CITY OF PUYALLUP TOSCANOS SINKHOLE EVALUATION

CITY OF PUYALLUP PIERCE COUNTY WASHINGTON TOSCANOS SINKHOLE EVALUATION G&O #15470 OCTOBER 2015

TABLE OF CONTENTS BACKGROUND...1 EXISTING SYSTEM...1 Stormwater Conveyance System...1 Video Inspection...2 Geotechnical Investigation...2 Hydrologic and Hydraulic Model...2 ALTERNATIVES...3 Do Nothing...3 Repair the Detention System...3 Replace the Detention System...4 Abandon the Detention System...4 RECOMMENDATION...4 LIST OF TABLES No. Table Page 1 Hydrologic Model Summary...3 LIST OF FIGURES No. Figure Follows Page 1 Vicinity Map...2 2 Drainage Area...2 3 Survey Base Map...2 4 Abandon Existing Detention System...4 APPENDICES Appendix A Geotechnical Investigation Appendix B Model Results Appendix C Cost Estimates Appendix D Existing System Hydraulic Profile Appendix E New System Hydraulic Profile i

Gray & Osborne, Inc., Consulting Engineers BACKGROUND In 2012, multiple surface settlements (sinkholes) appeared in the parking lot of the Toscanos Italian Grill restaurant in the vicinity of a stormwater detention system. The detention system is adjacent to Toscanos and located beneath the parking lot of a small commercial development along 29 th Street NE. This stormwater detention system in the vicinity of the intersection of East Main Avenue and 5 th Avenue NE in the City of Puyallup currently fails to function as designed. The City wishes to evaluate the feasibility of removing or rehabilitating the existing stormwater detention system to alleviate the drainage issues currently on site. EXISTING SYSTEM The existing system was installed in 1979 as part of the development of the nearby Linden Estates. Another portion of the system was installed as part of the Riverside Commercial Development in 1992. The detention system is comprised of 36-inch and 54-inch CMP pipes and is approximately 440 feet long. It extends within a 20-foot easement located in the parking lots of two retail/services buildings and Toscanos Italian Grill. The sinkholes seem to be on the downstream (northeast) end at the Toscanos Italian Grill parking lot at approximately 437 29 th Street NE. Lots 4 and 5 (including the Toscanos restaurant) were developed in 2003, almost 25 years aer installation of the detention system. The detention system discharges flows to the northeast to an outfall on the Puyallup River. Figure 1 indicates the location of the project site. STORMWATER CONVEYANCE SYSTEM Figure 2 shows the drainage basins that are tributary to the detention system and to the 24-inch concrete outfall. An area of approximately 38.7 acres is tributary to the 24-inch concrete outfall pipe. The detention system collects flows from approximately 24.5 acres of this area. The entire subbasin is fully developed and contains commercial retail buildings, apartments, and condominiums. Land cover in the subbasin is approximately 90 percent impervious. The City identifies the larger drainage basin as the Puyallup River South basin. The City has a stormwater base map in both AutoCAD and GIS, which was used to explore the existing system. The City s GIS base map includes infrastructure quality data from 2009, 2011, or 2013, when the various sections of the stormwater system in the project area were surveyed. All of the pipes, manholes, and inlets in the project s subbasin are labeled as being in good quality. The stormwater conveyance elements in the subbasin are partially commercially owned and partially publicly owned. Gray & Osborne conducted survey as part of this study in order to determine exact pipe sizes, slopes, materials, and locations, as well as to investigate the condition of the existing stormwater infrastructure. The survey base map may be seen on Figure 3. City of Puyallup 1 Toscanos Sinkhole Evaluation October 2015

Gray & Osborne, Inc., Consulting Engineers VIDEO INSPECTION The City of Puyallup maintenance staff completed a television inspection of the detention system in the summer of 2012 to investigate the potential pipe leakage. The investigation found many areas of groundwater infiltration into the pipe and found a large void about 19 feet to the west of Catch Basin D5-00418 in one of the 48-inch sections of the detention system. The pipe to the west of Catch Basin D5-00418 appears to be the primary source of the sinkhole problem. The other pipes in the system were found to have smaller amounts of infiltration that included material migration. These areas of infiltration are identified on Figure 3. In 2012, City crews filled the sinkhole using controlled density fill (CDF) within the parking lot. No video inspection was provided post repair. It is recommended that a re-inspection of the detention system be conducted to see if the infiltration continues to include material migration, as was apparent in 2012. The detention system should be thoroughly cleaned prior to the video inspection. GEOTECHNICAL INVESTIGATION A geotechnical investigation was conducted as part of this feasibility study by PanGEO, Inc. in June 2015 and is included as Appendix A. The investigation found soils on site to be comprised mostly of alluvium. Alluvium consists of dense sand, silt, and clay. The geotechnical investigation analyzed the subsurface condition surrounding the sinkholes with respect to groundwater levels and soil types. A cone penetration test (CPT) was conducted as part of the geotechnical investigation. That test found no evidence of voids or zones of disturbance within the parking lot. HYDROLOGIC AND HYDRAULIC MODEL A stormwater hydrologic model using the Santa Barbara Unit Hydrograph (SBUH) was used with an XP-SWMM hydraulic model methodology to determine peak flow and system capacity. For comparison, peak flow rates were also determined using the Western Washington Hydrology Model (WWHM). A summary of the results of the two models is shown in Table 1. 2 City of Puyallup October 2015 Toscanos Sinkhole Evaluation

Approximate Tributary Basin Stormwater Outfall Project Site LEGEND: City Limits Storm Pipes 10' Topo streams 0 500 1,000 CITY OF PUYALLUP ± TOSCANOS SINKHOLE FEASIBILITY STUDY FIGURE 1 - VICINITY MAP 2,000 Feet M:\PUYALLUP\15470 Toscanos Sinkhole Evaluation\GIS\Figure1.mxd

