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Home My WebLink AboutTIR-3957Renton 701 Townhomes DCI 15375 Technical Information Report Sunset’s Edge Townhomes a Planned Unit Development 701 Sunset Boulevard NE C17002053 Prepared: May 1, 2017 Revised October 10, 2017 DCI Project: 15375 Vested to 2009 Stormwater Standards Duncanson Company, Inc. 145 SW 155th Street, Suite 102 Seattle, Washington 98166 (206) 244-4141 R-3957 SURFACE WATER UTILITY rstraka 10/19/2017 DEVELOPMENT ENGINEERING rnair 10/24/2017 Renton 701 Townhomes DCI 15375 Table Of Contents 1. Project Overview 3 Figure 1.1 – Technical Information Report Worksheet Figure 1.2 – Vicinity Map Figure 1.3 – Soils Survey Map 2. Conditions and Requirements Summary 12 3. Offsite Analysis 15 Figure 3.1 – Offsite Analysis Map 4. Flow Control and Water Quality Facility Analysis and Design 19 Figure 4.1 – Predeveloped Basin Map Figure 4.2 – Postdeveloped Basin Map 5. Conveyance System Analysis and Design 34 6. Special Reports and Studies 36 7. Other Permits 62 8. CSWPPP Analysis and Design 64 9. Bond Quantities, Facility Summaries, and Declaration of Covenant 68 10. Operations and Maintenance Manual 120 2 Renton 701 Townhomes DCI 15375 1. Project Overview 3 Renton 701 Townhomes DCI 15375 1. Project Overview Note: This project is vested to 2009 Surface Water Standards. The proposed Sunset’s Edge (formerly Renton 701) Townhomes project is located at 701-707 Sunset Blvd NE in Renton, WA (tax lot 311990-0011 & -0010 & -0005). The existing parcel is 39,187 SF or 0.90 acres (per survey). Approximately 1,943 SF of right-of-way will be dedicated along Sunset Boulevard and improved with minor widening, a planter strip and a sidewalk. The Project Site basin area is 37,244 SF or 0.86 acres. Sunset Boulevard NE will be slightly widened with the addition of curb, gutter, sidewalk and planter strip. The Sunset Boulevard basin area is approximately 4,882 SF or 0.11 acres. The Site is bordered to the north by apartments, to the east by Sunset Blvd NE, to the south and west by forested PSE right-of-way. The project will access Sunset Blvd NE via a new private access drive extending west into the site. The site was previously improved with a small building with a paved and gravel access drive. Fill was also placed on the property to create a terraced area even with Sunset Boulevard. The building has been removed; however, the pavement and gravel areas remain in an unmaintained condition. The remainder of site is covered by trees, blackberry bushes, and grass. The USGS Soil Map identifies site soils to be Alderwood gravelly sandy loam and Ragnar-Indianola soils (Figure 1.4). Sanitary sewer exists along the western margin of the site. Water, and storm drainage systems are located within the Sunset Blvd NE right-of-way. Runoff from the existing Site generally sheet flows west through the PSE right-of-way and ultimately into the ditch and pipe system along Interstate 405. The project includes construction of 15 townhouse units in duplex to 5-plex configurations. A new internal private road and sidewalk will provide access to the units. A storm drain will collect runoff from the access drive, roof surfaces and some landscape areas. Sewer and water services and dry utilities will be stubbed to the new units. The site zoning allows for 75% impervious coverage, or 27,993 SF. The proposed impervious coverage is 21,111 SF or about 57%. An additional 3,488 SF of impervious area is proposed in the Sunset Boulevard NE right-of-way for a total new and replaced impervious area of 24,599 SF. Included are Figures 1.1 – Technical Information Report Worksheet, 1.2 – Vicinity Map, 1.3 – Soils Map. See Figures 4.1 and 4.2 for the Predeveloped and Postdeveloped Conditions basin maps. 4 5 6 7 8 9 Job No. 15375Drawn: HMDScale: NTS FIGURE 1.2 - Vicinity Map Civil Engineering · Surveying · Land Planning 145 SW 155th Street, Suite 102 Seattle, Washington 98166 Phone 206.244.4141 Fax 206.244.4455 405 900 10 Job No. 15375Drawn: HMDScale: NTS FIGURE 1.3 - Soil Map Civil Engineering · Surveying · Land Planning D U N C A N S O N C O M P A N Y, I N C. 145 SW 155th Street, Suite 102 Seattle, Washington 98166 Phone 206.244.4141 Fax 206.244.4455 11 Renton 701 Townhomes DCI 15375 2. Conditions and Requirements Summary 12 Renton 701 Townhomes DCI 15375 2. Preliminary Conditions and Requirements Summary Following is a discussion of how the Project will conform to the Core and Special Requirements of the 2009 King County Surface Water Design Manual (KCSWDM) and the City of Renton Amendments. King County Surface Water Design Manual Core Requirements: 1. Discharge at the Natural Location Runoff will continue to flow to the west toward the PSE and I-405 right-of-way. After detention, runoff will be discharged onto a rock pad. The 100-year peak discharge rate is less than 0.2 CFS for both the predeveloped and postdeveloped condition; therefore, discharge onto a rock pad is acceptable. Although City of Renton GIS shows the site and downstream areas to by landslide and erosion hazard, project runoff will be discharged at a location where downstream slopes are less than 15% for a distance of at least 50 feet, which is not an erosion or landslide hazard area by definition. Some landscape/vegetated areas will continue to sheet flow to the west. See also the Minimal Risk and Plan Review Letter by the Migizi Group, Project P970-T17, revised 7/12/17. 2. Offsite Analysis A Level 1 offsite analysis has been performed for this project. See Section 3 for more information. 3. Flow Control The Site is within Renton’s Peak Rate Flow Control Standard area. A detentions tank is proposed to control the peak discharge rates to match the existing conditions for the 2-, 10-, and 100-year storm events. Onsite stormwater management BMPs are proposed in the form of Permeable Pavers. See Section 4 for more information. A Flow Control BMP covenant will be required prior to permit issuance. 4. Conveyance System Conveyance will consist of roof drain collectors and 12-inch pipes. Renton’s conveyance standard is 6 inches of freeboard at the 25-year storm event. Detailed analysis of the conveyance system will be prepared at the final engineering/building permit stage. 5. Erosion and Sediment Control Erosion and sediment control issues and plans will be addressed at the final engineering stage. 6. Maintenance and Operations A Home Owners Association (HOA) will be responsible for maintenance of detention facility, maintenance of water quality facility, and maintenance of flow control BMP permeable pavers on the internal private access. 7. Financial Guarantees and Liability The project owner will provide financial guarantees and liability insurance for construction of the improvements. 13 Renton 701 Townhomes DCI 15375 8. Water Quality Basic Water Quality treatment will be provided in the form of a Stormfilter. Pre-settling is required. The project is attached single-family, which could be interpreted as multi-family. However, a leachable metal restrictive covenant will be recorded, so that the Project will meet Exception #4 of the Enhanced Basic Water Quality requirement. A nominal amount of New PGIS (1,670 SF) associated with the frontage improvements will remain untreated. This small amount of target surface is the pavement widening along the margin of Sunset Boulevard NE. This is public runoff at the high side of the project. For operation, maintenance and liability reasons, it is undesirable to route this public runoff into the project’s treatment and detention system. Due to topographic constraints, runoff would need to be pumped into or out of a treatment facility. Topography and/or space limitations preclude treatment with filter strip, biofiltration, or a linear sand filter. A treatment trade is not feasible since 100% of the onsite PGIS runoff will be treated. The untreated target PGIS is well below 5,000 SF. This small bypass meets the criteria of Section 1.2.8.2.D of the City of Renton Amendments to the 2009 KCSWDM. King County Surface Water Design Manual Special Requirements: (w/City of Renton Amendment) 1. Other Adopted Area-Specific Requirements No Area-Specific Requirements have been identified. 2. Flood Hazard Area Delineation This site does not contain and is not adjacent to a flood hazard area; therefore, this requirement does not apply. 3. Flood Protection Facilities This project does not rely on and does not propose to modify or construct a flood protection facility; therefore, this requirement does not apply. 4. Source Control A detailed Construction Stormwater Pollution Prevention Plan (CSWPPP), including appropriate source controls for site development activity is included in Section 8 of this report. 5. Oil Control This project is not a high use site; therefore, this requirement does not apply. 6. Aquifer Protection Area Per Reference 11-B of the City of Renton Amendment, this project site is not within and Aquifer Protection Area. 14 Renton 701 Townhomes DCI 15375 3. Offsite Analysis 15 Renton 701 Townhomes DCI 15375 3. Offsite Analysis Task 1 - Study Area Definition & Maps The study area is defined as the upstream contributing area located west of the Site and the downstream area extending 1 mile from the Project Site. Task 2 - Resource Review 1. Adopted Basin Plan, Basin Reconnaissance Summary Reports No special basin plan requirements were identified through the pre-application process. 2. FEMA Maps The Site is entirely within Zone X. The FEMA map did not reveal any problems. 3. Offsite Analysis Reports Finalized Drainage Studies No other offsite analyses were reviewed. 4. Sensitive Area Folio The Site has been identified as an Erosion Hazard and Landslide Area by City of Renton GIS, based on the much of the site slopes exceeding 15%. A steep slope exists along the western margin of the site; however, this was created by past filling activity. This slope is proposed to be reduced to 15 feet or less in height so as to not be a regulated slope. Project runoff will be discharged at a location where downstream slopes are less than 15% for a distance of at least 50 feet. 5. Drainage Complaints and Studies No downstream complaints have been identified for this Site. 6. Road Drainage Problems None noted. 7. King County Soils Survey The USGS Soil Map identifies site soils to be Alderwood gravelly sandy loam and Ragnar- Indianola soils (Figure 1.4). The soil map did not identify any drainage related problems. 8. Wetlands Inventory N/A 9. Migrating River Studies No channel migration hazard areas are within the study area. 10. WSDOE Clean Water Act Section 303d WSDOE Water Quality Assessment for Washington map was accessed on 10/25/16. The map indicate that John’s Creek, approximately ¼ mile downstream from the Site, is impaired for temperature, bacteria and dissolved oxygen. No mitigation is required at this time. 16 Renton 701 Townhomes DCI 15375 11. King County Designated Water Quality Problems There are no King County identified water quality problems listed in the 2009 KCSWDM Reference Section 10 posted on King County's Surface Water Design Manual website. 12. Stormwater Compliance Plans N/A Task 3 - Field Reconnaissance A field reconnaissance was conducted on November 19, 2015, (weather conditions were partly cloudy and dry). No evidence of flooding or erosion problems were observed. The upstream runoff is intercepted by a private drainage system to the north and Sunset Boulevard to the east. The resource review did not identify any conditions that warranted extended field review beyond a ¼ mile downstream. Task 4 - Drainage System Description And Problem Screening See Figure 3.1 – Offsite Analysis Map Runoff exists the property and flows northwest through PSE right-of-way down a well vegetated slope of less than 15% for at least 50 feet. Runoff continues west for another 200 feet through the PSE and I-405 rights-a-way consisting of well vegetated natural and constructed slopes. At the toe of the I-405 right-of-way cut embankment, runoff enters the stormwater conveyance system in Interstate 405. Safety concerns precluded direct inspection of the I405 conveyance system; however Renton GIS runoff is conveyed north in a pipe system for approximately 950 feet, near the vicinity of where John’s Creek is conveyed under I-405. The I-405 piped conveyance system appears to turn west at this location and convey runoff down the west slope of the right-of-way and combine with the piped flow of John’s Creek. This point of combination is at or beyond the ¼ mile downstream point from the Site. Task 5 – Mitigation of Existing or Potential Problems The project will provide Peak Rate Flow Control. No problems were identified that would warrant a higher level of flow control or additional mitigation. It is Duncanson Company’s opinion from the available information that the developed Site will not create or aggravate any downstream problems. 17 Job No. 15375Drawn: HMDScale: NTS FIGURE 3.1 - Offsite Analysis Map Civil Engineering · Surveying · Land Planning 145 SW 155th Street, Suite 102 Seattle, Washington 98166 Phone 206.244.4141 Fax 206.244.4455 18 Renton 701 Townhomes DCI 15375 4. Flow Control Analysis and Design 19 Renton 701 Townhomes DCI 15375 4. Flow Control and Water Quality Facility Analysis and Design Part A – Existing Site Hydrology The Site has been previously graded and filled, and was historically developed with a small building. Asphalt and crushed rock surfacing remain in the central, eastern portion of the site. Current aerial photography shows weeds and grass beginning to re-establish in previous parking/impervious areas. The brush line delineation is based on a noticeable difference in maturity and density of vegetation at the time of our survey in 2015. Between 1945 and 2010, the site contained a building and parking lot. Aerial imagery from 1977, 1980 and 2007 confirm the “existing conditions” impervious area are similar to that shown on Figure 4.1. If the previously existing building was included, the existing imperious area would most likely be more than what is accounted for here. These surfaces were modeled in their existing condition as impervious. A large portion of the Site is covered with brush, blackberries and only a few trees. These areas were modeled as 50% pasture and 50% forested. The slope in the south and western margin of the site is covered with small to medium size deciduous alder and maple trees. This portion of the Site was modeled as forested. Site soils consist of fill underlain by till; therefore, till soil conditions were assumed for stormwater modeling. See Figure 4.1—Predeveloped Conditions for delineation of these areas. KCRTS input parameters are tabulated below. Results A time series file was generated for the predeveloped conditions stated above, using SeaTac Region, scale factor 1.00, reduced record and hourly time steps. The time series files for the predeveloped basin has the following peaks: Site Basin Flow Frequency Analysis Time Series File:predev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.094 5 2/09/01 2:00 0.186 1 100.00 0.990 0.068 7 1/05/02 16:00 0.108 2 25.00 0.960 0.108 2 2/27/03 7:00 0.102 3 10.00 0.900 0.064 8 8/26/04 2:00 0.095 4 5.00 0.800 0.076 6 10/28/04 16:00 0.094 5 3.00 0.667 0.102 3 1/18/06 16:00 0.076 6 2.00 0.500 0.095 4 11/24/06 3:00 0.068 7 1.30 0.231 0.186 1 1/09/08 6:00 0.064 8 1.10 0.091 Computed Peaks 0.160 50.00 0.980 Predeveloped Site Basin Land Type Acres Impervious 0.25 Till Forest 0.395 Till Pasture 0.325 Total 0.97 20 SUNSET BLVD NEJob No. 15375Drawn: HMDScale: 1"=40' Fig 4.1 Pre-Developed Basin Map Civil Engineering · Surveying · Land Planning 145 SW 155th Street, Suite 102 Seattle, Washington 98166 Phone 206.244.4141 Fax 206.244.4455 D U N C A N S O N C O M P A N Y, I N C. 1 inch = ft. (IN FEET) GRAPHIC SCALE 40 SITE SITE 21 Renton 701 Townhomes DCI 15375 Part B – Developed Site Hydrology Project development will result in the addition of 24,599 SF of new and/or replaced impervious surface in the form of roof, patio, road, sidewalk and driveway. The remainder of the site was modeled as landscaping (till grass). The western edge of the property (0.25 acre till grass) will continue to sheet flow to the west and not be collected. Runoff from the Sunset Boulevard improvements (0.11 acres) will also bypass the detention facility. These areas were modeled separately so that the undetained bypass runoff could be combined with detention outflows for the purpose of verifying downstream point of compliance. There is 0.06 acres of pervious pavers on the site, however, no credit was applied for a slightly conservative design. See Figure 4.2—Postdeveloped Conditions for delineation of these areas. KCRTS input parameters are tabulated below. Postdeveloped Site Basin Land Type Acres Impervious 0.49 Till Grass 0.12 Total 0.61 Postdeveloped West Bypass Land Type Acres Bypass Till Grass 0.25 Total 0.25 Postdeveloped Sunset Blvd Land Type Acres Impervious 0.08 Till Grass 0.03 Total 0.11 Results The postdeveloped, BMP-credited time series files was generated using Seatac Region, scale factor 1.00, reduced record, hourly and 15-minute time steps. The time series files for the two postdeveloped basins computed the following peaks: 22 Renton 701 Townhomes DCI 15375 HOURLY TIME STEP RESULTS Site (undetained) Flow Frequency Analysis Time Series File:postdev site basin hourly.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.129 6 2/09/01 2:00 0.257 1 100.00 0.990 0.110 8 1/05/02 16:00 0.181 2 25.00 0.960 0.155 3 12/08/02 18:00 0.155 3 10.00 0.900 0.124 7 8/26/04 2:00 0.148 4 5.00 0.800 0.148 4 10/28/04 16:00 0.138 5 3.00 0.667 0.138 5 1/18/06 16:00 0.129 6 2.00 0.500 0.181 2 10/26/06 0:00 0.124 7 1.30 0.231 0.257 1 1/09/08 6:00 0.110 8 1.10 0.091 Computed Peaks 0.232 50.00 0.980 West Bypass Flow Frequency Analysis Time Series File:bypass west hourly.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.022 4 2/09/01 2:00 0.053 1 100.00 0.990 0.011 7 1/05/02 16:00 0.028 2 25.00 0.960 0.028 2 2/27/03 7:00 0.023 3 10.00 0.900 0.005 8 3/24/04 19:00 0.022 4 5.00 0.800 0.012 6 1/05/05 8:00 0.020 5 3.00 0.667 0.023 3 1/18/06 16:00 0.012 6 2.00 0.500 0.020 5 11/24/06 3:00 0.011 7 1.30 0.231 0.053 1 1/09/08 6:00 0.005 8 1.10 0.091 Computed Peaks 0.045 50.00 0.980 Sunset Bypass Flow Frequency Analysis Time Series File:bypass sunset hourly.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.022 6 2/09/01 2:00 0.044 1 100.00 0.990 0.018 8 1/05/02 16:00 0.030 2 25.00 0.960 0.027 3 2/27/03 7:00 0.027 3 10.00 0.900 0.021 7 8/26/04 2:00 0.024 4 5.00 0.800 0.024 4 10/28/04 16:00 0.024 5 3.00 0.667 0.024 5 1/18/06 16:00 0.022 6 2.00 0.500 0.030 2 10/26/06 0:00 0.021 7 1.30 0.231 0.044 1 1/09/08 6:00 0.018 8 1.10 0.091 Computed Peaks 0.039 50.00 0.980 23 Renton 701 Townhomes DCI 15375 Combined undetained Site + West Bypass + Sunset Bypass Flow Frequency Analysis Time Series File:postdev combo hourly.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.173 6 2/09/01 2:00 0.355 1 100.00 0.990 0.140 8 1/05/02 16:00 0.218 2 25.00 0.960 0.209 3 2/27/03 7:00 0.209 3 10.00 0.900 0.149 7 8/26/04 2:00 0.184 4 5.00 0.800 0.180 5 10/28/04 16:00 0.180 5 3.00 0.667 0.184 4 1/18/06 16:00 0.173 6 2.00 0.500 0.218 2 10/26/06 0:00 0.149 7 1.30 0.231 0.355 1 1/09/08 6:00 0.140 8 1.10 0.091 Computed Peaks 0.309 50.00 0.980 Note the combined 100-year peak flow increase is > 0.1 CFS confirming that a flow control facility is required. 