOVE
GWD
GYPSUM WALL BOARD
T.V.
TELEVISION OUTLET
HGT.
HEIGHT
TEL.
TELEPHONE
HOR.
HORIZONTAL
THK.
THICK
HTR
HEATER
THRU
THROUGH
HVAC
"HEATING, VENTIL. & AIR G'
TYP.
TYPICAL
I.D.
INSIDE DIAMETER
UNF.
UNFINISHED
ID
IDENTIFICATION
V.B.
VAPOR BARRIER
INSUL.
INSULATION
VERT.
VERTICAL
INT.
INTERIOR
W/C
WATER CLOSET
JCT
JUNCTION
W/M
WATER METER
JST.
JOIST
W/
WITH
W/O
WITHOUT
OWNER:
SITE ADDRESS:
LOT COVERAGE:
HEIGHT CALCULATION
YELLOW TULIPS LLC
BUILDING(including front porch and rear patios) 6249 SQ.FT. / 9.5 %
A-325' - FIN_ GRADE ELEVATION
PO BOX 5984
317XX 6th Place SW
WALKWAYS/PARKING 1391 SQ. FT.
B-325' - FIN. GRADE ELEVATION
KENT WA 98064
Federal Way WA 98023
ASPHALT DRIVEWAY 3396 SQ.FT.
C-325' - FIN. GRADE ELEVATION
TOTAL IMPERVIOUS SURF.: 11036 SQ.FT. / 16.78%
D-325' - FIN. GRADE ELEVATION
LEGAL DESCR.:
LOT SIZE 65,775 SQ. FT.(1.51 ACRE)
RIDGE ELEV. 357' 5 1/2"
MAX. IMPR. SURF. COVERAGE ALOWED: 50 %
BASE ELEVATION 325' 0"
POR OF N 1/2 OF S 1/2 OF SW 1/4 OF SE 1/4 W OF A LN
357'5 1/2" - 325'0" = 32'5 1/2"
BEG 394.5 FT E OF S 1/4 COR TH N 02-05--04 E 480.21 FT
TH N 44-35-04 E ELY 30 FT FOR RD LESS S 1/2
PARCEL # : 072104-9093
NO RETAINING WALLS PROPOSED ON SITE
ZONING RS 9.6
SHOP DRAWING FOR ROOF TRUSSES AND TJI WILL BE PROVIDED BY OTHERS.
PROJECT DESCRIPTION:
LOT SIZE
65,775 SQ.FT.
WETLAND BUFFER AREA
17,976 SQ.FT.
CONSTRUCT A NEW TWO STORY SINGLE FAMILY RESIDENCE.
IMPACTED AREA OF THE WETLAND BUFFER 1,741 SQ.FT.
TOTAL LIVING SPACE 7393 SQ.FT. AND 1260 SQ.FT. 2 ATTACHED GARAGES.
FIRE SPRINKLERS REQUIRED, DESIGN WILL BE PROVIDED BY OTHERS
DESIGNED PER 2012 IBC AND WA STATE
ENERGY CODE
TEMPORARY PARKING TO BE IMPROVED WITH CRUSHED ROCK.
OWNER/CONTRACTOR NOTES
THE FOLLOWING NOTES SHALL SERVE AS A GUIDE TO THE
CONTRACTOR TO VERIFY EACH CONDITION RATHER THE PRODUCT
MANUFACTURER OR SUPPLIER, AND/OR LOCAL JURISDICTIONS
FOR THEIR REQUIREMENTS PRIOR TO SUBMITTING A BID TO THE
OWNER OR PROCEEDING WITH THEIR WORK.
1. REVIEW MANUFACTURER'S PRODUCT LITERATURE AND
GENERAL NOTES FOR INSTALLATION, INSTRUCTIONS UNIQUE
TO THE PROJECT CONSTRUCTION TYPE.
A.. HVAC SYSTEM
B. ALL EXHAUST FANS AND DUSTING
C. RECEPTACLE BOXES(TV, TELEPHONE, ELECTR. PLUMBING)
2. REVIEW LOCAL JURISDICTION REQUIREMENTS FOR COMPLETE
INSTALLATION OF THE FOLLOWING:
A. FIRE SPRINKLER SYSTEM
B. FIRE AND ALARM SYSTEMS
C. FIRE EXTINGUISHER SIZE AND LOCATIONS
3. COORDINATE WITH THE FOLLOWING UTILITIES AND COMPLY
WITH LOCAL JURISDICTIONAL REQUIREMENTS:
TELEPHONE, CABLE TV, WATER/SEWER UTILITIES, TRASH
SERVICES, POWER UTILITY.