LEGEND: City Limits Storm Pipes Manholes Inlets Parcels Storm Basins 10' Topo streams 0 125 250 CITY OF PUYALLUP ± TOSCANOS SINKHOLE FEASIBILITY STUDY FIGURE 2 - DRAINGE AREA 500 Feet M:\PUYALLUP\15470 Toscanos Sinkhole Evaluation\GIS\toscano basin.mxd

PLAN 65 65 Areas of infiltration Identified on video inspection 60 60 55 55 20' 0 20' 40' SCALE: 1"=40' 50 50 45 45 40 40 CITY OF PUYALLUP TOSCONOS SINKHOLE EVALUATION 35 0+00 1+00 2+00 3+00 4+00 35 FIGURE 3 SITE PLAN AND PROFILE PROFILE

Gray & Osborne, Inc., Consulting Engineers TABLE 1 Hydrologic Model Summary SBUH WWHM Peak Flow Peak Peak Flow Peak Storm Event Frequency Design Storm at Detention System (cfs) Flow at Outfall (cfs) at Detention System (cfs) Flow at Outfall (cfs) 25-Year 3.5", Type 1A 19.9 31.4 15.2 23.9 100-Year 4.1", Type 1A 23.4 37.0 19.7 30.9 The hydraulic model assumed no backwater condition at the outfall to the Puyallup River. The maximum hydraulic grade, as well as applicable model results, may be seen for the 25- and 100-year storm events in Appendix B. Although the downstream stormwater conveyance does not have an open-channel flow capacity (based on Mannings equation) for the 25- or 100-year storm events, the model indicates that the hydraulic grade line (HGL) for these events are below the ground surface. The hydraulic model output shows that the maximum water elevation downstream of the detention system during the 25- and 100-year storm events is 6.3 and 4.4 feet below the ground surface, respectively. ALTERNATIVES The following alternatives were considered for the detention system and discussed below: Do Nothing Repair the Detention System Replace the Detention System Remove the Detention System Detailed cost estimates for each of the alternatives may be seen in Appendix C. DO NOTHING Because the surface settlements caused by the failing detention system require frequent ongoing maintenance to correct, doing nothing to this system is likely to lead to additional failures and is not considered to be a feasible alternative. REPAIR THE DETENTION SYSTEM The detention system may be lined in situ to eliminate the groundwater infiltration and material migration. Cured-in-place pipe (CIPP) lining is feasible for pipes as large as 96-inch diameter. A video inspection of the pipe, following cleaning, would confirm that City of Puyallup 3 Toscanos Sinkhole Evaluation October 2015

Gray & Osborne, Inc., Consulting Engineers the pipe is in adequate condition to be repaired by CIPP lining. Following CIPP lining, pressure grouting should be completed in the locations of active infiltration. The estimated cost to repair the detention system is $440,000. REPLACE THE DETENTION SYSTEM The detention system could be replaced with a new stormwater pipe. If the existing detention system was excavated and the top half of the pipe removed, a new pipe could be placed within the bottom half of the pipe at a slightly higher invert elevation. The new pipe could be backfilled in the same location as the current detention pipe. The hydraulic profile of the system using 24-inch diameter or 30-inch diameter pipes to replace the existing detention system is included in Appendix D. Following installation of the new pipe, pressure grouting should be completed in the locations of active infiltration. The estimated cost to replace the detention system is $344,000. ABANDON THE DETENTION SYSTEM The detention system could be abandoned if a new stormwater conveyance system was installed in 29 th Street NE and 5 th Avenue NE. The stormwater conveyance system would include 18- and 30-inch diameter pipe. The approximate alignment of the new conveyance system is shown on Figure 4. The hydraulic profile of the new system is included in Appendix E. The estimated cost to abandon the detention system is $517,000. RECOMMENDATION In the short term, it is recommended that another video inspection of the detention system be conducted, following a thorough cleaning of the system, to indicate if material is being actively transported through the system. This video inspection will be used to confirm the feasibility of the recommended long-term alternative of lining the detention system. 4 City of Puyallup October 2015 Toscanos Sinkhole Evaluation

4TH AVE NE 25' 12.5' 0 25' 50' SCALE: 1"=50' JOHN L SCOTT TOSCONOS CAFE CITY OF PUYALLUP TOSCONOS SINKHOLE EVALUATION FIGURE 4 ABANDON EXISTING DETENTION SYSTEM

APPENDIX A GEOTECHNICAL INVESTIGATION

June 29, 2015 File No. P-3681 Geotechnical & Earthquake Engineering Consultants Mr. Barry Baker, P.E. Gray & Osborne, Inc. 3710 168th St. NE, Suite B210 Arlington, WA 98223 Subject: Summary of Subsurface Exploration Settlement Evaluation 437 29 th Street NE, Puyallup, WA (Toscanos Italian Grill) Dear Mr. Baker, As requested, we completed a subsurface surface exploration program to assist the City with the settlement evaluation at the subject site. The approximate location of the site is shown in Figure 1. We understand that a city-owned storm pipe located in the parking lot in front of the subject building failed several years ago, and resulted in subsidence of ground surface. The City subsequently replaced a section of the storm pipe, and backfilled the excavation to repair the subsidence. We understand the City intends to evaluate if potential ground disturbance (i.e., if piping of soils) are present near the existing storm facility that may adversely impact the area in the future. SUBSURFACE EXPLORATION To evaluate if voids or disturbed zones may be present below the parking lot, Cone Penetration Test (CPT) was conducted at five locations on June 13, 2015. The approximate CPT locations (CPT-1 through CPT-5) are indicated on the attached Figures 2 and 3. The test was completed by In Situ Engineering of Snohomish, Washington, under a subcontract to PanGEO. In Situ Engineering uses an instrumented cone approximately 1½ inches in diameter, which is pushed against a truck at a slow steady rate into the soil to measure tip resistance (Qc), side friction (Fs), pore water pressure (u), and inclination (i). The readings on the soil are usually taken at about 2-3213 Eastlake Avenue East, Suite B Seattle, WA 98102 Tel: (206) 262-0370 Fax: (206) 262-0374