24 SUNSET BLVD NECivil Engineering · Surveying · Land Planning 145 SW 155th Street, Suite 102 Seattle, Washington 98166 Phone 206.244.4141 Fax 206.244.4455 D U N C A N S O N C O M P A N Y, I N C. 1 inch = ft. (IN FEET) GRAPHIC SCALE 40 Job No. 15375Drawn: HMDScale: 1"=40' Fig 4.2 Post-Developed Basin Map 25 Renton 701 Townhomes DCI 15375 Part C – Performance Standards The City of Renton specifies Peak Rate Flow Control and Basic Water Quality treatment as the required performance standards for this Site. Covenant restricting use of leachable materials will be recorded to allow basic water quality treatment instead of enhanced basic water quality treatment. Part D – Flow Control Systems BMPs Per the KCSWDM, the individual Site or Lots are required to have Flow Control BMPs. Full Dispersal is not considered feasible due to lack of available flow paths. Due to fill and till soils and slope considerations, infiltration was also deemed infeasible. Flow control BMPs are proposed to take the form permeable pavers for the internal site walkways. The individual lots sizes vary from 740 SF to 910 SF, which fall in the small lot category, requiring mitigation of at least 10% of the Site/Lot areas. There are permeable pavers adjacent to each lot. The sum of all the lot areas is 12,236 SF. There is approximately 2,447 SF of permeable pavers proposed. This averages out to 20% of the Site/Lot areas, thereby satisfying the BMP requirement. While the BMP requirement is satisfied, as a conservative measure, no credit was taken for less impervious area in computing post developed runoff. Flow Control Facility A detention tank was selected to provide flow control. Multiple iterations of level pool routing were run using KCRTS to find an acceptable configuration. An 100-foot long by 8-foot diameter detention tank was found to achieve the required performance including combination of the bypass runoff for downstream point of compliance. KCRTS detention sizing results are provided below. Note, on the design plans the actual invert of the detention tank was lowered by 0.5 feet to provide sediment storage, while holding the outlet invert to match these calculations. As seen from the stage storage table below, this results in a loss of only 200 CF of storage. This is more than compensated for by the much larger cross sectional area and volume gained by starting 0.5 feet above the pipe invert. Retention/Detention Facility Type of Facility: Detention Tank Tank Diameter: 8.00 ft Tank Length: 100.00 ft Effective Storage Depth: 7.50 ft Stage 0 Elevation: 160.00 ft Storage Volume: 4896. cu. ft Riser Head: 7.50 ft Riser Diameter: 12.00 inches Number of orifices: 2 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 0.88 0.058 2 4.50 0.63 0.019 4.0 Top Notch Weir: None 26 Renton 701 Townhomes DCI 15375 Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) 0.00 160.00 0. 0.000 0.000 0.00 0.01 160.01 4. 0.000 0.002 0.00 0.02 160.02 8. 0.000 0.003 0.00 0.03 160.03 12. 0.000 0.003 0.00 0.04 160.04 16. 0.000 0.004 0.00 0.05 160.05 20. 0.000 0.005 0.00 0.06 160.06 24. 0.001 0.005 0.00 0.07 160.07 28. 0.001 0.006 0.00 0.20 160.20 84. 0.002 0.009 0.00 0.33 160.33 145. 0.003 0.012 0.00 0.45 160.45 206. 0.005 0.014 0.00 0.58 160.58 275. 0.006 0.016 0.00 0.71 160.71 348. 0.008 0.018 0.00 0.84 160.84 424. 0.010 0.019 0.00 0.96 160.96 497. 0.011 0.021 0.00 1.09 161.09 579. 0.013 0.022 0.00 1.22 161.22 663. 0.015 0.023 0.00 1.34 161.34 743. 0.017 0.024 0.00 1.47 161.47 831. 0.019 0.025 0.00 1.60 161.60 922. 0.021 0.027 0.00 1.73 161.73 1014. 0.023 0.028 0.00 1.85 161.85 1101. 0.025 0.029 0.00 1.98 161.98 1196. 0.027 0.030 0.00 2.11 162.11 1293. 0.030 0.030 0.00 2.23 162.23 1384. 0.032 0.031 0.00 2.36 162.36 1483. 0.034 0.032 0.00 2.49 162.49 1583. 0.036 0.033 0.00 2.62 162.62 1684. 0.039 0.034 0.00 2.74 162.74 1778. 0.041 0.035 0.00 2.87 162.87 1881. 0.043 0.036 0.00 3.00 163.00 1984. 0.046 0.036 0.00 3.12 163.12 2079. 0.048 0.037 0.00 3.25 163.25 2183. 0.050 0.038 0.00 3.38 163.38 2287. 0.052 0.039 0.00 3.51 163.51 2391. 0.055 0.039 0.00 3.63 163.63 2487. 0.057 0.040 0.00 3.76 163.76 2590. 0.059 0.041 0.00 3.89 163.89 2694. 0.062 0.041 0.00 4.01 164.01 2789. 0.064 0.042 0.00 4.14 164.14 2892. 0.066 0.043 0.00 4.27 164.27 2995. 0.069 0.043 0.00 4.40 164.40 3096. 0.071 0.044 0.00 4.50 164.50 3174. 0.073 0.045 0.00 4.51 164.51 3182. 0.073 0.045 0.00 4.52 164.52 3190. 0.073 0.045 0.00 4.53 164.53 3197. 0.073 0.047 0.00 4.54 164.54 3205. 0.074 0.047 0.00 4.55 164.55 3213. 0.074 0.047 0.00 4.68 164.68 3313. 0.076 0.050 0.00 27 Renton 701 Townhomes DCI 15375 4.81 164.81 3411. 0.078 0.052 0.00 4.93 164.93 3502. 0.080 0.054 0.00 5.06 165.06 3598. 0.083 0.055 0.00 5.19 165.19 3693. 0.085 0.057 0.00 5.32 165.32 3787. 0.087 0.058 0.00 5.44 165.44 3871. 0.089 0.059 0.00 5.57 165.57 3961. 0.091 0.061 0.00 5.70 165.70 4049. 0.093 0.062 0.00 5.82 165.82 4128. 0.095 0.063 0.00 5.95 165.95 4212. 0.097 0.064 0.00 6.08 166.08 4293. 0.099 0.065 0.00 6.21 166.21 4371. 0.100 0.066 0.00 6.33 166.33 4440. 0.102 0.067 0.00 6.46 166.46 4512. 0.104 0.068 0.00 6.59 166.59 4580. 0.105 0.069 0.00 6.71 166.71 4639. 0.106 0.070 0.00 6.84 166.84 4699. 0.108 0.071 0.00 6.97 166.97 4753. 0.109 0.072 0.00 7.09 167.09 4798. 0.110 0.073 0.00 7.22 167.22 4841. 0.111 0.074 0.00 7.35 167.35 4874. 0.112 0.075 0.00 7.48 167.48 4895. 0.112 0.076 0.00 7.50 167.50 4896. 0.112 0.076 0.00 7.60 167.60 4896. 0.112 0.385 0.00 7.70 167.70 4896. 0.112 0.949 0.00 7.80 167.80 4896. 0.112 1.680 0.00 7.90 167.90 4896. 0.112 2.470 0.00 8.00 168.00 4896. 0.112 2.750 0.00 8.10 168.10 4896. 0.112 3.010 0.00 8.20 168.20 4896. 0.112 3.250 0.00 8.30 168.30 4896. 0.112 3.460 0.00 8.40 168.40 4896. 0.112 3.670 0.00 8.50 168.50 4896. 0.112 3.860 0.00 Hyd Inflow Outflow Peak Storage Stage Elev (Cu-Ft) (Ac-Ft) 1 0.26 0.07 6.29 166.29 4415. 0.101 2 0.18 0.04 2.95 162.95 1943. 0.045 3 0.16 0.03 2.64 162.64 1703. 0.039 4 0.15 0.03 2.63 162.63 1695. 0.039 5 0.14 0.05 4.93 164.93 3498. 0.080 6 0.13 0.06 5.26 165.26 3744. 0.086 7 0.12 0.03 1.99 161.99 1207. 0.028 8 0.11 0.03 1.92 161.92 1152. 0.026 Hyd R/D Facility Tributary Reservoir POC Outflow Outflow Inflow Inflow Target Calc 1 0.07 0.10 ******** ******* 0.13 2 0.04 0.04 ******** ******* 0.06 3 0.03 0.05 ******** ******* 0.08 4 0.03 0.03 ******** ******* 0.06 5 0.05 0.05 ******** ******* 0.09 6 0.06 0.04 ******** ******* 0.09 7 0.03 0.02 ******** ******* 0.04 28 Renton 701 Townhomes DCI 15375 8 0.03 0.03 ******** ******* 0.05 ---------------------------------- Route Time Series through Facility Inflow Time Series File:postdev site hourly.tsf Outflow Time Series File:TankOutHourly POC Time Series File:DSOut Hourly Inflow/Outflow Analysis Peak Inflow Discharge: 0.257 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 0.067 CFS at 11:00 on Jan 9 in Year 8 Peak Reservoir Stage: 6.29 Ft Peak Reservoir Elev: 166.29 Ft Peak Reservoir Storage: 4415. Cu-Ft : 0.101 Ac-Ft Add Time Series:post bypasses hourly.tsf Peak Summed Discharge: 0.135 CFS at 9:00 on Jan 9 in Year 8 Point of Compliance File:DSOut Hourly.tsf Flow Frequency Analysis Time Series File:tankouthourly.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0.058 2 2/09/01 19:00 0.067 6.29 1 100.00 0.990 0.030 8 1/05/02 18:00 0.058 5.26 2 25.00 0.960 0.041 5 3/06/03 21:00 0.056 5.13 3 10.00 0.900 0.030 7 8/24/04 0:00 0.054 4.93 4 5.00 0.800 0.036 6 1/05/05 10:00 0.041 3.94 5 3.00 0.667 0.054 4 1/18/06 22:00 0.036 2.96 6 2.00 0.500 0.056 3 11/24/06 7:00 0.030 1.99 7 1.30 0.231 0.067 1 1/09/08 11:00 0.030 1.92 8 1.10 0.091 Computed Peaks 0.064 5.90 50.00 0.980 Flow Frequency Analysis Time Series File:dsout hourly.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.091 2 2/09/01 18:00 0.135 1 100.00 0.990 0.054 7 1/05/02 16:00 0.091 2 25.00 0.960 0.087 4 2/27/03 7:00 0.089 3 10.00 0.900 0.042 8 8/26/04 2:00 0.087 4 5.00 0.800 0.060 6 1/05/05 8:00 0.086 5 3.00 0.667 0.086 5 1/18/06 16:00 0.060 6 2.00 0.500 0.089 3 11/24/06 4:00 0.054 7 1.30 0.231 0.135 1 1/09/08 9:00 0.042 8 1.10 0.091 Computed Peaks 0.120 50.00 0.980 29 Renton 701 Townhomes DCI 15375 Peak Flow Control Performance Check Note, for the purpose of this performance check, both bypass areas together with the detention tank release flows were added together to verify downstream point of compliance. Storm Event Predeveloped Peak Postdeveloped Peak Downstream POC 2-yr 0.076 0.060 10-yr 0.102 0.089 100-yr 0.186 0.135 30 Renton 701 Townhomes DCI 15375 Next, 15-minute time step runoff files were generated for the Site and Bypass Basin for the purposes of determining the peak release rate from the site for allowance of discharge onto a rock pad. The 15-minute Site runoff file was routed through the above designed detention system and the discharged was combined with the 15-minute Bypass basin. The result was a 100-year, 15- minute peak discharge rate of 0.164 CFS, which is less than 0.2 CFS and within the allowance for discharge onto a rock pad per Core Requirement #1. Detailed results are presented below: 15-MINUTE TIME STEP RESULTS Site (undetained) Flow Frequency Analysis Time Series File:postdev site 15min.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.234 6 8/27/01 18:00 0.639 1 100.00 0.990 0.163 8 9/17/02 17:45 0.468 2 25.00 0.960 0.468 2 12/08/02 17:15 0.321 3 10.00 0.900 0.188 7 8/23/04 14:30 0.269 4 5.00 0.800 0.254 5 10/28/04 16:00 0.254 5 3.00 0.667 0.269 4 10/27/05 10:45 0.234 6 2.00 0.500 0.321 3 10/25/06 22:45 0.188 7 1.30 0.231 0.639 1 1/09/08 6:30 0.163 8 1.10 0.091 Computed Peaks 0.582 50.00 0.980 West Bypass Flow Frequency Analysis Time Series File:postbypass west 15min.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.030 4 2/09/01 12:45 0.126 1 100.00 0.990 0.014 7 1/06/02 1:00 0.078 2 25.00 0.960 0.055 3 12/08/02 17:15 0.055 3 10.00 0.900 0.005 8 8/26/04 1:00 0.030 4 5.00 0.800 0.078 2 11/17/04 5:00 0.023 5 3.00 0.667 0.022 6 1/18/06 15:00 0.022 6 2.00 0.500 0.023 5 11/24/06 1:00 0.014 7 1.30 0.231 0.126 1 1/09/08 6:30 0.005 8 1.10 0.091 Computed Peaks 0.110 50.00 0.980 31 Renton 701 Townhomes DCI 15375 Detention Performance 15-minute Retention/Detention Facility Type of Facility: Detention Tank Tank Diameter: 8.00 ft Tank Length: 100.00 ft Effective Storage Depth: 7.50 ft Stage 0 Elevation: 160.00 ft Storage Volume: 4896. cu. ft Riser Head: 7.50 ft Riser Diameter: 12.00 inches Number of orifices: 2 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 0.88 0.058 2 4.50 0.63 0.019 4.0 Top Notch Weir: None Outflow Rating Curve: None Hyd Inflow Outflow Peak Storage Stage Elev (Cu-Ft) (Ac-Ft) 1 0.64 0.07 6.22 166.22 4374. 0.100 2 0.24 0.03 2.25 162.25 1403. 0.032 3 0.47 0.04 2.92 162.92 1919. 0.044 4 0.17 0.06 5.31 165.31 3777. 0.087 5 0.21 0.06 5.16 165.16 3669. 0.084 6 0.16 0.05 4.96 164.96 3526. 0.081 7 0.16 0.03 2.05 162.05 1250. 0.029 8 0.19 0.03 2.08 162.08 1269. 0.029 Hyd R/D Facility Tributary Reservoir POC Outflow Outflow Inflow Inflow Target Calc 1 0.07 0.13 ******** ******* 0.16 2 0.03 0.08 ******** ******* 0.11 3 0.04 0.05 ******** ******* 0.09 4 0.06 0.03 ******** ******* 0.08 5 0.06 0.02 ******** ******* 0.07 6 0.05 0.02 ******** ******* 0.07 7 0.03 0.01 ******** ******* 0.04 8 0.03 0.00 ******** ******* 0.03 ---------------------------------- Route Time Series through Facility Inflow Time Series File:postdev site 15min.tsf Outflow Time Series File:TankOut15min POC Time Series File:DSOut 15min 32 Renton 701 Townhomes DCI 15375 Downstream Discharge Rate without Bypass Flow Frequency Analysis Time Series File:tankout15min.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0.058 2 2/09/01 17:30 0.066 6.21 1 100.00 0.990 0.030 8 1/05/02 16:00 0.058 5.31 2 25.00 0.960 0.042 5 3/06/03 18:45 0.056 5.16 3 10.00 0.900 0.030 7 8/23/04 22:00 0.054 4.96 4 5.00 0.800 0.037 6 1/05/05 7:45 0.042 3.99 5 3.00 0.667 0.054 4 1/18/06 20:15 0.037 3.08 6 2.00 0.500 0.056 3 11/24/06 5:15 0.030 2.08 7 1.30 0.231 0.066 1 1/09/08 11:00 0.030 2.05 8 1.10 0.091 Computed Peaks 0.063 5.86 50.00 0.980 Downstream Discharge Rate with Bypass Flow Frequency Analysis Time Series File:dsout 15min.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.081 4 2/09/01 12:45 0.164 1 100.00 0.990 0.042 7 1/05/02 15:15 0.106 2 25.00 0.960 0.087 3 12/08/02 17:15 0.087 3 10.00 0.900 0.030 8 8/23/04 21:15 0.081 4 5.00 0.800 0.106 2 11/17/04 5:00 0.072 5 3.00 0.667 0.070 6 1/18/06 20:15 0.070 6 2.00 0.500 0.072 5 11/24/06 5:15 0.042 7 1.30 0.231 0.164 1 1/09/08 6:30 0.030 8 1.10 0.091 Computed Peaks 0.144 50.00 0.980 Part E – Water Quality System This site is in a Basic Water Quality area. A ZPG Stormfilter is proposed to provide water quality treatment. The Stormfilter is located downstream of the detention system. Therefore the design flow is the 2-year release rate from the facility, which is 0.037 CFS (16.65 GPM). An 18” Stormfilter has a design flow rate of 7.5 GPM/Cartridge. Therefore, a 3-cartridge ZPG Stormfilter is required. The plans include a note for the manufacturer to provide system specific sizing calculations. Stormfilters require presettling, which is not provided by this detention system. Therefore, a Vortechs presettling device is proposed. The Vortechs chamber is located upstream of detention, therefore the water quality design flow rate is 60% of the developed 2- year peak flow (15-minute), or 0.60x0.234 CFS = 0.14 CFS. A Vortechs Model 1000 has a design flow rate of 0.55 CFS. An Adjustment is requested to use a Vortechs device for pre-treatment. Vortechs are now approved by Renton for pre-treatment. Note, the Sunset Boulevard NE frontage involves less than 2,000 SF of new PGIS and less than 4,000 SF of total PGIS; therefore, this area is exempt from a water quality treatment facility. An elbow on the outlet of CB 7 is specified to provide oil/spill control 33 Renton 701 Townhomes DCI 15375 5. Conveyance System Analysis and Design 34 Renton 701 Townhomes DCI 15375 5. Conveyance System Analysis and Design This site has a very basic conveyance system consisting of two catch basins and a pipe conveying private road and roof runoff to the treatment and detention facilities. As a cursory check, the 100-year peak flow from all site area was computed with KCRTS (15-minute time series) with the following results. Flow Frequency Analysis Time Series File:postdev site basin 15min.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.234 6 8/27/01 18:00 0.639 1 100.00 0.990 0.163 8 9/17/02 17:45 0.468 2 25.00 0.960 0.468 2 12/08/02 17:15 0.321 3 10.00 0.900 0.188 7 8/23/04 14:30 0.269 4 5.00 0.800 0.254 5 10/28/04 16:00 0.254 5 3.00 0.667 0.269 4 10/27/05 10:45 0.234 6 2.00 0.500 0.321 3 10/25/06 22:45 0.188 7 1.30 0.231 0.639 1 1/09/08 6:30 0.163 8 1.10 0.091 Computed Peaks 0.582 50.00 0.980 The following pipe full calculation spreadsheet indicates the 12-inch pipe at 0.50% minimum slope can adequately convey the 100-year flow. With the 25-year site runoff at 0.47 CFS this represents approximately 20% of the full flow capacity of the flattest pipe run. All structures are over 2.5 feet deep to the invert. Minimum freeboard of 0.5’ will be provided for the 25- year peak runoff rate. Full Flow Capacity for Pipe Input Parameters n 0.013 Diameter 1.00 FT S 0.50% Slope Results Area 0.79 SQ. FT. Rh 0.25 FT Q 2.53 CFS V 3.22 Ft/Sec 35 Renton 701 Townhomes DCI 15375 6. Special Reports and Studies 36 Renton 701 Townhomes DCI 15375 6. Special Reports and Studies A geotechnical engineering report has been prepared by E3RA. A copy of that report is included in this Section. Also included is the minimum risk statement by Migizi Group. 37 MIGIZI GROUP, INC. PO Box 44840 PHONE (253) 537-9400 Tacoma, Washington 98448 FAX (253) 537-9401 May 5, 2017 Revised July 12, 2017 Totenham, LLC 50 116th Ave SE, Suite 111 Bellevue, WA 98004 Attention: Joe Notarangelo Subject: Minimal Risk and Plan Review Letter Sunset’s Edge Townhomes 701 Sunset Blvd NE P/Ns 3119900011, 3119900010, 3119900005 Renton, Washington MGI Project P970-T17 Dear Mr. Notarangelo: Migizi Group, Inc. (MGI) is pleased to submit this Revised Minimal Risk and Plan Review Letter as it pertains to the proposed Sunset’s Edge Townhome improvements planned at 701 Sunset Blvd NE in Renton, Washington. A Geotechnical Engineering Report was previously prepared for the subject property by E3RA, Inc., dated April 16, 2015. This letter has been prepared for the exclusive use of Totenham, LLC, and their consultants, for specific application to this project, in accordance with generally accepted geotechnical practice. SITE AND PROJECT DESCRIPTION The project site consists of three separate, but adjacent, tax parcels on the west side of Sunset Blvd NE, located directly northwest of its intersection with NE 7th St in Renton, Washington. The subject property contains a frontage on Sunset Blvd NE of approximately 200 feet, and extends west of the roadway ± 125 to 200 feet; encompassing just under one acre. Currently, the property is undeveloped, with the only distinguishing site feature being a “U” shaped gravel driveway which enters/exits Sunset Blvd NE along the east side of the site. Generally, the easternmost two-thirds of the property is relatively level, containing a slight slope from east to west, no steeper than 15 percent. The western third of the site consists of a moderate to steep slope which descends to the west at grades of 50 to 60 percent and represents an elevation change of 15 to 20 feet. Directly west of the subject property is a long, thin parcel owned by Puget Sound Energy, which 38 acts as a pathway for transmission towers which service the area. One such transmission tower is in close proximity to the project area. Areas west of this parcel are steeply sloped, and descend down to I-405. The western boundary of the site is approximately 200 feet east of I-405. Improvement plans involve the clearing/stripping of the site and developing 15 townhouses within its confines in 4 separate clusters. We understand that the townhouses will be three-story, wood-framed structures. Paved driving and parking surfaces will also be incorporated into the proposed development. Landslide Hazard The current City of Renton Landslide Hazard map indicates that the site is located in a “high” hazard area. However, the April 16, 2015 geotechnical report states that the eastern two-thirds of the site is relatively level and the western third of the site consists of a moderate to steep slope which descends to the west at grades of 50 to 60 percent and represents an elevation change of 15 to 20 feet. The slope face itself is densely vegetated with thin conifers, blackberry bushes, and other brush, and does not display any irregularities indicating slope failure, such as ancient or recent landslide scarps, hummocks, slide blocks, or jack-strawed trees. The report also indicates that subsurface explorations revealed relatively consistent subgrade conditions across the site. The entirety of the site contains a surface mantle of sod, topsoil, or gravel surfacing, typically no more than 6 inches thick. Underlying this material, a fill zone spans much of the site, typically extending to 4½ feet below existing grade. The uppermost 3 feet of the fill material is comprised of silty sand in a medium dense in-situ condition. From 3½ to 4½ feet below existing grade, logs, woody debris and general refuse were incorporated into the fill material. Native soils on site consist of glacial till deposited during the most recent glaciation of the area; the Vashon Stade of the Fraser Glaciation. Glacial till deposits observed in our subsurface explorations were all moderately weathered and comprised of gravelly, silty sand in a medium dense in-situ condition. Unweathered deposits are likely encountered with depth. In the Geologic Map of the Renton Quadrangle, King County, Washington, as prepared by the Department of the Interior United States Geological Survey (USGS) (1965), the project site is mapped as containing Qgt, orVashon Glacial Till. These deposits are described as being a generally compact, coherent, unsorted mixture of sand, silt, clay and gravel. The subsurface explorations generally correspond with the mapping performed by the USGS. Based on the foregoing, we conclude that the site is stable with respect to deep seated failure. In our opinion, the proposed development is suitable for the site conditions. Stormwater Discharge We understand that stormwater runoff will be discharged onto slopes of 15 percent or less. Based on the forgoing, it is our opinion that the discharge will not have a significant adverse effect on slope stability provided that sufficient erosion control measures are constructed at the discharge point. 