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Home My WebLink AboutSWP272208(2) 1 ENTRANCO i' i' I' I' i� ' PARK AVENUE NORTH REGIONAL DRAINAGE STUDY l' Park Avenue Improvements Project I Renton, Washington pF o mLL 9,0 6, P 94rF� SEPSEMO` February 1993 CITY OF RENTON U MEMORANDUM 14- (rOPr DATE: February 19, 1993 � 't TO: Ron Straka �g93 Egg 22 FROM: RichardEvans/46- OF �p SUBJECT: PARK AVENUE NORTH REGIONAL DRAINAGE� r 0 Attached is a copy of the final Park Avenue North Regional Drainage Study for your records. Thank you. ® ENTRANCO r� �t �i �[I ti rl rl PARK AVENUE NORTH Ir REGIONAL DRAINAGE STUDY Park Avenue Improvements Project Renton, Washington �r OF R� U ; . O rl o9,a ..u. �. �' ��rFO SEPTE�e� February 1993 �1 �1 l � I � 1 � f � 1 � 1 � PARK AVENUE NORTH II REGIONAL DRAINAGE STUDY r ' Park Avenue Improvements Project Renton, Washington Prepared for ■ ' The City of Renton ' Prepared by ENTRANCO 10900 NE 8th Street, Suite 300 Bellevue, Washington 98004 (206) 454-5600 ■ ' February 3, 1993 1 � I � E � R � 1 � CONTENTS Page I ' INTRODUCTION 1 DRAINAGE SYSTEM OVERVIEW 1 HYDROLOGY 5 GHYDRAULICS ' Garden Avenue North/North 8th Street System 8 Houser Way North System 8 Pond System 10 Analysis 10 RELATIONSHIP OF REGIONAL DRAINAGE ISSUES TO THE PARK AVENUE NORTH IMPROVEMENTS PROJECT 11 SUMMARY 14 REFERENCES 15 APPENDICES ' A -Summary of Previous Studies B-Basin Characteristics C- EXTRAN Modeling Assumptions i FIGURES Pai76 Y. Project Vicinity 2 ' 2. Regional Drainage Areas 3 I 3. Valley Floor Drainage Systems 4 4. Drainage Basins 6 5. Pipe System References g 1 ! TABLES Page Y. Predicted Runoff Flows in the North Renton Drainage Basin 7 2. Peak Flows in the North Renton Drainage Systems 12 3. Existing and Future Peak Water Elevations at Park Avenue North Outfall 13 i � 11 41 PARK AVENUE NORTH REGIONAL DRAINAGE STUDY INTRODUCTION This report summarizes information gathered by Entranco regarding the stormwater systems in the north Renton area (figure 1) for drainage studies conducted for the City of Renton and PACCAR. This report focuses on the overall condition of the regional drainage system relative to the proposed Park Avenue Improvements Project. The Park Avenue Improvements Project is a roadway widening project, and the purpose of this - report is to analyze potential conflicts between the proposed roadway drainage and tAe regional drainage system. The regional drainage system is composed of the storm drains conveying runoff from the North Renton drainage basin to Lake Washington. The information presented below is drawn from analyses of the Park Avenue North, Garden Avenue North, and Houser Way North drainage systems; these analyses are described in Appendix A. DRAINAGE SYSTEM OVERVIEW 10 The North Renton drainage basin consists of approx' ately 980 acr s of developed upland area east of 1-405 (see figure 2) which drains on o 250 acres of Iat valley floor west of 1-405. The main storm drain on the valley floor ru s we ath North Sth 10 Street from Houser Way North to Garden Avenue North, and then north along Garden Avenue North (figure 3). At the north end of Garden Avenue North, in the vicinity of Gene Coulon Memorial Beach Park, the water outlets into the first of a series of five open 10 channels which are connected by culverts. These channels are referred to as the lower ponds. The first and second ponds are on either side of Lake Washington Boulevard, the third and fourth are along the northern edge of the Puget Power property, and the 10 last pond is located in Gene Coulon Memorial Beach Park. All drainage from the North Renton basin flows through these ponds into Lake Washington. 10 The regional drainage system consists of all pipes conveying flow from the North Renton drainage basin to Lake Washington. The valley system consists of the pipes on the valley floor. 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C. ------------------ C------- ... . ...... -------------- .. . . J 1- I ( it II it 7 r c )r z PARK AVENUE NORTH REGIONAL DRAINAGE STUDY Figure 2 E N T R A N C 0 REGIONAL DRAINAGE AREAS 3 ' P2 OCAODOOGN09 I024-20•ENV♦FIG8.OGN LAKE Gene C`ulon WASHINGTON Memorial Beach ■ ' Park 11 N ,e 0 1/8 1/4 ' m 1 I r MILE � � m � I L E G E N D ` _L _ ' NE 12th ST a Flow Input (Table 8 O ® Pond System 1 • Park Avence Storm Drain Systems �� a• Main Valley Drainage System e , Z f • — _ Other Modeled Drainage System r 40 > � • Q i � � ''° ° z Ill ♦ W La y SO W v m Q Z r ti > N 8th ST , O ' Q - a 1 1 r o qO=> _ — 1 2 Z U.1 1 ' N St ST Q 1 1 1 w 1 ' � 1 N 4t ST � 1 a 2 \ ❑� 405 1 PARK AVENUE NORTH REGIONAL DRAINAGE STUDY E M T R A N C O Figure 3 ' VALLEY FLOOR DRAINAGE SYSTEMS 4 I � There are two points at which the Park Avenue North storm system interacts with the rest of the regional drainage system. Flow from the northern section of the Park Avenue I ' North project and from the first pond, which receives runoff from the rest of the North Renton basin, outfalls into the second pond. There is also a cross-connection along ' North Sth Street which could introduce small flows into the Park Avenue North system from the Garden Avenue North system, but its effects on the regional system would be minimal. The southern part of the Park Avenue North Improvements Project drains to ' the Cedar River, and does not affect the regional drainage system, so it is not consid- ered in this report. On-site drainage issues for Park Avenue North have been addressed in the design report (Entranco 1992a). I , HYDROLOGY I ' Most of the work defining the hydrology of the North Renton regional drainage sys- tem was accomplished by Entranco in the initial Garden Avenue Drainage Study ' (Entranco 1991). All of the areas draining to the pond system were determined, and di- vided into 17 contributing drainage basins using topographical maps and diagrams of the drainage systems provided by the City of Renton (figure 4). A large section of the Park ' Avenue Improvements Project is represented as basins 12 and 13. Basin 13 drains to the Cedar River, and any impact it would have on the regional drainage system would be minimal. Many of the basins have been divided into subbasins when finer detail was re- quired for a particular study. These subdivided basins include basins 10, 11, 13, 14, 18, and 19. The modeled characteristics of all of the basins and subbasins are shown in Appendix B. Times of concentration for the basins were determined using the methodology des- cribed in the 1990 King County Surface Water Design Manual (KCSWDM). The longest ' flow routes were determined using topographic maps and storm drain maps provided by the City of Renton. The time of concentration used for a basin was not changed ' throughout the studies, except for that of the PACCAR site (basin 14) in which the time of concentration was changed as site development progressed. See Appendix B. ' United States Department of Agriculture Soil Conservation Service (SCS) soil maps were used to find the curve numbers for pervious land within each subbasin (USDA SCS 1973). The amount of impervious surface within each basin was estimated on the basis ' of land use. Land use was determined from aerial photos and field observations. The amount of effective impervious surface within each land use was based upon the following percentages (USGS 1990): ' Percent Impervious Land Use _ Surfaces — � ' Residential 10-35 Multi-family 60 ' Commercial/Industrial 90 I ' 9102d20I Reports Id.n1012[031931 Ihw 5 G\CADD\DON\9102p 70\ENV\FQX1 _. -f t Il, tt 1',—--- .. tl �1— iI =:uA C �I ' �-- �o NE 20tnc l MILE L E G E N D I211 J.I No. subbasm Number kk -- Subboetn Boundary ,.._. Sheet Flom Shallow Concenirnted Flow I' C: I I •-►• Pipe Flow I ,. r� l I I. I. ,=ya ( :.' ,O II - =�, II II l• .CN aldk NE I, pih ST _._.. ..._ ..._. _..... i • °° ' it �f .. �5 . :, I .. U 90 _ 08 � l ell N 8th ST �\ �, ,I ,I I rJ 11 �I 14 \`\\._I 11 �1 mA 13 16 II NE 1r � ..❑ .._...._.I v 1 I 1 I I I iwI II „ �l / J I I � ` Ir 6 SA I � - I r II 1j 1, 77 1 i - PARK AVENUE NORTH REGIONAL DRAINAGE STUDY i E N Figure 4 T R A N C o DRAINAGE BASINS I 6 l ' Pond System The ponds are actually a series of open channels connected by culverts. The first pond is located between Park Avenue North and Lake Washington Boulevard. It re- ceives flows from three pipe systems: Garden Avenue North, Houser Way North and the ' North Basin system, which conveys the flows from Basins 2, 3, and 4 on the hillside (figure 4). There are two 48-inch diameter culverts under Lake Washington Boulevard which connect this pond to the second pond. The second pond is between Lake Washington Boulevard and the Burlington Northern Railroad tracks, and is the outfall for the Park Avenue North drainage system. Two 48-inch culverts lead from this pond to the ' third pond. The third and fourth ponds run along the eastern edge of the Puget Power property and are connected by three 60-inch culverts. One of the culverts is currently blocked by silt and vegetation. The final pond runs through Gene Coulon Memorial t Beach Park and into Lake Washington. Again, there are three 60-inch culverts connecting this pond to the previous one, but one is effectively blocked by vegetation. The vegetation within the channels reduces the flow of water through the pond sys- tem, although maintenance will improve those conditions. The analyses conducted for these studies assumed that the channels were in a maintained condition, per direction from the City of Renton. However, it should be noted that these ponds need to be maintained in order to provide the design flow capacity. As part of the drainage improvements for the PACCAR site, additional culverts have been installed between the first and second, and the second and third ponds. The con- veyance through the ponds was modeled to be 35 to 41 percent greater after the pond ' improvements and the other Garden Avenue North improvements. However, these were not in place during the analysis and were considered part of the improved conditions. tThe existing conditions do not include these additional culverts. Analysis Initially, the King County BWPIPE program, a steady-state backwater model, was ' used in an attempt to gain an understanding of the workings of these systems. Data was obtained from the City of Renton's pipe attribute listing, a number of plan sets of the area, and survey data conducted for different studies. A set of curves was developed which defined the flow capacities of different segments of these systems given the steady-state conditions. However, it was found that this