Geotechnical Engineering Study Settlement Evaluation: 437 29 th Street NE, Puyallup, WA June 29, 2015 inch vertical intervals, and provide a nearly continuous readout of soil stratigraphy, strength and other parameters. The results from the CPT are plotted on the CPT logs included in Appendix A. GEOLOGY According to the geologic map of the area compiled by Troost (in review), the surficial geologic unit at the project site is alluvium (map unit Qal). Alluvium typically consists of a sequence of loose to dense sand and silty sand, and so to stiff silt and clay. SUMMARY INTERPRETATION OF CPT DATA In general, the CPT data from the five test locations are quite consistent, and consisted of approximately 1½ to 3 feet thick crust of well-compacted granular soils. This upper crust is likely structural fill that was placed for the construction of the parking lot. Below the crust, an interbedded sequence of loose to medium dense sand to medium stiff to stiff silt was encountered in the CPT. We interpret this layer as the native alluvium. The measured CPT tip resistance within this layer is consistent with undisturbed alluvium typically found in this region. In summary, based on our evaluation of the CPT data, it is our opinion that no evidence of voids or zones of disturbance were encountered at the CPT locations. Please call should you have any questions regarding this proposal. Sincerely, Siew L. Tan, P.E. Principal Geotechnical Engineer Enclosures: Figure 1 Figure 2 Figure 3 Appendix A Vicinity Map Site and Exploration Plan Photos of Site Conditions with CPT Locations Summary CPT Logs (CPT-1 through CPT-5) 15-111 Toscano Settlement Evaluation Page 2 of 2 PanGEO, Inc.

Fig1_vicinity.ppt 6/29/2015(1:12 PM) JC Crop map to 6.85 x 7 SITE LOCATION Image Credit: Google Maps N Not to Scale Settlement Evaluation 437 29 th Street NE Puyallup, Washington Project No. VICINITY MAP Figure No. 15-111 1

29th St NE CPT-1 CPT-2 CPT-5 CPT-3 CPT-4 file.grf w/ file.dat 6/29/15 (8:32 ) TEA2 LEGEND: CPT Location Settlement Evaluation 437-29th Street NE Puyallup, WA SITE AND EXPLORATION PLAN Project No. Figure No. 15-111 2

CPT-4 CPT-3 CPT-1 CPT-5 CPT-2 file.grf w/ file.dat 6/29/15 (8:31 ) TEA2 Settlement Evaluation 437 29th Street NE Puyallup, WA Project No. PHOTOS OF SITE CONDITIONS WITH CPT LOCATIONS Figure No. 15-111 3

Geotechnical Engineering Study Settlement Evaluation: 437 29 th Street NE, Puyallup, WA June 29, 2015 Appendix A Summary CPT Logs

PanGeo Toscanos CPT-01 Operator: Brown/Mayfield Sounding: CPT-01 Cone Used: DDG1327 CPT Date/Time: 6/13/2015 7:16:57 AM Location: Toscanos Puyallup Job Number: 15111 Tip Resistance Friction Ratio Pore Pressure Soil Behavior Type* SPT N* 0 0 Qc TSF 160 Fs/Qc (%) 0 8 Pw PSI -15 20 Zone: UBC-1983 0 12 60% Hammer 0 50 5 10 Depth () 15 20 25 Maximum Depth = 15.09 feet Depth Increment = 0.164 feet 1 sensitive fine grained 2 organic material 3 clay InSitu Engineering 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *Soil behavior type and SPT based on data from UBC-1983

PanGeo Toscanos CPT-02 Operator: Brown/Mayfield Sounding: CPT-02 Cone Used: DDG1327 CPT Date/Time: 6/13/2015 7:40:01 AM Location: Toscanos Puyallup Job Number: 15111 Tip Resistance Friction Ratio Pore Pressure Soil Behavior Type* SPT N* 0 0 Qc TSF 160 Fs/Qc (%) 0 8 Pw PSI -15 20 Zone: UBC-1983 0 12 60% Hammer 0 50 5 10 Depth () 15 20 25 Maximum Depth = 24.93 feet Depth Increment = 0.164 feet 1 sensitive fine grained 2 organic material 3 clay InSitu Engineering 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *Soil behavior type and SPT based on data from UBC-1983

PanGeo Toscanos CPT-3 Operator: Brown/Mayfield Sounding: CPT-03 Cone Used: DDG1327 CPT Date/Time: 6/13/2015 8:15:45 AM Location: Toscanos Puyallup Job Number: 15111 Tip Resistance Friction Ratio Pore Pressure Soil Behavior Type* SPT N* 0 0 Qc TSF 160 Fs/Qc (%) 0 8 Pw PSI -15 20 Zone: UBC-1983 0 12 60% Hammer 0 50 5 10 Depth () 15 20 25 Maximum Depth = 15.09 feet Depth Increment = 0.164 feet 1 sensitive fine grained 2 organic material 3 clay InSitu Engineering 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *Soil behavior type and SPT based on data from UBC-1983

PanGeo Toscanos CPT-04 Operator: Brown/Mayfield Sounding: CPT-04 Cone Used: DDG1327 CPT Date/Time: 6/13/2015 8:33:49 AM Location: Toscanos Puyallup Job Number: 15111 Tip Resistance Friction Ratio Pore Pressure Soil Behavior Type* SPT N* 0 0 Qc TSF 160 Fs/Qc (%) 0 8 Pw PSI -15 20 Zone: UBC-1983 0 12 60% Hammer 0 50 5 10 Depth () 15 20 25 Maximum Depth = 14.93 feet Depth Increment = 0.164 feet 1 sensitive fine grained 2 organic material 3 clay InSitu Engineering 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *Soil behavior type and SPT based on data from UBC-1983

PanGeo Toscanos CPT-05 Operator: Brown/Mayfield Sounding: CPT-05 Cone Used: DDG1327 CPT Date/Time: 6/13/2015 8:55:21 AM Location: Toscanos Puyallup Job Number: 15111 Tip Resistance Friction Ratio Pore Pressure Soil Behavior Type* SPT N* 0 0 Qc TSF 160 Fs/Qc (%) 0 8 Pw PSI -15 20 Zone: UBC-1983 0 12 60% Hammer 0 50 5 10 Depth () 15 20 25 Maximum Depth = 15.09 feet Depth Increment = 0.164 feet 1 sensitive fine grained 2 organic material 3 clay InSitu Engineering 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *Soil behavior type and SPT based on data from UBC-1983