39 Wet Season Construction Based on the site explorations, it is our opinion that site grading during the “wet season” is feasible at this site. In general, all grading performed during the “wet season” should comply with the recommendations for site preparation presented in the April 16, 2015 geotechnical report. This should also include: • Daily inspections by a representative of MGI while grading activities are occurring to confirm that the grading and project are in compliance with all conditions of the permit; • Submission of field reports by the MGI field representative at regular intervals (e.g. weekly) documenting that the temporary erosion and sediment control plans are in place and functioning as intended; • Written field report documentation from the MGI representative after every rainfall in excess of one-half (0.5) inch in a 24-hour period to confirm that the grading and site soils remain in stable condition; and • Weekly or bi-weekly follow up monitoring reports after grading is completed and the site is stabilized, but before the geotechnical special inspector has submitted the certification that final erosion control measures have been installed. CONCLUSIONS AND RECOMMENDATIONS Minimal Risk Upon review of the Geotechnical Engineering Report prepared by E3RA, Inc. for the subject property, MGI agrees with the evaluation and provisions contained in the report. In our opinion, all portions of the site and adjacent properties that are disturbed or impacted by the proposed development will be stable or stabilized during construction and will continue to be stable after construction. Plan Review We reviewed Architectural Site Plan A1.1 dated May 3, 2017 prepared by Citizen Design, Civil Plans C1.1-C1.7, C2.1-C2.2, and C3.1-C3.3 dated May 1, 2017 prepared by Duncanson Company, and Structural Plans S1.0-S1.3, S2.0, S3.1-S3.4, S6.0-S6.1, and S9.0-S9.1 dated May 1, 2017 prepared by CT Engineering. Sheets C1.1 and C1.5 were revised. Based on our review, we conclude that the project plans have been prepared in general accordance with the geotechnical recommendations presented in the April 16, 2015 Geotechnical Engineering Report. 40 41 E RA 3 Geotechnical Engineering Report 701 Sunset Blvd NE Renton, Washington P/Ns 311990001, 3119900010, 3119900005 Submitted to: Totenham, LLC Attn: Joe Notarangelo 50 116th Ave SE, Suite 111 Bellevue, Washington 98004 Submitted by: E3RA, Inc. PO Box 44840 Tacoma, Washington 98448 (253) 537-9400 April 16, 2015 Project No. T15034 42 TABLE OF CONTENTS Page No. 1.0 SITE AND PROJECT DESCRIPTION .................................................................................... 1 2.0 EXPLORATORY METHODS ................................................................................................... 2 2.1 Test Pit Procedures ..................................................................................................... 2 3.0 SITE CONDITIONS ................................................................................................................. 3 3.1 Surface Conditions....................................................................................................... 3 3.2 Soil Conditions ............................................................................................................. 3 3.3 Groundwater Conditions .............................................................................................. 3 3.4 Seismic Conditions ...................................................................................................... 4 3.5 Liquefaction Potential .................................................................................................. 4 4.0 CONCLUSIONS AND RECOMMENDATIONS ....................................................................... 4 4.1 Site Preparation ........................................................................................................... 5 4.2 Spread Footings ........................................................................................................... 7 4.3 Slab-On-Grade Floors.................................................................................................. 8 4.4 Asphalt Pavement ........................................................................................................ 8 4.5 Structural Fill ................................................................................................................ 9 5.0 RECOMMENDED ADDITIONAL SERVICES ........................................................................ 10 6.0 CLOSURE .............................................................................................................................. 11 List of Tables Table 1. Approximate Locations and Depths of Explorations ...................................................................... 2 List of Figures Figure 1. Topographic and Location Map Figure 2. Site and Exploration Plan APPENDIX A Soil Classification Chart and Key to Test Data ........................................................................................... A-1 Logs of Test Pits TP-1 through TP-3................................................................................................ A-2…A-4 43 April 16, 2015 T15034 Totenham, LLC 50 116th Ave SE, Suite 111 Bellevue, WA 98004 Attention: Joe Notarangelo Subject: Geotechnical Engineering Report 701 Sunset Blvd NE P/Ns 3119900011, 3119900010, 3119900005 Renton, Washington Dear Mr. Notarangelo: E3RA, Inc. (E3RA) is pleased to submit this revised report describing the results of our geotechnical engineering evaluation for the improvements planned at 701 Sunset Blvd NE in Renton, Washington. This report has been prepared for the exclusive use of the Totenham, LLC and their consultants, for specific application to this project, in accordance with generally accepted geotechnical engineering practice. 1.0 SITE AND PROJECT DESCRIPTION The project site consists of three separate, but adjacent tax parcels on the west side of Sunset Blvd NE, located directly northwest of its intersection with NE 7th St in Renton, Washington, as shown on the enclosed Topographic and Location Map (Figure 1). The subject property contains a frontage on Sunset Blvd NE of approximately 200 feet, and extends west of the roadway ± 125 to 200 feet; encompassing just under one acre. Currently, the property is undeveloped, with the only distinguishing site feature being a “U” shaped gravel driveway which enters/exits Sunset Blvd NE along the east side of the site. Generally, the easternmost two-thirds of the property is relatively level, containing a slight slope from east to west, no steeper than 15 percent. The western third of the site consists of a moderate to steep slope which descends to the west at grades of 50 to 60 percent and represents an elevation change of 15 to 20 feet. Directly west of the subject property is long, thin parcel owned by Puget Sound Energy, which acts as a pathway for transmission towers which service the area. One such transmission tower is in close proximity to the project area. Areas west of this parcel are steeply sloped, and descend down to I-405. The western boundary of the site is approximately 200 feet east of I-405. Improvement plans involve the clearing/stripping of the site and developing 10 to 12 townhouses within its confines. Preliminary discussions have the townhouses being three-story, wood-framed structures. Garages will either be attached or detached, with no preliminary layouts available thus far. Paved driving and parking surfaces will also be incorporated into the proposed development. 44 2.0 EXPLORATORY METHODS We previously explored surface and subsurface conditions at the project site on January 21, 2015. Our exploration and evaluation program comprised the following elements: • Surface reconnaissance of the site; • Three test pits (designated TP-1 through TP-3), advanced on January 21, 2015; and • A review of published geologic and seismologic maps and literature. Table 1 summarizes the approximate functional locations and termination depths of our subsurface explorations, and Figure 2 depicts their approximate relative locations. The following sections describe the procedures used for excavation of test pits. TABLE 1 APPROXIMATE LOCATIONS AND DEPTHS OF EXPLORATIONS Exploration Functional Location Termination Depth (feet) TP-1 TP-2 TP-3 Eastern third of the site, north end of “U” shaped gravel driveway Eastern third of the site, south end of “U” shaped gravel driveway Centrally within the site, west of the “U” shaped gravel driveway 7½ 7½ 7½ The specific number and locations of our explorations were selected in relation to the existing site features, under the constraints of surface access, underground utility conflicts, and budget considerations. It should be realized that the explorations performed and utilized for this evaluation reveal subsurface conditions only at discrete locations across the project site and that actual conditions in other areas could vary. Furthermore, the nature and extent of any such variations would not become evident until additional explorations are performed or until construction activities have begun. If significant variations are observed at that time, we may need to modify our conclusions and recommendations contained in this report to reflect the actual site conditions. 2.1 Test Pit Procedures Our exploratory test pits were excavated with a rubber-tracked mini-excavator operated by an excavation contractor under subcontract to E3RA. A geotechnical engineer from our firm observed the test pit excavations, collected soil samples, and logged the subsurface conditions. The enclosed test pit logs indicate the vertical sequence of soils and materials encountered in each test pit, based on our field classifications. Where a soil contact was observed to be gradational or undulating, our logs indicate the average contact depth. We estimated the relative density and consistency of the in-situ soils by means of the excavation characteristics and the stability of the test pit sidewalls. Our logs also indicate the approximate depths of any sidewall caving or groundwater seepage observed in the test pits. The soils were classified visually in general accordance with the system described in Figure A-1, which includes a key to the exploration logs. Summary logs of the explorations are included as Figures A-2 through A-4. 45 3.0 SITE CONDITIONS The following sections present our observations, measurements, findings, and interpretations regarding, surface, soil, groundwater, and infiltration conditions. 3.1 Surface Conditions As previously described, the project site consists of three separate but adjacent tax parcels on the west side of Sunset Blvd NE, located directly northwest of its intersection with NE 7th St, in Renton, Washington. It is located on the outskirts of a larger residential development further to the east, and is positioned on the top of a small ridgeline which runs north/south, forming the eastern boundary of I-405. The eastern two-thirds of the site is relatively level, containing a slight slope (less than 15 percent) from east to west. This portion of the site has limited vegetation, containing only a sparse grass cover and limited gravel surfacing along the “U” shaped driveway. The western third of the site consists of a moderate to steep slope which descends to the west at grades of 50 to 60 percent and represents an elevation change of 15 to 20 feet. The slope face itself is densely vegetated with thin conifers, blackberry bushes, and other brush, and does not display any irregularities indicating slope failure, such as ancient or recent landslide scarps, hummocks, slide blocks, or jack-strawed trees. The adjacent property to the west is owned by Puget Sound Energy, and acts as a pathway for transmission towers servicing the area. A narrow driveway to this property is located directly south of the project site. The western boundary of the PSE property is marked by a chainlink fence, with areas west of this mark being steeply sloped and directly descend down to I-405. No hydrologic features were observed on site, such as seeps, springs, ponds and streams. 3.2 Soil Conditions Our subsurface explorations revealed relatively consistent subgrade conditions across the site. The entirety of the site contains a surface mantle of sod, topsoil, or gravel surfacing, typically no more than 6 inches thick. Underlying this material, a fill zone spans much of the site, typically extending to 4½ feet below existing grade. The uppermost 3 feet of the fill material is comprised of silty sand in a medium dense in-situ condition. From 3½ to 4½ feet below existing grade, logs, woody debris and general refuse were incorporated into the fill material. Native soils on site consist of glacial till deposited during the most recent glaciation of the area; the Vashon Stade of the Fraser Glaciation. Glacial till deposits observed in our subsurface explorations were all moderately weathered and comprised of gravelly, silty sand in a medium dense in-situ condition. Unweathered deposited are likely encountered with depth. In the Geologic Map of the Renton Quadrangle, King County, Washington , as prepared by the Department of the Interior United States Geological Survey (USGS) (1965), the project site is mapped as containing Qgt, or Vashon Glacial Till. These deposits are described as being a generally compact, coherent, unsorted mixture of sand, silt, clay and gravel. Our subsurface explorations generally correspond with the mapping performed by the USGS. The enclosed exploration logs (Appendix A) provide a detailed description of the soil strata encountered in our subsurface explorations. 3.3 Groundwater Conditions At the time of our reconnaissance and subsurface explorations (January 21, 2015), we did not encounter groundwater seepage in any of our subsurface explorations which extended to a maximum depth of 7½ feet below existing grade. Given the fact that our subsurface explorations were performed in what is generally 46 considered the wet season (December through April), we do not anticipate that groundwater levels will rise higher than that which we observed, and we do not anticipate that groundwater will adversely impact the proposed improvements. 3.4 Seismic Conditions Based on our analysis of subsurface exploration logs and our review of published geologic maps, we interpret the onsite soil conditions to generally correspond with site class D, as defined by Table 20.3-1 in ASCE 7, per the 2012 International Building Code (IBC). Using 2012 IBC information on the USGS Design Summary Report website, Risk Category I/II/III seismic parameters for the site are as follows: Ss = 1.436 g SMS = 1.436 g SDS = 0.957 g S1 = 0.539 g SM1 = 0.809 g SD1 = 0.539 g Using the 2012 IBC information, MCER Response Spectrum Graph on the USGS Design Summary Report website, Risk Category I/II/III, Sa at a period of 0.2 seconds is 1.44 g and Sa at a period of 1.0 seconds is 0.54g. The Design Response Spectrum Graph from the same website, using the same IBC information and Risk Category, Sa at a period of 0.2 seconds is 0.96 g and Sa at a period of 1.0 seconds is 0.54g. 3.5 Liquefaction Potential Liquefaction is a sudden increase in pore water pressure and a sudden loss of soil shear strength caused by shear strains, as could result from an earthquake. Research has shown that saturated, loose, fine to medium sands with a fines (silt and clay) content less than about 20 percent are most susceptible to liquefaction. Our subsurface explorations did not encounter any loose sand layers or lenses. 4.0 CONCLUSIONS AND RECOMMENDATIONS Improvement plans involve the clearing/stripping of the site and developing 10 to 12 townhouses within its confines. Preliminary discussions have the townhouses being three-story, wood-framed structures. Garages will either be attached or detached, with no preliminary layouts yet available. Paved driving and parking surfaces will also be incorporated into the proposed development. We offer these recommendations: • Feasibility: Based on our field explorations, research, and evaluations, the proposed structure and pavements appear feasible from a geotechnical standpoint. • Foundation Options: Given the fact that a zone of organic-laden fill material underlies the site and could result in post-construction settlement if not removed, we recommend the over- excavation of the building footprint down to native soils; a depth of approximately 4½ feet. Foundation elements should be constructed on undisturbed native soils, or on structural fill bearing pads that extend down to native soils. The thickness of structural fill bearing pads, if used, is at the discretion of the developer. Recommendations for Spread Footings are provided in Section 4.2. • Floor Options: Floor sections should bear on medium dense or denser native soils or on properly compacted structural fill that extends down to medium dense or denser native soil. We recommend over-excavation of slab-on-grade floor subgrades to a minimum depth of 47 4½ feet. Slab-on-grade floors should either be constructed on undisturbed native soils or on properly compacted structural fill as a floor subbase. If floor construction occurs during wet conditions, it is likely that a geotextile fabric, placed between the structural fill floor subbase and native soils, will be necessary. Recommendations for slab-on-grade floors are included in Section 4.3. Fill underlying floor slabs should be compacted to 95 percent (ASTM:D-1557). • Pavement Sections: After removal of any organics underlying pavements, we recommend a conventional pavement section comprised of an asphalt concrete pavement over a crushed rock base course over a properly prepared (compacted) subgrade or a granular subbase. All soil subgrades should be thoroughly compacted, then proof-rolled with a loaded dump truck or heavy compactor. Any localized zones of yielding subgrade disclosed during this proof-rolling operation should be overexcavated to a depth of 12 inches and replaced with a suitable structural fill material. The following sections of this report present our specific geotechnical conclusions and recommendations concerning site preparation, spread footings, slab-on-grade floors, asphalt pavement, and structural fill. The Washington State Department of Transportation (WSDOT) Standard Specifications and Standard Plans cited herein refer to WSDOT publications M41-10, Standard Specifications for Road, Bridge, and Municipal Construction, and M21-01, Standard Plans for Road, Bridge, and Municipal Construction , respectively. 4.1 Site Preparation Preparation of the project site should involve erosion control, temporary drainage, clearing, stripping, excavations, cutting, subgrade compaction, and filling. Erosion Control: Before new construction begins, an appropriate erosion control system should be installed. This system should collect and filter all surface water runoff through silt fencing. We anticipate a system of berms and drainage ditches around construction areas will provide an adequate collection system. Silt fencing fabric should meet the requirements of WSDOT Standard Specification 9-33.2 Table 3. In addition, silt fencing should embed a minimum of 6 inches below existing grade. An erosion control system requires occasional observation and maintenance. Specifically, holes in the filter and areas where the filter has shifted above ground surface should be replaced or repaired as soon as they are identified. Temporary Drainage: We recommend intercepting and diverting any potential sources of surface or near-surface water within the construction zones before stripping begins. Because the selection of an appropriate drainage system will depend on the water quantity, season, weather conditions, construction sequence, and contractor's methods, final decisions regarding drainage systems are best made in the field at the time of construction. Based on our current understanding of the construction plans, surface and subsurface conditions, we anticipate that curbs, berms, or ditches placed around the work areas will adequately intercept surface water runoff. Clearing and Stripping: After surface and near-surface water sources have been controlled, sod, topsoil, and root-rich soil should be stripped from the site. Our explorations and field observations indicate that the topsoil horizon is typically 6 inches or less in overall thickness. An organic ridden fill zone was encountered from 3½ to 4½ feet below existing grade, which will also need to be over-excavated within the proposed building footprint. Stripping is best performed during a period of dry weather. 