4. THE FOLLOWING ITEMS SHALL BE BIDED DESIGN SYSTEM.
THE CONTRACTOR SHALL PROVIDE A COMPLETE SYSTEM
TO THE OWNER AND BUILDING DEP. WHICH COMPLIES
WITH ALL JURISDICTIONAL REQUIREMENTS:
A. HVAC SYSTEM
B. PLUMBING SYSTEM
C. ELECTRICAL
D. FIRE SPRINKLER SYSTEM
E. FIRE ALARM SYSTEM
EXISTING ELEVATION
- PROPOSED ELEVATION
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Main Floor: 4526 sq.ft
Upper Floor: 2867 sq.ft.
Total Living.: 7393 sq.ft.
Garage(A): 662 sq.ft
Garage(B): 598 sq.ft
Covered Front Porch: 132 sq.ft
Rear Concrete Patios: 387 sq.ft
Balconies: 286 sq.ft
Project number 188
Date 02-22-2011
Drawn by Y. M.
Phone 253-275-8422
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LEGEND
JA
•'_ CONIFEROUS TREE
goUndal • . .`, • ; • e, i :% : t ' a' -`- DECIDUOUS TREE
j ° d� _:.� :• - `..- .. - - �•>° -'' FIR TREE
' •_ CEDAR TREE
. _ �' •'•d
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:.a
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• :4. = • ' p, :� _ d •- : COTTONWOOD
"•, _ - �a `p - e°' : •° ;:.`" PINE
` f CHERRY
! HOLLY
>,:..,d:., ', _ - ,: _ - "•- •. .�-d• DOGWOOD
' �, � �'`-�•,�,", '� -` ,� ..,�-_ " �: �., "},:'I':�°� TREES TO BE RETAINED
�:: -••�:.*+•.d6`ffi':w.^-..sss._'_:. .^_ram--.-�a.�::�.._,r ....;
65,1775 / 43,1560=1.51(lot size) X 25 = 37.75 min. units needed to retain
Existing Trees Trees to be Retain
Tree Size
# of Trees
Tree Units
Total Units
1"to6"dbh
>6" to 12" dbh
>12" to 18" dbh
13
24
29
7
10
x1
x 1.5
x 2.0
x 2.5
x 3.0
13
36
58
17.5
30
>18" to 24" dbh
> 24" dbh
Total Existing Tree Units
154.5
Tree Size
# of Trees
Tree Units
Total Units
1"to6"dbh
4
x1
4
>6" to 12" dbh
19
x 1.5
28.5
>12' to 18" dbh
16
x 2.0
32
>18' to 24" dbh
3
x 2.5
7.5
> 24" dbh
6
x 3.0
18
Total Tree Units Remains
90
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Main Floor: 4526 sq.ft
Upper Floor: 2867 sq.ft.
Total Living.: 7393 sq.ft.
Garage(A): 662 sq.ft
Garage(B): 598 sq.ft
Covered Front Porch: 132 sq.ft
Rear Concrete Patios: 387 sq.ft
Balconies: 286 sq.ft
Project number 188
Date 02-22-2011
Drawn by Y. M.
Phone 253-275-8422
,viv I
Scale As indicated
1
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SYMBOL
SCIENTIFIC NAME
SHRUBS: 4'-6' O/C
Rosa nutkana
Rosa pisocarpa
g
Salix scouleriana
Oemleria cerasiformis
COMMON NAME SIZE QUANTITY
Nootka rose 2 gallon container 28
Cluster rose 2 gallon container 28
Scouler's willow 2 gallon container 28
Indian plum 2 gallon container 28 i
/
/
EMERGENTS: Clumps of 4; 1' O/C ;
Carex deweyana Dewey's sedge 10" plugs 27
Carex utriculata northern territory 10" plugs 27
sedge
Juncus ensifolius Dagger leaf rush 10" plugs 27
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