APPENDIX B MODEL RESULTS

Untitled Day [0] Time 00:01:00 Step 1 Conduit 10172 from D4-10172 to D4-10179 Conduit 406 from D5-00406 to D5-00404 Conduit 404 from D5-00404 to D4-11658 0.0 162.8 325.7 488.5 651.4 814.2 977.0 1139.9 1302.7 1465.6 1628.4 60.0 50.0 40.0

Pipes Name Upstream Node Name Downstream Node Name Diameter (Height) Length Downstream Invert Elevation Upstream Invert Elevation Maximum Water Elevation (US) Design Full Flow cfs Max Flow cfs Pipe Surcharge at U/S m Duration of Surcharged Flow min 404 D5-00404 D4-11658 2.000 239.100 37.470 38.290 43.695 13.250 31.068 3.405 48.687 5.405 11658 D4-11658 D4-08576 2.000 150.000 32.860 37.320 38.669 39.010 31.065 0.000 0.000 1.349 8576 D4-08576 0 2.000 70.600 33.080 32.660 34.107 74.480 31.063 0.000 0.000 1.296 406 D5-00406 D5-00404 2.000 195.700 38.990 39.040 45.907 3.620 24.329 4.867 49.524 6.867 405 D5-00405 D5-00406 2.000 148.200 39.190 40.080 47.568 17.530 24.322 5.488 47.427 7.488 418 D5-00418 D5-00405 2.000 111.500 40.280 40.250 48.381 3.710 19.698 6.131 44.322 8.101 417 D5-00417 D5-00418 3.000 115.300 40.450 40.690 48.480 30.430 19.691 4.790 32.733 7.931 414 D5-00414 D5-00415 4.500 127.100 39.900 42.480 48.483 280.170 8.747 1.503 25.892 8.582 415 D5-00415 D5-00416 4.500 125.500 39.420 39.900 48.482 121.620 8.290 4.082 28.991 9.061 416 D5-00416 D5-00417 4.500 62.400 40.690 39.420 48.481 280.540 7.547 4.561 28.991 9.060 10172 D4-10172 D4-10179 1.500 218.000 48.720 51.060 51.771 10.880 4.206 0.000 90.429 1.950 10179 D4-10179 D4-10181 1.500 32.000 48.090 48.520 50.670 12.180 4.206 0.650 1342.385 2.529 10181 D4-10181 D5-00414 1.500 33.000 49.680 47.910 50.619 24.330 4.205 1.209 1345.154 2.556 Max Depth 09/11/15 14:47:04 1/1

Manholes Name Ground Invert Max Water Volume of Duration of EGL Surcharge Subcatchme Rainfall Max Flow Freeboard nt Elevation (Spill Elevation Elevation Ponded Flow Surcharge Reference cfs Elevation at Max Crest) Stored (min) HGL 0 35.100 33.080 33.956 ^3 0.000 sec 0.000 0.000 33.956 0.000 1.140 D4-08576 1 44.660 32.660 34.107 0.000 0.000 0.000 37.159 0.000 10.550 D4-11658 54.420 37.320 38.669 0.000 0.000 0.000 40.838 0.000 15.750 D5-00404 1 50.090 38.290 43.695 0.000 36.515 25Yr SCS 6.820 44.599 2.705 6.390 D5-00406 62.140 39.040 45.907 0.000 47.427 0.000 46.806 4.717 16.230 D5-00405 1 58.480 40.080 47.568 0.000 40.792 25Yr SCS 4.715 47.568 5.288 10.910 D5-00417 1 57.240 40.690 48.479 0.000 21.163 25Yr SCS 13.478 48.479 3.290 8.760 D5-00416 55.120 39.420 48.478 0.000 28.991 0.000 48.481 4.561 6.640 D5-00414 1 57.580 42.480 48.482 0.000 0.000 25Yr SCS 2.244 48.482 0.000 9.100 D5-00415 55.200 39.900 48.481 0.000 25.892 0.000 48.483 4.082 6.720 D5-00418 59.350 40.250 48.380 0.000 32.733 0.000 48.966 4.931 10.970 D4-10181 55.090 47.910 50.619 0.000 1342.385 0.000 50.882 1.029 4.470 D4-10179 55.120 48.520 50.670 0.000 90.429 0.000 50.995 0.450 4.450 D4-10172 1 56.360 51.060 51.771 0.000 0.000 25Yr SCS 4.207 51.771 0.000 4.590 09/11/15 14:45:05 1/1

Untitled Day [0] Time 00:01:00 Step 1 Conduit 10172 from D4-10172 to D4-10179 Conduit 406 from D5-00406 to D5-00404 Conduit 404 from D5-00404 to D4-11658 0.0 162.8 325.7 488.5 651.4 814.2 977.0 1139.9 1302.7 1465.6 1628.4 60.0 50.0 40.0