48 Site Excavations: Based on our explorations, we expect that excavations will encounter loose to medium dense silty fill soils and weathered glacial till which can be easily excavated using standard excavation equipment. Dewatering: Groundwater was not observed in any of our test pit explorations which extended to a maximum depth of 7½ below existing grade. Given the fact that our test pit explorations were performed in what is generally considered the rainy season, we do not anticipate that groundwater levels will rise higher than that which we observed, nor do we anticipate that groundwater will adversely affect the proposed development. If groundwater is encountered, we anticipate that an internal system of ditches, sumpholes, and pumps will be adequate to temporarily dewater excavations. Temporary Cut Slopes: All temporary soil slopes associated with site cutting or excavations should be adequately inclined to prevent sloughing and collapse. Temporary cut slopes in site soils should be no steeper than 1½H:1V, and should conform to Washington Industrial Safety and Health Act (WISHA) regulations. Subgrade Compaction: Exposed subgrades for the foundations of the planned additions should be compacted to a firm, unyielding state before new concrete or fill soils are placed. Any localized zones of looser granular soils observed within a subgrade should be compacted to a density commensurate with the surrounding soils. In contrast, any organic, soft, or pumping soils observed within a subgrade should be overexcavated and replaced with a suitable structural fill material. Site Filling: Our conclusions regarding the reuse of onsite soils and our comments regarding wet-weather filling are presented subsequently. Regardless of soil type, all fill should be placed and compacted according to our recommendations presented in the Structural Fill section of this report. Specifically, building pad fill soil should be compacted to a uniform density of at least 95 percent (based on ASTM:D-1557). Onsite Soils: We offer the following evaluation of these onsite soils in relation to potential use as structural fill: • Surficial Organic Soil and Organic-Rich Fill Soils: Where encountered, surficial organic soils, like duff, topsoil, root-rich soil, and organic-rich fill soils are not suitable for use as structural fill under any circumstances, due to high organic content. Consequently, this material can be used only for non-structural purposes, such as in landscaping areas. • Silty Sand Fill Soils: Much of the site is overlain by 4 feet of fill material. This material contains a high relative fines (percent silt/clay) content and should be considered extremely moisture sensitive. Reuse of this soil type should be limited to summer months and moisture conditioning should be anticipated. • Glacial Till: This material type underlies much of the project site and is encountered with depth. These soils are moisture sensitive and will be difficult to reuse during wet weather conditions. Permanent Slopes: All permanent cut slopes and fill slopes should be adequately inclined to reduce long-term raveling, sloughing, and erosion. We generally recommend that no permanent slopes be steeper than 2H:1V. For all soil types, the use of flatter slopes (such as 2½H:1V) would further reduce long-term erosion and facilitate revegetation. 49 Slope Protection: We recommend that a permanent berm, swale, or curb be constructed along the top edge of all permanent slopes to intercept surface flow. Also, a hardy vegetative groundcover should be established as soon as feasible, to further protect the slopes from runoff water erosion. Alternatively, permanent slopes could be armored with quarry spalls or a geosynthetic erosion mat. 4.2 Spread Footings In our opinion, conventional spread footings will provide adequate support for the new additions if the subgrades are properly prepared. Footing Depths and Widths: For frost and erosion protection, the bases of all exterior footings should bear at least 18 inches below adjacent outside grades, whereas the bases of interior footings need bear only 12 inches below the surrounding slab surface level. To reduce post-construction settlements, continuous (wall) and isolated (column) footings should be at least 18 and 24 inches wide, respectively. Bearing Subgrades: Given the fact that a zone of organic-laden fill material underlies the site and could result in post-construction settlement if not removed, we recommend the over-excavation of the building footprint down to native soils; a depth of approximately 4½ feet. Foundation elements should be constructed on undisturbed native soils, or on structural fill bearing pads that extend down native soils and compacted to a density of at least 95 percent (based on ASTM:D-1557). The thickness of structural fill bearing pads, if used, is at the discretion of the developer. If foundation construction occurs during wet conditions, it is possible that a geotextile fabric, placed between the bearing pad and native soils, will be necessary. In general, before footing concrete is placed, any localized zones of loose soils exposed across the footing subgrades should be compacted to a firm, unyielding condition, and any localized zones of soft, organic, or debris-laden soils should be overexcavated and replaced with suitable structural fill. Lateral Overexcavations: Because foundation stresses are transferred outward as well as downward into the bearing soils, all structural fill placed under footings, should extend horizontally outward from the edge of each footing. This horizontal distance should be equal to the depth of placed fill. Therefore, placed fill that extends 24 inches below the footing base should also extend 24 inches outward from the footing edges. Subgrade Observation: All footing subgrades should consist of firm, unyielding, native soils, or structural fill materials that have been compacted to a density of at least 95 percent (based on ASTM:D-1557). Footings should never be cast atop loose, soft, or frozen soil, slough, debris, existing uncontrolled fill, or surfaces covered by standing water. Bearing Pressures: In our opinion, for static loading, footings that bear on a properly prepared subgrade, or structural fill bearing pads can be designed for a preliminary allowable soil bearing pressure of 2,000 psf. A one-third increase in allowable soil bearing capacity may be used for short-term loads created by seismic or wind related activities. Footing Settlements: Assuming that structural fill soils are compacted to a medium dense or denser state, we estimate that total post-construction settlements of properly designed footings bearing on properly prepared subgrades will not exceed 1 inch. Differential settlements for comparably loaded elements may approach one-half of the actual total settlement over horizontal distances of approximately 50 feet. 50 Footing Backfill: To provide erosion protection and lateral load resistance, we recommend that all footing excavations be backfilled on both sides of the footings and stemwalls after the concrete has cured. Either imported structural fill or non-organic onsite soils can be used for this purpose, contingent on suitable moisture content at the time of placement. Regardless of soil type, all footing backfill soil should be compacted to a density of at least 90 percent (based on ASTM:D-1557). Lateral Resistance: Footings that have been properly backfilled as recommended above will resist lateral movements by means of passive earth pressure and base friction. We recommend using an allowable passive earth pressure of 250 psf for and an allowable base friction coefficient of 0.35 for site soils. 4.3 Slab-On-Grade Floors In our opinion, soil-supported slab-on-grade floors can be used if the subgrades are properly prepared. We offer the following comments and recommendations concerning slab-on-grade floors. Floor Subbase: We recommend over-excavation of slab-on-grade floor subgrades to a minimum depth of 4 ½ feet. Slab-on-grade floors should either be constructed on undisturbed native soils or on properly compacted structural fill as a floor subbase. If floor construction occurs during wet conditions, it is likely that a geotextile fabric, placed between the structural fill floor subbase and native soils, will be necessary. All subbase fill should be compacted to a density of at least 95 percent (based on ASTM:D-1557). Capillary Break and Vapor Barrier: To retard the upward wicking of moisture beneath the floor slab, we recommend that a capillary break be placed over the 12 inch subbase. Ideally, this capillary break would consist of a 4-inch-thick layer of pea gravel or other clean, uniform, well-rounded gravel, such as “Gravel Backfill for Drains” per WSDOT Standard Specification 9-03.12(4), but clean angular gravel can be used if it adequately prevents capillary wicking. In addition, a layer of plastic sheeting (such as Crosstuff, Visqueen, or Moistop) should be placed over the capillary break to serve as a vapor barrier. During subsequent casting of the concrete slab, the contractor should exercise care to avoid puncturing this vapor barrier. 4.4 Asphalt Pavement Since asphalt pavements will be used for the new driveway and parking areas, we offer the following comments and recommendations for pavement design and construction. Subgrade Preparation: After removal of any surficial sod, topsoil, or organic-rich fill, all soil subgrades should be thoroughly compacted, then proof-rolled with a loaded dump truck or heavy compactor. Any localized zones of yielding subgrade disclosed during this proof-rolling operation should be over excavated to a maximum depth of 12 inches and replaced with a suitable structural fill material. All structural fill should be compacted according to our recommendations given in the Structural Fill section. Specifically, the upper 2 feet of soils underlying pavement section should be compacted to at least 95 percent (based on ASTM D-1557), and all soils below 2 feet should be compacted to at least 90 percent. Pavement Materials: For the base course, we recommend using imported crushed rock, such as "Crushed Surfacing Top Course” per WSDOT Standard Specification 9-03.9(3). If a subbase course is needed, we recommend using imported, clean, well-graded sand and gravel such as “Ballast” or “Gravel Borrow” per WSDOT Standard Specifications 9-03.9(1) and 9-03.14, respectively. 51 Conventional Asphalt Sections: A conventional pavement section typically comprises an asphalt concrete pavement over a crushed rock base course. We recommend using the following conventional pavement sections: Minimum Thickness Pavement Course Parking Areas Driveways Asphalt Concrete Pavement 2 inches 3 inches Crushed Rock Base 4 inches 6 inches Granular Fill Subbase (if needed) 6 inches 8 inches Compaction and Observation: All subbase and base course material should be compacted to at least 95 percent of the Modified Proctor maximum dry density (ASTM D-1557), and all asphalt concrete should be compacted to at least 92 percent of the Rice value (ASTM D-2041). We recommend that an E3RA representative be retained to observe the compaction of each course before any overlying layer is placed. For the subbase and pavement course, compaction is best observed by means of frequent density testing. For the base course, methodology observations and hand-probing are more appropriate than density testing. Pavement Life and Maintenance: No asphalt pavement is maintenance-free. The above described pavement sections present our minimum recommendations for an average level of performance during a 20-year design life; therefore, an average level of maintenance will likely be required. Furthermore, a 20-year pavement life typically assumes that an overlay will be placed after about 10 years. Thicker asphalt and/or thicker base and subbase courses would offer better long-term performance, but would cost more initially; thinner courses would be more susceptible to “alligator” cracking and other failure modes. As such, pavement design can be considered a compromise between a high initial cost and low maintenance costs versus a low initial cost and higher maintenance costs. 4.5 Structural Fill The term "structural fill" refers to any material placed under foundations, retaining walls, slab-on-grade floors, sidewalks, pavements, and other structures. Our comments, conclusions, and recommendations concerning structural fill are presented in the following paragraphs. Materials: Typical structural fill materials include clean sand, gravel, pea gravel, washed rock, crushed rock, well-graded mixtures of sand and gravel (commonly called "gravel borrow" or "pit-run"), and miscellaneous mixtures of silt, sand, and gravel. Recycled asphalt, concrete, and glass, which are derived from pulverizing the parent materials, are also potentially useful as structural fill in certain applications. Soils used for structural fill should not contain any organic matter or debris, nor any individual particles greater than about 6 inches in diameter. Fill Placement: Clean sand, gravel, crushed rock, soil mixtures, and recycled materials should be placed in horizontal lifts not exceeding 8 inches in loose thickness, and each lift should be thoroughly compacted with a mechanical compactor. Compaction Criteria: Using the Modified Proctor test (ASTM:D-1557) as a standard, we recommend that structural fill used for various onsite applications be compacted to the following minimum densities: 52 Fill Application Minimum Compaction Footing subgrade and bearing pad Foundation backfill Slab-on-grade floor subgrade and subbase Asphalt pavement base Asphalt pavement subgrade (upper 2 feet) Asphalt pavement subgrade (below 2 feet) 95 percent 90 percent 95 percent 95 percent 95 percent 90 percent Subgrade Observation and Compaction Testing: Regardless of material or location, all structural fill should be placed over firm, unyielding subgrades prepared in accordance with the Site Preparation section of this report. The condition of all subgrades should be observed by geotechnical personnel before filling or construction begins. Also, fill soil compaction should be verified by means of in-place density tests performed during fill placement so that adequacy of soil compaction efforts may be evaluated as earthwork progresses. Soil Moisture Considerations: The suitability of soils used for structural fill depends primarily on their grain-size distribution and moisture content when they are placed. As the "fines" content (that soil fraction passing the U.S. No. 200 Sieve) increases, soils become more sensitive to small changes in moisture content. Soils containing more than about 5 percent fines (by weight) cannot be consistently compacted to a firm, unyielding condition when the moisture content is more than 2 percentage points above or below optimum. For fill placement during wet-weather site work, we recommend using "clean" fill, which refers to soils that have a fines content of 5 percent or less (by weight) based on the soil fraction passing the U.S. No. 4 Sieve. 5.0 RECOMMENDED ADDITIONAL SERVICES Because the future performance and integrity of the structural elements will depend largely on proper site preparation, drainage, fill placement, and construction procedures, monitoring and testing by experienced geotechnical personnel should be considered an integral part of the construction process. Consequently, we recommend that E3RA be retained to provide the following post-report services: • Review all construction plans and specifications to verify that our design criteria presented in this report have been properly integrated into the design; • Prepare a letter summarizing all review comments (if required); • Check all completed subgrades for footings and slab-on-grade floors before concrete is poured, in order to verify their bearing capacity; • Prepare a post-construction letter summarizing all field observations, inspections, and test results (if required); and 53 54 701 Sunset Blvd NE Renton, Washington Topographic and Location Map FIGURE 1 T15034 APPROXIMATE SITE LOCATION E3RA, Inc. P.O. Box 44840 Tacoma, WA 98448 55 56 APPENDIX A SOIL CLASSIFICATION CHART AND KEY TO TEST DATA LOG OF TEST PITS 57 CLAYEY GRAVELS, POORLY GRADED GRAVEL-SAND-CLAY MIXTURES SILTS AND CLAYSCOARSE GRAINED SOILSMore than Half > #200 sieveLIQUID LIMIT LESS THAN 50 LIQUID LIMIT GREATER THAN 50 CLEAN GRAVELS WITH LITTLE OR NO FINES GRAVELS WITH OVER 15% FINES CLEAN SANDS WITH LITTLE OR NO FINESMORE THAN HALF COARSE FRACTION IS SMALLER THAN NO. 4 SIEVE MORE THAN HALF COARSE FRACTION IS LARGER THAN NO. 4 SIEVE INORGANIC SILTS, MICACEOUS OR DIATOMACIOUS FINE SANDY OR SILTY SOILS, ELASTIC SILTS ORGANIC CLAYS AND ORGANIC SILTY CLAYS OF LOW PLASTICITY OH INORGANIC SILTS AND VERY FINE SANDS, ROCK FLOUR,SILTY OR CLAYEY FINE SANDS, OR CLAYEY SILTS WITHSLIGHT PLASTICITY CH SILTY GRAVELS, POORLY GRADED GRAVEL-SAND-SILT MIXTURES SANDS SILTS AND CLAYS Figure A-1 INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY,GRAVELLY CLAYS, SANDY CLAYS, SILTY CLAYS,LEAN CLAYS E3RA R-Value Sieve Analysis Swell Test Cyclic Triaxial Unconsolidated Undrained Triaxial Torvane Shear Unconfined Compression (Shear Strength, ksf) Wash Analysis (with % Passing No. 200 Sieve) Water Level at Time of Drilling Water Level after Drilling(with date measured) RV SA SW TC TX TV UC (1.2) WA (20) Modified California Split Spoon Pushed Shelby Tube Auger Cuttings Grab Sample Sample Attempt with No Recovery Chemical Analysis Consolidation Compaction Direct Shear Permeability Pocket Penetrometer CA CN CP DS PM PP PtHIGHLY ORGANIC SOILS TYPICAL NAMES GRAVELS ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTS WELL GRADED GRAVELS, GRAVEL-SAND MIXTURES MAJOR DIVISIONS PEAT AND OTHER HIGHLY ORGANIC SOILS WELL GRADED SANDS, GRAVELLY SANDS POORLY GRADED SANDS, GRAVELLY SANDS SILTY SANDS, POOORLY GRADED SAND-SILT MIXTURES CLAYEY SANDS, POORLY GRADED SAND-CLAY MIXTURES POORLY GRADED GRAVELS, GRAVEL-SAND MIXTURES SOIL CLASSIFICATION CHART AND KEY TO TEST DATA GW GP GM GC SW SP SM SC ML FINE GRAINED SOILSMore than Half < #200 sieveLGD A NNNN02 GINT US LAB.GPJ 11/4/05INORGANIC CLAYS OF HIGH PLASTICITY, FAT CLAYS CL OL MH SANDS WITH OVER 15% FINES 58 GB S-1 GB S-2 GP SM SM SM 0.5 3.5 4.5 7.5 (GP) Gray gravel with sand and some silt (medium dense, moist) (Gravel Surfacing) (SM) Brown silty sand (medium dense, moist) (Fill) (SM) Dark brown silty sand with logs, woody debris and general refuse (loose, moist) (Fill) (SM) Light brown silty sand with some gravel (medium dense, moist) (Weathered Till) No caving observed No groundwater seepage observed The depths on the test pit logs are based on an average of measurements across the test pit and should be considered accurate to 0.5 foot. Bottom of test pit at 7.5 feet. NOTES GROUND ELEVATION LOGGED BY DMW EXCAVATION METHOD EXCAVATION CONTRACTOR GROUND WATER LEVELS: CHECKED BY DATE STARTED 1/21/15 COMPLETED 1/21/15 AT TIME OF EXCAVATION --- AT END OF EXCAVATION --- AFTER EXCAVATION --- TEST PIT SIZE SAMPLE TYPENUMBERDEPTH(ft)0.0 2.5 5.0 7.5 TEST PIT NUMBER TP-1 PAGE 1 OF 1 Figure A-2 CLIENT Totenham, LLC PROJECT NUMBER T15034 PROJECT NAME 701 Sunset Blvd NE PROJECT LOCATION Renton, Washington COPY OF GENERAL BH / TP LOGS - FIGURE.GDT - 4/3/15 16:53 - Z:\2015 JOB FILES\T15034 TOTENHAM, LLC - 701 NE SUNSET BLVD, RENTON GEOTECH\T15034 TEST PITS.GPJE3RA, Inc. E3RA, Inc. P.O. Box 44840 Tacoma, WA 98448 Telephone: 253-537-9400 Fax: 253-537-9401 U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION 59 GB S-1 GB S-2 GP SM SM SM 0.5 3.5 4.5 7.5 (GP) Gray gravel with sand and some silt (medium dense, moist) (Gravel Surfacing) (SM) Brown silty sand (medium dense, moist) (Fill) (SM) Dark brown silty sand with logs, woody debris and general refuse (loose, moist) (Fill) (SM) Light brown silty sand with some gravel (medium dense, moist) (Weathered Till) No caving observed No groundwater seepage observed The depths on the test pit logs are based on an average of measurements across the test pit and should be considered accurate to 0.5 foot. Bottom of test pit at 7.5 feet. NOTES GROUND ELEVATION LOGGED BY DMW EXCAVATION METHOD EXCAVATION CONTRACTOR GROUND WATER LEVELS: CHECKED BY DATE STARTED 1/21/15 COMPLETED 1/21/15 AT TIME OF EXCAVATION --- AT END OF EXCAVATION --- AFTER EXCAVATION --- TEST PIT SIZE SAMPLE TYPENUMBERDEPTH(ft)0.0 2.5 5.0 7.5 TEST PIT NUMBER TP-2 PAGE 1 OF 1 Figure A-3 CLIENT Totenham, LLC PROJECT NUMBER T15034 PROJECT NAME 701 Sunset Blvd NE PROJECT LOCATION Renton, Washington COPY OF GENERAL BH / TP LOGS - FIGURE.GDT - 4/3/15 16:53 - Z:\2015 JOB FILES\T15034 TOTENHAM, LLC - 701 NE SUNSET BLVD, RENTON GEOTECH\T15034 TEST PITS.GPJE3RA, Inc. E3RA, Inc. P.O. Box 44840 Tacoma, WA 98448 Telephone: 253-537-9400 Fax: 253-537-9401 U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION 60 SM SM SM 0.5 3.5 4.5 7.5 Sod and Topsoil (SM) Brown silty sand (medium dense, moist) (Fill) (SM) Dark brown silty sand with logs, woody debris and general refuse (loose, moist) (Fill) (SM) Light brown silty sand with some gravel (medium dense, moist) (Weathered Till) No caving observed No groundwater seepage observed The depths on the test pit logs are based on an average of measurements across the test pit and should be considered accurate to 0.5 foot. Bottom of test pit at 7.5 feet. NOTES GROUND ELEVATION LOGGED BY DMW EXCAVATION METHOD EXCAVATION CONTRACTOR GROUND WATER LEVELS: CHECKED BY DATE STARTED 1/21/15 COMPLETED 1/21/15 AT TIME OF EXCAVATION --- AT END OF EXCAVATION --- AFTER EXCAVATION --- TEST PIT SIZE SAMPLE TYPENUMBERDEPTH(ft)0.0 2.5 5.0 7.5 TEST PIT NUMBER TP-3 PAGE 1 OF 1 Figure A-4 CLIENT Totenham, LLC PROJECT NUMBER T15034 PROJECT NAME 701 Sunset Blvd NE PROJECT LOCATION Renton, Washington COPY OF GENERAL BH / TP LOGS - FIGURE.GDT - 4/3/15 16:53 - Z:\2015 JOB FILES\T15034 TOTENHAM, LLC - 701 NE SUNSET BLVD, RENTON GEOTECH\T15034 TEST PITS.GPJE3RA, Inc. E3RA, Inc. P.O. Box 44840 Tacoma, WA 98448 Telephone: 253-537-9400 Fax: 253-537-9401 U.S.C.S.GRAPHICLOGMATERIAL DESCRIPTION 61 Renton 701 Townhomes DCI 15375 7. Other Permits 62 Renton 701 Townhomes DCI 15375 7. Other Permits Building and right-of-way use permits are anticipated for initial site development. Less than 1 ac will be disturbed for the total project development; therefore, NPDES coverage is not required. 