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HomeMy WebLinkAboutSWP272265(3) ' HOUSER WAY IMPROVEMENTS PROJECT ' FINAL DRAINAGE REPORT ' Prepared by Entranco For the City of Renton December 2, 1994 ' Technical Information Report completed January, 1994 Technical Appendix A completed December, 1994 1 ' January 18, 1994 Draft- For Review Only ' Technical Information Report ' HOUSER WAY IMPROVEMENTS PROJECT Prepared for City of Renton 200 Mill Avenue South Renton, Washington 98005 Prepared by ' ENTRANCO 10900 NE 8th Street, Suite 300 ' Bellevue, Washington 98004 (206) 454-5600 January 1994 DRAFT CONTENTS Page 1. Project Overview 1-1 11. Preliminary Conditions Summary 11-1 111. Off-Site Analysis IUpstream Analysis Y 111-1 Downstream Analysis 111-3 IV. Retention/Detention Analysis and Design Existing Site Hydrology 1V--1 Developed Site Hydrology IV-2 Hydrologic Analysis IV-3 ' Retention/Detention System 1V--3 Water Quality 1V-4 ' V. Conveyance Systems Analysis and Design On-site System V-1 ' Regional System V-2 Vl. Special Reports and Studies V1-1 ' Vll. Basin and Community Planning Areas V11-1 Vlll. Other Permits V111-1 IX. Erosion/Sedimentation Control Design 1X--1 ' X. Bond Quantities Worksheet, Retention/ Detention Facility Summary Sheet and Sketch, and Declaration of Covenant X-1 93010/Reports/TIR(1/18/94)/jew I DRAFT FIGURES Page l-1 T1R Worksheet /-3 ' 1-2 Vicinity Map /-5 11-1 Drainage Basin 11-3 111-1 Tributary Basin Map 111-5 ' IV-1 Existing Site Map IV-5 IV-2 Developed Site Map 1V-6 1V-3 Wetpond/Wetland Schematic IV-7 TABLES Page ' III-1 Precip itation Values Used in Hydrologic Analysis 24-Hour Storms 111-1 111-2 Off-Site Flow Summary 1I1-2 IV-1 Predevelopment Design Hydrographs IV-1 1V-2 Hydrologic Parameters for Predevelopment Conditions IV-1 IV-3 Post-Development Design Hydrographs IV-2 IV-4 Hydrologic Parameters for Post- Development' Development Conditions IV-2 IV-5 Hydrologic Parameters for Water ' Quality Storm IV-4 V-1 Houser Way Conveyance Preliminary ' Design Parameters V-1 V-2 25-Year Storm Characteristics V-3 93010/Reports/TIR(1/18l94)!jcw (( DRAFT ' I. PROJECT OVERVIEW The Houser Way Improvements project would construct a roadway from Sunset IBoulevard North to North 8th Street along a currently undeveloped alignment just west of 1-405 in the City of Renton (figures 1-1 and 1-2). The project would convert 1.83 acres of pervious land to impervious roadway, bicycle path, and sidewalk along the length of the 2,700-foot project. There are 497 acres of land that drain to the project site. Of this, 364 acres drain to a regional storm system that crosses the site at the extreme north end. The other 133 acres drain via several storm systems and overland flow to the south end of existing site, and then through the site. The site is situated at a point where hillside drainage reaches the valley floor, and this site, as well as several other sites downstream from the project, have flooded during large storm events in the past. Hydrologic and hydraulic modeling of ' the area have shown that the existing site floods for three reasons: • Flows from its tributary basin exceed the capacity of the existing channel on the valley floor • Flows back up from the overtaxed regional system on the valley floor during high ' flows • Overflows from surcharged pipe systems on the hillside enter the south end of the ' project site It is predicted that 17.8 acre-feet of flooding occurs in the area for a 25-year storm event. ' Approximately two acre-feet are retained within the project corridor. The remaining 15.8 acre-feet disperses onto the valley floor, on properties adjacent to the project corridor. The roadway project would mitigate these problems in several ways. First, the project would construct a 54-inch storm line to convey the flows that enter the south end of the site, both from this tributary area and from the surcharged systems on the hillside. This line would discharge at Garden Avenue North and North 8th Street to an existing 72-inch storm drain. This 72-inch storm drain runs along Garden Avenue North and discharges into a series of open channels which eventually enter Lake Washington. A cross- connection also would be inserted between the new 54-inch line and the existing 42-inch storm line, which runs along North 8th Street. This cross-connection would increase the conveyance capacity of the 42-inch pipe along North 8th Street, and reduce the flows that currently back up onto the site. Also, a wetpond and a wetland would be constructed for the project and would connect to the 54-inch storm line. These areas would be allowed to flood for the 25-year storm and larger, which would prevent ' increased flooding downstream. The new 54-inch storm line would be outfitted with a restrictor orifice at the North 8th ' Street/Houser Way North intersection. Unrestricted high flows carried by the new line would raise the water levels downstream and increase the risks of flooding in some ' 930101 Repoft I TIR(1/18194)/jcw I-1 DRAFT ' locations. By installing the orifice, the flooding would be contained at the project area instead of creating new flooding downstream. It is estimated that the proposed storm drainage improvements associated with the project would alleviate at least 12-acre-feet 1 of flooding during a 25-year design storm event as compared with existing conditions. On-site flows would be conveyed to a ditch which would run along the west side of the roadway. The ditch would carry the run-off from the site to the wetpond that would be constructed on the east side of the North 8th Street/Houser Way North intersection. After leaving the wetpond, site flows would run through a constructed wetland ' immediately north of the wetpond, and enter the new 54-inch storm drain (see figure IV-3). Both the wetpond and the constructed wetland would be designed to receive ' water that would back up from the regional system during large storm events. 