Pipes Name Upstream Node Name Downstream Node Name Diameter (Height) Length Downstream Invert Elevation Upstream Invert Elevation Maximum Water Elevation (US) Design Full Flow cfs Max Flow cfs Pipe Surcharge at U/S m Duration of Surcharged Flow min 11658 D4-11658 D4-08576 2.000 150.000 32.860 37.320 38.863 39.010 36.688 0.000 0.000 1.543 8576 D4-08576 0 2.000 70.600 33.080 32.660 34.224 74.480 36.686 0.000 0.000 1.400 404 D5-00404 D4-11658 2.000 239.100 37.470 38.290 45.614 13.250 36.691 5.324 56.503 7.324 416 D5-00416 D5-00417 4.500 62.400 40.690 39.420 52.172 280.540 9.948 8.252 36.581 12.751 417 D5-00417 D5-00418 3.000 115.300 40.450 40.690 52.171 30.430 23.251 8.481 40.573 11.586 418 D5-00418 D5-00405 2.000 111.500 40.280 40.250 52.036 3.710 23.260 9.786 51.689 11.756 405 D5-00405 D5-00406 2.000 148.200 39.190 40.080 50.926 17.530 28.724 8.846 54.837 10.846 406 D5-00406 D5-00404 2.000 195.700 38.990 39.040 48.653 3.620 28.735 7.613 57.253 9.613 415 D5-00415 D5-00416 4.500 125.500 39.420 39.900 52.174 121.620 7.960 7.774 36.581 12.752 414 D5-00414 D5-00415 4.500 127.100 39.900 42.480 52.176 280.170 10.930 5.196 33.641 12.274 10172 D4-10172 D4-10179 1.500 218.000 48.720 51.060 52.771 10.880 4.921 0.211 120.571 3.595 10179 D4-10179 D4-10181 1.500 32.000 48.090 48.520 52.315 12.180 4.997 2.295 1353.154 4.156 10181 D4-10181 D5-00414 1.500 33.000 49.680 47.910 52.246 24.330 5.115 2.836 1355.385 4.266 Max Depth 09/11/15 14:55:13 1/1

Manholes Name Ground Invert Max Water Volume of Duration of EGL Surcharge at Subcatchme Rainfall Max Flow Freeboard nt Elevation Elevation Elevation Ponded Surcharge Reference cfs Elevation Max HGL (Spill Crest) Flow Stored (min) 0 35.100 33.080 34.060 ^3 0.000 sec 0.000 0.000 34.060 0.000 1.040 D4-08576 1 44.660 32.660 34.224 0.000 0.000 0.000 37.496 0.000 10.440 D4-11658 54.420 37.320 38.863 0.000 0.000 0.000 41.525 0.000 15.560 D5-00404 1 50.090 38.290 45.614 0.000 44.216 100Yr S 8.070 46.852 4.624 4.480 D5-00406 62.140 39.040 48.652 0.000 54.837 0.000 49.880 7.463 13.490 D5-00405 1 58.480 40.080 50.926 0.000 48.390 100Yr S 5.579 50.926 8.646 7.550 D5-00417 1 57.240 40.690 52.168 0.000 29.732 100Yr S 15.948 52.168 6.981 5.070 D5-00416 55.120 39.420 52.168 0.000 36.581 0.000 52.171 8.252 2.950 D5-00414 1 57.580 42.480 52.172 0.000 12.158 100Yr S 2.655 52.172 0.996 5.410 D5-00415 55.200 39.900 52.171 0.000 33.641 0.000 52.174 7.774 3.030 D4-10181 55.090 47.910 52.244 0.000 1353.154 0.000 52.360 2.656 2.850 D4-10179 55.120 48.520 52.311 0.000 120.571 0.000 52.421 2.095 2.810 D4-10172 1 56.360 51.060 52.769 0.000 5.444 100Yr S 4.978 52.769 0.211 3.590 D5-00418 59.350 40.250 52.033 0.000 40.573 0.000 52.830 8.586 7.320 09/11/15 14:54:00 1/1

APPENDIX C COST ESTIMATES

City of Puyallup Preliminary Construction Cost Estimate Toscanos Sinkhole Evaluation Repair Existing Detention System August 2015 Item Quantity Unit Cost Total 1 Mobilization/Demobilization 1 LS $ 25,000 $ 25,000 2 Minor Changes 1 LS $ 5,000 $ 5,000 3 Surveying, Staking and Record Dwgs 1 LS $ 2,000 $ 2,000 4 Traffic Control 1 LS $ 2,000 $ 2,000 5 Environmental Controls 1 LS $ 3,000 $ 3,000 6 Trench Excavation Safety Systems 0 LS $ 1,000 $ - 7 Dewatering 1 LS $ 1,000 $ 1,000 8 Removal of Structure and Obstruction 1 LS $ 1,000 $ 1,000 9 Locate Existing Utilities 1 LS $ 1,000 $ 1,000 10 Cast In Place Pipe 430 LF $ 350 $ 150,500 11 Pressure Grouting 6 EA $ 3,000 $ 18,000 12 Cement Concrete Sidewalk 0 SY $ 50 $ - 13 Bankrun Gravel for Trench Backfill 0 TN $ 25 $ - 14 Crushed Surfacing Base Course 0 TN $ 25 $ - 15 Hot Mix Asphalt 4 TN $ 100 $ 400 16 Landscaping Restoration 0 LS $ 1,000 $ - Subtotal $ 208,900 Contingency (25%) $ 52,225 Subtotal $ 261,125 Sales Tax (9.4%) $ 24,546 Total $ 285,671 Total Construction Cost (Rounded) $ 286,000 All Overhead (25%) $ 72,000 Total Project Cost (Rounded) $ 358,000 M:\PUYALLUP\15470 Toscanos Sinkhole Evaluation\Costs Toscanos.xlsx\Repair 8/28/2015

City of Puyallup Preliminary Construction Cost Estimate Toscanos Sinkhole Evaluation Replace Existing Detention System August 2015 Item Quantity Unit Cost Total 1 Mobilization/Demobilization 1 LS $ 25,000 $ 25,000 2 Minor Changes 1 LS $ 5,000 $ 5,000 3 Surveying, Staking and Record Dwgs 1 LS $ 2,000 $ 2,000 4 Traffic Control 1 LS $ 2,000 $ 2,000 5 Environmental Controls 1 LS $ 3,000 $ 3,000 6 Trench Excavation Safety Systems 1 LS $ 1,000 $ 1,000 7 Dewatering 1 LS $ 1,000 $ 1,000 8 Removal of Structure and Obstruction 1 LS $ 20,000 $ 20,000 9 Locate Existing Utilities 1 LS $ 2,000 $ 2,000 10 24" CPEP (Including bedding, backfill) 430 LF $ 80 $ 34,400 11 Pressure Grouting 6 EA $ 5,000 $ 30,000 12 Cement Concrete Sidewalk 310 SY $ 50 $ 15,500 13 Bankrun Gravel for Trench Backfill 900 TN $ 25 $ 22,500 14 Crushed Surfacing Base Course 180 TN $ 25 $ 4,500 15 Hot Mix Asphalt 320 TN $ 100 $ 32,000 16 Landscaping Restoration 1 LS $ 1,000 $ 1,000 Subtotal $ 200,900 Contingency (25%) $ 50,225 Subtotal $ 251,125 Sales Tax (9.4%) $ 23,606 Total $ 274,731 Total Construction Cost (Rounded) $ 275,000 All Overhead (25%) $ 69,000 Total Project Cost (Rounded) $ 344,000 M:\PUYALLUP\15470 Toscanos Sinkhole Evaluation\Costs Toscanos.xlsx\Replace 8/24/2015