system is too complex to accu- rately model using the steady-state assumptions, so the dynamic model EXTRAN was used. This model was formulated to find the flows and water levels in every part of the system at five-second time steps over a 24-hour period. A schematic of the model, the major assumptions of the model, and a sample input file are shown in Appendix D. The EXTRAN model was updated and improved a number of times and was used to analyze several different options for drainage improvements. The capacities of the elements in the regional drainage system—based on the most recent model �{' 91024201 R"09 Idon1012(23193)Ihw 10 improvements—are shown in table 2. The existing condition indicates the situation at the beginning of the study, and the improved condition is the current state of the system, including the improvements in the pond system and along Garden Avenue North. The improvements result in increased flow through the pond system and the Garden Avenue North/North 8th Street lines, and conveyance through the rest of the system is not affected (table 2). A slight decrease in peak flow is modeled to occur at the end of the Park Avenue North line, but this does not affect the capacity of the Park Avenue North system, as explained in the next section. The information in table 2 shows the predicted peak flows in the drainage system for the specific storm events modeled. This is not necessarily equivalent to pipe capacity. In systems such as this one, flow through a pipe is determined both by the amount of water entering the pipe and by the water level immediately downstream of the pipe. The amount of flow through the pipe is reduced when water level downstream increases, so pipe capacity will change as the water level changes throughout a given storm. It is F ' therefore possible that the pipes may adequately convey higher flows than those reported in table 2 under some circumstances, while the reported flows may exceed the system capacity if they occur at a time in the storm when there are higher downstream ' water levels. RELATIONSHIP OF REGIONAL DRAINAGE ISSUES TO THE PARK AVENUE NORTH IMPROVEMENTS PROJECT ' Several ongoing projects could have an impact on the drainage from the Park Avenue North Improvements Project. Since the cross-connection between the Garden ' Avenue North system and the Cedar River was found to have such a small capacity, the system draining to the Cedar River will probably not be impacted greatly by any of these proposed changes. One exception would be if the improvements involve removing the ' cross-connection, although this probably would not greatly increase flows or flooding in the Park Avenue North system. The part of the Park Avenue North system most vulnerable to impact is the northern part of the project, which drains to the pond/channel ' system and through Gene Coulon Memorial Beach Park. The improvements which are most likely to affect the Park Avenue North system are ' the combination of increased conveyance through the pond system and increased con- veyance in the regional drainage system due to the addition of the 72-inch diameter pipe along Garden Avenue North. The effect on the Park Avenue North system would be ' dictated by the level of water in the second pond, where the outfall for that system is lo- cated. The pond improvements would tend to decrease the water level, improving the drainage off of Park Avenue North, while the addition of the 72-inch pipe would increase the amount of flow delivered to the ponds and may have the reverse effect, i.e., pond levels would tend to rise. � ' 9102&20/Ra As+dnn1012(213193)1hw b s Table 2 Peak Flows in the North Renton Drainage Systems a (cubic feet per second) Design Storm 2-year 10-year 25-year 100-year Drainage System Existing Improved Existing Improved Existing Improved Existing Improved Garden Avenue Northa 102.0 122.2 113.9 209.4 130.2 198.79 116.79 214.09 North 8th Streetb 59.8 77.8 62.0 82.7 62.6 82.9 64.4 83.0 Pond Systemc 143.5 201.9 211.2 284.4 234.1 316.0 251.4 339.2 North Basin/Houser Way Northd 60.2 60.2 99.7 99.6 107.4 109.7 115.7 117.6 ^' Park Avenue North at 21.8 21.5 36.4 32.6 40.0 37.0 43.2 42.4 Pond 2e Park Avenue North at 21.4 21.4 32.5 32.5 35.8 37.8 40.2 40.8 Lake Washington Blvd.f a. Existing is flow in pipe 102, Improved is sum of the peak flows In pipes 102 and 603 b. Peak flow through pipe 201 c. Peak flow through pond 5 d. Sum of peak flows in pipes 401 and 403 e. Peak flow in pipe 154 f. Peak flow In pipe 152 g. Flows reduced by backwater effects may be lower in larger storms The EXTRAN model indicated that there would be a period of time during the height ' of the storm events in which the improvements would cause higher tailwater conditions for the Park Avenue North system outfall. This could reduce the flow of water through the system. However, increased water levels in the Park Avenue North pipe system ' were observed in the model only in the two pipes closest to the outfall for a duration of less than two hours for the 25-year design storm. Flows in the rest of the Park Avenue North system were not affected, as shown in table 2. �t The peak water levels at the outfall (table 3) are modeled to increase slightly due to ' the improvements. But increased water levels occur only for a short period; over the duration of the storm, water levels in Pond 2 tend to be slightly lower. These levels do not lead to flooding in the Park Avenue North system. The backwater analysis ' conducted for the Park Avenue Improvements Project indicated that the Park Avenue North system would be unaffected by backwater if the water level at the outlet was less than or equal to 21.1 feet, so the backwater should have no effect on the conveyance } ' from the system for storms up to and including the 100-year event. Table 3 Existing and Future Peak Water Elevations at Park Avenue North Outfall (feet) Design Storm Existing Future 2-year 19.2 19.5 10-year 20.3 20.4 t25-year 20.6 20.8 100-year 20.8 21.0 ' The Park Avenue Improvements Project is unlikely to have a significant regional im- pact on the drainage system as currently designed, as the increased volumes generated by the Park Avenue Improvements Project are relatively small compared to the total runoff conveyed through the pond system. Specifics regarding the on-site drainage from the Park Avenue Improvements Project are not included here, but can be found in the Final Design Studies (Entranco 1992a). At the time of development of the Park Avenue Final Design Studies, the plans to improve the Garden Avenue North drainage system involved intersecting the 48-inch pipe at the Park Avenue North outlet with a new 72-inch pipe. This pipe would have I ' 9102420/Re M.I d.a 1012 MW3)jhw 13 conveyed water under the Burlington Northern Railroad tracks to the pond system further downstream. A biofiltraticn swale was proposed in the Final Design Studies to be built in conjunction with that design. However, since the design for the 72-inch pipe has changed so that it would outlet in the first pond, the concept for providing biofiltration in ' the proposed area will have to be altered accordingly. The revised biofiltration concept would also have to consider the roadway alignment for the Park Avenue North/Lake Washington Boulevard Project as designed by Tudor Engineering Company (Tudor ' 1991). Additionally, the improvements to the ponds would probably eliminate the option of ' designing a sedimentation pond in the pond/channel system, one of the suggested i alternatives in the Final Design Studies. Sedimentation ponds are designed to remove ■ particles from the water, primarily by slowing the water and allowing the particles to fall ' out. Since the purpose of the pond improvements is to increase the conveyance through the ponds, installing a sedimentation facility would be counter-productive. ' Despite the design changes which would be necessary due to the conflicts described ' above, it may still be possible to construct a biofiltration facility for the stormwater from the Park Avenue North project area. However, space is a major constraint and it is not known whether there is adequate room for such a facility. The alternative for water qual- ity enhancement would be to construct a wet vault as described in the Final Design ' Studies (Entranco 1992a). ' SUMMARY A series of modeling efforts have been undertaken to characterize the drainage sys- tems around Garden Avenue North, Houser Way North, and Park Avenue North in Renton, Washington. The regional drainage system was found to be too complex to adequately model with steady-state models, so a model using the EXTRAN module of ' the US EPA's Storm Water Management Model was developed and refined. The pro- posed improvements to the regional system were not found to have a significant impact on the drainage from the proposed Park Avenue Improvements Project as currently de- signed. However, the water surface elevations in table 3 determined in this study should fbe used to verify any effects on the final design. I ' I , i ' i1 9102b201 Reports l d.0012(W,93)1hw 14 REFERENCES Entranco 1991 Garden Avenue Drainage Study. Prepared for PACCAR, Inc. October 1, 1991. Addended October 16, November 21, and December 19, 1991, and August 7, 1992. 1992a Final Design Studies. Park Avenue Improvements Project: Storm Drainage Analysis. Prepared for the City of Renton. May 1992. 