63 Renton 701 Townhomes DCI 15375 8. CSWPPP Analysis and Design 64 Renton 701 Townhomes DCI 15375 8. CSWPPP Analysis and Design Part A – ESC Plan Analysis and Design Core Requirement #5 stipulates nine minimum requirements be incorporated into project construction to minimize erosion and limit sediment transport to drainage facilities, water resources and adjacent properties. The following brief narrative discusses compliance with each of the nine requirements: Clearing Limits Clearing limits have been delineated on the TESC plans. Cover Measures Cover measures have been addressed in the TESC plans. Perimeter Protection Perimeter protection will be used as Primary Treatment and will consist of silt fence (in accordance with KCSWDM Appendix D, Section D.3.3.1). Fence location and installation has been specified on the TESC plans. Traffic Area Stabilization A stabilized construction entrance will be used to limit sediment transport. It has been designed in accordance with KCSWDM Appendix D, Section 3.4.1. The entrance location and details are shown on the TESC Plans. Rock surfacing is shown for internal access, parking and staging area stabilization. Sediment Retention The disturbed area is less than 1 acre. Therefore a sediment trap is proposed for sediment retention. From the hydrologic analysis in Section 4, the 2-year peak flow is 0.234 CFS. Per KCSWDM Section D3.5.1, the required surface area of the sediment trap is: SA = 2,080 SF/CFS x 0.234 CFS = 490 SF. Surface Water Collection An interceptor dike/swale is proposed to collect site runoff around the downslope perimeter of the site and convey it to the sediment trap. A pipe slope drain is proposed to convey runoff from the upper portion of the site to the sediment trap located at the lower plateau. 65 Renton 701 Townhomes DCI 15375 Dewatering Control When to Install: Dewatering control measures shall be used whenever there is a potential for runoff from dewatering of utilities, excavations, foundations, etc. Measures to install: 1. Foundation, vault, excavation, and trench dewatering water that has similar characteristics to stormwater runoff at the site shall be discharged into a controlled conveyance system prior to discharge to a sediment trap or sediment pond. Foundation and trench dewatering water that has similar characteristics to stormwater runoff at the site must be disposed of through one of the following options depending on site constraints: a) Infiltration, b) Transport offsite in a vehicle, such as a vacuum flush truck, for legal disposal in a manner that does not pollute surface waters, c) Discharge to the sanitary sewer discharge with approval from King County and the City of Renton if there is no other option, or d) Use of a sedimentation bag with outfall to a ditch or swale for small volumes of localized dewatering. 2. Clean, non-turbid dewatering water, such as well-point ground water, may be discharged via stable conveyance to systems tributary to surface waters, provided the dewatering flow does not cause erosion or flooding of receiving waters. 3. Highly turbid or contaminated dewatering water (high pH or other) shall be handled separately from stormwater. See Section D.2.2 , SWPPS Measures. Part B – SWPPS Plan Design The following brief narrative discusses compliance with the minimum pollution-generating activities typically associated with construction as required for the SWPPS plan: Storage and Handling of Liquids Paints, solvents, pesticides, form oils and concrete admixtures are anticipated but shall be kept inside garage or under cover and out of elements. Application to comply with all local, state and federal requirements and manufacturer recommendations. Storage and Stockpiling of Construction Materials and Wastes Storage and stockpiling of materials will occur on site. A stockpile location is located on the TESC plans. A plastic covering detail and note is included in the plans(in accordance with KCSWDM Appendix D, Section D.3.2.D) for covering soil stockpiles. Fueling Fueling is expected to be provided by service trucks. On-site storage of fuel is not anticipated. A note is include on the plans specifying lighting if fueling will occur at night. Maintenance, Repairs and Storage of Vehicles and Equipment A note is included on the plans that specify the use of drip pans or plastic when maintenance is performed. 66 Renton 701 Townhomes DCI 15375 Concrete Saw Cutting, Slurry and Washwater Disposal A sump is shown on the plans for slurry and washwater disposal. Handling of pH Elevated Water Concrete flatwork including building and sidewalks will be less than 10,000 SF and runoff will sheetflow to surrounding areas. Most concrete will be covered with roof within several months. The size of exposed concrete surfaces and the duration of exposure are not anticipated to be substantial enough to cause any significant pH change. Application of Chemicals including Pesticides and Fertilizers No pesticides are anticipated. Disturbed slopes are anticipated to be stabilized by hydroseeding. No other fertilizer application is anticipated. Source Controls This project includes construction of a street, utilities, and street and asphalt shoulder widening. Various types of source controls were considered; the following source controls shall be implemented (refer to the King County Stormwater Pollution Prevention Manual): - A-8: Storage of Solid Waste and Food Waste - A-13: Vehicle Washing and Steam Cleaning - A-17: Fueling Operations - A-18: Vehicle & Equipment Repair and Maintenance - A-26: Landscaping Activities - A-27: Clearing and Grading of Land for Small Construction Projects - A-31: Vehicle and Equipment Parking and Storage A note is included on the plans that specifies that the contractor shall develop a spill prevention plan and maintain appropriate spill response supplies for any toxic or hazardous liquids stored or used on site. 67 Renton 701 Townhomes DCI 15375 9. Bond Quantities, Facility Summaries, and Declaration of Covenant 68 Renton 701 Townhomes DCI 15375 9. Bond Quantities, Facility Summaries, and Declaration of Covenant Bond quantity worksheets are included on the following pages. Facility summary forms and sketch are also included on the following pages. A signed and notarized Declaration of Covenants for maintenance of the stormwater facilities and flow control BMPs (permeable pavers) and a leachable materials covenant will be provided prior to construction permit approval. Draft copies are enclosed. 69 Planning Division |1055 South Grady Way – 6th Floor | Renton, WA 98057 (425) 430‐7200Date Prepared: Name:PE Registration No:Firm Name:Firm Address:Phone No.Email Address:Project Name: Project Owner:CED Plan # (LUA):Phone:CED Permit # (U):Address: Site Address:Street Intersection:Addt'l Project Owner:Parcel #(s):Phone:Address: Clearing and grading greater than or equal to 5,000 board feet of timber? Yes/No:noWater Service Provided by:If Yes, Provide Forest Practice Permit #:Sewer Service Provided by: SITE IMPROVEMENT BOND QUANTITY WORKSHEETPROJECT INFORMATIONCITY OF RENTONCITY OF RENTON1 Select the current project status/phase from the following options: For Approval ‐ Preliminary Data Enclosed, pending approval from the City; For Construction ‐ Estimated Data Enclosed, Plans have been approved for contruction by the City; Project Closeout ‐ Final Costs and Quantities Enclosed for Project Close‐out SubmittalPhoneEngineer Stamp Required (all cost estimates must have original wet stamp and signature)Clearing and GradingUtility ProvidersN/AProject Location and DescriptionProject Owner InformationSunset's EdgeBellevue, WA 98004311990‐0011, ‐0010 & ‐0005Tottenham LLC16‐000864425‐898‐23008/31/2017Prepared by:FOR APPROVALProject Phase 1haroldd@duncansonco.comHarold Duncanson29647Duncanson Co145 SW 155th Street, #102, Burien 98166206‐244‐4141701 Sunset Boulevard NE50 116th Ave SE, STE 111Additional Project OwnerNE 7th Street########AddressAbbreviated Legal Description:Lot 2, City of Renton LLA95‐154City, State, ZipPage 2 of 14Ref 8‐H Bond Quantity WorksheetSECTION I PROJECT INFORMATIONUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 8/31/2017 70 CED Permit #:########UnitReference #PriceUnitQuantity CostBackfill & compaction‐embankmentESC‐16.50$ CY Check dams, 4" minus rockESC‐2SWDM 5.4.6.380.00$ Each3240.00Catch Basin ProtectionESC‐335.50$ Each5177.50Crushed surfacing 1 1/4" minusESC‐4WSDOT 9‐03.9(3)95.00$ CY252,375.00DitchingESC‐59.00$ CY15135.00Excavation‐bulkESC‐62.00$ CY Fence, siltESC‐7SWDM 5.4.3.11.50$ LF300450.00Fence, Temporary (NGPE)ESC‐81.50$ LF Geotextile FabricESC‐92.50$ SY Hay Bale Silt TrapESC‐100.50$ Each HydroseedingESC‐11SWDM 5.4.2.40.80$ SY20001,600.00Interceptor Swale / DikeESC‐121.00$ LF180180.00Jute MeshESC‐13SWDM 5.4.2.23.50$ SY Level SpreaderESC‐141.75$ LF Mulch, by hand, straw, 3" deepESC‐15SWDM 5.4.2.12.50$ SY Mulch, by machine, straw, 2" deepESC‐16SWDM 5.4.2.12.00$ SY Piping, temporary, CPP, 6"ESC‐1712.00$ LF Piping, temporary, CPP, 8"ESC‐1814.00$ LF30420.00Piping, temporary, CPP, 12"ESC‐1918.00$ LF Plastic covering, 6mm thick, sandbaggedESC‐20SWDM 5.4.2.34.00$ SY200800.00Rip Rap, machine placed; slopesESC‐21WSDOT 9‐13.1(2)45.00$ CY10450.00Rock Construction Entrance, 50'x15'x1'ESC‐22SWDM 5.4.4.11,800.00$ Each Rock Construction Entrance, 100'x15'x1'ESC‐23SWDM 5.4.4.13,200.00$ Each13,200.00Sediment pond riser assemblyESC‐24SWDM 5.4.5.22,200.00$ Each Sediment trap, 5' high berm ESC‐25SWDM 5.4.5.119.00$ LF20380.00Sed. trap, 5' high, riprapped spillway berm section ESC‐26SWDM 5.4.5.170.00$ LF10700.00Seeding, by handESC‐27SWDM 5.4.2.41.00$ SY Sodding, 1" deep, level groundESC‐28SWDM 5.4.2.58.00$ SY Sodding, 1" deep, sloped groundESC‐29SWDM 5.4.2.510.00$ SY TESC SupervisorESC‐30110.00$ HR121,320.00Water truck, dust controlESC‐31SWDM 5.4.7140.00$ HR 4560.00UnitReference #PriceUnitQuantity Cost EROSION/SEDIMENT SUBTOTAL:12,987.50SALES TAX @ 10%1,298.75EROSION/SEDIMENT TOTAL:14,286.25(A)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR EROSION & SEDIMENT CONTROLDescriptionNo.(A)WRITE‐IN‐ITEMS Page 3 of 14Ref 8‐H Bond Quantity WorksheetSECTION II.a EROSION_CONTROLUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 8/31/2017 71 CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostGENERAL ITEMS Backfill & Compaction‐ embankmentGI‐16.00$ CY 160960.0080480.00Backfill & Compaction‐ trenchGI‐29.00$ CYClear/Remove Brush, by hand (SY)GI‐31.00$ SYBollards ‐ fixedGI‐4 240.74$ EachBollards ‐ removableGI‐5 452.34$ EachClearing/Grubbing/Tree RemovalGI‐6 10,000.00$ AcreExcavation ‐ bulkGI‐72.00$ CY13002,600.00Excavation ‐ TrenchGI‐85.00$ CYFencing, cedar, 6' highGI‐9 20.00$ LFFencing, chain link, 4'GI‐1038.31$ LFFencing, chain link, vinyl coated, 6' highGI‐11 20.00$ LFFencing, chain link, gate, vinyl coated, 20' GI‐12 1,400.00$ EachFill & compact ‐ common barrowGI‐13 25.00$ CY140035,000.00Fill & compact ‐ gravel baseGI‐14 27.00$ CYFill & compact ‐ screened topsoilGI‐15 39.00$ CYGabion, 12" deep, stone filled mesh GI‐16 65.00$ SYGabion, 18" deep, stone filled mesh GI‐17 90.00$ SYGabion, 36" deep, stone filled meshGI‐18 150.00$ SYGrading, fine, by handGI‐19 2.50$ SYGrading, fine, with graderGI‐20 2.00$ SY 440880.00220440.008301,660.00Monuments, 3' LongGI‐21 250.00$ EachSensitive Areas SignGI‐22 7.00$ EachSodding, 1" deep, sloped groundGI‐23 8.00$ SYSurveying, line & gradeGI‐24850.00$ Day1850.0032,550.00Surveying, lot location/linesGI‐25 1,800.00$ AcreTopsoil Type A (imported)GI‐26 28.50$ CYTraffic control crew ( 2 flaggers )GI‐27 120.00$ HR 161,920.00Trail, 4" chipped woodGI‐28 8.00$ SYTrail, 4" crushed cinderGI‐29 9.00$ SYTrail, 4" top courseGI‐30 12.00$ SYConduit, 2"GI‐31 5.00$ LFWall, retaining, concreteGI‐32 55.00$ SF1508,250.00Wall, rockeryGI‐33 15.00$ SFSUBTOTAL THIS PAGE:3,760.001,770.0050,060.00(B)(C)(D)(E)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR STREET AND SITE IMPROVEMENTSQuantity Remaining (Bond Reduction) (B)(C)Page 4 of 14Ref 8‐H Bond Quantity WorksheetSECTION II.b TRANSPORTATIONUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 8/31/2017 72 CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR STREET AND SITE IMPROVEMENTSQuantity Remaining (Bond Reduction) (B)(C)ROAD IMPROVEMENT/PAVEMENT/SURFACINGAC Grinding, 4' wide machine < 1000syRI‐1 30.00$ SYAC Grinding, 4' wide machine 1000‐2000sy RI‐2 16.00$ SYAC Grinding, 4' wide machine > 2000syRI‐3 10.00$ SYAC Removal/DisposalRI‐4 35.00$ SY 22770.00Barricade, Type III ( Permanent )RI‐5 56.00$ LFGuard RailRI‐6 30.00$ LFCurb & Gutter, rolledRI‐7 17.00$ LFCurb & Gutter, verticalRI‐8 12.50$ LF1802,250.00Curb and Gutter, demolition and disposal RI‐9 18.00$ LFCurb, extruded asphaltRI‐10 5.50$ LFCurb, extruded concreteRI‐11 7.00$ LFSawcut, asphalt, 3" depthRI‐12 1.85$ LF 200370.00Sawcut, concrete, per 1" depthRI‐13 3.00$ LFSealant, asphaltRI‐14 2.00$ LF 200400.00Shoulder, gravel, 4" thickRI‐15 15.00$ SYSidewalk, 4" thickRI‐16 38.00$ SY1606,080.00Sidewalk, 4" thick, demolition and disposal RI‐17 32.00$ SYSidewalk, 5" thickRI‐18 41.00$ SYSidewalk, 5" thick, demolition and disposal RI‐19 40.00$ SYSign, Handicap RI‐20 85.00$ EachStriping, per stallRI‐21 7.00$ EachStriping, thermoplastic, ( for crosswalk )RI‐22 3.00$ SFStriping, 4" reflectorized lineRI‐23 0.50$ LFAdditional 2.5" Crushed SurfacingRI‐243.60$ SYHMA 1/2" Overlay 1.5" RI‐25 14.00$ SYHMA 1/2" Overlay 2"RI‐26 18.00$ SY 1502,700.00HMA Road, 2", 4" rock, First 2500 SYRI‐27 28.00$ SYHMA Road, 2", 4" rock, Qty. over 2500SY RI‐28 21.00$ SYHMA Road, 4", 6" rock, First 2500 SYRI‐29 45.00$ SY 1506,750.0060027,000.00HMA Road, 4", 6" rock, Qty. over 2500 SY RI‐30 37.00$ SYHMA Road, 4", 4.5" ATBRI‐31 38.00$ SYGravel Road, 4" rock, First 2500 SYRI‐32 15.00$ SYGravel Road, 4" rock, Qty. over 2500 SYRI‐33 10.00$ SYThickened EdgeRI‐34 8.60$ LFSUBTOTAL THIS PAGE:10,990.008,330.0027,000.00(B)(C)(D)(E)Page 5 of 14Ref 8‐H Bond Quantity WorksheetSECTION II.b TRANSPORTATIONUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 8/31/2017 73 CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR STREET AND SITE IMPROVEMENTSQuantity Remaining (Bond Reduction) (B)(C)PARKING LOT SURFACING No.2" AC, 2" top course rock & 4" borrowPL‐1 21.00$ SY2" AC, 1.5" top course & 2.5" base course PL‐2 28.00$ SY4" select borrowPL‐35.00$ SY1.5" top course rock & 2.5" base coursePL‐4 14.00$ SYSUBTOTAL PARKING LOT SURFACING:(B)(C)(D)(E)LANDSCAPING & VEGETATION No.Street TreesLA‐1Median LandscapingLA‐2Right‐of‐Way LandscapingLA‐3Wetland LandscapingLA‐4SUBTOTAL LANDSCAPING & VEGETATION:(B)(C)(D)(E)TRAFFIC & LIGHTING No.SignsTR‐1Street Light System ( # of Poles)TR‐2 3,000.00$ LS 13,000.00Traffic SignalTR‐3Traffic Signal ModificationTR‐4SUBTOTAL TRAFFIC & LIGHTING:3,000.00(B)(C)(D)(E)WRITE‐IN‐ITEMSRPM, Misc Striping & Turn Arrows2,500.00$ LS 12,500.00Driveway & ADA Ramp1,500.00$ LS11,500.00SUBTOTAL WRITE‐IN ITEMS:2,500.001,500.00STREET AND SITE IMPROVEMENTS SUBTOTAL:20,250.0011,600.0077,060.00SALES TAX @ 10%2,025.001,160.007,706.00STREET AND SITE IMPROVEMENTS TOTAL:22,275.0012,760.0084,766.00(B)(C)(D)(E)Page 6 of 14Ref 8‐H Bond Quantity WorksheetSECTION II.b TRANSPORTATIONUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 8/31/2017 74 CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostDRAINAGE (CPE = Corrugated Polyethylene Pipe, N12 or Equivalent) For Culvert prices, Average of 4' cover was assumed. Assume perforated PVC is same price as solid pipe.) Access Road, R/DD‐126.00$ SY* (CBs include frame and lid)BeehiveD‐290.00$ EachThrough‐curb Inlet FrameworkD‐3 400.00$ Each 1400.00CB Type ID‐4 1,500.00$ Each 11,500.0011,500.00CB Type ILD‐5 1,750.00$ Each 11,750.00CB Type II, 48" diameterD‐6 2,300.00$ Each12,300.00 for additional depth over 4' D‐7 480.00$ FT31,440.00CB Type II, 54" diameterD‐8 2,500.00$ Each for additional depth over 4'D‐9 495.00$ FTCB Type II, 60" diameterD‐10 2,800.00$ Each25,600.00 for additional depth over 4'D‐11 600.00$ FT84,800.00CB Type II, 72" diameterD‐12 6,000.00$ Each for additional depth over 4'D‐13 850.00$ FTCB Type II, 96" diameterD‐14 14,000.00$ Each for additional depth over 4'D‐15 925.00$ FTTrash Rack, 12"D‐16 350.00$ EachTrash Rack, 15"D‐17 410.00$ EachTrash Rack, 18"D‐18 480.00$ EachTrash Rack, 21"D‐19 550.00$ EachCleanout, PVC, 4"D‐20 150.00$ EachCleanout, PVC, 6"D‐21 170.00$ EachCleanout, PVC, 8"D‐22 200.00$ EachCulvert, PVC, 4" D‐23 10.00$ LFCulvert, PVC, 6" D‐2413.00$ LF4005,200.00Culvert, PVC, 8" D‐25 15.00$ LFCulvert, PVC, 12" D‐26 23.00$ LFCulvert, PVC, 15" D‐27 35.00$ LFCulvert, PVC, 18" D‐28 41.00$ LFCulvert, PVC, 24"D‐29 56.00$ LFCulvert, PVC, 30" D‐30 78.00$ LFCulvert, PVC, 36" D‐31 130.00$ LFCulvert, CMP, 8"D‐32 19.00$ LFCulvert, CMP, 12"D‐33 29.00$ LFSUBTOTAL THIS PAGE:3,650.0020,840.00(B)(C)(D)(E)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESQuantity Remaining (Bond Reduction) (B)(C)Page 7 of 14Ref 8‐H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 8/31/2017 75 CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESQuantity Remaining (Bond Reduction) (B)(C)DRAINAGE (Continued)Culvert, CMP, 15"D‐34 35.00$ LFCulvert, CMP, 18"D‐35 41.00$ LFCulvert, CMP, 24"D‐36 56.00$ LFCulvert, CMP, 30"D‐37 78.00$ LFCulvert, CMP, 36"D‐38 130.00$ LFCulvert, CMP, 48"D‐39 190.00$ LFCulvert, CMP, 60"D‐40 270.00$ LFCulvert, CMP, 72"D‐41 350.00$ LFCulvert, Concrete, 8"D‐42 42.00$ LFCulvert, Concrete, 12"D‐43 48.00$ LFCulvert, Concrete, 15"D‐44 78.00$ LFCulvert, Concrete, 18"D‐45 48.00$ LFCulvert, Concrete, 24"D‐46 78.00$ LFCulvert, Concrete, 30"D‐47 125.00$ LFCulvert, Concrete, 36"D‐48 150.00$ LFCulvert, Concrete, 42"D‐49 175.00$ LFCulvert, Concrete, 48"D‐50 205.00$ LFCulvert, CPE Triple Wall, 6" D‐51 14.00$ LFCulvert, CPE Triple Wall, 8" D‐52 16.00$ LFCulvert, CPE Triple Wall, 12" D‐5324.00$ LFCulvert, CPE Triple Wall, 15" D‐54 35.00$ LFCulvert, CPE Triple Wall, 18" D‐55 41.00$ LFCulvert, CPE Triple Wall, 24" D‐56 56.00$ LFCulvert, CPE Triple Wall, 30" D‐57 78.00$ LFCulvert, CPE Triple Wall, 36" D‐58 130.00$ LFCulvert, LCPE, 6"D‐5960.00$ LFCulvert, LCPE, 8"D‐60 72.00$ LFCulvert, LCPE, 12"D‐61 84.00$ LF 433,612.0025021,000.00Culvert, LCPE, 15"D‐62 96.00$ LFCulvert, LCPE, 18"D‐63 108.00$ LFCulvert, LCPE, 24"D‐64 120.00$ LFCulvert, LCPE, 30"D‐65 132.00$ LFCulvert, LCPE, 36"D‐66 144.00$ LFCulvert, LCPE, 48"D‐67 156.00$ LFCulvert, LCPE, 54"D‐68 168.00$ LFSUBTOTAL THIS PAGE:3,612.0021,000.00(B)(C)(D)(E)Page 8 of 14Ref 8‐H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 8/31/2017 76 CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESQuantity Remaining (Bond Reduction) (B)(C)DRAINAGE (Continued)Culvert, LCPE, 60"D‐69 180.00$ LFCulvert, LCPE, 72"D‐70 192.00$ LFCulvert, HDPE, 6"D‐71 42.00$ LFCulvert, HDPE, 8"D‐72 42.00$ LFCulvert, HDPE, 12"D‐73 74.00$ LFCulvert, HDPE, 15"D‐74 106.00$ LFCulvert, HDPE, 18"D‐75 138.00$ LFCulvert, HDPE, 24"D‐76 221.00$ LFCulvert, HDPE, 30"D‐77 