93010/Reports/TIR(1/18194)1 jcw 1-2 Page 1 of 2 King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET PART I PROJECT OWNER PROJECT ProjectOwner C` `+ o Rt..�e, Project Name (4o-:,tom ' Address Location Phone Township Z 3 A.) Project Engineer Range SE Company Section 8 1 Project Size AC '7.2 Address Phone Upstream Drainage Basin Size AC V77 PART 4 OTHER PERMITS Cj Subdivision �DOF/G HPA Shoreline Management ' Short Subdivision C] COE 404 � Rockery Grading DOE Dam Safety � Structural Vaults 0 Commercial F-1 FEMA Floodplain 0 Other Other d COE Wetlands HPA ' PART 5 SITE COMMUNITYDRAINAGE BASIN Community e, o Drainage Basin Lake LJaS4;,,g-}oh PART 6 SITE CHARACTERISTICS ' River E:1 Floodplain [,Stream... Eo` Wetlands ' 0 Critical Stream Reach Seeps/SpdNs 0 Depressions/Swales [� High Groundwater Table E::] Lake ED Groundwater Recharge ' F-1 Steep Slopes Other _ Ie!9io„al �loea s�®�nge 0 Lakeside/Erosion Hazard SOILSPART 7 Soil T Slopes Erosion Potential Erosive Velocities SO `10 1 � Additional Sheets Attatched I/90 ' King County Building and Land Development Division Page 2 of 2 TECHNICAL INFORMATION REPORT (T1R) WORKSHEET PART 8-DEVELOPMENT LIMITATIONS ' REFERENCE LIMITATION/SiTE CONSTRAINT Ch.4-Downstream Analysis Lj. ,'JrA 5�0.-,.w��i C�••v<,tic-ce � + •�f•.aw EZ C4. 3- Osrcre it M �G��tiJ F1�a 71owS rAie, Si}f �w �� �C.�e S �.i.. tVe•� Q Q Q Additional Sheets Attatched PART 9 ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS ' DURING CONSTRUCTION FOLLOWING CONSTRUCTION Q Sedimentation Facilities Q Stabilize Exposed Surface Q Stabilized Construction Entrance Q Remove and Restore Temporary ESC Facilities ' Q Perimeter Runoff Control Q Clean and Remove All Silt and Debris Q Clearing and Grading Restrictions Q Ensure Operation of Permanent Facilities Q Cover Practices Q Flag Limits of NGPES ' Q Construction Sequence Q Other Q Other PART 10 SURFACE WATER SYSTEM Grass Lined Channel Q Tank Q Infiltration Method of Analysis ' ✓ Pipe System Q Vault Q Depression nGU A / FA7-R W Q Open Channel Q Energy Dissapator Q Flow Dispersal Compensation/Mitigation Q Dry Pond E—�Wetland Q Waiver of Eliminated Site Storage Wet Pond Q Stream Q Regional Detention Brief Description of System Operation ' Facility Related Site Limitations Q Additional Sheets Attatched Reference Facility Limitation PART 11 STRUCTURAL ANALYSIS PART 12 EASEMENTSfrRACTS (May require special structural review) Q Drainage Easement Q Cast in Place Vault Q Other Access Easement ' Q Retaining Wall Q Native Growth Protection Easement Q Rockery>4'High Q Tract Q Structural on Steep Slope Q Other ' PART 14 SIGNATURE OFPROFESSIONAL I or a civil engineer under my supervision have visited the site.Actual site conditions as observed were incorporated into this worksheet and the attatchments. To the best of my knowledge the information provided here is accurate. sr•,.sD-* 1190 N: 24,n ST � Y zxe a�a hE zoin sr o ' 0 �/a 'A 41JEST SCALE: I"=y4 MILE as > LAKE WASHINGTON i 3 r Ni Qih S7 0 ® th DCO o PR G� wF Ahn O r6M OJECT ME M D LOCAT/ON '� 51n R alh s Z L P NC 4in ST esmern PtN QOfn m Q N 84h ST �L�® $ AEj3 At s,n R ¢xd � Mr Tin cc a (� ' Qhn ST N 61h ST l �1I�j^JIf in61A p 9 00�S7a DUF-'-51h 51 . N 4ih S pop p 0 n;; N ao 3rd S N 0 51 91= o A r oa0aao� �x S abd ST D ©© 4���----2�� d 57 AY AV S ate---� TOM � \ ' DDD � a �D 1 10 � s ad ST o � 3 0 SOD K Q t��. �D�Qa000D fY S 3rd R SrPL Nn Q00 0 g i sn qq S 61h ST 00 0 O sw D� Tin ST n Tih PD ' $0],- ==PQh 4" Y l"i hl Sw! Apr ST S FEMiON VALAC(R Sr c ' Houser Way Technical Information Report ® ENTRANGO Figurel - 2 ' Vicinity Map ' DRAFT ' II. PRELIMINARY CONDITIONS SUMMARY This section will address the requirements set forth by the King County Surface Water Design Manual Core and Special Requirements listed in Chapter 1. Figure II-1 shows the existing site drainage basin. King County Surface Water Design Manual Core Requirements ' 1. Discharge at a natural location (1.2.1): Flow from the project area would continue to be discharged to the existing storm drainage system. 2. Off-site Analysis (1.2.2): This subject is covered in Sections III and IV. 3. Runoff Control (1.2.3): A. Peak Rate Runoff Control: This subject is addressed in section IV. Detention would be provided to maintain the existing 2- and 10-year peak discharge rates from the site. This will be achieved by the construction of a wetpond with a live storage volume of 10,050 cubic feet. ' B. Biofiltration: A wetpond would be provided in lieu of biofiltration for this project. Also, stormwater from the project would discharge into a constructed wetland and thereby receive additional treatment. This subject is further addressed in 1 Section IV. 4. Conveyance Facilities (1.2.4): Pipes and open-channel conveyance systems are ibeing designed to accommodate, at a minimum, the 25-year peak flow rate from the design storm. This issue is covered in Section V. ' 5. Erosion/Sedimentation Control Plan (1.2.5): As part of the project, a series of sediment controls would need to be constructed to address specific conditions on ' the construction site. These issues are covered in Section IX. 6. Maintenance and Operation (1.2.6): Since this is a City of Renton road, the City ' would assume maintenance of all drainage facilities and systems. 7. Bonds and Liability (1.2.7): N/A ' King County Surface Water Design Manual Special Requirements 1. Critical Drainage Areas (1.3.1): There are no critical basins within the project. 