1992b Houser Way Regional Drainage Analysis. Prepared for the City of Renton. June 4, 1992 Draft. King County Department of Public Works 1990 King County Surface Water Design Manual. Renton, City of; Storm Water Utility s 1988 North Renton Basin, Interim Drainage Study to Address Development West of 1-405 (Garden Plaza - Park Plaza). May 1988. ' Tudor Engineering Company 1991 Pre-Final Submittal, Park Avenue/Lake Washington Boulevard Grading, Paring, and Drainage Plan. September 26, 1991. United States Department of Agriculture, Soil Conservation Service (USDA SCS) ' 1973 Soil Survey of King County, Washington. United States Geological Survey (USGS) 1990 Characterization and Simulation of Rainfall - Runoff Relations for Headwater Basins in Western King and Snohomish Counties, Washington. Water- Resources Investigations Report 89-4052. �1 �' 9102620/Re ns I dvn1012(2f3/90)1hw 15 10 10 10 10 10 Appendix A � , SUMMARY OF PREVIOUS STUDIES APPENDIX A SUMMARY OF PREVIOUS STUDIES GARDEN AVENUE DRAINAGE STUDY The Garden Avenue Drainage Study began with a steady-state backwater analysis of the Garden Avenue North storm drain system as it related to the proposed PACCAR site development. The steady-state analyses indicated that even design flows as low as the two-year return rate were capable of causing wide-scale flooding on the valley floor, due to high flows from the hillside and backwater effects from water levels in the first pond. Also, the pipe system on the PACCAR site was found to be inadequate to convey the two-year peak flows from the basin (Basin 15) draining to the PACCAR system. An 18- inch restrictor pipe in the PACCAR pipe system caused flooding on the site; the pipe s ' was found to have a maximum flow of only 7 cfs under optimal flow conditions, and the peak flow through it for the 2-year storm was estimated to be 12.9 cfs. ' The same backwater analysis was performed for the system with the cross-connec- tion at North 8th Street, outfalling to the Cedar River. The flow from the Garden Avenue North system to the Cedar River was found to be small. Depending on the tailwater conditions, the amount of flow entering this system via the cross-connection would be limited to a maximum of 4 to 6 cfs. A set of operational curves was produced for seven sections of the regional stormwater system. These curves define the expected flow given various headwater and tailwater conditions. The curves and a map of the modeled sections are included at the end of this appendix (figures Al-13). However, the system was found to be too complex to be modeled adequately using steady-state assumptions; these assumptions would ' tend to overestimate the amount of flooding which would occur under storm conditions. It was suggested that another model, such as the EXTRAN block of the Storm Water Management Model (SWMM), be used to obtain a more accurate understanding of the ' dynamics of the system. ' GARDEN AVENUE ADDENDUM #1 A second study was conducted to determine what drainage alternatives were avail- able for the PACCAR development. The study examined several potential alternatives, including enlarging the culverts for the pond/channel system, bypassing stormflow down Houser Way North, and enlarging the existing Garden Avenue North storm drain. Results of a steady-state backwater analysis demonstrated that a combination of in- creased capacity in both the pond/channel system and the valley storm drain system would reduce flooding on the valley floor. Improving the valley floor pipe system without improving the pond conveyance was shown to result in better drainage in the Garden �' 9102L201 Rwm/d.0012(21193)jhw A.1 Street North area, but with considerable flooding in the pond system. Conversely, the effect of increasing the size of the pond system culverts would be negated somewhat unless the capacity of the Garden Avenue North line were increased. GARDEN AVENUE ADDENDUM #2 ' After the second part of the Garden Avenue study was completed, ENTRANCO be- gan to analyze the valley floor drainage using the EXTRAN module of the SWMM. The EXTRAN model offers a more detailed analysis of the valley floor drainage, allowing the ' dynamic routing of full hydrographs through the storm drain system. The difference be- tween EXTRAN modeling and the previously used steady-state modeling is that the EXTRAN model allows conditions to be tracked throughout the duration of a storm, ' whereas the steady-state analysis permits only a snapshot of conditions at one flow rate and assumes that that flow rate is maintained for an indefinite period of time. 4 ' The EXTRAN model developed for the study represented over 115 pipes and 120 structures for the principal drainage system on the valley floor. Information used to de- fine the system was obtained from a combination of sources including field survey, exist- ing plan sets, and the City of Renton database. A schematic of the modeled representa- tion of the system is included in Appendix C of this report, along with a model input file. The model was run to represent 24-hour storms, and the hydrographs entering the sys- tem were developed as explained in the Hydrology section of the main body of this re- port. The predicted volume of flooding throughout the system for the 25-year storm event was approximately 16 acre-feet, of which sixty percent was located on the undeveloped ' PACCAR site. Flooding on the PACCAR site served to promote flooding on adjacent properties. Flood waters built up on the northwest corner of the property, and this water spilled over onto adjacent the low-lying areas along Garden Avenue North, west of the ' PACCAR site. The runoff that ponded on the PACCAR site came from three sources: rainfall onto the site, flooding due to inadequate conveyance in the storm drain line through the property, and discharge from the North 8th Street line. On the pre-developed PACCAR site, a drainage ditch conveyed stormwater to the northwest corner of the site. The outlet of this ditch was a 24-inch diameter pipe which flowed into the North 8th Street storm line. When the North 8th Street storm drain began to surcharge as a result of high flows from the upland areas, water flowed back onto the PACCAR site through the ditch outlet. During the simulation of the 25-year storm event, approximately 4.3 acre-feet of runoff was diverted onto the PACCAR site through the ditch outlet. Discharge onto the site averaged 5.5 cfs over a 9.5 hour period, with a maximum discharge of 17 cfs. The January 9, 1990 storm event was modeled, and the results were compared with t ' field observations. According to the EXTRAN model, approximately 3.5 acre-feet of 9102420/Ra Oft r d.M012 M319311hw A.2 runoff entered the site through the ditch outlet. The maximum water surface elevation modeled for this storm was approximately 27.5 feet, which is reasonably close to the levels that were observed on the site. The EXTRAN model was used to evaluate potential drainage alternatives for the PACCAR development. This addendum evaluated the need for pumping stormwater offsite, as well as bypass alternatives for some of the flows currently conveyed by the ' North 8th Street and Garden Avenue North pipe systems. Among the assumptions for this analysis was improvement of the conveyance ca- pacity of the pond system. The assumed pond improvements included enlarged culverts beneath both Lake Washington Boulevard and the Burlington Northern Railroad tracks, with the existing 48-inch diameter culverts (two at each location) replaced by three 60- ' inch culverts at each location. The PACCAR site was assumed to be filled to 29 feet of elevation, with the southern half of the site draining, preferably via gravity, to the Garden Avenue North system, and the northern half draining to an onsite detention pond. $ Pumping would be necessary to introduce water from the detention pond to the Garden Avenue North system. The pipe system through the PACCAR site was replaced by a 36-inch bypass pipe. This pipe was designed to convey the flows from basin 15 without flooding the site, and connects to the existing storm drain at the intersection of North 8th Street and Garden Avenue North. This study looked at the feasibility of bypassing flows from North 8th Street, which currently flow into the Garden Avenue North system, down Houser Way North to allow some capacity in the Garden Avenue North line for use by the PACCAR development. ' However, model runs indicated that the installation of a Houser Way North bypass would not eliminate the necessity of pumping, nor would it significantly reduce the maximum water levels at the PACCAR outfall. Also, it was found that gravity drainage would not be ' possible for the southern half of the site, necessitating additional pumping. Cross-con- nections with the North 8th Street system would be removed, so flooding from that storm system onto the PACCAR site would be reduced, but the amount of flooding at North 8th Street and Houser Way North would be increased, from 3.8 to 7.5 acre-feet for the 25- year design storm. The pumping and bypass solutions were later abandoned in light of new information that allowed a more viable solution, i.e., expanding the conveyance down Garden Avenue North. It is important to note that aU model runs evaluating improvement alternatives throughout all the studies assumed that the pond system channels were cleaned and maintained. Field inspections have shown that in many places there currently are bushes and other vegetation which reduce the flow capacity of the system. Per the City of Renton, it was assumed that, in the future, the necessary maintenance will occur to ensure unrestricted flow. ■ ' 910 201 Ae ns l dmn 1 012 1213/9 31 1hw A.3 GARDEN AVENUE ADDENDUM #3 Addendum No. 3 described the results of EXTRAN model runs to evaluate the im- pacts of placing a 72-inch line along Garden Avenue North, paralleling the existing sys- tem and connecting with the North 8th Street storm drain. This line was partially installed as part of past improvements. ' The results of the EXTRAN modeling indicated that this alternative would significantly increase the capacity of the overall drainage system and would allow PACCAR to dis- charge stormwater from its developed site via gravity drainage. It would also reduce overall flooding relative to the existing conditions. Additionally, the flooding on the PACCAR site and the flooding from runoff onto adjacent properties would be alleviated. ' Lower water levels along the existing Garden Avenue North storm drain and at the outlet from the PACCAR site were predicted. The flow through the ponds was shown to increase by about 25 percent. However, this design considered the 72-inch pipe to outL ' let into the third pond, and in the final design, this pipe outlets into the first pond. Later runs indicate that discharging to the first pond does not change the conclusions regard- ing this improvement alternative. HOUSER WAY REGIONAL DRAINAGE ANALYSIS The EXTRAN model developed for the Garden Avenue studies was further refined for the Houser Way Regional Drainage Analysis. The purpose of this study was to analyze the existing conditions in the vicinity of the Houser Way Relocation Improvements pro- ject, and then to evaluate several alternatives to improve the regional runoff conveyance through that area. Model improvements included increasing the detail of the represented drainage along ' Houser Way North. Information was gathered from plan sets supplied by the City of Renton and field investigations. Basins 10 and 19 were broken into subbasins to more precisely model the flows around the Houser Way North systems. Some hydrographs which had been combined earlier to represent a