276.00$ LFCulvert, HDPE, 36"D‐78 331.00$ LFCulvert, HDPE, 48"D‐79 386.00$ LFCulvert, HDPE, 54"D‐80 441.00$ LFCulvert, HDPE, 60"D‐81 496.00$ LFCulvert, HDPE, 72"D‐82 551.00$ LFPipe, Polypropylene, 6"D‐83 84.00$ LFPipe, Polypropylene, 8"D‐84 89.00$ LFPipe, Polypropylene, 12"D‐85 95.00$ LFPipe, Polypropylene, 15"D‐86 100.00$ LFPipe, Polypropylene, 18"D‐87 106.00$ LFPipe, Polypropylene, 24"D‐88 111.00$ LFPipe, Polypropylene, 30"D‐89 119.00$ LFPipe, Polypropylene, 36"D‐90 154.00$ LFPipe, Polypropylene, 48"D‐91 226.00$ LFPipe, Polypropylene, 54"D‐92 332.00$ LFPipe, Polypropylene, 60"D‐93 439.00$ LFPipe, Polypropylene, 72"D‐94 545.00$ LFCulvert, DI, 6"D‐95 61.00$ LFCulvert, DI, 8"D‐96 84.00$ LFCulvert, DI, 12"D‐97 106.00$ LFCulvert, DI, 15"D‐98 129.00$ LFCulvert, DI, 18"D‐99 152.00$ LFCulvert, DI, 24"D‐100 175.00$ LFCulvert, DI, 30"D‐101 198.00$ LFCulvert, DI, 36"D‐102 220.00$ LFCulvert, DI, 48"D‐103 243.00$ LFCulvert, DI, 54"D‐104 266.00$ LFCulvert, DI, 60"D‐105 289.00$ LFCulvert, DI, 72"D‐106 311.00$ LFSUBTOTAL THIS PAGE:(B)(C)(D)(E)Page 9 of 14Ref 8‐H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 8/31/2017 77 CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESQuantity Remaining (Bond Reduction) (B)(C)Specialty Drainage ItemsDitching SD‐19.50$ CYFlow Dispersal Trench (1,436 base+)SD‐3 28.00$ LF French Drain (3' depth)SD‐4 26.00$ LFGeotextile, laid in trench, polypropylene SD‐53.00$ SYMid‐tank Access Riser, 48" dia, 6' deep SD‐6 2,000.00$ EachPond Overflow SpillwaySD‐7 16.00$ SYRestrictor/Oil Separator, 12"SD‐8 1,150.00$ Each 11,150.0011,150.00Restrictor/Oil Separator, 15"SD‐9 1,350.00$ EachRestrictor/Oil Separator, 18"SD‐10 1,700.00$ EachRiprap, placedSD‐11 42.00$ CY10420.00Tank End Reducer (36" diameter)SD‐12 1,200.00$ Each22,400.00Infiltration pond testingSD‐13 125.00$ HRPermeable PavementSD‐14Permeable Concrete SidewalkSD‐15 40.00$ SY2309,200.00Culvert, Box __ ft x __ ftSD‐16SUBTOTAL SPECIALTY DRAINAGE ITEMS:1,150.0013,170.00(B)(C)(D)(E)STORMWATER FACILITIES (Include Flow Control and Water Quality Facility Summary Sheet and Sketch)Detention PondSF‐1Each Detention TankSF‐2 50,000.00$ Each 150,000.00Detention VaultSF‐3Each Infiltration PondSF‐4Each Infiltration TankSF‐5Each Infiltration VaultSF‐6Each Infiltration TrenchesSF‐7Each Basic Biofiltration SwaleSF‐8Each Wet Biofiltration SwaleSF‐9Each WetpondSF‐10Each WetvaultSF‐11Each Sand FilterSF‐12Each Sand Filter VaultSF‐13Each Linear Sand FilterSF‐14Each Proprietary FacilitySF‐15 20,000.00$ Each 120,000.00Bioretention FacilitySF‐16Each SUBTOTAL STORMWATER FACILITIES:70,000.00(B)(C)(D)(E)Page 10 of 14Ref 8‐H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 8/31/2017 78 CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESQuantity Remaining (Bond Reduction) (B)(C)WRITE‐IN‐ITEMS (INCLUDE ON‐SITE BMPs)WI‐1WI‐2WI‐3WI‐4WI‐5WI‐6WI‐7WI‐8WI‐9WI‐10WI‐11WI‐12WI‐13WI‐14WI‐15SUBTOTAL WRITE‐IN ITEMS:DRAINAGE AND STORMWATER FACILITIES SUBTOTAL:8,412.00125,010.00SALES TAX @ 10%841.2012,501.00DRAINAGE AND STORMWATER FACILITIES TOTAL:9,253.20137,511.00(B)(C)(D)(E)Page 11 of 14Ref 8‐H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 8/31/2017 79 CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostConnection to Existing WatermainW‐1 2,000.00$ Each 12,000.0012,000.00Ductile Iron Watermain, CL 52, 4 Inch Diameter W‐2 50.00$ LFDuctile Iron Watermain, CL 52, 6 Inch Diameter W‐3 56.00$ LFDuctile Iron Watermain, CL 52, 8 Inch Diameter W‐4 60.00$ LFDuctile Iron Watermain, CL 52, 10 Inch Diameter W‐5 70.00$ LFDuctile Iron Watermain, CL 52, 12 Inch Diameter W‐6 80.00$ LF 504,000.0036529,200.00Gate Valve, 4 inch DiameterW‐7 500.00$ EachGate Valve, 6 inch DiameterW‐8 700.00$ EachGate Valve, 8 Inch DiameterW‐9 800.00$ EachGate Valve, 10 Inch DiameterW‐10 1,000.00$ EachGate Valve, 12 Inch DiameterW‐11 1,200.00$ Each 22,400.0056,000.00Fire Hydrant AssemblyW‐12 4,000.00$ Each28,000.00Permanent Blow‐Off AssemblyW‐13 1,800.00$ Each11,800.00Air‐Vac Assembly, 2‐Inch DiameterW‐14 2,000.00$ EachAir‐Vac Assembly, 1‐Inch DiameterW‐15 1,500.00$ EachCompound Meter Assembly 3‐inch Diameter W‐16 8,000.00$ EachCompound Meter Assembly 4‐inch Diameter W‐17 9,000.00$ EachCompound Meter Assembly 6‐inch Diameter W‐18 10,000.00$ EachPressure Reducing Valve Station 8‐inch to 10‐inch W‐19 20,000.00$ EachWATER SUBTOTAL:8,400.00 47,000.00SALES TAX @ 10%840.004,700.00WATER TOTAL:9,240.0051,700.00(B)(C)(D)(E)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR WATERQuantity Remaining (Bond Reduction) (B)(C)Page 12 of 14Ref 8‐H Bond Quantity WorksheetSECTION II.d WATERUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 8/31/2017 80 CED Permit #:########ExistingFuture PublicPrivateRight‐of‐WayImprovementsImprovements(D) (E)DescriptionNo. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Quant. CostClean OutsSS‐1 1,000.00$ EachGrease Interceptor, 500 gallonSS‐2 8,000.00$ EachGrease Interceptor, 1000 gallonSS‐3 10,000.00$ EachGrease Interceptor, 1500 gallonSS‐4 15,000.00$ EachSide Sewer Pipe, PVC. 4 Inch DiameterSS‐5 80.00$ LFSide Sewer Pipe, PVC. 6 Inch DiameterSS‐6 95.00$ LF23021,850.00Sewer Pipe, PVC, 8 inch DiameterSS‐7 105.00$ LFSewer Pipe, PVC, 12 Inch DiameterSS‐8 120.00$ LFSewer Pipe, DI, 8 inch DiameterSS‐9 115.00$ LF24027,600.00Sewer Pipe, DI, 12 Inch DiameterSS‐10 130.00$ LFManhole, 48 Inch DiameterSS‐11 6,000.00$ Each424,000.00Manhole, 54 Inch DiameterSS‐13 6,500.00$ EachManhole, 60 Inch DiameterSS‐15 7,500.00$ EachManhole, 72 Inch DiameterSS‐17 8,500.00$ EachManhole, 96 Inch DiameterSS‐1914,000.00$ EachPipe, C‐900, 12 Inch DiameterSS‐21 180.00$ LFOutside DropSS‐24 1,500.00$ LSInside DropSS‐25 1,000.00$ LSSewer Pipe, PVC, ____ Inch DiameterSS‐26Lift Station (Entire System)SS‐27LSSANITARY SEWER SUBTOTAL:73,450.00SALES TAX @ 10%7,345.00SANITARY SEWER TOTAL:80,795.00(B)(C)(D)(E)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR SANITARY SEWERQuantity Remaining (Bond Reduction) (B)(C)Page 13 of 14Ref 8‐H Bond Quantity WorksheetSECTION II.e SANITARY SEWERUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 8/31/2017 81 82 83 84 Return Address: City Clerk’s Office City of Renton 1055 S Grady Way Renton, WA 98057 DECLARATION OF COVENANT AND EASEMENT FOR INSPECTION AND MAINTENANCE OF DRAINAGE FACILITIES AND ON-SITE BMPS Grantor: Grantee: City of Renton Legal Description: Assessor's Tax Parcel ID#: IN CONSIDERATION of the approved City of Renton (check one of the following) residential building permit, commercial building permit, clearing and grading permit, subdivision permit, or short subdivision permit for application file No. LUA/SWP_______________________ relating to the real property ("Property") described above, the Grantor(s), the owner(s) in fee of that Property, hereby covenants(covenant) with the City of Renton, a political subdivision of the state of Washington, that he/she(they) will observe, consent to, and abide by the conditions and obligations set forth and described in Paragraphs 1 through 9 below with regard to the Property, and hereby grants(grant) an easement as described in Paragraphs 2 and 3. Grantor(s) hereby grants(grant), covenants(covenant), and agrees(agree) as follows: 1. The Grantor(s) or his/her(their) successors in interest and assigns ("Owners ") shall at their own cost, operate, maintain, and keep in good repair, the Property's drainage facilities constructed as required in the approved construction plans and specifications __________ on file with the City of Renton and submitted to the City of Renton for the review and approval of permit(s) _____________________________. The property's drainage facilities are shown and/or listed on Exhibit A. The property’s drainage facilities shall be maintained in compliance with the operation and maintenance schedule included and attached herein as Exhibit B. Drainage facilities include pipes, channels, flow control facilities, water quality facilities, on-site best management practices (BMPs) and other engineered structures designed to manage and/or treat stormwater on the Property. On-site BMPs include dispersion and infiltration devices, bioretention, permeable pavements, rainwater harvesting systems, tree retention credit, reduced impervious surface footprint, vegetated roofs and other measures designed to mimic pre-developed hydrology and minimize stormwater runoff on the Property. 2. City of Renton shall have the right to ingress and egress over those portions of the Property necessary to perform inspections of the stormwater facilities and BMPs and conduct maintenance activities specified in this Declaration of Covenant and in accordance with the Renton Municipal Code. City of Renton shall provide at least 30 days written notice to the Owners that entry on the Property is 85 planned for the inspection of drainage facilities. After the 30 days, the Owners shall allow the City of Renton to enter for the sole purpose of inspecting drainage facilities. In lieu of inspection by the City, the Owners may elect to engage a licensed civil engineer registered in the state of Washington who has expertise in drainage to inspect the drainage facilities and provide a written report describing their condition. If the engineer option is chosen, the Owners shall provide written notice to the City of Renton within fifteen days of receiving the City’s notice of inspection. Within 30 days of giving this notice, the Owners, or engineer on behalf of the Owners, shall provide the engineer’s report to the City of Renton. If the report is not provided in a timely manner as specified above, the City of Renton may inspect the drainage facilities without further notice. 3. If City of Renton determines from its inspection, or from an engineer’s report provided in accordance with Paragraph 2, that maintenance, repair, restoration, and/or mitigation work is required to be done to any of the drainage facilities, City of Renton shall notify the Owners of the specific maintenance, repair, restoration, and/or mitigation work (Work) required pursuant to the Renton Municipal Code. The City shall also set a reasonable deadline for the Owners to complete the Work, or to provide an engineer’s report that verifies completion of the Work. After the deadline has passed, the Owners shall allow the City access to re-inspect the drainage facilities unless an engineer’s report has been provided verifying completion of the Work. If the Work is not completed within the time frame set by the City, the City may initiate an enforcement action and/or perform the required maintenance, repair, restoration, and/or mitigation work and hereby is given access to the Property for such purposes. Written notice will be sent to the Owners stating the City’s intention to perform such work. This work will not commence until at least seven (7) days after such notice is mailed. If, within the sole discretion of the City, there exists an imminent or present danger, the seven (7) day notice period will be waived and maintenance and/or repair work will begin immediately. 4. The Owners shall assume all responsibility for the cost of any maintenance, repair work, or any measures taken by the City to address conditions as described in Paragraph 3. Such responsibility shall include reimbursement to the City within thirty (30) days of the receipt of the invoice for any such work performed. Overdue payments will require payment of interest at the maximum legal rate allowed by RCW 19.52.020 (currently twelve percent (12%)). If the City initiates legal action to enforce this agreement, the prevailing party in such action is entitled to recover reasonable litigation costs and attorney’s fees. 5. The Owners are required to obtain written approval from City of Renton prior to filling, piping, cutting, or removing vegetation (except in routine landscape maintenance) in open vegetated stormwater facilities (such as swales, channels, ditches, ponds, etc.), or performing any alterations or modifications to the drainage facilities referenced in this Declaration of Covenant. 6. Any notice or consent required to be given or otherwise provided for by the provisions of this Agreement shall be effective upon personal delivery, or three (3) days after mailing by Certified Mail, return receipt requested. 7. With regard to the matters addressed herein, this agreement constitutes the entire agreement between the parties, and supersedes all prior discussions, negotiations, and all agreements whatsoever whether oral or written. 8. This Declaration of Covenant is intended to protect the value and desirability and promote efficient and effective management of surface water drainage of the real property described above, and shall inure to the benefit of all the citizens of the City of Renton and its successors and assigns. This 86 Declaration of Covenant shall run with the land and be binding upon Grantor(s), and Grantor's(s') successors in interest, and assigns. 9. This Declaration of Covenant may be terminated by execution of a written agreement by the Owners and the City that is recorded by King County in its real property records. IN WITNESS WHEREOF, this Declaration of Covenant for the Inspection and Maintenance of Drainage Facilities is executed this _____ day of ____________________, 20_____. GRANTOR, owner of the Property GRANTOR, owner of the Property STATE OF WASHINGTON ) COUNTY OF KING )ss. On this day personally appeared before me: , to me known to be the individual(s) described in and who executed the within and foregoing instrument and acknowledged that they signed the same as their free and voluntary act and deed, for the uses and purposes therein stated. Given under my hand and official seal this _____ day of ____________________, 20_____. Printed name Notary Public in and for the State of Washington, residing at My appointment expires 87 BUILDING GARAGE HOUSE CONCRETE ASPHALT BRUSH BRUSH BRUSH BRUSH BUILDING BUILDING SUNSET BLVD. NENE 7TH S T .BUILDING 1BUILDING 2BUILDING 3BUILDING 4SUNSET BLVD NE 88 Exhibit B Sunset’s Edge Townhomes Storm Drainage Facilities Operation and Maintenance Manual 89 90 91 92 93 94 95 96 97 98 99 StormFilter Inspection and Maintenance Procedures ENGINEERED SOLUTIONS 100 In addition to these two activities, it is important to check the condition of the StormFilter unit after major storms for potential damage caused by high flows and for high sediment accumulation that may be caused by localized erosion in the drainage area. It may be necessary to adjust the inspection/ maintenance schedule depending on the actual operating conditions encountered by the system. In general, inspection activities can be conducted at any time, and maintenance should occur, if warranted, during dryer months in late summer to early fall. Maintenance Frequency The primary factor for determining frequency of maintenance for the StormFilter is sediment loading. A properly functioning system will remove solids from water by trapping particulates in the porous structure of the filter media inside the cartridges. The flow through the system will naturally decrease as more and more particulates are trapped. Eventually the flow through the cartridges will be low enough to require replacement. It may be possible to extend the usable span of the cartridges by removing sediment from upstream trapping devices on a routine as-needed basis, in order to prevent material from being re-suspended and discharged to the StormFilter treatment system. The average maintenance lifecycle is approximately 1-5 years. Site conditions greatly influence maintenance requirements. StormFilter units located in areas with erosion or active construction may need to be inspected and maintained more often than those with fully stabilized surface conditions. Regulatory requirements or a chemical spill can shift maintenance timing as well. The maintenance frequency may be adjusted as additional monitoring information becomes available during the inspection program. Areas that develop known problems should be inspected more frequently than areas that demonstrate no problems, particularly after major storms. Ultimately, inspection and maintenance activities should be scheduled based on the historic records and characteristics of an individual StormFilter system or site. It is recommended that the site owner develop a database to properly manage StormFilter inspection and maintenance programs.. 2 3 Maintenance Guidelines The primary purpose of the Stormwater Management StormFilter® is to filter and prevent pollutants from entering our waterways. Like any effective filtration system, periodically these pollutants must be removed to restore the StormFilter to its full efficiency and effectiveness. Maintenance requirements and frequency are dependent on the pollutant load characteristics of each site. Maintenance activities may be required in the event of a chemical spill or due to excessive sediment loading from site erosion or extreme storms. It is a good practice to inspect the system after major storm events. Maintenance Procedures Although there are many effective maintenance options, we believe the following procedure to be efficient, using common equipment and existing maintenance protocols. The following two-step procedure is recommended:: 1. Inspection • Inspection of the vault interior to determine the need for maintenance. 2. Maintenance • Cartridge replacement • Sediment removal Inspection and Maintenance Timing At least one scheduled inspection should take place per year with maintenance following as warranted. First, an inspection should be done before the winter season. During the inspection the need for maintenance should be determined and, if disposal during maintenance will be required, samples of the accumulated sediments and media should be obtained. Second, if warranted, a maintenance (replacement of the filter cartridges and removal of accumulated sediments) should be performed during periods of dry weather. 101 2 3 Inspection Procedures The primary goal of an inspection is to assess the condition of the cartridges relative to the level of visual sediment loading as it relates to decreased treatment capacity. It may be desirable to conduct this inspection during a storm to observe the relative flow through the filter cartridges. If the submerged cartridges are severely plugged, then typically large amounts of sediments will be present and very little flow will be discharged from the drainage pipes. If this is the case, then maintenance is warranted and the cartridges need to be replaced. Warning: In the case of a spill, the worker should abort inspection activities until the proper guidance is obtained. Notify the local hazard control agency and Contech Engineered Solutions immediately. To conduct an inspection: Important: Inspection should be performed by a person who is familiar with the operation and configuration of the StormFilter treatment unit. 1. If applicable, set up safety equipment to protect and notify surrounding vehicle and pedestrian traffic. 2. Visually inspect the external condition of the unit and take notes concerning defects/problems. 3. Open the access portals to the vault and allow the system vent. 4. Without entering the vault, visually inspect the inside of the unit, and note accumulations of liquids and solids. 5. Be sure to record the level of sediment build-up on the floor of the vault, in the forebay, and on top of the cartridges. If flow is occurring, note the flow of water per drainage pipe. Record all observations. Digital pictures are valuable for historical documentation. 6. Close and fasten the access portals. 7. Remove safety equipment. 8. If appropriate, make notes about the local drainage area relative to ongoing construction, erosion problems, or high loading of other materials to the system. 9. Discuss conditions that suggest maintenance and make decision as to weather or not maintenance is needed. Maintenance Decision Tree The need for maintenance is typically based on results of the inspection. The following Maintenance Decision Tree should be used as a general guide. (Other factors, such as Regulatory Requirements, may need to be considered) 1. Sediment loading on the vault floor. a. If >4” of accumulated sediment, maintenance is required. 2. Sediment loading on top of the cartridge. a. If >1/4” of accumulation, maintenance is required. 