9W10/Reports/TIR(1/18194)/jcw I I-1 ' DRAFT 2. Compliance with an Existing Master Drainage Plan (1.3.2): There are no master drainage plans covering the project site. 3. Conditions Requiring a Master Drainage Plan (1.3.3): The project does not require a master drainage plan. ' 4. Adopted Basin or Community Plans(1.3.4): There are no Adopted Basin or Community Plans covering the project site. 5. Special Water Quality Controls (1.3.5): A wetpond will be used to treat all drainage from the developed site. ' 6. Coalescing Plate Oil/Water Separators (1.3.6): The project will not increase impervious area by five acres or more. ' 7. Closed Depressions (1.3.7): The project is not tributary to any closed depressions. ' 8. Use of Lakes, Wetlands or Closed Depressions for Peak Rate Runoff Control (1.3.8): The project will not use a lake, wetland, or closed depression for peak rate runoff control. A constructed wetland will be added and will provide some regional flood storage in much the same way as currently occurs on-site during large storm events. 9. Delineation of 100-Year Floodplain (1.3.9): The project is not within any Federal Emergency Management Agency designated floodplain. ' 10. Flood Protection Facilities for Class 1 and 2 Streams (1.3.10): There are no existing or proposed flood protection facilities for a Class 1 or 2 Stream within the project. The drainage on the existing site is not classified as either a Class 1 or Class 2 Stream per the King County Sensitive Areas Ordinance. ' 11. Geotechnical Analysis and Report (1.3.11): A complete geotechnical analysis will be performed for the entire project, including factors related to surface and groundwater. Areas of particular attention are seepage faces on steep slopes, changes in soil bearing strength due to saturation and liquefaction, and the effects of groundwater interception by the drainage facilities. ' 12. Soils Analysis and Report (1.3.12): Soils in the area have been evaluated and are adequate (Golder Associates 1994). The site consists entirely of fill material, which is characterized in the Golder report. ' 93010/Reports/TIR(1118/94)/jcw 11-2 ' 0 1000 2000 3000 ' SCALE IN FEET Legend Basin boundary Areas to be drained by underdrains Wetlands a ' Burlington Northern , Railroad , ♦♦ C/)CO • ♦ ♦ , �' ♦ PACCAR � ` _ ' 1 - 405 '` - - - - - - - - d Houser Way Technical Information Report t E IV T R /S M O Figure1 DrainnageeBasin Basin DRAFT ' III. OFF-SITE ANALYSIS ' Upstream Analysis Detailed information relating to this analysis is contained in the Garden Avenue Drainage ' Study (Entranco 1991). The Tributary Basin Map (figure III-1) is a representation of the basins and subbasins used in the analysis. Actual data used for the hydrologic analysis was taken from 1 inch = 200 feet, five-foot contour interval topographic maps. Land use was determined from aerial photographs and field inspection. Hydrologic analysis was performed using SCS/SBUH methods on WaterWorks Software following the guidelines in the 1990 King County Surface Water Design Manual. The subbasin hydrographs for Subbasins A—D ' were then routed through the site and valley floor system using the EPA Surface Water Management Model (SWMM) EXTRAN module. Flow data given is from EXTRAN-routed hydrographs. A summary of data from the hydrologic analysis is listed in tables III-1 and ' III-2. Table 111-1 Precipitation Values Used in Hydrologic Analysis 24-Hour Storms (inches) 2-Year 10-Year 25-Year 100-Year 2.0 2.9 3.4 3.9 ' The off-site areas contribute large amounts of flow during major storm events. When these flows leave the relatively steep hillside drainage systems and enter the virtually flat pipes on the valley floor, the valley pipes quickly exceed their capacity and flood. Much ' of this flooding occurs on the project site. To compound the flooding issue, the systems on the hillside appear to exceed their capacity for the 10-year storm and larger storms. Excess runoff follows a drainage course toward the south, before entering the project site by means of a 30-inch CMP near the Sunset Boulevard Interchange. This flooding during large storm events is a major concern in the design of the Houser Way North ' project. The 54-inch regional bypass pipe and the storage in the on-site areas through use of a restrictor, both described in later sections, are designed to mitigate the impacts of the flooding. ' 93010/Reports/TIR(1/18/94)1)cw III-1 ' DRAFT Table 111-2 ' Off-Site Flow Summary Location of Outfall Flows(cfs) to Project ' Tributary Area Site Subbasin (Acres) 2-Yr. 10-Yr. 25-Yr. 100-Yr. (Station) Description ' A 87 26 85 110 121 9+20 Regional drainage from east of 1-405 via 30-inch corrugated metal pipe (CMP). Flows include overflow from subbasins C and D during storms larger ' than the 2-year event. B 7.1 1.1 1.6 1.9 2.2 11+30 A section of 1-405 parallel 12+90 to the project which drains ' 15+50 to the right-of-way by 16+80 means of four 8-inch 18+50 HDPE pipes and two 12- inch CMP pipes. C 37 3.4 3.4 3.4 3.4 15+60 Drainage from roadway 20+60 system along Sunset Boulevard North, which drains to the right-of--way ' by two 18-inch CMP pipes. D 364 60 62 62 62 27+00 Regional drainage from east of 1-405. E 0.81 0.1 0.1 0.2 0.2 18+50 Hillside subbasin currently to draining to project site by ' 22+50 overland flow. F 0.62 0.0 0.1 0.1 0.2 6+50 Hillside subbasin currently to draining to project site by 12+50 overland flow. ' 93010/Reports/TIR(1118/94)/icw 111-2 DRAFT ' Downstream Analysis Standard Requirements (based on King County Surface Water Design Manual) ' 1. Analysis shall extend at least 0.25 mile downstream, and to a point where the project site constitutes no more than 15 percent of the basin (1.2.2-1). ' 2. Level 1 Analysis is required if levels 2 or 3 are not required. It shall show on a map downstream pipe sizes, channel characteristics, and a narrative of problems (1.2.2-2). 