group of basins were split into individual basin hydrographs. The modeled storm drainage systems were extended to capture flows from these individual basins on the hillside to the north and the east of the site. The net result of these model improvements is to more accurately represent the function of the systems in the immediate vicinity of Houser Way North. A critical assumption was developed to deal with flooding on the hillside. Flooding is predicted at the uppermost point of the pipe from the hillside to the North 8th Street storm sewer. That point is called junction 1207 in this version of the model (see Appendix C). Due to the formulation of the EXTRAN model, the water which floods does not return to the system, and is lost. Since the flooding was observed to be significant (over 12 acre-feet for the 25-year storm), an alternate pathway for this water was �' 91020.20/Repent l Enn 1012(WT9311hw A.4 i� modeled. Based on topographic information and previous studies (City of Renton 1988), it was assumed that this water would appear as street flooding until reaching a swale along 1-405, where it would proceed to flow under 1-405 and into the vacated Houser Way North right-of-way. Although this assumption is based on precedent, and results in a more reasonable simulation than if the loss of stormwater volume were ignored, it is not certain that this is ' the path taken by the floodwaters, and it is unlikely that all of the predicted flooding would occur at this point. The pipe systems further up in the basin were modeled in an effort to check their operation, and these pipes were found to be overloaded and flood- ing, thus decreasing the flow reaching junction 1207. This indicates that there is some attenuation of high flows within the pipe system in the east basins, and that the actual flows to junction 1207 are lower than the modeled flows. The hydrograph method used is unable to account for attenuation in the pipe system; therefore, modeled results can be assumed to represent a worst-case scenario. s The proposed improvements to the Garden Avenue North system were assumed to have occurred. The improvements include both the completion of the 72-inch storm drain down Garden Avenue North and increasing the size of the culverts between the ponds. The conveyance between the first two ponds was assumed to be increased by the addition of two 54-inch culverts, and one 84-inch culvert was assumed to be added ' to the culverts between the second and third ponds. The analysis of this system indicated that under the modeled conditions, the North ' 8th Street line would reach maximum flow during rainfall events approximately the size of the 10-year, 24-hour storm. Instead of passing larger flows, this pipe would serve to create a restriction on the pipes entering the valley floor system at the intersection of ' North 8th Street and Houser Way North, and introduce a backwater situation upstream. The pond system, on the other hand, does not appear to reach its maximum conveyance even during the large flow events. However, the increasing levels in the ponds did begin ' to show backwater effects on the pipes entering the pond system. Street flooding seemed to be relatively unchanged by increasing the size of the cul- verts in the pond system relative to the preimproved model runs. The flooding at the Houser Way North underpass was estimated at 0.1, 0.7, 1.4, and 2.5 acre-feet for the 2-, 10-, 25-, and 100-year design storms, respectively. No flooding was predicted along Garden Avenue North; however, the backwater conditions caused by the North 8th Street pipe do lead to flooding at North 8th Street and Houser Way North. As noted be- fore, one of the critical assumptions for this modeling was the routing of overflow waters from the area on the hillside to the channel in the Houser Way North right-of-way. It is primarily this flow which seems to result in the flooding in the vicinity of the intersection. ' Again, it is not certain how much of this flow is actually attenuated in the systems on the hillside. Any attenuation would probably lead to lower predicted flooding on the valley floor. �' 9102b201 Repo,I d.n1012(219I93)jhw A.5 It was assumed that the primary impact that Houser Way North improvements would ' have on the regional stormwater system would be to replace the existing open channel with a large-diameter pipe. All three alternatives considered to improve the Houser Way North drainage system involve replacing the channel with a 72-inch pipe. One alterna- tive was to replace the 42-inch North 8th Street pipe with a 72-inch pipe. The second alternative also upgraded the North 8th Street pipe to 72-inch and removed a cross-con- nection between the 72-inch Garden Avenue North pipe system and the smaller Garden ' Avenue North pipe system. The third alternative was to build a 10-foot wide swale and overflow pipe along Houser Way North north of North 8th Street to divert flow from the North 8th Street line and pick up drainage from the hillside. Replacement of the channel with a large pipe was found to not affect the operation of the regional drainage system. The existing flooding continues, as well as the existing ' flows, so the replacement cannot be considered to be a drainage improvement. Of the three alternatives, the second appears to be superior to the first, as the removal of the, cross-connection seems to improve drainage in the Garden Avenue North lines. In both of the first two alternatives, flooding is reduced but the water levels in the North 8th Street line are increased, which affects the drainage from the PACCAR site. The third ' alternative does not reduce flooding as much as the other two, but it provides biofiltration and does not affect the drainage from the PACCAR site. ' Further unpublished investigation in this area evaluated an additional alternative for drainage improvements. There is a site on the hillside, in Basin 9, which appears to provide an opportunity for detention. Storm flows from several pipe systems on the hill- side could be diverted to a pond constructed on this site, and model runs incorporating such detention have shown that the operation of the regional drainage system may be improved. Also, the size of the pipe necessary to replace the channel along Houser Way North could be downsized if such detention were in place. ' GARDEN AVENUE ADDENDUM #4 Addendum No. 4 verified the proposed Garden Avenue North improvements using the refined model formulation as devised for the Houser Way Regional Drainage Analysis. The improvements included installing the additional culverts in the pond sys- tem as described above and completing the 72-inch line along Garden Avenue North. Modifications of the model included use of the final design elevations and specifications in the model formulation. The proposed improvements were estimated to increase the conveyance of the pond system by approximately 35 percent. Predicted flooding would decrease relative to the ' conditions previous to the PACCAR development. The risk of erosion in the three downstream ponds would not increase. �' 9102420/Reports/dron 1012(VM)jhw A.6 Due to higher water levels in the ponds, a small backwater effect was found on the outfall for the Park Avenue North system during part of the storm. However, this was ob- served to be localized at the downstream end of the system and to be of short duration. The conveyance of stormwater from Park Avenue North was unaffected, and the maxi- mum water levels within the system decreased slightly. Problems arising in the construction of the drainage improvements along Garden Avenue North forced a modification of the design of those improvements. The changes included moving the location of a cross-connection between the two Garden Avenue North pipes and downsizing the connection between the 72-inch pipe and the North 8th Street line. When the connection between the 72-inch Garden Avenue North pipe and the North 8th Street pipe was 48 inches, these modifications were found to mimic the original design of the system. The design flows and water levels for the revised system, along with those for the most recent version of the model of the system (circa 1991), are presented in the main body of this report. t ' 9102a201Ri na141"1012(YX93)j� A.7 11 \ c:0cadd0dgM91024-200env0tldb.dgn 9 LAKE cane cowon WASHINGTON MemorialPark Beach o Park o 0 1/8 114 m N � P MILE � 1 0 L E G E N D I NE 12th S i NO, Basin Number I9 ' Basin Boundary 900 Backwater Analysis Flow Routes 4111111 Upper Basin Flow Input �• I8-5 Ld NO Operational Curve Flow Segment 40 > II-3 Q IB-4 Lower Pond System Z w w 9oZ 8-3 <!n w ❑ v CO 12 II-2 in � IB-2 Z Z Z LU ` II-I IB-1 1 a N 8th ST Y OQ II-4 14 4 1 14-6' L (" J � © 10 w-1 z 1 w 14 3 I'dN 5t ST a 14-2 1 z 17 a 1 N 4t ST \ 40 ' PARK AVENUE DRAINAGE SYSTEM Figure A-1 EJI T R A N C O ' BACKWATER ANALYSIS FLOW ROUTE A.8 Figure A-2 Operational Curve Flow Segment is Flow from Pond 1 to Lake Washington for Various Headwater and Taiiwater Elevations Overflow zs0 250 I y 240 � 230 HW= 24.5 Ft E 220 �— _T. s � z7a L HW= 23.5Ft 200 0 r 3 10 LL 0 I80 -�i HW= 22.5 Ft no 16o , HW= 21.5Ft tso ------------- 12 17 14 15 16 17 Level of Laka Washington Figure A-3 Operational Curve Flow Segment 2: Flow from North Sth Street to Pond 1 for Various Headwater and Tailwater Elevations 1ao 90 HW'28.p Ft eo HVV1 27.0 Ft ' 70 o � HW'26.0 Ft L60 _ HW' = 25. t OYe /0 F ?'0 rn � o so _ ' 0 40 30 20 ' 10 20.0 20.5 21.0 27.5 22.0 22.5 23.0 23.5 24.0 24.5 ' Level of Pond 1 A.9 u Figure A-4 Operational Curve Flow Segment 3: Flow from Garden Avenue Junction to the Cedar River for Various Headwater and Tailwater Elevations 5. 5.2 J 5 R R co, 4.8 4.s n v 4.4 a 4' � '0 �. 