3. Submerged cartridges. a. If >4” of static water above cartridge bottom for more than 24 hours after end of rain event, maintenance is required. (Catch basins have standing water in the cartridge bay.) 4. Plugged media. a. If pore space between media granules is absent, maintenance is required. 5. Bypass condition. a. If inspection is conducted during an average rain fall event and StormFilter remains in bypass condition (water over the internal outlet baffle wall or submerged cartridges), maintenance is required. 6. Hazardous material release. a. If hazardous material release (automotive fluids or other) is reported, maintenance is required. 7. Pronounced scum line. a. If pronounced scum line (say ≥ 1/4” thick) is present above top cap, maintenance is required. 102 Important: Care must be used to avoid damaging the cartridges during removal and installation. The cost of repairing components damaged during maintenance will be the responsibility of the owner. C. Set the used cartridge aside or load onto the hauling truck. D. Continue steps a through c until all cartridges have been removed. Method 2: A. This activity will require that maintenance personnel enter the vault to remove the cartridges from the under drain manifold and place them under the vault opening for lifting (removal). Disconnect each filter cartridge from the underdrain connector by rotating counterclockwise 1/4 of a turn. Roll the loose cartridge, on edge, to a convenient spot beneath the vault access. B. Unscrew the cartridge cap. C. Remove the cartridge hood and float. D. At location under structure access, tip the cartridge on its side. E. Empty the cartridge onto the vault floor. Reassemble the empty cartridge. F. Set the empty, used cartridge aside or load onto the hauling truck. G. Continue steps a through e until all cartridges have been removed. 4 5 Maintenance Depending on the configuration of the particular system, maintenance personnel will be required to enter the vault to perform the maintenance. Important: If vault entry is required, OSHA rules for confined space entry must be followed. Filter cartridge replacement should occur during dry weather. It may be necessary to plug the filter inlet pipe if base flows is occurring. Replacement cartridges can be delivered to the site or customers facility. Information concerning how to obtain the replacement cartridges is available from Contech Engineered Solutions. Warning: In the case of a spill, the maintenance personnel should abort maintenance activities until the proper guidance is obtained. Notify the local hazard control agency and Contech Engineered Solutions immediately. To conduct cartridge replacement and sediment removal maintenance: 1. If applicable, set up safety equipment to protect maintenance personnel and pedestrians from site hazards. 2. Visually inspect the external condition of the unit and take notes concerning defects/problems. 3. Open the doors (access portals) to the vault and allow the system to vent. 4. Without entering the vault, give the inside of the unit, including components, a general condition inspection. 5. Make notes about the external and internal condition of the vault. Give particular attention to recording the level of sediment build-up on the floor of the vault, in the forebay, and on top of the internal components. 6. Using appropriate equipment offload the replacement cartridges (up to 150 lbs. each) and set aside. 7. Remove used cartridges from the vault using one of the following methods: Method 1: A. This activity will require that maintenance personnel enter the vault to remove the cartridges from the under drain manifold and place them under the vault opening for lifting (removal). Disconnect each filter cartridge from the underdrain connector by rotating counterclockwise 1/4 of a turn. Roll the loose cartridge, on edge, to a convenient spot beneath the vault access. Using appropriate hoisting equipment, attach a cable from the boom, crane, or tripod to the loose cartridge. Contact Contech Engineered Solutions for suggested attachment devices. B. Remove the used cartridges (up to 250 lbs. each) from the vault. 103 4 5 8. Remove accumulated sediment from the floor of the vault and from the forebay. This can most effectively be accomplished by use of a vacuum truck. 9. Once the sediments are removed, assess the condition of the vault and the condition of the connectors. 10. Using the vacuum truck boom, crane, or tripod, lower and install the new cartridges. Once again, take care not to damage connections. 11. Close and fasten the door. 12. Remove safety equipment. 13. Finally, dispose of the accumulated materials in accordance with applicable regulations. Make arrangements to return the used empty cartridges to Contech Engineered Solutions. Related Maintenance Activities - Performed on an as-needed basis StormFilter units are often just one of many structures in a more comprehensive stormwater drainage and treatment system. In order for maintenance of the StormFilter to be successful, it is imperative that all other components be properly maintained. The maintenance/repair of upstream facilities should be carried out prior to StormFilter maintenance activities. In addition to considering upstream facilities, it is also important to correct any problems identified in the drainage area. Drainage area concerns may include: erosion problems, heavy oil loading, and discharges of inappropriate materials. Material Disposal The accumulated sediment found in stormwater treatment and conveyance systems must be handled and disposed of in accordance with regulatory protocols. It is possible for sediments to contain measurable concentrations of heavy metals and organic chemicals (such as pesticides and petroleum products). Areas with the greatest potential for high pollutant loading include industrial areas and heavily traveled roads. Sediments and water must be disposed of in accordance with all applicable waste disposal regulations. When scheduling maintenance, consideration must be made for the disposal of solid and liquid wastes. This typically requires coordination with a local landfill for solid waste disposal. For liquid waste disposal a number of options are available including a municipal vacuum truck decant facility, local waste water treatment plant or on-site treatment and discharge. 104 Inspection Report Date: Personnel: Location: ————————————System Size: ——————————————————————————————————— System Type: Vault Cast-In-Place Linear Catch Basin Manhole Other Sediment Thickness in Forebay: ——————————————————————————————————————————— Sediment Depth on Vault Floor: ——————————————————————————————————————————— Structural Damage: ———————————————————————————————————————————————— Estimated Flow from Drainage Pipes (if available): ———————————————————————————————————— Cartridges Submerged: Yes No Depth of Standing Water: —————————————————————— StormFilter Maintenance Activities (check off if done and give description) Trash and Debris Removal: ——————————————————————————————————————————— Minor Structural Repairs: ———————————————————————————————————————————— Drainage Area Report ————————————————————————————————————————————— Excessive Oil Loading: Yes No Source: ——————————————————————— Sediment Accumulation on Pavement: Yes No Source: ——————————————————————— Erosion of Landscaped Areas: Yes No Source: ——————————————————————— Items Needing Further Work: ———————————————————————————————————————————— Owners should contact the local public works department and inquire about how the department disposes of their street waste residuals. Other Comments: ————————————————————————————————————————————————————————— ————————————————————————————————————————————————————————— ————————————————————————————————————————————————————————— ————————————————————————————————————————————————————————— ————————————————————————————————————————————————————————— ————————————————————————————————————————————————————————— ————————————————————————————————————————————————————————— ————————————————————————————————————————————————————————— Review the condition reports from the previous inspection visits. Date: 105 StormFilter Maintenance Report Date: —————————————Personnel: ———————————————————————————————————— Location: ————————————System Size: ——————————————————————————————————— System Type: Vault Cast-In-Place Linear Catch Basin Manhole Other List Safety Procedures and Equipment Used: —————————————————————————————————————— ————————————————————————————————————————————————————————— ————————————————————————————————————————————————————————— System Observations Months in Service: Oil in Forebay (if present): Yes No Sediment Depth in Forebay (if present): ———————————————————————————————————————— Sediment Depth on Vault Floor: ——————————————————————————————————————————— Structural Damage: ———————————————————————————————————————————————— Drainage Area Report Excessive Oil Loading: Yes No Source: ————————————————————————— Sediment Accumulation on Pavement: Yes No Source: ————————————————————————— Erosion of Landscaped Areas: Yes No Source: ————————————————————————— StormFilter Cartridge Replacement Maintenance Activities Remove Trash and Debris: Yes No Details: —————————————————————————— Replace Cartridges: Yes No Details: —————————————————————————— Sediment Removed: Yes No Details: —————————————————————————— Quantity of Sediment Removed (estimate?): Minor Structural Repairs: Yes No Details: ————————————————————————— Residuals (debris, sediment) Disposal Methods: —————————————————————————————————————— Notes: —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— —————————————————————————————————————————————————————————— 106 ENGINEERED SOLUTIONS Vortechs® Guide Operation, Design, Performance and Maintenance 107 2 3 Vortechs® The Vortechs system is a high-performance hydrodynamic separator that effectively removes finer sediment (e.g. 50-microns (µm), oil, and floating and sinking debris. The swirl concentration operation and flow controls work together to minimize turbulence and provide stable storage of captured pollutants. Precast models can treat peak design flows up to 30-cfs (850-L/s); cast-in-place models handle even greater flows. A typical system is sized to provide a specific removal efficiency of a predefined particle size distribution (PSD). Operation Overview Stormwater enters the swirl chamber inducing a gentle swirling flow pattern and enhancing gravitational separation. Sinking pollutants stay in the swirl chamber while floatables are stopped at the baffle wall. Vortechs systems are usually sized to efficiently treat the frequently occurring runoff events and are primarily controlled by the low flow control orifice. This orifice effectively reduces inflow velocity and turbulence by inducing a slight backwater that is appropriate to the site. During larger storms, the water level rises above the low flow control orifice and begins to flow through the high flow control. Any layer of floating pollutants is elevated above the invert of the Floatables Baffle Wall, preventing release. Swirling action increases in relation to the storm intensity, while sediment pile remains stable. When the storm drain is flowing at peak capacity, the water surface in the system approaches the top of the high flow control. The Vortechs system will be sized large enough so that previously captured pollutants are retained in the system, even during these infrequent events. As a storm subsides, treated runoff decants out of the Vortechs system at a controlled rate, restoring the water level to a dry- weather level equal to the invert of the inlet pipe. The low water level facilitates easier inspection and cleaning, and significantly reduces maintenance costs by reducing pump-out volume. Design Basics Each Vortechs system is custom designed based on site size, site runoff coefficient, regional precipitation intensity distribution, and anticipated pollutant characteristics. There are two primary methods of sizing a Vortechs system. The first is to determine which model size provides the desired removal efficiency at a given flow for a defined particle size or PSD. The second and more in depth method is the summation of Rational Rainfall Method™ which uses a summation process described below in detail and is used when a specific removal efficiency of the net annual sediment load is required. Typically Vortechs systems are designed to achieve an 80% annual solids load reduction based on lab generated performance curves for either 50-µm particles, or a particle gradation found in typical urban runoff (see performance section of this manual for more information). The Rational Rainfall Method™ Differences in local climate, topography and scale make every site hydraulically unique. It is important to take these factors into consideration when estimating the long-term performance of any stormwater treatment system. The Rational Rainfall Method combines site-specific information with laboratory generated performance data, and local historical precipitation records to estimate removal efficiencies as accurately as possible. 108 2 3 High Flow Control The high flow control, or weir, is sized to pass the peak system capacity minus the peak orifice flow when the water surface elevation is at the top of the weir. This flow control is also a Cippoletti type weir. The weir flow control is sized by solving for the crest length and head in the following equation: Qweir = Cd •L• (h)3/2 Where: Qweir = flow through weir, cfs (L/s) Cd = Cippoletti weir coefficient = 3.37 (based on lab testing) h = available head, ft (m) (height of weir) L = design weir crest length, ft (m) Bypass Calculations In most all cases, pollutant removal goals can be met without treating peak flow rates and it is most feasible to use a smaller Vortechs system configured with an external bypass. In such cases, a bypass design is recommended by Contech Engineered Solutions for each off-line system. To calculate the bypass capacity, first subtract the system’s treatment capacity from the peak conveyance capacity of the collection system (minimum of 10-year recurrence interval). The result is the flow rate that must be bypassed to avoid surcharging the Vortechs system. Then use the following arrangement of the Francis formula to calculate the depth of flow over the bypass weir. H = (Qbypass /(Cd • L))2/3 Where: H = depth of flow over bypass weir crest, ft (m) Qbypass = required bypass flow, cfs (L/s) Cd = discharge coefficient = 3.3 for rectangular weir L = length of bypass weir crest, ft The bypass weir crest elevation is then calculated to be the elevation at the top of the Cippoletti weir minus the depth of flow. Hydraulic Capacity In the event that the peak design flow from the site is exceeded, it is important that the Vortechs system is not a constriction to runoff leaving the site. Therefore, each system is designed with enough hydraulic capacity to pass the 100-year flow rate. It is important to note that at operating rates above 100-gpm/ft2 (68-Lps/m2) of the swirl chamber area (peak treatment capacity), captured pollutants may be lost. When the system is operating at peak hydraulic capacity, water will be flowing through the gap over the top of the flow control wall as well as the orifice and the weir. Short duration rain gauge records from across the United States and Canada were analyzed to determine the percent of the total annual rainfall that fell at a range of intensities. US stations’ depths were totaled every 15 minutes or hourly and recorded in 0.01-inch increments. Depths were recorded hourly with 1-mm resolution at Canadian stations. One trend was consistent at all sites; the vast majority of precipitation fell at low intensities and high intensity storms contributed relatively little to the total annual depth. These intensities, along with the total drainage area and runoff coefficient for each specific site, are translated into flow rates using the Rational Rainfall Method. Since most sites are relatively small and highly impervious, the Rational Rainfall Method is appropriate. Based on the runoff flow rates calculated for each intensity, operating rates within a proposed Vortechs system are determined. Performance efficiency curve determined from full scale laboratory tests on defined sediment PSDs is applied to calculate solids removal efficiency. The relative removal efficiency at each operating rate is added to produce a net annual pollutant removal efficiency estimate. Once a system size is established, the internal elements of the system are designed based on information provided by the site engineer. Flow control sizes and shapes, sump depth, oil spill storage capacity, sediment storage volume and inlet and outlet orientation are determined for each system. In addition, bypass weir calculations are made for off-line systems. Flow Control Calculations Low Flow Control The low flow control, or orifice, is typically sized to submerge the inlet pipe when the Vortechs system is operating at 20% of its treatment capacity. The orifice is typically a Cippoletti shaped aperture defined by its flat crest and sides which incline outwardly at a slope of 1 horizontal to 4 vertical. Qorfice = Cd • A • 2gh Where: Qorifice = flow through orifice, cfs (L/s) Cd = orifice coefficient of discharge = 0.56 (based on lab tests) A = orifice flow area, ft2 (m2) (calculated by orifice geometry) h = design head, ft (m) (equal to the inlet pipe diameter) g = acceleration due to gravity (32.2-ft/s2 (9.81-m/s2) The minimum orifice crest length is 3-in (76-mm) and the minimum orifice height is 4-in (102-mm). If flow must be restricted beyond what can be provided by this size aperture, a Fluidic-Amp™ HydroBrake flow control will be used. The HydroBrake allows the minimum flow constriction to remain at 3-in (76-mm) or greater while further reducing flow due to its unique throttling action. 109 4 5 Performance Full Scale Laboratory Test Results Laboratory testing was conducted on a full scale Vortechs model 2000. The 150-µm curve demonstrates the results of tests using particles that passed through a 60-mesh sieve and were retained on a 100-mesh sieve. The 50-µm curve is based on tests of particles passing through a 200-mesh sieve and retained on a 400-mesh sieve (38-µm). A gradation with an average particle size (d50) of 80-µm, containing particles ranging from 38–500-µm in diameter was used to represent typical stormwater solids. (Table 1) As shown, the Vortechs system maintains positive total suspended solids (TSS), defined by the tested gradations, removal efficiencies over the full range of operating rates. This allows the system to effectively treat all runoff from large, infrequent design storms, as well as runoff from more frequent low-intensity storms. Typical Vortechs systems are designed to treat peak flows from 1.6-cfs (45-L/s) up to 30-cfs (850-L/s) online without the need for bypass. However, external bypasses can be configured to convey peak flows around the system if treatment capacity is exceeded. The system can also be configured to direct low flows from the last chamber of the system to polishing treatment when more stringent water quality standards are imposed. In all configurations, high removal efficiencies are achieved during the lower intensity storms, which constitute the majority of annual rainfall volume. Full report available at www.conteches.com/vortechs. Particle Size Percentage of Sample Distribution (µm) Make-Up <63 42% 63 - 75 4% 75 - 100 9% 100 - 150 7% 150 - 250 11% >250 27% Table 1: Particle gradation of typical urban runoff used for efficiency curve 0 (0) 10 (7) 20 (14) 30 (20) 40 (27) 50 (34) 60 (41) 70 (48) 80 (54) 90 (61) 100 (68) 20% 0% 40% 60% 80% 100% Operating Rate gpm/ft2 (L/s/m2)Removal Efficiency50-micron 150-microntypical gradation Figure 1: Vortechs model 2000 Removal Efficiencies Laboratory Testing Full reports available at www.conteches.com/vortechs Technical Bulletin 1: Removal Efficiencies for Selected Particle Gradations Technical Bulletin 2: Particle Distribution of Sediments and the Effect on Heavy Metal Removal Technical Bulletin 3: Sizing for Net Annual Sediment Removal Technical Bulletin 3a: Determining Bypass Weir Elevation for Off- Line Systems Technical Bulletin 4: Modeling Long Term Load Reduction: The Rational Rainfall Method Technical Bulletin 5: Oil Removal Efficiency Field Monitoring Following are brief summaries of the field tests completed to date. Full reports available at www.conteches.com/vortechs DeLorme Mapping Company Yarmouth, ME Contech Engineered Solutions Prior to this premier field test of the Vortechs system, Contech developed an extensive body of laboratory data to document total suspended solids (TSS) removal efficiency. Contech performed this field study in order to compare the performance predicted using laboratory data to the performance of a correctly sized system in the field. The study site was the headquarters of DeLorme Mapping in Yarmouth, Maine. The building, driveway, parking lot and ancillary facilities were constructed in 1996. A Vortechs model 11000 was installed to treat runoff from the 300-space, 4-acre (1.62-ha) parking lot. The main purpose of the DeLorme study was to verify that the sizing methodology developed from our full-scale laboratory testing was valid and an accurate means of predicting field performance. The results of the study confirmed our sizing methodology. Village Marine Drainage Lake George, NY New York State Department of Environmental Conservation, Division of Water The New York State DEC used funds obtained in a Section 319 grant to initiate a study of the effectiveness of the Vortechs system to remove sediment and other pollutants transported Testing Period May 1999 to Dec 1999 # of Storms Sampled 20 Mean Influent Concentration 328-mg/L Mean Effluent Concentration 60-mg/L Removal Efficiency 82% 110 Timothy Edwards Middle School South Windsor, CT UCONN Department of Civil & Environmental Engineering This study of the Vortechs system was published as a thesis by Susan Mary Board, as part of the requirements for a Master of Science degree from the University of Connecticut. Her objective was to determine how well the Vortechs system retained pollutants from parking lot runoff, including total suspended solids (TSS), nutrients, metals, and petroleum hydrocarbons. A Vortechs model 5000 was installed in 1998 to treat runoff from the 82-space parking lot of Timothy Edwards Middle School. The entire watershed was approximately 2 acres (0.81 ha), and was 80% impervious. Additionally, the Vortechs system was particularly effective in removing zinc (85%), lead (46%), copper (56%), phosphorus (67%) and nitrate (54%). The study concluded that the Vortechs system significantly reduced effluent concentrations of many pollutants in stormwater runoff. 