3. Level 2 Analysis is required if it is found there is a lack of capacity; overtopping, ' scouring, bank sloughing, or sedimentation; flooding of structures, road access, or septic fields; or significant destruction of aquatic habitat. Analysis shall be performed at each problem site for the 2-, 10-, and 100-year events; using Manning's equation and tape and hand level measurements. Problems shall be evaluated for existing and proposed conditions (1.2.2-3). ' 4. Level 3 Analysis is required where the proposed project site constitutes 15 percent of the flow. Analysis must be done using licensed survey and standard ' step backwater methods (1.2.2-2). 5. Solution of Problem. It must be shown that the project will neither aggravate an ' existing problem nor cause a new one. Where the project will aggravate a problem, mitigation must be provided (1.2.2-3). 6. Discharge at a natural location is required to produce no significant impacts to the downstream property (1.2.1-1). ' Special Requirements (based on P-suffix, basin or community plans, and critical designations) ' None. Stormflows on the project site currently travel in an open channel to a 42-inch concrete ' storm drain along North 8th Street. The Houser Way flows, combined with regional flows from the east, travel 900 feet west in this system to Garden Avenue North. At Garden Avenue North, the flows enter a 72-inch concrete storm drain that runs along Garden ' Avenue North and discharges into a series of open channels which eventually enter Lake Washington. The lake is approximately 0.9 miles downstream of the project site (figure I11-1). Several studies have focused on the flooding and conveyance limitations in the downstream storm systems (Entranco 1991 and 1992). The regional system has been ' modeled using the EXTRAN module of the EPA's Stormwater Management Model (SWMM). The system downstream of the project is limited due to flat slopes in the pipes ' 9W10/Reports/TIR(1/18194)/jcw 111-3 ' DRAFT ' and high tailwater levels in the channel system. The construction of the 72-inch storm drain parallel to the existing 48- and 54-inch storm drains in 1992 increased the capacity of the system along Garden Avenue North, enabling it to convey the 25-year storm ' without flooding. This project would include the construction of a 54-inch concrete storm drain to convey ' regional flows that enter the south end of the project site. During large storm events (10- year design storm and larger), this includes flood waters which come from surcharged systems on the hill east of 1-405. These flows currently flood the project area, spilling ' over onto adjacent properties. Allowing these flows to enter the downstream system would cause surcharged pipes and flooding in several downstream areas. Because of this, a restrictor mechanism would be constructed to force some of the flood waters to remain on the project site to prevent increased flooding downstream. This would cause some on-site flooding; however, it would be reduced from existing levels. Further ' discussion of the regional impacts of this project can be found in Section V. ' 93010/Reports/TIR(1/18/94)/jcw 111-4 P.-\CADD\DGN\930I0-20\ENV\FIC.DGN 9f X. D� HE ZOth "•' sr N LAKE WASHINGTON Dr s X.X ::►k': :�tn: ;: R- D r C : . C D: :D S� �Q''`'( E a� � ^ mm MH MomX, r ' I F O 0000a �o �Q Qo D ' L E G E N D PROJECT SITE •••.. EXISTING STORMWATER SYSTEM Q DOWNSTREAM BASIN AREA UPSTREAM BASIN AREA l H ) UPSTREAM BASIN ' D 'h %x m+ POSSIBLE FLOOD OVERFLOW ROUTE MILE HOUSER WAY TECHNICAL INFORMATION REPORT Figure III-1 ' E N T R A N C O TRIBUTARY BASIN MAP DRAFT IV.RETENTION/DETENTION ANALYSIS AND DESIGN Existing Site Hydrology The project site is located west of 1-405 and east of the Burlington Northern Railroad ' tracks between Sunset Boulevard North and North 8th Street in Renton (figure IV-1). The site consists of 7.2 acres with shrubs and small trees, and the drainage basin boundaries are defined by the edge of pavement on 1-405 and the fill for the railroad tracks. The slope on the hillside between 1-405 and the project is approximately 3:1. A 0.25-acre portion of the site at the north end of the project is already developed as ' public roadway, but the rest of the area is currently undeveloped. Design hydrograph results are listed in table IV-1 and the assumptions used to determine these are in table IV-2. ' Table IV-1 Predevelopment Design Hydrographs Flow Volume Storm (cfs) (acre-ft) ' 2-Year 0.42 0.39 10-Year 1.03 0.76 ' 100-Year 1.82 1.23 Table IV-2 ' Hydrologic Parameters for Predevelopment Conditions Area (acres) ' Pervious 6.53 Impervious 0.25 Total 6.78 Note: Time of concentration = 61.6 minutes 1 930101 Reports/TIR(1/18/94)/pw IV-1 ' DRAFT ' Developed Site Hydrology Site development would result in an increase of 1.83 acres of impervious area. Also, ' 0.41 acres of roadway which currently enter other city drainage systems would drain to the Houser Way project. In all, the project drainage would service 2.5 acres of impervious area. ' The developed site would contain only one on-site drainage basin (figure IV-2). Design hydrograph results are listed in table IV-3 and the assumptions used to determine these are in table IV-4. Table IV-3 Post-Development Design Hydrographs Flow Volume ' Storm (cfs) (acre-ft) 2-Year 1 .03 0.62 ' 10-Year 1.87 1.06 100-Year 2.91 1.59 ' Table IV-4 Hydrologic Parameters for Post-Development Conditions ' Area (acres) ' Pervious 4.70 Impervious 2.49 Total 7.19 Note: Minimum time of