1 a a a a H Fr 3.61 w=zs.o;;l 5 3.5 /y c 3.4 2S0Fr ` 3.3 7 a1 1 ' 2.8 2.6 24 ' 2.2 18.0 18.5 19.0 19.5 20.0 20.5 21.0 21.5 22.0 22.5 23.0 Level of Cedar River Figure A-5 ' Operational Curve Flow Segment 4: Flow from PACCAR Outlet to Garden Avenue Junction for Various Headwater and Tailwater Elevations 130 - 120 Ove,r/ow - 110 HW=33.0 F� too I so HW=31.0 Fi e 80 a L 70 - HW=29.o Ft a 60 = a 50 3 o li 40 30 i HW = 27.OFt 20 i to -', of 24.5 25.0 25.5 26.0 26.5 27.0 27.5 28 Water level at Garden do N Sth A.10 1 Figure A-e 1 Operational Curve Flow Segment 5: Flow from Lower PACCAR Junction to North 3th Street for Various Headwater and Taiiwater Elevations 16 �1 15 1 ` Overflow 14 1 13 HyN t2 � 28.SFf 1 t yW,2 1 0 `u' 10 ; BFI e 0. g y� a 27 o , 6 1 ° � .o 4 i f 1 ' 0 26.0 26.5 27.0 27.5 26.0 Water level at PACCAR and N 8th Street Figure A-7 ' Operational Curve Flow Segment 6: Flow from Middle PACCAR Junction to Lower PACCAR Junction for Various Headwater and Tailwater Elevations 16 = - � ' - 14 ' 13 12 HW=32.0 Ft kW`3f.pFf � � a g _ a I 1 6 ' a t7_ 5 4 I ti� 1 3 I o 2 290 t 0 25.0 26.5 27.0 27.5 28.0 28.5 29.0 1 Water level at rant junction A.11 Figure A-8 Operational Curve Flow Segment 7: Flow from the Inflow to PACCAR to Middle PACCAR Junction for Various Headwater and Tailwater Elevations Cverfjow s � S HW`3t5Pt 31.0 Ft Ix J 3oS F o j 2 j .0 0 29.0 29.5 30.0 30.5 31.0 Water leval at second junction ' A.12 ' Figure A-9 Alternative 1: Flow from Pond 1 to Lake Washington with Three 72-inch Culverts [ installed Between Pond 2 and Pond 3 (Burlington Northern Railroad Culverts) l for Various Headwater Elevations ' 300 EIOverflow I 260 -4 24.5 Ft r ' 260 rT ■ E 240 1 ' e 220 _ 22.5 Ft e I a 200 ' a t 180 m Q 160 ' = 20.5 Ft 0 140 ' 120 y 19.5 Ft 100 ' ao I 18.5 Ft 60 12 13 14 15 16 17 Lake Washington level Figure A-10 ' Alternative 2: Flow from Pond 1 to Lake Washington with Three 72-inch Culverts Installed Between Pond 1 and Pond 2 (Lake Washington Boulevard Culverts) _ for Various Headwater Elevations 320 - Overflow ' 300 280 24.5 Ft 260 = I E u 240 ' n 22.5 Ft e z2o —►--- c ' a 200 ' m 160 — t 160 _ 20.5 Ft a 140 L 120 - ' 19.5 Ft y 100 10 )E 3E f 80 ' 18.5 F[ _ 60 12 13 14 15 16 17 Lake Washington Tavel A.13 ' Figure A-11 Alternative 3: Flow From North Sth Street to Pond 1 if Garden Avenue Pipe is Enlarged to 72 Inches for Various Headwater Elevations 200 _ 190 ` Overflow 16a ' no - 28 Ft 160 27 Ft 15a 140 t 130 I 10 ', � 110 � xx 10a 90 SO 25 Ft I 1 ' 70 60 -1 50 J 40 16.5 19 19.5 20 20.5 21 21.5 22 22.5 23 23.5 24 24.5 t Pond 1 Level Figure A-12 Alternative 4: Flow from PACCAR Outlet to Garden Avenue Junction ' if North 8th Street Pipe is Enlarged to 72 Inches 450 -- for Various Headwater Elevations Overflow 400 i u 33 Ft 350 i �t a 300 a 31 Ft 250 ' t a a I 750 29 Ft too 28 Ft ' sa 27 Ft ' 24,5 25 25.5 26 26.5 27 27.5 26 Water level at Garden Avenue �, A.14 Figure A-13 ' Alternative 7: Flow through New 72-Inch Storm Line Along Houser Avenue from North Sth Street to Pond 1 for Various Headwater Elevations 320 Ei _ _ _ El _ _ r i Overflow ■1 300 ' 33 Ft zeo 26a 240 t 22a 31 Fr a 200 a I 0 160 - 40 ' ° 120 29 Ft !L 8 8 s4 d 3 fr s4 � 100 28 Ft ' 80 60 40 ' 20 -' 27 Ft ' i 5.5 19 19.5 20 20.5 21 21.5 22 22.5 23 23.5 24 24.5 Pond 1 Water La cl t A.15 Appendix B � ' BASIN CHARACTERISTICS APPENDIX B BASIN CHARACTERISTICS The Basin Summary section of this appendix (pages B.2-6.12) provides the specific hydrologic parameters used to model each drainage basin. Information developed for individual subbasins as determined for the Houser Way Regional Drainage Analysis is t provided on pages B.13-13.15. The third section, the Basin Result Summary (pages B.16-13.19) gives the hydrograph characteristics for the basins in the study, including the Houser Way North basins. The Basin ID column indicates both the basin and the storm event. The first part of each ID is the basin number, and the second part indicates the storm. IDs with letters are for the following storms: A= 2-year Storm B = 10-year Storm } C = 25-year Storm D = 100-year Storm i �' 91024201 Re K.I d.1012(2W3)I" B.1 9/11/92 Entranco Engineers, Inc. page 1 ' P 4 ----------------PACCAR / GARDEN AVENUE DRAINAGE STUDY Basin Hydrographs ----------------------------------------------- ' BASIN SUMMARY BASIN ID: 10-2 NAME: B10-2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 55 . 00 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 23 . 00 Acres ' TIME INTERVAL. . . . : 10. 00 min CN. . . . : 82 . 00 TIME OF CONC. . . . . : 59.30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 32 . 00 Acres ' CN. . . . : 98. 00 PEAK RATE: 9 .42 cfs VOL: 5 . 97 Ac-ft TIME: 490 min BASIN ID: 11. 1A NAME: B11, SB1-2YR t SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7. 00 Acres BASEFLOWS: 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0. 66 Acres ' TIME INTERVAL. . . . : 10. 00 min CN. . . . : 88 . 00 TIME OF CONC. . . . . : 12 . 20 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 6. 34 Acres ' CN. . . . : 98 . 00 PEAK RATE: 2 . 93 cfs VOL: 0. 99 Ac-ft TIME: 480 min BASIN ID: 11.2A NAME: B11, SB2-2YR ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 12 . 60 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 1. 18 Acres ' TIME INTERVAL. . . . : 10. 00 min CN. . . . : 88 . 00 TIME OF CONC. . . . . : 13 . 20 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 11. 42 Acres ' CN. . . . : 98 . 00 PEAK RATE: 5. 19 cfs VOL: 1. 78 Ac-ft TIME: 480 min 6.2 ' 9/11/92 Entranco Engineers, Inc. page 2 ' PACCAR / GARDEN AVENUE DRAINAGE STUDY / Basin_Hydrographs___________________________________ BASIN SUMMARY BASIN ID: 11. 3A NAME: B11, SB3-2YR ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 2 . 10 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0. 20 Acres ' TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 88 . 00 TIME OF CONC. . . . . : 9 . 60 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA. . : 1. 90 Acres CN. . . . : 98 . 00 ' PEAK RATE: 0 . 91 cfs VOL: 0.30 Ac-ft TIME: 480 min BASIN ID: 11.4A NAME: B11, SB4-2YR ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 5. 30 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0.51 Acres ' TIME INTERVAL. . . . : 10. 00 min CN. . . . : 88 . 00 TIME OF CONC. . . . . : 6 . 30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 4 . 79 Acres CN. . . . .. 98 . 00 PEAK RATE: 2 . 41 cfs VOL: 0.75 Ac-ft TIME: 470 min BASIN ID: 12-2 NAME: B12-2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 61. 00 Acres BASEFLOWS: 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA ' PRECIPITATION. . . . : 2 . 00 inches AREA. . : 6 . 00 Acres ■ TIME INTERVAL. . . . : 10. 00 min CN. . . . : 88 . 00 TIME OF CONC. . . . . : 20. 10 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 55. 00 Acres ' CN. . . . : 98 . 00 PEAK RATE: 22 .44 cfs VOL: 8 . 62 Ac-ft TIME: 480 min ' B.3 t9/11/92 Entranco Engineers, Inc. page 3 ' PACCAR / GARDEN AVENUE DRAINAGE STUDY Basin Hydrographs BASIN SUMMARY ' BASIN ID: 13-2 NAME: B13-2YR SBUH METHODOLOGY ' TOTAL AREA. . . . . . . : 91. 00 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2. 00 inches AREA. . : 23 . 00 Acres ' TIME INTERVAL. . . . : 10. 00 min CN. . . . : 88 . 00 TIME of CONC. . . . . : 132 . 00 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 68 . 00 Acres CN. . 98. 00 ' PEAK RATE: 13 . 48 cfs VOL: 11.90 Ac-ft TIME: 500 min ' BASIN ID: 14 . 1A NAME: B14,SB1-2YR t ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 6. 60 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0. 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 98 . 00 TIME OF CONC. . . . . : 5 . 30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 6 . 60 Acres CN. . . . : 98 . 00 ' PEAK RATE: 3 . 30 cfs VOL: 0 . 98 Ac-ft TIME: 470 min BASIN ID: 14 . 2A NAME: B14 , SB2-2YR ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 12. 50 Acres BASEFLOWS: 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0 . 00 Acres ' TIME INTERVAL. . . . : 10. 00 min CN. . . . : 98 . 00 TIME OF CONC. . . . . : 11. 60 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA. . : 12 . 50 Acres CN. . . . : 98 . 00 PEAK RATE: 5.54 cfs VOL: 1. 85 Ac-ft TIME: 480 min 8.4 9/11/92 Entranco Engineers, Inc. page 4 �' -- PACCAR / GARDEN AVENUE DRAINAGE STUDY Basin Hydrographs - ---------- ------------------------------------------------------ BASIN SUMMARY BASIN ID: 14 . 3A NAME: B14,SB3-2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 15. 80 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0. 00 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 98 . 00 TIME OF CONC. . . . . : 11.30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA. . : 15 . 80 Acres CN. . . . : 98 . 00 PEAK RATE: 7. 03 cfs VOL: 2 . 34 Ac-ft TIME: 480 min BASIN ID: 14 .4A NAME: B14 , SB4-2YR ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 15. 10 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 .00 inches AREA. . : 10. 30 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 89 . 00 TIME OF CONC. . . . . : 60. 00 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 4 . 80 Acres CN. . . . : 98 . 00 PEAK RATE: 2 . 49 cfs VOL: 1. 59 Ac-ft TIME: 490 min BASIN ID: 14 . 5A NAME: B14 , SB5-2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 20. 00 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 12 .70 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 89 . 00 TIME OF CONC. . . . . : 29 . 00 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 7 . 30 Acres CN. . . . : 98 . 00 48 PEAK RATE: 4 .71 cfs VOL: 2 . 17 Ac-ft TIME: 480 min �' 13.5 ' 9/11/92 Entranco Engineers, Inc. page 5 ' PACCAR / GARDEN AVENUE DRAINAGE STUDY Basin Hydrographs --------------------------------------------------------- BASIN SUMMARY ' BASIN ID: 14 . 6A NAME: B14 , SB6-2YR ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 6. 10 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 6 . 10 Acres ' TIME INTERVAL. . . . : 10. 00 min CN. . . . : 89 . 00 TIME OF CONC. . . . . : 78 . 00 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 0. 00 Acres CN. . . . : 98 . 00 ' PEAK RATE: 0. 66 cfs VOL: 0. 52 Ac-ft TIME: 500 min ' BASIN ID: 15-2 NAME: B15-2YR } ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 48 . 00 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 8 . 00 Acres ' TIME INTERVAL. . . . : 10. 00 min CN. . . . : 81. 00 TIME OF CONC. . . . . : 18 . 00 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 40 . 00 Acres CN. . . . : 98 . 00 ' PEAK RATE: 16. 72 cfs VOL: 6. 32 Ac-ft TIME: 480 min BASIN ID: 15A2 NAME: B15 w/o 405 - 2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 38 . 00 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 7 . 00 Acres ' TIME INTERVAL. . . . : 10. 00 min CN. . . . .. 80. 00 TIME OF CONC. . . . . : 18. 00 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 31. 00 Acres ' CN. . . . : 98 . 00 PEAK RATE: 12 .94 cfs VOL: 4 . 91 Ac-ft TIME: 480 min B.6 9 11 92 / / Entranco Engineers, Inc. page 6 ----------PACCAR-/-GARDEN AVENUE DRAINAGE STUDY Basin Hydrographs -- BASIN SUMMARY BASIN ID: 15B2 NAME: B15 W/O 405 OR LAND - 2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 30. 00 Acres BASEFLOWS: 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 6. 00 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 82 . 00 TIME OF CONC. . . . . : 15.20 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 24 . 