4 5 by stormwater to Lake George, Lake George Village, New York. “Since the 1970s, when there was a rapid increase in the rate and concentration of development along the southwestern shores of Lake George, we have been concerned about the impact of stormwater discharges into the lake,” said Tracy West, co-author of the study. The study concluded that the Village and Town of Lake George should consider installing additional Vortechs systems in areas where sedimentation and erosion have been identified as non- point source pollution problems. Harding Township Rest Area Harding Township, NJ RTP Environmental Associates This third party evaluation was performed under a U.S. Environmental Protection Agency grant, administered by the New Jersey Department of Environmental Protection. A. Roger Greenway, principal of RTP Environmental Associates, Inc., conducted the study in conjunction with Thonet Associates, which assisted with data analysis and helped develop best management practices (BMP) recommendations. The Vortechs model 4000 was sized to handle a 100-year storm from the 3 acre (1.21 ha) paved parking area at the Harding Rest Stop, located off the northbound lane of I-287 in Harding Township, New Jersey. The study concluded that truck rest stops and similar parking areas would benefit from installing stormwater treatment systems to mitigate the water quality impacts associated with stormwater runoff from these sites. Testing Period Feb 2000 to Dec 2000 # of Storms Sampled 13 Mean Influent Concentration 801-mg/L Mean Effluent Concentration 105-mg/L Removal Efficiency 88% Testing Period May 1999 to Nov 2000 # of Storms Sampled 5 Mean Influent Concentration (TSS) 493-mg/L Mean Effluent Concentration (TSS) 35-mg/L Removal Efficiency (TSS) 93% Mean Influent Concentration (TPH) 16-mg/L Mean Effluent Concentration (TPH) 5-mg/L Removal Efficienty (TPH) 67% Testing Period Jul 2000 to Apr 2001 # of Storms Sampled weekly composite samples taken Mean Influent Concentration 324-mg/L Mean Effluent Concentration 73-mg/L Removal Efficiency 77% 111 6 7 Maintenance The Vortechs system should be inspected at regular intervals and maintained when necessary to ensure optimum performance. The rate at which the system collects pollutants will depend more heavily on site activities than the size of the unit, e.g., unstable soils or heavy winter sanding will cause the swirl chamber to fill more quickly but regular sweeping will slow accumulation. Inspection Inspection is the key to effective maintenance and is easily performed. Pollutant deposition and transport may vary from year to year and regular inspections will help ensure that the system is cleaned out at the appropriate time. Inspections should be performed twice per year (i.e. spring and fall) however more frequent inspections may be necessary in equipment washdown areas and in climates where winter sanding operations may lead to rapid accumulations. It is useful and often required as part of a permit to keep a record of each inspection. A simple inspection and maintenance log form for doing so is provided on the following page, and is also available on conteches.com. The Vortechs system should be cleaned when inspection reveals that the sediment depth has accumulated to within 12 to 18 inches (300 to 450 mm) of the dry-weather water surface elevation. This determination can be made by taking two measurements with a stadia rod or similar measuring device; one measurement from the manhole opening to the top of the sediment pile and the other from the manhole opening to the water surface. Note: To avoid underestimating the volume of sediment in the chamber, the measuring device must be carefully lowered to the top of the sediment pile. Finer, silty particles at the top of the pile typically offer less resistance to the end of the rod than larger particles toward the bottom of the pile. Cleaning Cleaning of the Vortechs system should be done during dry weather conditions when no flow is entering the system. Clean- out of the Vortechs system with a vacuum truck is generally the most effective and convenient method of excavating pollutants from the system. If such a truck is not available, a “clamshell” grab may be used, but it is difficult to remove all accumulated pollutants using a “clamshell”. In installations where the risk of petroleum spills is small, liquid contaminants may not accumulate as quickly as sediment. However, an oil or gasoline spill should be cleaned out immediately. Motor oil and other hydrocarbons that accumulate on a more routine basis should be removed when an appreciable layer has been captured. To remove these pollutants, it may be preferable to use adsorbent pads to solidify the oil since these pads are usually much easier to remove from the unit individually and less expensive to dispose of than the oil/water emulsion that may be created by vacuuming the oily layer. Floating trash can be netted out if you wish to separate it from the other pollutants. Cleaning of a Vortechs system is typically done by inserting a vacuum hose into the swirl chamber and evacuating this chamber of water and pollutants. As water is evacuated, the water level outside of the swirl chamber will drop to a level roughly equal to the crest of the lower aperture of the swirl chamber. Floating pollutants will decant into the swirl chamber as the water level is drawn down. This allows most floating material to be withdrawn from the same access point above the swirl chamber. Floating material that does not decant into the swirl chamber during draw down should be skimmed from the baffle chamber. Sediment may accumulate outside the swirl chamber. If this is the case, it may be necessary to pump out other chambers. It is advisable to check for sediment accumulation in all chambers during inspection and maintenance. These maintenance recommendations apply to all Vortechs systems with the following exceptions: 1.It is strongly recommended that when cleaning systems larger than the Model 16000 the baffle chamber be drawn down to depth of three feet prior to beginning clean-out of the swirl chamber. Drawing down this chamber prior to the swirl chamber reduces adverse structural forces pushing upstream on the swirl chamber once that chamber is empty. 2.Entry into a Vortechs system is generally not required as cleaning can be done from the ground surface. However, if manned entry into a system is required the entire system should be evacuated of water prior to entry regardless of the system size. Manhole covers should be securely seated following cleaning activities to prevent leakage of runoff into the system from above and also to ensure proper safety precautions. If anyone physically enters the unit, Confined Space Entry procedures need to be followed. Disposal of all material removed from the Vortechs system should be done in accordance with local regulations. In many locations, disposal of evacuated sediments may be handled in the same manner as disposal of sediments removed from catch basins or deep sump manholes. Check your local regulations for specific requirements on disposal. Contech has created a network of Certified Maintenance Providers (CCMP’s) to provide maintenance on Vortechs systems. To find a CCMP in your area please visit www.conteches.com/ maintenance. 112 Vortechs Inspection & Maintenance Log 6 7 1.The water depth to sediment is determined by taking two measurements with a stadia rod: one measurement from the manhole opening to the top of the sediment pile and the other from the manhole opening to the water surface. If the difference between these measurements is less than eighteen inches the system should be cleaned out. Note: To avoid underestimating the volume of sediment in the chamber, the measuring device must be carefully lowered to the top of the sediment pile. 2.For optimum performance, the system should be cleaned out when the floating hydrocarbon layer accumulates to an appreciable thickness. In the event of an oil spill, the system should be cleaned immediately. Date Water depth to sediment Floatable layer thickness Describe maintenance performed Maintenance personnel Comments Vortech Model: ________________________________Location: _______________________________________________________ 113 O & M INSTRUCTIONS FOR PERMEABLE PAVEMENT�� X�� 114 Exhibit C Legal Descriptions TAX PARCEL 3119900005: TRACT 1, HARRIES GARDEN HOME TRACTS, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 34 OF PLATS, PAGE 38, RECORDS OF KING COUNTY, WASHINGTON. TAX PARCEL 3119900010: THE SOUTH 50 FEET OF TRACT 2, HARRIES GARDEN HOME TRACTS, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 34 OF PLATS, PAGE(S) 38, RECORDS OF KING COUNTY, WASHINGTON. TAX PARCEL 3119900011: ALL THAT PORTION OF TRACT 3, HARRIES GARDEN HOME TRACTS, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 34 OF PLATS, PAGE 38, IN KING COUNTY, WASHINGTON; EXCEPT THE NORTH 50.00 FEET THEREOF; AND THAT PORTION OF THE NORTH 50 FEET OF TRACT 2, HARRIES GARDEN HOME TRACTS, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 34 OF PLATS, PAGE 38, IN KING COUNTY, WASHINGTON, MORE PARTICULARLY DESCRIBED AS FOLLOWS: BEGINNING AT THE NORTHEAST CORNER OF SAID TRACT 2, SAID POINT BEING ALSO ON THE WEST MARGIN OF SUNSET BOULEVARD N.E. (SUNSET HWY.). AS NOW ESTABLISHED AND SAID POINT BEING A NON TANGENT POINT ON A CURVE TO THE LEFT FROM WHICH POINT THE RADIUS OF SAID CURVE BEARS SOUTH 78°23’41" EAST AT 985.37 FEET; THENCE ALONG THE EAST LINE OF SAID TRACT AND ALONG SAID CURVE AND MARGIN, THROUGH A CENTRAL ANGLE OF 2°57’18", AN ARC DISTANCE OF 50.82 FEET TO A POINT OF NON TANGENCY FROM WHICH POINT THE RADIUS OF SAID CURVE BEARS SOUTH 81°20’59" EAST AT 985.37 FEET, SAID POINT BEING ALSO THE SOUTHEAST CORNER OF THE SAID NORTH 50 FEET OF TRACT 2; THENCE SOUTH 89°51’00" WEST, ALONG THE SOUTH LINE OF SAID NORTH 50 FEET, 185.11 FEET TO THE SOUTHWEST CORNER OF SAID NORTH 50 FEET; THENCE NORTH 15°10’30" WEST ALONG THE WEST LINE OF SAID TRACTS 2 AND 3, A DISTANCE OF 103.54 FEET TO THE NORTHWEST CORNER OF THE SOUTH 50.00 FEET OF SAID TRACT 3; THENCE NORTH 89°51’00" EAST ALONG THE NORTH LINE THEREOF 126.55 FEET; THENCE SOUTH 00°09’00" EAST 50.00 FEET TO A POINT ON THE NORTH LINE OF SAID TRACT 2; THENCE NORTH 89°51’00" EAST ALONG SAID LINE 94.47 FEET TO THE POINT OF BEGINNING. ALSO KNOWN AS LOT 2 OF CITY OF RENTON LOT LINE ADJUSTMENT NO. LUA 95-154 LLA RECORDED ON NOVEMBER 16, 1995 AS RECORDING NO. 9511169011, IN THE OFFICIAL RECORDS OF KING COUNTY, WASHINGTON. 115 RECORDING REQUESTED BY AND WHEN RECORDED MAIL TO: CITY CLERK’S OFFICE CITY OF RENTON 1055 SOUTH GRADY WAY RENTON, WA 98057 DECLARATION OF COVENANT PROHIBITING USE OF LEACHABLE METALS Grantor: _ Grantee: City of Renton Legal Description: _________________________________________________________________________________ _________________________________________________________________________________ Additional Legal(s) on: Assessor's Tax Parcel ID#: IN CONSIDERATION of the approved City of Renton ________________________ permit for application file No. LUA/SWP relating to real property legally described above, the undersigned as Grantor(s), declares(declare) that the above described property is hereby established as having a prohibition on the use of leachable metals on those portions of the property 116 exposed to the weather for the purpose of limiting metals in stormwater flows and is subject to the following restrictions. The Grantor(s) hereby covenants(covenant) and agrees(agree) as follows: no leachable metal surfaces exposed to the weather will be allowed on the property. Leachable metal surfaces means a surface area that consists of or is coated with a non-ferrous metal that is soluble in water. Common leachable metal surfaces include, but are not limited to, galvanized steel roofing, gutters, flashing, downspouts, guardrails, light posts, and copper roofing. City of Renton or its municipal successors shall have a nonexclusive perpetual access easement on the Property in order to ingress and egress over the Property for the sole purposes of inspecting and monitoring that no leachable metal is present on the Property. This easement/restriction is binding upon the Grantor(s), its heirs, successors, and assigns unless or until a new drainage or site plan is reviewed and approved by the City of Renton or its successor. 117 IN WITNESS WHEREOF, this Declaration of Covenant is executed this _____ day of ____________________, 20_____. GRANTOR, owner of the Property GRANTOR, owner of the Property STATE OF WASHINGTON ) COUNTY OF KING )ss. On this day personally appeared before me: _____________________________________________, to me known to be the individual(s) described in and who executed the within and foregoing instrument and acknowledged that they signed the same as their free and voluntary act and deed, for the uses and purposes therein stated. Given under my hand and official seal this _____ day of ____________________, 20_____. Printed name Notary Public in and for the State of Washington, residing at My appointment expires 118 TAX PARCEL 3119900005: TRACT 1, HARRIES GARDEN HOME TRACTS, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 34 OF PLATS, PAGE 38, RECORDS OF KING COUNTY, WASHINGTON. TAX PARCEL 3119900010: THE SOUTH 50 FEET OF TRACT 2, HARRIES GARDEN HOME TRACTS, ACCORDING TO THE PLAT THEREOF TAX PARCEL 3119900011: ALL THAT PORTION OF TRACT 3, HARRIES GARDEN HOME TRACTS, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 34 OF PLATS, PAGE 38, IN KING COUNTY, WASHINGTON; EXCEPT THE NORTH 50.00 FEET THEREOF; AND THAT PORTION OF THE NORTH 50 FEET OF TRACT 2, HARRIES GARDEN HOME TRACTS, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 34 OF PLATS, PAGE 38, IN KING COUNTY, WASHINGTON, MORE PARTICULARLY DESCRIBED AS FOLLOWS: BEGINNING AT THE NORTHEAST CORNER OF SAID TRACT 2, SAID POINT BEING ALSO ON THE WEST MARGIN OF SUNSET BOULEVARD N.E. (SUNSET HWY.). AS NOW ESTABLISHED AND SAID POINT BEING A NON TANGENT POINT ON A CURVE TO THE LEFT FROM WHICH POINT THE RADIUS OF SAID CURVE BEARS SOUTH 78°23’41" EAST AT 985.37 FEET; THENCE ALONG THE EAST LINE OF SAID TRACT AND ALONG SAID CURVE AND MARGIN, THROUGH A CENTRAL ANGLE OF 2°57’18", AN ARC DISTANCE OF 50.82 FEET TO A POINT OF NON TANGENCY FROM WHICH POINT THE RADIUS OF SAID CURVE BEARS SOUTH 81°20’59" EAST AT 985.37 FEET, SAID POINT BEING ALSO THE SOUTHEAST CORNER OF THE SAID NORTH 50 FEET OF TRACT 2; THENCE SOUTH 89°51’00" WEST, ALONG THE SOUTH LINE OF SAID NORTH 50 FEET, 185.11 FEET TO THE SOUTHWEST CORNER OF SAID NORTH 50 FEET; THENCE NORTH 15°10’30" WEST ALONG THE WEST LINE OF SAID TRACTS 2 AND 3, A DISTANCE OF 103.54 FEET TO THE NORTHWEST CORNER OF THE SOUTH 50.00 FEET OF SAID TRACT 3; THENCE NORTH 89°51’00" EAST ALONG THE NORTH LINE THEREOF 126.55 FEET; THENCE SOUTH 00°09’00" EAST 50.00 FEET TO A POINT ON THE NORTH LINE OF SAID TRACT 2; THENCE NORTH 89°51’00" EAST ALONG SAID LINE 94.47 FEET TO THE POINT OF BEGINNING. ALSO KNOWN AS LOT 2 OF CITY OF RENTON LOT LINE ADJUSTMENT NO. LUA 95-154 LLA RECORDED ON NOVEMBER 16, 1995 AS RECORDING NO. 9511169011, IN THE OFFICIAL RECORDS OF KING COUNTY, WASHINGTON. 119 Renton 701 Townhomes DCI 15375 10. Operations and Maintenance Manual 120 Renton 701 Townhomes DCI 15375 10. Operations and Maintenance Manual Operation and maintenance information is included as part of the Facility and On-Site BMP Covenant included in Section 9 above.. 121 DenisLawMayor0Community&EconomicDevelopmentC.E.“Chip”Vincent,AdministratorAugust29,2017HaroldDuncanson,PEDuncansonCompany,Inc.1455Wl5SStreet,Suite102Seattle,Washington98166RE:Sunset’sEdgeTownhomesPUD(C17002053)—UseofVortechs(Contech)hydrodynamicseparatordevicetoprovidepresettlingupstreamof$tormfilter—Adjustment2017-06DearMr.Duncanson:TheCityofRentonhascompletedreviewoftheadjustmentrequestforSunset’sEdgeTownhomes(C17002053)inaccordancewiththeCityadopted2009KingCountySurfaceWaterDesignManual(KCSWDM)andassociatedCityAmendments.Astheapplicant’sengineer,youarerequestinganadjustmentfromthe2009KCSWDMtouseVortechs(Contech)hydrodynamicseparatordevicetoprovidepresettlingupstreamofaStormfiltermediafilterfacilityasneededforBasicWaterQualitytreatment.Findings:1.Theprojectisazerolotline15unitmulti-familyPUDprojectandislocatedat701SunsetBlvdNE.2.Thestormfacilitiesfortheprojectwillbeprivatelymaintained.3.TheprojectisvestedtotheCityadopted2009KingCountySurfaceWaterDesignManual(KCSWDM)andassociated2009CityAmendments4.Atthetimeofadoptionofthe2009SurfaceWaterManual,theVortechsdevicedidnotyethaveEcologyGULDapprovalandsowasnotanapprovedpresettlingfacility.TheVortechshassincereceivedGULDapproval.5.DepartmentofEcology’srecommendationwasthattheVortechssystem,sizedat35GPM/sfshouldprovide,ataminimum,equivalentperformancetoapresettlingbasinasdefinedintheStormwaterManagementManualforWesternWashington.6.Thecurrent2017CityofRentonSurfaceWaterManualacceptstheuseofVortechsforpre-treatmentforprivatelymaintainedfacilities.Basedontheinformationprovidedintheenclosedadjustmentrequest,theuseofVortechs(Contech)hydrodynamicseparatordevicetoprovidepresettlingupstreamofStormfllterisapprovedfortheSunset’sEdgeTownhomesPUDwiththefollowingconditionsofusethatarerequiredbytheDepartmentofEcology(GULDapproval).1055SouthGradyWay,Renton,WA98057rentonwa.gov Design,assemble,install,operate,andmaintainVortechsSystemsinaccordancewithapplicableCONTECHProductDesignManualVersion4.1(April2006)ormostcurrentversions,andtheEcologyDecision.2.DischargesfromtheVortechsSystemshallnotcauseorcontributetowaterqualitystandardsviolationsinreceivingwaters.Ifyouhaveanyquestionsaboutthisadjustment,pleasecontactBrianneBannwarth,DevelopmentEngineeringManager,at(425)430-7299orRonStraka,SurfaceWaterUtilityEngineeringManager,at(425)430-7248.RonaldJ.Straka,P.E.SurfaceWaterUtilityEngineeringManagerPage2of2August29,2017Conditions:1.Sincerely,BrianneBannwarth,RE.DevelopmentEngineeringManagercc:LysHornsby,PB.,UtilitySystemsDirectorGaryFink,civilEngineer1WRohiniNair,PlanReviewerMaltHerrera,SeniorPlanner1055SouthGradyWay,Renton,WAp8057rentonwa.gov