concentration =42.9 minutes ' 930101 Reports/TIR(1/1&94)/icw IV-2 DRAFT Hydrologic Analysis Hydrographs were computed using WaterWorks hydrologic software and SBUH ' methodology, and a King County design rainfall distribution. The time step used in all of the hydrographs was 10 minutes and the abstraction coefficient was 0.20. All pervious ' areas were represented by SCS curve number (CN) 82 and all impervious areas were CN 98. Because of the existing flooding on the site for large storms, it is not possible to separe on-site flows from regional flood waters above the 10-year event. Therefore, the 2/10 detention standard was used: the 2-year and 10-year peak flow rates will be held to th ' existing rates. Above the 10-year storm, water levels in the detention wetpond and the 4 constructed wetland will be allowed to equilibrate, providing the maximum storage '7 volume for regional flood waters and thereby attenuating some regional flooding. Retention D/ etention System 5 o Standard Requirements (based on King County Surface Water Design Manual) ' 1. Flow rate must be at or below existing 2- and 10-year peak rates and the volume to reduce flow to these rates must be increased by 30 percent without increasing the pond depth. The system will then be evaluated for the 100-year storm and if adverse impacts occur, additional mitigation may be required (1.2.3-2 and 3). 2. Detention ponds are to be open ponds, unless there is no practicable alternative, ' and may be combined with wetponds (1.2.3-3). 3. Bypasses may be permitted if discharge is to the same subbasin and flow rate is ' compensated for at the detention facility (1.2.3-6). 4. Off-site flow greater then 50 percent of the 100-year on-site flow must be carried 1 in a separate system around the detention facility (1.2.3-6). Special Requirements (based on P-suffix, basin or community plans, and critical designations) None. On-site detention would be provided in a detention pond located at the north end of the project site (figure IV-2). The detention pond would be designed to keep the flows ' leaving the project to the predevelopment levels for the 2- and 10-year storms, plus a 30 percent safety factor to the volume. The detention volume required to meet this standard is approximately 10,050 cubic feet. The allowable outflows from the detention pond for ' the 2- and 10-year storms would be the same as the existing flows-0.42 and 1.03 cfs, respectively (table IV-1) 93010/Reports/TIR(I I B/94)J jcw IV-3 ' DRA ts The detention pond would discharge into a constructed wetland immediately to the not (figure IV-3). From the wetland, the stormflows would enter the new 54-inch storm lim at the intersection of Houser Way North and North 8th Street. 1 Water QualityCr 7e r v- Water quality enhancement would be accomplished by constructing the combined t i detention/wetpond facility. The wetpond function would be created by excavating dead ' storage volume beneath the invert of the detention facility. The amount of this dead storage is equal to the runoff volume for the storm with one-third of the 2-year rainfall. This volume was found to be 0.11-acre-feet. The assumptions used to find this volume ' are listed in table IV-5. Table IV-5 ' Hydrologic Parameters for Water Quality Storm Area (acres) Pervious 4.70 ' Impervious 2.49 ' Total 7.19 Note: Water Quality Storm Rainfall 0.67 inch 1 The minimum area of the wetpond would be 1.0 percent of the impervious surface area. For this project, the minimum surface area is 0.025 acre, or approximately 1,100 square feet. ' Because the treated stormwater from the site would pass through the constructed ' wetland, an added level of water quality enhancement would be gained over a wetpond alone. ' 93010/Reports!TIR(1/18194)/icw IV-4 0 1000 2000 3000 Legend SCALE IN FEET -- Existing drainage to site D Off-site basin Wetland Burlington Northern Railroad co f O PACCAR y °° ' „ cn ' s , (D • , 1 - 405 C B B C 1 1 Houser Way Technical Information Report ' ENTRANC ® Figure IV - 1 Existing Site 0 1000 2000 3000 Legend SCALE IN FEET - - — Basin boundary Regional system Wet and/wetlands stem Roadway drainage pipe Ditch ' , r Underdrain Burlington Northern ' 1 ;,I '� •'•,,`, All. Railroad C/) CO PACCAR a� , ! � .�, ,\ •® '��,� ��..-, '-Wit.-....._.� . .�.. if 4 }t IN- \ � ♦, �-� z�,�,��_ � '�'''�� Wit'.-�.":�f'L"'F"".%'�'�"` .` '✓ •�„ !� "'�`4'` " , �� :�` .,�` � "�...:...__+''^tea...._., ;_w.�...«�«.....,,.,,�«..,_.,,,,,.�..__.. ���♦��v� ^�♦♦!n� „ , ' ..�!!C.•.,�.....,..-...7 �, ..- i - 405 �t Houser Way Technical Information Report _ ' ENTRA, NCO FigureIV - 2 Developed Site ' 54 inch Pipe Outlet Control ' Constructed Structure Wetland Wetpond Y Existing Restrictor ' 42 inch Pipe 1 ' Houser Way Technical Information Report ENTRANCO Figure IV - 3 ' Wetpond/Wetland Schematic ' DRAFT ' V. CONVEYANCE SYSTEMS ANALYSIS AND DESIGN Standard Requirements (based on King County Surface Water Design Manual) ' 1. Facilities must convey the 100-year flow without overtopping the crown of the roadway, flooding buildings, and if sheet flow occurs it must pass through a ' drainage easement (1.2.1-3). 2. New pipe systems and culverts must convey the 25-year flow with at least 0.5 ' feet of freeboard (1.2.4-1). 