City of Puyallup Preliminary Construction Cost Estimate Toscanos Sinkhole Evaluation Abandon Existing Detention System August 2015 Item Quantity Unit Cost Total 1 Mobilization/Demobilization 1 LS $ 35,000 $ 35,000 2 Minor Changes 1 LS $ 5,000 $ 5,000 3 Surveying, Staking and Record Dwgs 1 LS $ 2,000 $ 2,000 4 Traffic Control 1 LS $ 8,000 $ 8,000 5 Environmental Controls 1 LS $ 4,000 $ 4,000 6 Trench Excavation Safety Systems 1 LS $ 4,000 $ 4,000 7 Dewatering 1 LS $ 2,000 $ 2,000 8 Removal of Structure and Obstruction 1 LS $ 5,000 $ 5,000 9 Locate Existing Utilities 1 LS $ 5,000 $ 5,000 10 30" CPEP (Including bedding, backfill) 240 LF $ 100 $ 24,000 11 18" CPEP (Including bedding, backfill) 380 LF $ 70 $ 26,600 12 12" CPEP (Including bedding, backfill) 120 LF $ 60 $ 7,200 13 Catch Basin, Type 2, 48" (Basic to 8') 2 EA $ 2,500 $ 5,000 14 Catch Basin, Type 2, 54" (Basic to 8') 4 EA $ 3,000 $ 12,000 15 Catch Basin, Type 2, 54" (Over 8') 27 VF $ 200 $ 5,400 16 Connection to Existing System 2 EA $ 2,000 $ 4,000 17 Foundation Gravel 10 TN $ 20 $ 200 18 CDF to Abandon Existing Detention System 160 CY $ 150 $ 24,000 19 Cement Concrete Sidewalk 360 SY $ 50 $ 18,000 20 Bankrun Gravel for Trench Backfill 1,500 TN $ 25 $ 37,500 21 Crushed Surfacing Base Course 300 TN $ 25 $ 7,500 22 Hot Mix Asphalt 550 TN $ 100 $ 55,000 23 Landscaping Restoration 1 LS $ 5,000 $ 5,000 Subtotal $ 301,400 Contingency (25%) $ 75,350 Subtotal $ 376,750 Sales Tax (9.4%) $ 35,415 Total $ 412,165 Total Construction Cost (Rounded) $ 413,000 All Overhead (25%) $ 104,000 Total Project Cost (Rounded) $ 517,000 M:\PUYALLUP\15470 Toscanos Sinkhole Evaluation\Costs Toscanos.xlsx\Abandon 8/24/2015

APPENDIX D EXISTING SYSTEM HYDRAULIC PROFILE

Conduit 10172 from D4-10172 to D4-10179 Untitled Day [0] Time 00:01:00 Step 1 Conduit 406 from D5-00406 to D5-00404 Conduit 404 from D5-00404 to D4-11658 0.0 162.8 325.7 488.5 651.4 814.2 977.0 1139.9 1302.7 1465.6 1628.4 60.0 50.0 40.0 D4-10172 0.00 10172 D4-10179 D4-10181 D5-00414 0.00 0.00 0.00 414 D5-00415 0.00 415 D5-00416416 D5-00417 0.00 0.00 417 D5-00418 0.00 418 D5-00405 0.00 405 D5-00406 0.00 406 D5-00404 0.00 404 D4-11658 0.00 11658 D4-085768576 0.00 0 0.00 218.00 32.00 33.00 127.10 125.50 62.40 115.30 111.50 148.20 195.70 239.10 150.00 70.60

Pipes Name Upstream Node Name Downstream Node Name Diameter (Height) Length Downstream Invert Elevation Upstream Invert Elevation Maximum Water Elevation (US) Design Full Flow cfs Max Flow cfs Pipe Surcharge at U/S m Duration of Surcharged Flow min 8576 D4-08576 0 2.000 70.600 33.080 32.660 34.232 74.480 37.093 0.000 0.000 1.407 11658 D4-11658 D4-08576 2.000 150.000 32.860 37.320 38.879 39.010 37.094 0.000 0.000 1.559 404 D5-00404 D4-11658 2.000 239.100 37.470 38.290 45.745 13.250 37.093 5.455 49.294 7.455 406 D5-00406 D5-00404 2.000 195.700 38.990 39.040 48.851 3.620 29.053 7.811 49.960 9.811 405 D5-00405 D5-00406 2.000 148.200 39.190 40.080 51.173 17.530 29.053 9.093 46.846 11.093 418 D5-00418 D5-00405 2.000 111.500 40.280 40.250 52.305 3.710 23.494 10.055 43.725 12.025 417 D5-00417 D5-00418 2.000 115.300 40.450 40.690 53.473 10.320 23.494 10.783 42.739 12.783 416 D5-00416 D5-00417 2.000 62.400 40.690 39.420 53.539 32.270 8.038 12.119 712.444 14.053 415 D5-00415 D5-00416 2.000 125.500 39.420 39.900 53.671 13.990 7.843 11.771 712.444 14.119 414 D5-00414 D5-00415 2.000 127.100 39.900 42.480 53.805 32.230 7.662 9.325 99.524 13.771 10181 D4-10181 D5-00414 1.500 33.000 49.680 47.910 53.876 24.330 5.139 4.466 1355.308 5.895 10179 D4-10179 D4-10181 1.500 32.000 48.090 48.520 53.945 12.180 4.970 3.925 1353.000 5.786 10172 D4-10172 D4-10179 1.500 218.000 48.720 51.060 54.421 10.880 4.959 1.861 120.571 5.225 Max Depth 08/12/15 07:56:24 1/1