00 Acres CN. . . . : 98 . 00 PEAK RATE: 10. 69 cfs VOL: 3 .87 Ac-ft TIME: 480 min BASIN ID: 16-2 NAME: B16-2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 87 . 00 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 41. 00 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 81. 00 TIME OF CONC. . . . . : 41. 20 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA. . : 46 . 00 Acres CN. . . . : 98 . 00 PEAK RATE: 15.96 cfs VOL: 8 .87 Ac-ft TIME: 480 min BASIN ID: 17-2 NAME: B17-2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 123 . 00 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2. 00 inches AREA. . : 46. 00 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 83 . 00 TIME OF CONC. . . . . : 50. 20 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA. . : 77 . 00 Acres CN. . . . : 98 . 00 49 PEAK RATE: 24 . 10 cfs VOL: 14 . 05 Ac-ft TIME: 490 min B.7 9/11/92 Entranco Engineers, Inc. page 7 PACCAR / GARDEN AVENUE DRAINAGE STUDY Basin Hydrographs 1 BASIN SUMMARY BASIN ID: 18. 1A NAME: B18 , SB1-2YR 1 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 4 . 90 Acres BASEFLOWS: 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0.57 Acres 1 TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 88 . 00 TIME OF CONC. . . . . : 4 . 80 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 4 . 33 Acres CN. . . . : 98 . 00 �1 PEAK RATE: 2 . 34 cfs VOL: 0. 69 Ac-ft TIME: 470 min 11 } BASIN ID: 18. 2A NAME: B18 , SB2-2YR 1 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 5. 00 Acres BASEFLOWS: 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0 .58 Acres 1 TIME INTERVAL. . . . : 10. 00 min CN. . . . : 88 . 00 TIME OF CONC. . . . . : 4 . 80 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 4 .42 Acres 1 CN. . . . : 98 . 00 PEAK RATE: 2 . 39 cfs VOL: 0. 70 Ac-ft TIME: 470 min � 1 BASIN ID: 18 . 3A NAME: B18, SB3-2YR 1 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 5 . 40 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA 1 PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0 . 62 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 88 . 00 TIME OF CONC. . . . . : 4 . 80 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 4 . 78 Acres 1 CN. . . . : 98 . 00 PEAK RATE: 2 . 59 cfs VOL: 0.76 Ac-ft TIME: 470 min I 1 � 1 t 1 B.8 10 ' 9/11/92 Entranco Engineers, Inc. page 8 ---- PACCAR / GARDEN AVENUE DRAINAGE STUDY Basin Hydrographs ----BASIN SUMMARY BASIN ID: 18 . 4A NAME: B18,SB4-2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 7 . 00 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0. 81 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 88 . 00 TIME OF CONC. . . . . : 5. 00 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 6. 19 Acres PEAK RATE: 3 . 32 cfs VOL: 0 . 98 Ac-ft TIME: 98 470 min BASIN ID: 18 . 5A NAME: B18 , SB5-2YR ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 4 . 20 Acres BASEFLOWS: 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA ' PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0. 48 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 88 . 00 TIME OF CONC. . . . . : 5. 20 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 3 . 72 Acres ' PEAK RATE: 1. 98 cfs VOL: 0 . 59 Ac-ft TIME: 98 4770 min BASIN ID: 19-2 NAME: B19-2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 50. 00 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 20 . 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 82 . 00 TIME OF CONC. . . . . : 30.50 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 30 . 00 Acres ' CN. . . . : 98 . 00 PEAK RATE: 11. 62 cfs VOL: 5. 52 Ac-ft TIME: 480 min 7 ' i � ' B.9 9/11/92 Entranco Engineers, Inc. page 9 ' Basin-HydroACCAR-/-GARDEN-AVENUE-DRAINAGE-STUDY ---------------- Basin Hydrographsgraphs ' BASIN SUMMARY BASIN ID: 2-2 NAME: 2yr storm, basin 2 ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 60. 00 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 36. 00 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 69 . 00 TIME OF CONC. . . . . : 28 . 90 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA. . : 24. 00 Acres CN. . . . . 98 . 00 PEAK RATE: 8. 23 cfs VOL: 4 . 20 Ac-ft TIME: 480 min BASIN ID: 3-2 NAME: B3-2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 116. 00 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 58 . 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 73 . 00 TIME OF CONC. . . . . : 35 . 40 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 58 . 00 Acres CN. . . . : 98 . 00 48 PEAK RATE: 18 .71 cfs VOL: 10. 12 Ac-ft TIME: 480 min BASIN ID: 4-2 NAME: B4-2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 184 . 00 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 83 . 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 82 . 00 TIME OF CONC. . . . . : 105 . 00 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 101. 00 Acres CN. . . . : 98 . 00 50 PEAK RATE: 22 . 98 cfs VOL: 19 .42 Ac-ft TIME: 500 min 8.10 9/11/92 Entranco Engineers, Inc. page 10 ----- PACCAR / GARDEN AVENUE DRAINAGE STUDY Basin Hydrographs BASIN SUMMARY BASIN ID: 6-2 NAME: B6-2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 139 . 00 Acres BASEFLOWS: 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 67 . 00 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 87. 00 TIME OF CONC. . . . . : 61.86 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . . 72 . 00 Acres CN. . . . : 98 . 00 49 PEAK RATE: 24 . 68 cfs VOL: 15.70 Ac-ft TIME: 490 min k BASIN ID: 7-2 NAME: B7-2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 102 . 00 Acres BASEFLOWS: 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 45. 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 84 . 00 TIME OF CONC. . . . . : 67 . 30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 57. 00 Acres CN. . . . : 98 . 00 49 PEAK RATE: 16 . 78 cfs VOL: 11. 22 Ac-ft TIME: 490 min BASIN ID: 8-2 NAME: B8-2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 37 . 00 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 14 . 00 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 83 . 00 TIME OF CONC. . . . . : 26.30 min IMPERVIOUS AREA ABSTRACTION COEFF: 0. 20 AREA. . : 23 . 00 Acres CN. . . . : 98 . 00 PEAK RATE: 9 . 50 cfs VOL: 4 . 21 Ac-ft TIME: 480 min 6.11 9/11/92 Entranco Engineers, Inc. page 11 --------- PACCAR / GARDEN AVENUE DRAINAGE STUDY Basin Hydrographs ------------------------------------------------------- BASIN SUMMARY BASIN ID: 9-2 NAME: B9-2YR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 38 . 00 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 28 . 00 Acres TIME INTERVAL. . . . : 10. 00 min CN. . . . : 77 . 00 TIME OF CONC. . . . . : 29 . 60 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 10 . 00 Acres CN. . 98 . 00 PEAK RATE: 4 .27 cfs VOL: 2 .52 Ac-ft TIME: 480 min 6.12 Subbasins Delineated for the Houser Way Regional Drainage Analysis Basin: 10.1 Total Area: 23 Acres Time of Concentration: 41.2 Minutes Pervious Area Area 8.3 Acres CN 81 Impervious Area Area 14.9 Acres CN 98 Basin: 10.2 Total Area: 12 Acres Time of Concentration: 5.57 Minutes Pervious Area Area 3.3 Acres CN 81 Impervious Area Area 8.7 Acres CN 98 Basin: 19 Total Area: 48 Acres Time of Concentration: 30.5 Minutes Pervious Area Area 24.4 Acres 84 Impervious Area Area 23.6 Acres CN 98 Basin: 405.1 Total Area: 4.13 Acres Time of Concentration: 3.93 Minutes Pervious Area Area 0 Acres CN 81 Impervious Area Area 4.13 Acres CN 98 91024-2O Re91enal Oralnage Study(MZ92)aw 8.13 Basin: 405.2 Total Area: 1.10 Acres Time of Concentration: 2.47 Minutes Pervious Area Area 0 Acres 81 Impervious Area Area 1.10 Acres CN 98 Basin: 405.3 Total Area: 1.38 Acres Time of Concentration: 3.37 Minutes Pervious Area Area 0 Acres 81 Impervious Area t Area 1.38 Acres CN 98 Basin: 405.4 Total Area: 0.46 Acres Time of Concentration: 1.96 Minutes Pervious Area Area 0 Acres CN 81 Impervious Area Area 0.46 Acres CN 98 Basin: 405.5 Total Area: 0.69 Acres Time of Concentration: 41.2 Minutes Pervious Area Area 0 Acres CN 81 ' Impervious Area Area 0.69 Acres CN 98 �' 9102420 Regional Orainage Study(IW1292(aw B.14 � Basin: 405.6 Total Area: 6.89 Acres Time of Concentration: 9.55 Minutes Pervious Area Area 0 Acres 81 Impervious Area Area 6.89 Acres CN gg Basin: 405.7 Total Area: 7.12 Acres Time of Concentration: 9.55 Minutes Pervious Area Area 0 Acres CN 81 Impervious Area ' Area 7.12 Acres CN 98 I ' 91024-20 Regional Oninage Study(t0112 2)caw B 15 q ' 9/11/92 Entranco Engineers, Inc. page 1 PACCAR / GARDEN AVENUE DRAINAGE STUDY East Basin Hydrographs BASIN RESULT SUMMARY ' BASIN -----VOLUME---- -RATE- ----TIME----- Hydrograph --ID--- cf_---Ac_ft----__cfs- -min- hours Methodology ' 10-10 418595 9 . 61 15 . 49 490 8 . 17 SBUH Method 10-2 260270 5.97 9.42 490 8 . 17 SBUH Method ' 10-25 509819 11. 70 19. 03 490 8 . 17 SBUH Method 10100 602580 13 . 83 22 . 63 490 8 . 17 SBUH Method 11. 1A 43148 0.99 2 . 93 480 8 . 00 SBUH Method 11. 1B 65562 1.51 4 . 41 480 8 . 00 SBUH Method ' 11. 1C 78096 1. 79 5 . 23 480 8 . 00 SBUH Method 11. 1D 90671 2 . 08 6. 05 480 8. 00 SBUH Method 11.2A 77690 1.78 5. 19 480 8 . 00 SBUH Method 11. 2E 118038 2 .71 7.81 480 8. 00 SBUH Method ' 11. 2C 140606 3 .23 9 . 26 480 8 . 00 SBUH Method 11. 2D 163237 3 .75 10 . 72 480 8 . 00 SBUH Method 11. 3A 12938 0.30 0 . 91 480 8 . 00 SBUH }Method 11. 3B 19662 0. 45 1.37 480 8 . 00 SBUH Method ' 11. 3C 23422 0. 54 1. 63 480 8 . 00 SBUH Method 11. 3D 27194 0 . 62 1. 88 480 8 . 00 SBUH Method 11. 4A 32639 0 .75 2 . 41 470 7 . 83 SBUH Method ' 11. 4B 49604 1. 14 3 . 64 470 7 . 83 SBUH Method 11. 4C 59095 1. 36 4 . 33 470 7 . 83 SBUH Method 11. 4D 68612 1. 58 5 . 01 470 7 . 83 SBUH Method 12-10 570475 13 . 10 33 . 86 480 6. 00 SBUH Method ' 12-2 375272 8 . 62 22 . 44 480 8 . 00 SBUH Method 12-25 679679 15 . 60 40.20 480 8 . 00 SBUH Method 12100 789203 18 . 12 46 . 53 480 8 . 00 SBUH Method 13-10 803142 18.44 21. 19 500 8 . 33 SBUH Method ' 13-2 518569 11. 90 13 .48 500 8 . 33 SBUH Method 13-25 963505 22 . 12 25.53 500 8 . 33 SBUH Method 13100 1124851 25 .82 29 . 90 500 8 . 33 SBUH Method ' 14 . 1A 42510 0.98 3 . 30 470 7 . 83 SBUH Method 14 . 1B 63937 1.47 4 . 90 470 7 . 83 SBUH Method 14 . 1C 75870 1. 74 5. 78 470 7 . 83 SBUH Method 14 .1D 87814 2 . 02 6. 66 470 7 . 83 SBUH Method ' 14 .2A 80511 1. 85 5.54 480 8 . 00 SBUH Method 14 .2B 121092 2 .78 8 . 22 480 8 . 00 SBUH Method 14 . 2C 143693 3 . 30 9 . 70 480 8 . 00 SBUH Method 14 . 2D 166315 3 .82 11 . 17 480 8 . 00 SBUH Method ' 14 . 3A 101766 2 .34 7. 03 480 8 . 00 SBUH Method 14 . 3B 153060 3 . 