3. Drainage ditches must convey the 25-year flow with 0.5 feet of freeboard and ' must convey the 100-year flow without overtopping the crown of the roadway (1 .2.4-2). ' 4. Discharge at a natural location is required to produce no significant impacts to the downstream property (1.2.1-1). Special Requirements (based on P-suffix, basin or community plans, and critical designations) ' None. ' On-site System The on-site flows would drain via several 12-inch concrete pipe and catch basin systems ' to a ditch running along the west side of the roadway. The ditch would be designed to convey the 100-year peak flow from the basin (2.94 cfs) without overtopping. The preliminary design for this ditch is in Table V-1. ' Table V-1 Houser Way Conveyance Preliminary Design ' Parameters ' Bottom width 3.0 feet Slope 0.5% Design depth 0.77 feet Side slope 2:1 ' Top width 6.1 feet t ' 93010!Reports/TIR(1/ta/94)/jcw V-1 ' DRAFT ' With this design, the 100-year peak velocity in the ditch would be 0.84 feet per second, considerably less than the maximum allowable velocity of 5 feet per second. ' Portions of this ditch may require lining to prevent groundwater contamination. Regional System Regional off-site flows would be conveyed through the project site by a 54-inch concrete ' pipe tightline placed parallel to the roadway on the east side. This pipe would start at the 30-inch storm drain crossing under 1-405 at approximately station 9+20 (subbasin A) and would collect the drainage from subbasins B and C that discharges to the existing sites. ' It would also receive subsurface flows from the hillside via underdrains from subbasins E and F. The pipe would extend along Houser Way North to North 8th Street, and west along North 8th Street to Garden Avenue North, where it would drain into the existing 72- inch storm drain. A cross-connection to the existing 42-inch pipe would be inserted at North 8th Street at Houser Way North. The proposed pipe would serve both to convey the regional flows through the Houser Way project and to improve the regional ' conveyance along North 8th Street. The EXTRAN modeling verified that the 54-inch pipe would be sufficient to carry the ' peak stormflows for the 25-year design event; it would surcharge, but the water level in the system would not reach the ground elevation or cause flooding. ' The increased regional conveyance would result in higher peak water levels downstream. Because of this, a 36-inch restrictor orifice or a slide gate would be placed ' in the 54-inch line and the wetland/detention pond system would be connected to the regional system immediately upstream of the restrictor (figure IV-3). The effect of this would be to back water into the wetpond and constructed wetland during the peak flow ' periods and keep water levels downstream from increasing unacceptably. In this way, the developed site would provide flood storage much in the same way that the existing site currently does. For the 25-year storm event, EXTRAN modeling indicates that this ' system would result in 12-acre-feet less flooding than existing conditions and would keep the maximum water level at Garden Avenue North and North 8th Street to 25.0 feet, a level above which flooding is likely to occur along Garden Avenue North south of North 8th Street. The restrictor orifice could be modified in the future. Table V-2 compares the effects of the regional improvements at several downstream ' locations. ' 93010/Reports/TIR(1/19/94)/)cvw V-2 DRAFT Table V-2 ' 25-Year Storm Characteristics Characteristic Existing Post-Project ' Flooding (acre-ft) Houser Way Vicinity 17.8 5.8 ' Garden Avenue North 0.0 0.0 Maximum Water Level (ft) North 8th and Garden Street North 24.1 24.9 Gene Coulon Park 19.6 20.0 ' Maximum Flow (cfs) Garden Avenue North 72-inch 98 129 ' 54/48-inch 33 46 Gene Coulon Park 304 347 Velocity, fps 2.2 2.2 ' Without a restrictor in the 54-inch line, the peak flows in this line during the 25-year storm would be increased from 52 cfs to 123 cfs. In addition to the higher downstream water levels, the 72-inch storm line along Garden Avenue North would be impacted, where ' several pipe reaches would surcharge and the peak flows would be increased to 157 cfs. With the restrictor, the pipes would not surcharge. Therefore, the restrictor allows some capacity to be retained in the 72-inch line during the 25-year peak flows. 93010/Reports/TIR(1/18/94)1 jcw V-3 ' DRAFT VI. SPECIAL REPORTS AND STUDIES The sensitive areas on this project will warrant special studies to fully assess impacts ' and alternatives. The following special studies will be performed for this project: 1. STREAMS ' Not applicable. ' 2. WETLANDS A wetland study was conducted by Adolfson Associates, Inc. (Adolfson Associates, Inc. 1993) and was submitted as a separate document. Appropriate mitigation has not yet been determined, but will be included as part of the final design. ' 3. FLOODPLAIN Not applicable. 4. GEOTECHNICAL/SOILS The geotechnical analysis was conducted by Golder Associates, Inc. (Golder Associates 1994) and was submitted as a separate document. 5. CLOSED DEPRESSION Not applicable. Additional analysis of the regional conveyance system, hydrology, and downstream impacts can be found in several reports. These include: North Renton Basin, Interim Drainage Study to Address Development West of 1-405. City of Renton Storm Water Utility, May 1988. Garden Avenue Drainage Study. Prepared for PACCAR, Inc. by Entranco, October 1, 1991. Addendums in October 16, November 21 and December 19, 1991 and August 7, 1992. Regional Drainage Analysis, Houser Way, Renton, 9 Y � y, ton, Washington. Prepared for City of Renton by Entranco, June 4, 1992. Renton Monitoring Plan Technical Memorandum. Prepared for City of ' Renton by Entranco, June 4, 1993. Wetland Delineation. Technical Memorandum. Prepared for Entranco by ' Adolfson Associates, Inc., July 27, 1993. ' 93010/Reports/TIR(1/18/94)/jcw VI-1 1 DRAFT 1 Preliminary Geotechnical Engineering Report. Houser Way Relocation Stage II. Prepared for Entranco by Golder Associates, January 13, 1994. i 1 i 1 1 i 1 1 i 1 i 1 ' 93010/Reports/TIR(1/1&94)/jcw VI-2 DRAFT ' VII. BASIN AND COMMUNITY PLANNING AREAS There are no Basin or Community Plans currently in effect for the project site. ' The City of Renton is conducting a study of stormwater quality in the project area, but it is unlikely that there would be any recommendations from that study which would cause ' a substantial change in the project design. If that study is completed before final design of this project, its recommendations will be considered. The City of Renton is preparing a Comprehensive Plan for this area, but it is unlikely that the Plan would have a substantial effect on this project. ' 93010/Reports/TIR(1/18/94)/icw V I I-1 DRAFT ' Vlll. OTHER PERMITS Permits required for this project include: iHydraulics Permit Approval, Department of Fisheries and the Department of Wildlife - For work within the ordinary high water mark of surface waters. Requires work to avoid ' or minimize effects on fishery resources and habitat. Clearing And Grading Permit, City of Renton, Department of Planning. Section 404 Water Quality Approval, Army Corps of Engineers - Filling and clearing in wetlands and headwaters of streams with a mean annual flow of five cubic feet per second or greater. Requires a review of alternatives and mitigation for any losses or negative impacts. Section 401 Water Quality Certification, Department of Ecology - For any activity which may result in any discharge to a surface water. Usually processed in conjunction with Section 404 Water Quality Approval, where appropriate. 1 Water Quality Modification, Department of Ecology - For activities which will unavoidably violate state water quality criteria on a short-term basis. This permit may be required before Ecology can issue a Section 401 Water Quality Certification. ' 93010/Reports/TIR(1/18/94)/icw V 111-1 DRAFT IX. EROSION/SEDIMENTATION CONTROL DESIGN Standard Requirements (based on King County Surface Water Design Manual) The Erosion/Sediment Control Plan shall include the following: ' 1. Facilities required include rock quarry pad construction access, sedimentation pond, and filter fabric fencing in smaller areas (1.2.5-1). ' 2. Timing - For the period November 1 through March 1, disturbed areas greater than 5,000 square feet left undisturbed for more than 12 hours must be covered with mulch, sodding, or plastic covering. A construction phasing plan shall be provided to ensure that control measures are installed prior to clearing and grading (1.2.5-1). 3. Planning - Plan shall limit tributary drainage to an area to be cleared and graded. Clearing limits shall be delineated, staked, and flagged (1.2.5-1). 1 4. Revegetation - Revegetate areas to be cleared as soon as practicable after grading (1.2.5-1). ISpecial Requirements (based on P-suffix, basin or community plans, and critical designations) None. To avoid erosion, runoff from all disturbed areas must be transported to sediment ponds. Interception ditches will be required along the bases of all fills. Erosion control fences will be placed at the downstream edges of all disturbed areas. ' 93010/Fepoft/M(1118194)/1ew IX-1 ' DRAFT X. BOND QUANTITIES WORKSHEET, RETENTION/DETENTION FACILITY SUMMARY SHEET AND SKETCH, AND DECLARATION OF COVENANT ' Because this project would be constructed and maintained b the City of Renton no Y Y , bond or declaration of covenant would be required. ' 93010 1 Reports/TIR(1/18/94)/jcw X-1 DRAFT ' XI. MAINTENANCE AND OPERATIONS MANUAL Not applicable. ' 93010/Reports I TIR(Ill8/94)1 pw XI-1 r r Technical Appendix A rThe final drainage design for the Houser Way Improvements Project is similar to that proposed in the January, 1994 Houser Way Improvements rProject Technical Information Report. The only major difference is that the proposed regional conveyance system has been changed to be in an enlarged ditch between the roadway and the Burlington Northern Railroad tracks. Also, the regional conveyance improvements along N 8th Street will not be included in this project. EXTRAN analyses indicate that the proposed ' regional ditch system would be adequate to minimize flooding for the existing downstream system and would eliminate flooding after conveyance improvements along N 8th Street are completed. This appendix includes the design calculations performed to confirm the capacities and design velocities of the onsite pipes for the proposed Houser Way Improvements Project, as well as those which would convey offsite flows through the project. These pipes are referenced according to the roadway station of the catch basin at the inlet of the pipe. rThe performance of the regional system, including the ditch and the pipe system connecting the ditch to the N 8th Street system, was confirmed using EXTRAN modeling. r 1 r t 1 r r r r �e r - r m m m m m M M m m = r m m � � Roadway drainage outfalls 1 1/14/94 Houser Way Drainage Calcs Sta 19+67 Sta 21 +17 Sta 22+67 Pipe D 1 ft Pipe D 1 ft Pipe D 1 ft L 28 ft L 26 ft L 25 ft n 0.012 n 0.012 n 0.012 s 0.205 ft/ft s 0.2 ft/ft s 0.1916 ft/ft depth 0.1 ft depth 0.11 ft depth 0.12 ft d/D 0.100 d/D 0.110 d/D 0.120 A/D'2 0.0409 A/D"2 0.047 A/D'2 0.0534 A 0.0409 sf A 0.047 sf A 0.0534 sf R/D 0.0635 R/D 0.0695 R/D 0.0754 R 0.0635 ft R 0.0695 ft R 0.0754 ft Design Q 0.35 cfs Design Q 0.40 cfs Design Q 0.44 cfs Q 0.37 cfs Q 0.44 cfs Q 0.52 cfs v 8.9 fps v 9.4 fps v 9.7 fps Sta 24+17 Sta 25+62 Sta 27+12 Pipe D 1 ft Pipe D 1 ft Pipe D 1 ft L 26 ft L 23 ft L 22 ft n 0.012 n 0.012 n 0.012 s 0.1629 ft/ft s 0.1608 ft/ft s 0.1436 ft/ft depth 0.12 ft depth 0.1 ft depth 0.1 ft d/D 0.120 d/D 0.100 d/D 0.100 A/D'2 0.0534 A/D"2 0.0409 A/D"2 0.0409 A 0.0534 sf A 0.0409 sf A 0.0409 sf R/D 0.0754 R/D 0.0635 R/D 0.0635 R 0.0754 ft R 0.0635 ft R 0.0635 