Manholes Name Ground Subcatchme Elevation nt (Spill Crest) Invert Elevation Max Water Elevation Volume of Ponded Flow Stored Duration of Surcharge (min) sec Rainfall Reference Max Flow cfs EGL Elevation Surcharge at Max HGL 0 35.100 33.080 34.067 0.000 0.000 0.000 34.067 0.000 1.030 D4-08576 1 44.660 32.660 34.232 0.000 0.000 0.000 37.517 0.000 10.430 D4-11658 54.420 37.320 38.879 0.000 0.000 0.000 41.569 0.000 15.540 D5-00404 1 50.090 38.290 45.745 0.000 38.127 100Yr SCS 8.070 47.012 4.755 4.350 D5-00406 62.140 39.040 48.851 0.000 46.846 0.000 50.106 7.661 13.290 D5-00405 1 58.480 40.080 51.173 0.000 41.067 100Yr SCS 5.579 51.173 8.893 7.310 D5-00418 59.350 40.250 52.305 0.000 42.013 0.000 53.121 9.855 7.050 D5-00417 1 57.240 40.690 53.473 0.000 42.739 100Yr SCS 15.948 53.473 10.783 3.770 D5-00416 55.120 39.420 53.539 0.000 712.444 0.000 53.623 12.119 1.580 D5-00415 55.200 39.900 53.671 0.000 99.524 0.000 53.756 11.771 1.530 D5-00414 1 57.580 42.480 53.805 0.000 21.488 100Yr SCS 2.655 53.805 2.625 3.780 D4-10181 55.090 47.910 53.876 0.000 1353.000 0.000 53.994 4.286 1.210 D4-10179 55.120 48.520 53.945 0.000 120.571 0.000 54.065 3.725 1.180 D4-10172 1 56.360 51.060 54.421 0.000 16.688 100Yr SCS 4.978 54.421 1.861 1.940 Freeboard 08/12/15 07:53:57 1/1

Conduit 10172 from D4-10172 to D4-10179 Untitled Day [0] Time 00:01:00 Step 1 Conduit 406 from D5-00406 to D5-00404 Conduit 404 from D5-00404 to D4-11658 0.0 162.8 325.7 488.5 651.4 814.2 977.0 1139.9 1302.7 1465.6 1628.4 60.0 50.0 40.0 D4-10172 0.00 10172 D4-10179 D4-10181 D5-00414 0.00 0.00 0.00 414 D5-00415 0.00 415 D5-00416416 D5-00417 0.00 0.00 417 D5-00418 0.00 418 D5-00405 0.00 405 D5-00406 0.00 406 D5-00404 0.00 404 D4-11658 0.00 11658 D4-085768576 0.00 0 0.00 218.00 32.00 33.00 127.10 125.50 62.40 115.30 111.50 148.20 195.70 239.10 150.00 70.60

Pipes Name Upstream Node Name Downstream Node Name Diameter (Height) Length Downstream Invert Elevation Upstream Invert Elevation Maximum Water Elevation (US) Design Full Flow cfs Max Flow cfs Pipe Surcharge at U/S m Duration of Surcharged Flow min 8576 D4-08576 0 2.000 70.600 33.080 32.660 34.232 74.480 37.082 0.000 0.000 1.407 11658 D4-11658 D4-08576 2.000 150.000 32.860 37.320 38.878 39.010 37.082 0.000 0.000 1.558 404 D5-00404 D4-11658 2.000 239.100 37.470 38.290 45.741 13.250 37.081 5.451 49.800 7.451 406 D5-00406 D5-00404 2.000 195.700 38.990 39.040 48.845 3.620 29.044 7.805 50.468 9.805 405 D5-00405 D5-00406 2.000 148.200 39.190 40.080 51.167 17.530 29.044 9.087 47.626 11.087 418 D5-00418 D5-00405 2.000 111.500 40.280 40.250 52.298 3.710 23.488 10.048 44.383 12.018 417 D5-00417 D5-00418 2.000 115.300 40.450 40.690 53.465 10.320 23.487 10.775 43.167 12.775 416 D5-00416 D5-00417 2.500 62.400 40.690 39.420 53.486 58.520 8.111 11.566 91.333 14.045 415 D5-00415 D5-00416 2.500 125.500 39.420 39.900 53.526 25.370 7.901 11.126 91.333 14.066 414 D5-00414 D5-00415 2.500 127.100 39.900 42.480 53.568 58.440 7.697 8.588 46.202 13.626 10181 D4-10181 D5-00414 1.500 33.000 49.680 47.910 53.639 24.330 5.194 4.229 1356.077 5.658 10179 D4-10179 D4-10181 1.500 32.000 48.090 48.520 53.708 12.180 5.009 3.688 1353.692 5.549 10172 D4-10172 D4-10179 1.500 218.000 48.720 51.060 54.185 10.880 4.958 1.625 120.571 4.988 Max Depth 08/12/15 08:10:42 1/1