51 10. 44 480 8 . 00 SBUH Method 14 .3C 181628 4 . 17 12 . 31 480 8 . 00 SBUH Method ' 14 . 3D 210222 4 . 83 14 . 18 480 8 . 00 SBUH Method 14 .4A 69351 1. 59 2 . 49 490 8 . 17 SBUH Method 14 .4B 114161 2 . 62 4 . 28 490 8 . 17 SBUH Method 14 . 4C 139861 3 .21 5 . 31 490 8 . 17 SBUH Method ' 14 . 4D 165911 3 . 81 6 . 35 490 8 . 17 SBUH Method 14 . 5A 94409 2 . 17 4.71 480 8 . 00 SBUH Method 14 .5B 154145 3 . 54 7 . 93 480 8 . 00 SBUH Method 14 .5C 188332 4 . 32 9 .78 480 8 . 00 SBUH Method ' 14 . 5D 222952 5 . 12 11. 64 480 8 . 00 SBUH Method 14 . 6A 22762 0 . 52 0 . 66 500 8 . 33 SBUH Method �' B.16 9/11/92 Entranco Engineers, Inc. page 2 PACCAR / GARDEN AVENUE DRAINAGE STUDY ' East Basin Hydrographs BASIN RESULT SUMMARY ' BASIN -----VOLUME---- -RATE- ----TIME----- Hydrograph ■1 ID ---cf-- Ac-ft --cfs_- -min- hours Methodology ■ , 14 . 6B 40072 0 . 92 1. 28 490 8 . 17 SBUH Method 14 . 6C 50152 1. 15 1. 64 490 8. 17 SBUH Method ' 14 . 6D 60435 1. 39 2 . 02 490 8 . 17 SBUH Method 15-10 423420 9.72 25 . 65 480 8 . 00 SBUH Method 15-2 275192 6.32 16 .72 480 8 . 00 SBUH Method 15-25 507093 11. 64 30. 67 480 8 . 00 SBUH Method ' 15100 591383 13 .58 35.72 480 8 . 00 SBUH Method 15A10 330178 7. 58 19 .94 480 8 . 00 SBUH Method 15A2 213961 4 . 91 12 . 94 480 8 . 00 SBUH Method 15A25 395932 9 . 09 24.98 480 8. 00 SBUH Method 15A99 462248 10. 61 29 . 13 480 8 . 00 SBUH Method 15B10 260827 5 . 99 16 . 50 480 8 . 00 SBUH Method 15B2 168711 3 . 87 10 . 69 460 8 . 00 SBUHSMethod ' 15B25 312925 7. 18 19 . 78 480 8 . 00 SBUH Method 15B99 365450 8 . 39 23 . 08 480 8 . 00 SBUH Method 16-10 629737 14 . 46 26.85 480 8 . 00 SBUH Method 16-2 386256 8 .87 15.96 480 8 . 00 SBUH Method ' 16-25 771078 17.70 33 .25 480 8 . 00 SBUH Method 16100 915309 21. 01 39 .81 480 8 . 00 SBUH Method 17-10 974103 22 . 36 39 . 00 480 8 . 00 SBUH Method 17-2 612021 14 . 05 24 . 10 490 8 . 17 SBUH Method ' 17-25 1181499 27. 12 47. 63 480 8 . 00 SBUH Method 17100 1391790 31. 95 56.41 480 8 . 00 SBUH Method 18 . 1A 29888 0. 69 2 .34 470 7 . 63 SBUH Method ' 18 . 1B 45527 1. 05 3 . 55 470 7 . 83 SBUH Method 18 . 1C 54283 1. 25 3 .35 480 8 . 00 SBUH Method 18 . 1D 63069 1. 45 4 . 89 470 7 . 83 SBUH Method 18 . 2A 30502 0. 70 2 . 39 470 7 . 83 SBUH Method 18. 2B 46462 1. 07 3 . 62 470 7 . 83 SBUH Method 18. 2C 55397 1. 27 4 . 30 470 7 . 83 SBUH Method 18.2D 64362 1. 48 4 . 99 470 7 . 83 SBUH Method 18 . 3A 32961 0 .76 2 .59 470 7 . 83 SBUH Method ' 18 . 3B 50200 1. 15 3 .91 470 7 . 83 SBUH Method 18 . 3C 59852 1. 37 4 . 65 470 7 . 83 SBUH Method 18 . 3D 69535 1. 60 5. 39 470 7 . 83 SBUH Method 18 . 4A 42707 0. 98 3 . 32 470 7 . 83 SBUH Method 18 . 4B 65050 1. 49 5. 03 470 7.83 SBUH Method 18 . 4C 77560 1. 78 5. 98 470 7 .83 SBUH Method 18 . 4D 90111 2 . 07 6 . 92 470 7. 83 SBUH Method 18 . 5A 25642 0. 59 1. 98 470 7 .83 SBUH Method 18 . 5B 39051 0. 90 2 . 99 470 7.83 SBUH Method 18 . 5C 46557 1. 07 3 . 56 470 7 . 83 SBUH Method 18 . 5D 54089 1. 24 4 . 12 470 7 . 83 SBUH Method 19-10 385055 8 . 84 18 . 99 480 8 . 00 SBUH Method 19-2 240324 5 . 52 11. 62 480 8 . 00 SBUH Method 19-25 468311 10. 75 23 . 26 480 8 . 00 SBUH Method " 19100 552907 12 . 69 27 . 60 480 8 . 00 SBUH Method 2-10 313103 7 . 19 13 . 63 480 8 . 00 SBUH Method 2-100 476414 10 . 94 21.70 480 8 . 00 SBUH Method �' B.17 t9/11/92 Entranco Engineers, Inc. page 3 PACCAR / GARDEN AVENUE DRAINAGE STUDY ' East Basin Hydrographs --------------- ------- ------------------------------------_ BASIN RESULT SUMMARY 1 BASIN -----VOLUME---- -RATE- ----TIME----- Hydrograph 4l1711 ID --cf-- Ac-ft --cfs- -min- hours Methodology --2-2-----182922----4-20------8-23-----480----8 . 00 SBUH Method =_ 2-25 392801 9. 02 17 .51 480 8 . 00 SBUH Method 3-10 729568 16.75 31 .49 480 8 . 00 SBUH Method 3-100 1078271 24 .75 47 .82 480 8 . 00 SBUH Method 3-2 441006 10 . 12 18 .71 480 8 . 00 SBUH Method 3-25 901052 20 . 69 39 .47 480 8 . 00 SBUH Method 4-10 1370325 31. 46 38 . 27 500 8. 33 SBUH Method 4-100 1981890 45. 50 56 . 50 490 8 . 17 SBUH Method 4-2 845982 19 . 42 22 . 98 500 8 . 33 SBUH Method ' 4-25 1673348 38 .41 47 . 25 500 8 . 33 SBUH Method 6-10 1099295 25.24 40. 72 490 8 . 17 SBUH Method 6-100 1576967 36.20 59 . 25 490 8 . 17 SBUH Method 6-2 684007 15.70 24 . 68 490 817 SBUH $Method ' 6-25 1336654 30. 69 49 . 93 490 8 .. 17 SBUH Method 7-10 786492 18 . 06 27 . 71 490 8 . 17 SBUH Method 7-100 1131359 25.97 40. 51 490 8 . 17 SBUH Method 7-2 488645 11. 22 16. 78 490 8 . 17 SBUH Method ' 7-25 957623 21. 98 34 . 05 490 8 . 17 SBUH Method 8-10 292254 6. 71 15. 37 480 8 . 00 SBUH Method 8-100 417804 9.59 22 . 18 480 8 . 00 SBUH Method ' 8-2 183467 4. 21 9 . 50 480 8 . 00 SBUH Method 8-25 354589 8 . 14 18 . 75 480 8 . 00 SBUH Method 9-10 198751 4 .56 8 . 67 480 8 . 00 SBUH Method 9-100 309311 7 . 10 14 . 40 480 8 . 00 SBUH Method ' 9-2 109961 2 . 52 4 . 27 480 8 . 00 SBUH Method 9-25 252845 5. 80 11. 45 480 8 . 00 SBUH Method �' B.18 1' �� Table B-i Stormflows from Subbasins Delineated for Houser Way Analysis Volume Peak Rate Time Basin Design Storm (cf) (acre-ft) (cfs) (min) 10.1 2 16,5744 3.8 4.83 470 10 264,078 6.1 7.82 470 ' 25 320,526 7.4 9.55 470 100 377,937 8.7 11.32 470 10.2 2 94,779 2.2 4.47 470 ' 10 148,266 3.4 7.31 460 25 178,812 4.1 8.83 460 100 209,754 4.8 10.37 460 19 2 335,286 7.7 11 470 10 525168 12.1 17.47 470 25 6,429,333 14.8 21.61 470 100 762,723 17.5 25.82 470 405.1 2 39,933 0.9 2.19 460 10 60,012 1.4 3.25 460 25 71,154 1.6 3.83 460 100 82,404 1.9 4.42 460 �t 405.2 2 10,395 0.2 0.62 460 10 16,128 0.4 0.93 460 25 18,954 0.4 1.09 460 100 21,897 0.5 1.26 460 405.3 2 13,392 0.3 0.75 460 10 20,169 0.5 1.11 460 25 23,643 0.5 1.31 460 100 27,360 0.6 1.51 460 405.4 2 4,392 0.1 0.27 460 10 6,660 0.2 0.4 460 25 8,001 0.2 0.47 460 100 8991 0.2 0.54 460 405.5 2 6,543 0.2 0.39 460 10 10,152 0.2 0.58 460 25 11,988 0.3 0.68 460 100 13,554 0.3 0.79 460 405.6 2 66,330 1.5 3.14 470 10 99,603 2.3 4.66 470 25 118,188 2.7 5.5 470 100 136,971 3.1 6.34 470 405.7 2 68,508 1.6 3.25 470 10 103,185 2.4 4.82 470 25 122,175 2.8 5.69 470 100 141,525 3.2 6.55 470 �' 9102420/Reports 1 tlnn1012 J2/319311hw B.19 Appendix C EXTRAN MODELING ASSUMPTIONS i f� f' APPENDIX C f' EXTRAN MODELING ASSUMPTIONS The formulation of the EXTRAN model used for these analyses has been developed from various data sets provided by the City of Renton, SSOE, WSDOT, and Entranco ' field and survey investigations. Some of the data conflicted with other data sets, and in these cases the most recent data was generally used. The source code for the model as well as a schematic of the junctions follow this section. The hydrograph cards appended ' onto the model are not included, but they are available upon request. The hydrology for the model runs was determined by Entranco for the original ' Garden Avenue Drainage Study report from maps, aerial photographs, and field investi- gation. Subsequent investigation resulted in minor changes which were incorporated into the model. Hydrographs were created with the Santa Barbara Urban Hydrograph ° ' method, using the King County 24-hour hydrograph. The actual hydrograph generation was performed either on the King County HYD program or by using WaterWorks. In the case of basins which had more than one inlet to the stormwater system, the hydrograph flows were split into equal portions and placed in the appropriate junctions. There are 51 individual inlet points in the system, and 30 of those inlets result from splitting 5 larger hydrographs. The attached model code is for the post-developed condition with the proposed im- provements. Among the features which differ in the pre-developed condition are the pipe ' system and condition of the PACCAR site, which was modeled to include a series of storage areas for flood waters, the lack of a 72-inch pipe from junction 1605 to 1612 and ' smaller culverts between Ponds 1 (1001), 2 (2001) and 3 (3001). One of the critical assumptions regarding the lower pond system is that the channels ' are well maintained to allow maximum flow. Currently, the ponds are not in a condition to allow such flow. ' The level of Lake Washington is assumed to be at 15 feet above mean sea level. This tends to be a conservative estimate because the U.S. Army Corps of Engineers regulates the lake water level, and in the winter, when the modeled storm events are ' likely to occur, the lake is closer to an elevation of 13 feet. However, backwater analyses using the King County BWPIPE model indicated a change in lake level between 12 and 17 feet of elevation has no effect on the conveyance through the pond system. fThe EXTRAN model was prone to instabilities. An instability results in extreme fluc- tuations in water levels and/or flows at a given point in the system over a short period of time, which often affects several pipes and junctions in the area of the instability. These are a result of the equations in the model and do not necessarily have physical signifi- cance, although they generally occurred at times when there was a large increase in the amount of flow through an area. Several methods were used to deal with instability �' 91026W 1 Repass/Ean101212p19311hw C.1 problems. The most common method used in this model was replacing a relatively short pipe with an equivalent pipe of longer length. This was done by decreasing the Manning's "n" of the longer pipe so that the flow through the pipe was similar. Occasionally, a long pipe was also shortened by using the same method. The pipes in this system were modeled as being between 100 and 500 feet long. Another method was representing a pipe between two manholes as an orifice. It was found that instabili- ties tended to occur in some manholes having two pipes which flow out of that manhole. In cases where this happened, the higher pipe was replaced with an orifice in the model formulation. Finally, some open channels in the system experienced instability. The op- eration was sometimes improved by representing the channels as large storage junc- tions. The first pond, junction 1000, is one example of this occurrence. The EXTRAN model does not take entrance losses, exit losses and minor losses due to bends into account. In order to accurately model the system, the Manning's "n"s in the pipes must be increased to mimic the losses. To find the appropriate changes in the t Manning's "n", runs through the system were compared to runs of the BWPIPE model, which does account for these losses. It was found that an increase of "n" to 0.017 for concrete pipes and 0.030 for corrugated metal pipes produced the same flow/headwater relationships