ft Design Q 0.44 cfs Design Q 0.29 cfs Design Q 0.29 cfs Q 0.48 cfs Q 0.32 cfs Q 0.31 cfs v 8.9 fps v 7.9 fps v 7.5 fps Roadway drainage outfalls 11/14/94 Houser Way Drainage Calcs Sta 28+62 Sta 30+12 Sta 31 +62 Pipe D 1 ft Pipe D 1 ft Pipe D 1 ft L 19 ft L 20 ft L 19 ft n 0.012 n 0.012 n 0.012 s 0.1326 ft/ft s 0.1015 ft/ft s 0.0763 ft/ft depth 0.12 ft depth 0.13 ft depth 0.14 ft d/D 0.120 d/D 0.130 d/D 0.140 A/D'2 0.0534 A/D"2 0.06 A/D"2 0.0668 A 0.0534 sf A 0.06 sf A 0.0668 sf R/D 0.0754 R/D 0.0813 R/D 0.0871 R 0.0754 ft R 0.0813 ft R 0.0871 ft Design Q 0.43 cfs Design Q 0.44 cfs Design Q 0.44 cfs Q 0.43 cfs Q 0.45 cfs Q 0.45 cfs v 8.1 fps v 7.4 fps v 6.7 fps Sta 33+12 Sta 18+17 Pipe D 1 ft Pipe D 1 ft L 18 ft L 40 ft n 0.012 n 0.012 s 0.0517 ft/ft s 0.165 ft/ft depth 0.16 ft depth 0.14 ft d/D 0.160 d/D 0.140 A/D"2 0.0811 A/D'2 0.0668 A 0.0811 sf A 0.0668 sf R/D 0.0986 R/D 0.0871 R 0.0986 ft R 0.0871 ft Design Q 0.46 cfs Design Q 0.65 cfs Q 0.49 cfs Q 0.66 cfs v 6.0 fps v 9.9 fps rr r� �r ■r rr r rr rr r rr rr r rr rr rr rr r r■� r■ Offsite drainage outfalls 11/14/94 Houser Way Drainage Calcs Sta 19+40 Sta 21 +39 Sta 22+96 Pipe D 2.5 ft Pipe D 1 ft Pipe D 1 ft L 52 ft L 70 ft L 49 ft n 0.012 n 0.012 n 0.012 s 0.019 ft/ft s 0.1045 ft/ft s 0.1 ft/ft depth 2.1 ft depth 0.19 ft depth 0.19 ft d/D 0.840 d/D 0.190 d/D 0.190 A/D'2 0.7043 A/D'2 0.1039 A/D"2 0.1039 A 4.401875 sf A 0.1039 sf A 0.1039 sf R/D 0.3038 R/D 0.1152 R/D 0.1152 R 0.7595 ft R 0.1152 ft R 0.1152 ft Design Q 62.6 cfs Design Q 0.95 cfs Design Q 0.95 cfs Q 62.71 cfs Q 0.99 cfs Q 0.97 cfs v 14.2 fps v 9.5 fps v 9.3 fps Sta 25+50 Sta 26+98 Sta 27+91 Pipe D 1.5 ft Pipe D 1 ft Pipe D 1 ft L 51 ft L 46 ft L 46 ft n 0.012 n 0.012 n 0.012 s 0.036 ft/ft s 0.0672 ft/ft s 0.0385 ft/ft depth 0.48 ft depth 0.21 ft depth 0.24 ft d/D 0.320 d/D 0.210 d/D 0.240 A/D'2 0.2167 A/D"2 0.1199 A/D"2 0.1449 A 0.487575 sf A 0.1199 sf A 0.1449 sf R/D 0.1801 R/D 0.1259 R/D 0.1416 R 0.27015 ft R 0.1259 ft R 0.1416 ft Design Q 4.6 cfs Design Q 0.95 cfs Design Q 0.95 cfs Q 4.80 cfs Q 0.97 cfs Q 0.96 cfs v 9.8f s v 8.1 fps v 6.6f s Offsite drainage outfalls 1 1/14/94 Houser Way Drainage Calcs Sta 30+74 N. Sunset pipe Pipe D 1.5 ft Pipe D 1.5 ft L 39 ft L 67 ft n 0.012 n 0.024 s 0.03 ft/ft s 0.38 fOft depth 0.43 ft depth 0.18 ft d/D 0.287 d/D 0.120 A/D'2 0.189 A/D"2 0.0534 A 0.42525 sf A 0.12015 sf R/D 0.1662 R/D 0.0754 R 0.2493 ft R 0.1131 ft Design Q 3.4 cfs Design Q 0.95 cfs Q 3.62 cfs Q 1.08 cfs v 8.5 fps v 9.0 fps Northern roadway drainage 11/18/94 Houser Way Drainage Calcs Sta 34+50 Sta 34+64.3 Sta 35+06 Pipe D 1 ft Pipe D 1 ft Pipe D 1 ft L 12 ft L 49 ft L 57 ft n 0.012 n 0.012 n 0.012 s 0.0412 ft/ft s 0.005 ft/ft s 0.005 ft/ft depth 0.09 ft depth 0.36 ft depth 0.48 ft d/D 0.090 d/D 0.360 d/D 0.480 A/D'2 0.035 A/D"2 0.2546 A/D"2 0.3727 A 0.035 sf A 0.2546 sf A 0.3727 sf R/D 0.0574 R/D 0.1978 R/D 0.2434 R 0.0574 ft R 0.1978 ft R 0.2434 ft Design Q 0.14 cfs Design Q 0.76 cfs Design Q 1.25 cfs Q 0.13 cfs Q 0.76 cfs Q 1.28 cfs v 3.8f s v 3.0fps v 3.4f s Sta 36+59 Sta 36+26 Sta 35+62 (rt) Pipe D 1 ft Pipe D 1 ft Pipe D 1 ft L 48 ft L 48 ft L 39 ft n 0.012 n 0.012 n 0.012 s 0.005 ft/ft s 0.005 ft/ft s 0.005 ft/ft depth 0.34 ft depth 0.36 ft depth 0.66 ft d/D 0.340 d/D 0.360 d/D 0.660 A/D'2 0.2355 A/D"2 0.2546 A/D'2 0.5499 A 0.2355 sf A 0.2546 sf A 0.5499 sf R/D 0.1891 R/D 0.1978 R/D 0.2899 R 0.1891 ft R 0.1978 ft R 0.2899 ft Design Q 0.69 cfs Design Q 0.78 cfs Design Q 2.13 cfs Q 0.68 cfs Q 0.76 cfs Q 2.11 cfs v 2.9f s v 3.0f s v 3.8fps Northern roadway drainage 11/18/94 Houser Way Drainage Calcs Sta 35+62 (rt) Pipe D 1 ft L 102 ft n 0.012 s 0.0114 ft/ft depth 0.55 ft d/D 0.550 A/D'2 0.4426 A 0.4426 sf R/D 0.2649 R 0.2649 ft Design Q 2.40 cfs Q 2.42 cfs v 5.5 fps Adilk SHEET NO. OF < iENTRANCO JOB NO. r - 3 (D- z. 11) PROJECT CALCULATIONS FORrx:. .:J MADE BY I'f'S DATE CHECKED BY DATE � 2 - 4 0q (�} 1 r _ 7 4- . 3•��., �..�� off' � �.,•�;-1 i �^ -- 1 1 . .r SHEET NO. OF S t ENTRANCO JOB NO. I - 9 3 PROJECT CALCULATIONS FOR MADE BY DATE "!, Y-,y CHECKED BY DATE 4 1 GO,IC,s� ,z7� Jv n SHEET NO. OF e ENTRANCO JOB NO. — PROJECT ' CALCULATIONS FOR MADE BY I DATE 'I ry Ja CHECKED BY DATE �•L•: `J•'�f. ��•S�^j , r I^� c d - - �/«'"J - �.{� �,.1-... fir: 17 CC C S SHEET NO. i OF ENTRANCO JOB NO. - PROJECT CALCULATIONS FOR MADE BY DATE z ; CHECKED BY DATE AJ e-v v T P V r_..�-.....i....'.'. ..:.. 3�Y i �r t:J i`v �,� ''' (— J / w.C r. 'j - - ✓�4. D w`' ,..i. way_ _ `•- ;� t G � _ _ - - �r?cR ?�Lt ;e.JaaS � ISJ � r50� lLr C+�a S .� 0i37,7 Q� _ acr ---- - zS r i SHEET NO. w OF { ' ENTRANCO JOB NO. PROJECT ' CALCULATIONS FOR MADE BY DATE CHECKED BY DATE r r)l�♦ 7. r � -r SHEET NO. I OF , 1 ENTRANCO JOB NO. i - 9 3 PROJECT CALCULATIONS FOR T.,U� MADE BY DATE CHECKED BY DATE 1 5 �'r9E �'� ter•- ?I+a� L / � � � J '� , / ,- 0. 5'S � Do2 � �IrG C'r5 ' SHEET NO. OF _ ENTRANCO JOB NO. PROJECT CALCULATIONS FOR MADE BY / :S DATE !!1 MIsN CHECKED BY DATE C d , �i .�z h _ '3'Z x = - 3 2'9 to 5 y ' Gti z.7 -IS -3o� �oao`7b� = 0 . c = :,: '7� SHEET NO. OF ' ENTRANCO JOB NO. PROJECT /'o�<.r ' CALCULATIONS FOR _ MADE BY DATE I CHECKED BY DATE 71, Is C) — — — — — — c, - D A SHEET NO. OF ' ENTRANCO JOB NO. / 9 3 c I L -? c PROJECT /-1" P- c — — — — —— —— 1 CALCULATIONS FOR ��` MADE BY DATE CHECKED BY DATE --- pe iz" c P - 12 ) LP= - — � 2-3 �a C .SS - 1 _ ----- _ qo--E:z-= - ---- - - --- SHEET NO. OF z 1 © ENTRANCO JOB NO. 5' 3 PROJECT CALCULATIONS FOR - ', ' r• -;, w. MADE BY M DATE CHECKED BY DATE 2 ,5 r \ + (6,4X7) -7 z 7 .S L:ly,8a 2•73 LL y35ta t a 9) q35,43 /n1 1 LAC !...pe v;s- S 1 SHEET NO. = OF 430 ENTRANCO J 0 B NO. PROJECT CALCULATIONS FOR MADE BY DATE — CHECKEDBY DATE -3 P 60 ck - lot, 7-7 13