Manholes Name Subcatchme nt Ground Elevation (Spill Crest) Invert Elevation Max Water Elevation Volume of Ponded Flow Stored ^3 Duration of Surcharge (min) sec Rainfall Reference Max Flow cfs EGL Elevation Surcharge at Max HGL Freeboard 0 35.100 33.080 34.067 0.000 0.000 0.000 34.067 0.000 1.030 D4-08576 1 44.660 32.660 34.232 0.000 0.000 0.000 37.517 0.000 10.430 D4-11658 54.420 37.320 38.878 0.000 0.000 0.000 41.567 0.000 15.540 D5-00404 1 50.090 38.290 45.741 0.000 39.318 100Yr SC 8.070 47.007 4.751 4.350 D5-00406 62.140 39.040 48.845 0.000 47.626 0.000 50.099 7.655 13.300 D5-00405 1 58.480 40.080 51.166 0.000 41.428 100Yr SC 5.579 51.166 8.887 7.310 D5-00418 59.350 40.250 52.297 0.000 42.420 0.000 53.112 9.848 7.050 D5-00417 1 57.240 40.690 53.464 0.000 40.085 100Yr SC 15.948 53.464 10.275 3.780 D5-00416 55.120 39.420 53.485 0.000 91.333 0.000 53.520 11.566 1.640 D5-00415 55.200 39.900 53.526 0.000 46.202 0.000 53.561 11.126 1.670 D5-00414 1 57.580 42.480 53.567 0.000 20.640 100Yr SC 2.655 53.567 2.388 4.010 D4-10181 55.090 47.910 53.639 0.000 1353.692 0.000 53.757 4.049 1.450 D4-10179 55.120 48.520 53.707 0.000 120.571 0.000 53.828 3.488 1.410 D4-10172 1 56.360 51.060 54.184 0.000 15.703 100Yr SC 4.978 54.184 1.625 2.180 08/12/15 08:09:37 1/1

APPENDIX E NEW SYSTEM HYDRAULIC PROFILE

Conduit 10172 from D4-10172 to D4-10179 Conduit 6 from D4-10181 to CB5 Untitled Day [0] Time 00:01:00 Step 1 Conduit 406 from D5-00406 to D5-00404 Conduit 404 from D5-00404 to D4-11658 0.0 162.5 324.9 487.4 649.8 812.3 974.8 1137.2 1299.7 1462.1 1624.6 60.0 50.0 40.0 D4-10172 0.00 10172 D4-10179 D4-10181 0.00 0.00 6 CB5 0.00 5 CB4 0.00 4 CB3 0.00 3 CB2 0.00 2 CB1 0.00 418 D5-00405 0.00 405 D5-00406 0.00 406 D5-00404 0.00 404 D4-11658 0.00 11658 D4-085768576 0.00 0 0.00 218.00 32.00 250.00 36.00 50.00 35.00 150.00 50.00 148.20 195.70 239.10 150.00 70.60

Pipes Name Upstream Node Name Downstream Node Name Diameter (Height) Length Downstream Invert Elevation Upstream Invert Elevation Maximum Water Elevation (US) Design Max Full Flow Flow cfs cfs Pipe Surcharge at U/S m 8576 D4-08576 0 2.000 70.600 33.080 32.660 34.232 74.480 37.101 0.000 1.407 11658 D4-11658 D4-08576 2.000 150.000 32.860 37.320 38.879 39.010 37.101 0.000 1.559 404 D5-00404 D4-11658 2.000 239.100 37.470 38.290 45.747 13.250 37.100 5.457 7.457 406 D5-00406 D5-00404 2.000 195.700 38.990 39.040 48.854 3.620 29.059 7.814 9.814 405 D5-00405 D5-00406 2.000 148.200 39.190 40.080 51.178 17.530 29.058 9.098 11.098 418 CB1 D5-00405 2.000 50.000 40.280 40.267 51.687 3.650 23.500 9.420 11.407 2 CB2 CB1 2.500 150.000 40.260 40.810 52.158 24.840 23.498 8.848 11.427 3 CB3 CB2 2.500 35.000 40.818 40.940 52.267 24.220 23.497 8.827 11.340 4 CB4 CB3 2.500 50.000 40.945 41.120 52.424 24.270 23.497 8.804 11.322 5 CB5 CB4 1.500 36.000 46.900 47.160 52.607 8.930 8.367 3.947 5.524 6 D4-10181 CB5 1.500 250.000 47.160 47.910 53.147 5.750 5.459 3.737 5.447 10179 D4-10179 D4-10181 1.500 32.000 48.090 48.520 53.217 12.180 5.184 3.197 5.057 10172 D4-10172 D4-10179 1.500 218.000 48.720 51.060 53.696 10.880 5.047 1.136 4.497 Max Depth 08/14/15 09:25:38 1/1

Manholes Name Ground Subcatchme Elevation nt (Spill Crest) Invert Elevation Max Water Elevation Volume of Ponded Flow Stored ^3 Duration of Surcharge (min) sec Rainfall Reference Max Flow cfs EGL Elevation Surcharge at Max HGL 0 35.100 33.080 34.067 0.000 0.000 0.000 34.067 0.000 1.030 D4-08576 1 44.660 32.660 34.232 0.000 0.000 0.000 37.518 0.000 10.430 D4-11658 54.420 37.320 38.879 0.000 0.000 0.000 41.569 0.000 15.540 D5-00404 1 50.090 38.290 45.747 0.000 39.010 100Yr SC 8.070 47.014 4.757 4.340 D5-00406 62.140 39.040 48.854 0.000 48.092 0.000 50.110 7.664 13.290 D5-00405 1 58.480 40.080 51.177 0.000 42.306 100Yr SC 5.579 51.177 8.898 7.300 CB1 59.000 40.260 51.686 0.000 39.714 0.000 52.506 8.927 7.310 CB2 54.000 40.810 52.157 0.000 36.333 0.000 52.497 8.840 1.840 CB3 54.000 40.940 52.267 0.000 35.810 0.000 52.607 8.822 1.730 CB4 1 53.000 41.120 52.424 0.000 25.729 100Yr SC 15.948 52.702 4.024 0.580 CB5 1 53.000 47.000 52.606 0.000 25.217 100Yr SC 2.655 52.725 3.947 0.390 D4-10181 55.090 47.910 53.147 0.000 23.343 0.000 53.266 3.557 1.940 D4-10179 55.120 48.520 53.216 0.000 21.484 0.000 53.337 2.997 1.900 D4-10172 1 56.360 51.060 53.695 0.000 13.410 100Yr SC 4.978 53.695 1.136 2.660 Freeboard 08/14/15 09:15:47 1/1