as the runs accounting for entrance and exit losses. An additional 0.005 increase mimicked a 90-degree bend. Therefore, in the model formulation, these ad- justed Manning's "n"s were used. The final set of assumptions dealt with flooding issues. The EXTRAN model monitors the amount of water which overflows out of a manhole and reports it as flooding, but the water does not reenter the stormwater system and is lost. In order to mimic the effects of street flooding, much of which would end up reentering the system at another point or later in the storm, storage junctions and channels were used to represent the area which would flood. The top elevations of the manholes which contribute to the flooding are raised enough to place an orifice between the flooding manhole and the storage junc- tion/channel. In this way, the water is not lost, and the actual amount of flooding at any given time can be determined using the height of water in the storage junction. The issue of flooding on the hillside is related to this. The highest manhole repre- sented on the hillside, junction 1207, displayed flooding at high flows. The flooding was assumed to enter the street and then a nearby swale to be conveyed to another point in the system. This agrees with an earlier report by the City of Renton, but the amount of flow which actually follows this route is suspect. It is likely that attenuation occurs in the system further up the hill, resulting in less flood flow. However, with this formulation of the model it was not possible to determine the amount of attenuation, and therefore the amount of water which is shown to flood is the maximum possible flooding. 9102620/R"p"na/dran1012(2/3r931 jhw C.2 0 8 8 0 0 1 2 EXTRAN MODEL MODEL OF ROUSER WAY DRAINAGE CONFIRMATION;10-YEAR 43200 2 0 13 15 0 0 1 450 51 15 0.05 1203 1000 750 1101 1830 1401 1351 1700 1460 1461 1001 2001 3001 851 201 75 301 110 601 307 102 610 801 820 100 430 403 ISO ' 700 1700 750 6 4 15 1600 0 0 .110 2.0 2.5 710 1710 1203 1 2 100 .012 711 1711 1710 1 2 480 .017 73 730 1700 1 3 500 0 0 .017 740 1740 1203 1 3 500 .021 741 1741 1740 6 1 6 200 .045 1.0 1.0 742 1742 1741 1 2 150 .030 75 750 1203 1 2.5 100 .009 100 1100 1001 1 4 235 .017 101 1101 1100 1 4 100 .010 102 1102 1101 1 4.5 225 0 00.017 5 103 1103 1102 1 4.5 200 0 .30.014 ' 104 1104 1103 1 4.5 200 0 00.017 105 1105 1104 1 4.5 220 0. 00.017 106 1106 1105 1 4.5 290 0 .30.017 107 1107 1101 1 4. 5 120 0 00.017 108 1108 1107 1 4.5 180 0 00.017 109 1109 1108 1 4 175 0 00.017 110 1199 1109 1 4 384 1. 1 00.022 ' 199 1000 1199 1 4 100 .4 0.010 201 1201 1612 1 3. 5 300 0 00.017 202 1202 1201 1 3.5 370 0 00.017 203 1203 1202 1 3.5 485 0 00.017 ' 204 1204 1203 1 1.75 150 0.017 205 1205 1204 1 2 500 0.017 206 1206 1205 1 2 150 0.017 207 1207 1206 1 2 182 0.017 ' 250 1250 730 6 3 8 300 .080 1.0 1.0 251 1251 1250 6 3 8 300 .080 1.0 1.0 252 1252 1251 6 3 8 300 .080 1.0 1.0 253 1253 1252 2 2 40 300 .030 ' 254 1207 1253 1 3 100 1.5 .007 301 1300 1301 1 1. 5 385 0 0.420.017 302 1301 1302 1 1.5 100 0 0.021 303 1302 1303 1 1.5 100 0 00.025 ' 304 1303 1304 1 1.5 225 .390.030 305 1304 1305 1 1.5 135 0 0.030 306 1305 1306 1 1.5 270 0 00.030 ' 307 1306 1307 1 2.25 346 0.017 308 1307 1308 1 2 450 0 0.0.017 309 1308 1309 1 2 140 0 00.017 310 1309 1310 1 2 147 0.45 0.017 311 1310 1311 1 2 277 0 00.017 312 1311 1312 1 2 133 0 00.017 313 1312 1313 1 2 150 00.017 314 1313 1316 1 2 169 0.58 00.017 ' 317 1316 1317 1 2 200 0 0.017 318 1317 1318 1 2 150 0.017 319 1318 3000 1 2 500 0.027 320 1319 1320 1 1 327 00.017 ' 321 1320 1321 1 1 157 00.017 ' C.3 i� 322 1321 1322 1 1 193 0 0.017 323 1322 1323 1 2 390 0 00.030 ' 324 1323 1324 1 2 270 0 00.030 325 1324 1325 1 2 250 0 00.030 326 1325 1326 1 2 250 0 00.030 327 1326 1327 1 2 270 0 00.030 328 1327 1328 1 2 270 0 00.017 329 1328 1316 1 2 380 0 00.017 351 1351 1352 1 6 100 0.004 352 1312 1351 1 6 100 0.004 ' 401 1401 1001 1 3 295 .30.017 402 1402 1401 1 3 100 0.028 403 1403 1402 1 3 220 . 10.030 ' 404 1404 1403 1 1.5 130 .017 405 1405 1403 1 3 200 .030 430 1430 1001 1 2.5 242 .017 431 1431 1430 1 2 100 .007 ' 432 1432 1431 1 2 120 0.030 433 1433 1432 1 2 100 1.30.029 434 1434 1433 1 2 100 0.030 s 435 1435 1434 1 2 130 0.030 ' 436 1436 1435 1 2 480 0.030 437 1437 1436 1 1. 5 440 0.030 438 1438 1437 1 1.5 190 .030 439 1439 1438 1 1.5 150 .030 ' 450 1.450 1430 1 2.5 100 .007 ' 451 1451 1450 1 2 100 0.025 452 1452 1451 1 2 125 0.030 453 1453 1452 1 2 225 0.030 ' 454 1454 1453 1 2 200 0.030 i 461 1461 1460 2 2 40 100 .030 f 462 1401 1461 1 3 100 1.5 .007 601 1601 1001 1 6 100 0.014 ' 602 1602 1601 1 6 225 0.017 603 1603 1602 1 6 198 0.017 604 1604 1603 1 6 190 0.017 ' 605 1605 1604 1 6 133 0.017 606 1606 1605 1 6 180 .017 607 1607 1606 1 6 102 .017 608 1608 1607 1 6 174 .017 ' 609 1609 1608 1 6 300 .017 610 1610 1609 1 6 300 .017 611 1611 1610 1 6 165 .017 612 1699 1611 1 6 264 .017 ' 699 1612 1699 1 4 100 1.10.013 j 800 1000 1801 1 4 100 .017 !l 801 1801 1802 1 3.5 160 .017 802 1802 1803 1 3.5 290 .017 ' 803 1803 1804 1 3.5 300 .017 d 804 1804 1805 1 3.5 300 .017 805 1805 1806 1 3.5 300 .017 806 1806 1807 1 3.5 137 .017 ' 807 1807 1808 1 3. 5 100 .009 808 1808 1809 1 2. 5 186 .017 809 1809 1810 1 2 . 5 147 .017 ' 810 1810 1811 1 2.5 100 .012 811 1811 1812 1 2.5 113 .017 812 1812 1813 1 2.5 100 .011 813 1813 1814 1 2.5 100 .011 ' 814 1814 1815 1 2. 5 100 .017 820 1829 1801 1 2. 5 100 .017 I ' CA �1 830 1830 1840 1 1. 5 200 .017 840 1840 1841 1 1.5 176 .017 ' 841 1841 1842 1 1.5 124 .017 842 1842 1843 1 1.5 200 .017 843 1843 1844 1 1.25 200 .017 844 1844 1845 1 1.25 217 .017 ' 845 1845 1846 1 1 250 .017 846 1846 1847 1 1 250 .017 851 1801 1852 1 3 100 0.004 852 1852 1853 1 3 300 .017 853 1853 1854 1 3 300 .017 854 1854 1855 1 3 300 .017 855 1855 1856 1 3 156 .017 856 1856 1857 1 3 300 .017 857 1857 1858 1 3 300 .017 858 1858 1859 1 3 300 .017 859 1859 1860 1 3 216 .017 860 1860 1861 1 3 300 .017 ' 861 1861 1862 1 3 300 .017 862 1862 1.863 1 3 300 .017 863 1863 1864 1 3 300 .017 i ' 864 1864 1865 1 3 100 .004 11 1001 2001 2 5. 5 10.3 100 0.027 21 2001 3001 2 7.3 8.7 100 0.027 3 3001 3002 6 7 3.25 166 0.045 0.8 10 ' 31 3002 4001 2 5 11.7 100 0.027 4 4001 4002 6 7 6.5 100 0.038 5 3.6 41 4002 5001 2 5 11.7 100 0.035 5 5001 5002 6 7 7.5 500 0.052 3 3 ' 150 1150 2001 1 4 400 0.035 151 1151 1150 1 4 480 0.017 152 1152 1151 1 4 480 .017 153 1153 1152 1 4 480 .017 154 1154 1153 1 4 480 .017 99999 1700 43 37 1710 36 31 ' 17 35 31 730 30 110 89 1740 35.5 32.2 1741 37 34.5 1742 80.0 68.8 750 39 34.5 1351 34 26.4 1352 34 26.4 t1353 34 26.4 1001 26.0 15.2 1100 40.0 16.4 1101 24.4 16.4 ' 1102 25.3 17.1 1103 25.5 16.7 1104 25.3 17.0 ' 110 2 . 1 . 1106 27.9 19.7 1107 27.8 20 1108 27.7 19.4 ' 1109 28.7 20.5 1199 29.019.55 1000 30.4 19.0 1300 30.4 21 ' 1301 30 21.6 �' C.5 1302 28 21.4 t1303 29 21.2 1304 29 21.7 1305 29 20 1306 29 20 ' 1307 30.5 19.0 1308 27.8 18.5 1309 28.6 18.3 1310 28 18.0 ' 1311 27.6 17.6 1312 27.2 17.3 1313 27 17 1316 26.6 16.9 ' 1317 27.5 16.8 1318 27.5 17.2 3000 24 15 1319 28.1 23.1 ' 1320 28.1 23.1 1321 28.9 22.9 1322 30 22.6 1323 30 21.5 ' 1324 29.4 21.1 I 1325 28.9 20.6 1326 27.7 20 1327 26.9 19.4 ' 1328 26.8 18.1 I 1201 30.6 21.5 1202 33.2 23.6 ' 1203 37.4 28.8 I 1204 89.4 85.4 1205170.4162.1 1206186.4178.9 ' 1207209.0195.8 1250 115 112 1251 138 135 1252162.4158.8 ' 1253208.1204. 5 1401 32.3 21.8 1402 51.2 40.7 1403 96.4 84.4 ' 1404121.3 110 1405 104 90.1 1430 28.1 20.5 1431 28.1 20.6 ' 2432 31.7 22.2 1433 29.9 24.8 1434 29.8 25.7 1431 30.2 25.2 1436 31.6 26.8 1437 32.8 28.3 1438 33.5 28.7 1439 93 87.5 ' 1450 28.7 20.6 1451 31.5 22 1452 33.5 27.0 ' 1453 35.4 28.2 1454 31.5 28.5 1460 32.2 28.6 1461 31.5 28.4 ' 1801 27.8 20.6 1802 27.0 20.9 ' C.6 i0 .. 10 1803 26.6 21.5 1804 26.9 22.1 180 27. 2 . 1806 27.4 23.3 10 1807 27.4 23.6 1808 27.9 23.7 2809 30 24.4 181010 31 25.0 10 1811 31 25.4 1812 31 2S.8 113 31 26. 1314 31.5 26.3 1815 35 26.7 18 28 21*3 1830 30 2924.254.25 1840 30 24.8 1841 35.3 30.1 184 36 3 .1 1843 37.2 32. 1 1844 38.4 33.1 4 1845 39.8 34.1 184 39 3 . 1847 40 36.8 1852 28.0 20.8 1853 29.5 21.5 1854 3 . 2 . 1855 34.7 23.0 1856 37.8 23.4 1857 38.5 24.1 1858 3 .4 24. 1859 38.0 25.6 1860 38.3 26.2 1861 38.9 26.9 1862 38.4 27.7 1863 33.8 28.4 1864 36.0 29.2 1865 37.1 29.9 2001 26 14.9 3001 29 15 3002 22.8 14.8 4001 2 .8 14. 4002 255.2 14.3 5001 25.2 14.3 5002 30 12.3 160 24. 16. 1602 26.7 16.3 1603 24.8 16.4 1604 25.2 16.4 160 25.4 1 . 1606 25.4 17.0 1607 26.4 18.2 1608 27.6 18.4 16 2 . 1 . 1610 10 28. 5 19.0 1611 29.5 19.2 1612 29.8 20.7 1699 29.6 19.4 1150 26.0 18. 1 1151 24.3 19.4 115 28 2 . 1153 29 22.4 C.7 ' 1154 30 23.8 99999 1351 3490000 1352 3490000 1353 3470000 1830 2925000 14 31.5 0 1460 60 31.6 550500 1461 31.5 5500 1001 26.0 500 1742 80.0 6500 99999 1199 1699 1 12.56 1 ' 1000 1300 1 1.77 1 1 1307 1319 1 0.79 1 5.5 1204 1605 1 7.07 1 0 1351 1303 1 0.79 1 0.6 ' 1311 1304 1 0.79 1 0.2 1351 1305 1 0.79 1 0.0 1351 1301 1 0.79 1 1.6 1351 1306 1 0.79 1 0.1 4 1351 1307 1 0.79 1 1.4 1830 1829 1 0.86 1 0 1830 1829 1 1.08 1 1.34 1602 1100 1 12.6 1 1460 1432 1 7.07 1 1461 1451 1 7.07 1 99999 99999 99999 5002 3000 99999 99999 2 15 99999 1404 1405 1207 1301 1303 1305 1307 1309 1311 1313 1317 1321 1323 1325 1327 1808 1810 1812 1814 1815 1841 1843 1845 1847 1865 1154 1604 1102 1104 1106 1108 1109 1001 1451 1431 1433 1435 1437 1700 1711 1710 1405 1452 1453 1454 1439 1742 730 1742 1700 1252 C.8 '' Y LAKE 'RASH I N6TCN �I LEGEW T O P I PE JLWT I ON 5L172 ' 0 STORME JUNCTION 5001 2000 JUNCT I ON NMER &v7- .PIPE/OPEN CHANNEL 4001 E INFLOW OR OUTFL.C1 1001 ' 200E 14N too I E- 1001 1 40 1 1 402 1 403 100 1440 19G I 1 404 1 1 50 1 405 l I GOl 1430 1450 145 I + ' 1101 l LOZ 193 I S 1 952 1151 11OZ 1403 I932 1433 C 1453 1435 0 11 52 1103 I G04 143 1 454 1 1 04 1405 160G I436 D n n i 153 1105 1 437 W A I 407 Z 1 439 I 154 I I OG 2 1 G16 1436 1107 1 609 1 7 1 1 1 7-41 1 742� NOT TO SGALE 1106 m a I 0 ]log Z 1411 1710 1740 1199 1411 N N N o 1300 I coo1 61 2 1 20 I 120Z 1203 1 30 1 N.Stl%. St. 750 ' 351 1302 1 253 a. = = '^ 1 352 -1303 1601 a a o a o 125Z E-- 1 353 ' 1 304 I aoz 181.1 1 an 1 700 1 Z5 1 - _ - - - - 0 _ N 1 043 i 657 1 250 305 1603 & p O O O O 1 644 CEDAR' 1 304 I a04 — — — — 1 656 1 730 R I VER ^ 1 307 1 605 - 1 845 1 654 1326 1 31 9 I aaG 1 647 164c 1&4 1 ' 1327 1 320 1 007 1 bA 1 1 32G 1 32 1 1 606 1 642 IWL-OV2 ON VALLEY FLR]R DI9TriniRD ^ s a o a 6L I3 EQUALLY TO .U,4T10J5 a o 0 16G4 IN VICINITY. 645 0,1.1,sr 6, 1 9?Z tPARK AVENUE NORTH REGIONAL DRAINAGE STUOY 4011 [ HTRAH CO Figure C-1 ' Schematic of Pipe System Modeled with Extran C.s �.. :�::} i I �. I I