HomeMy WebLinkAboutAppendix D - MAPTPRELIMINARY DRAFT FOR MULTI-AGENCY PERMITTING TEAM (MAPT) REVIEW
APPENDICES
I-405 Water Resource Initiative at Panther Creek Wetlands
Panther Creek Watershed Rehabilitation Conceptual Plan
A PPENDIX D
Hydraulic and Hydrologic Analyses
Memoranda
PRELIMINARY DRAFT FOR MULTI-AGENCY PERMITTING TEAM (MAPT) REVIEW
APPENDICES
I-405 Water Resource Initiative at Panther Creek Wetlands
Panther Creek Watershed Rehabilitation Conceptual Plan
December 22, 2006 nhc
MEMORANDUM
northwest hydraulic consultants inc. 16300 christensen road, suite 350
seattle, washington 98188-3418
(206) 241-6000
fax no. (206) 439-2420
DATE: December 22, 2006
TO: WSDOT I-405 Project Team
FROM: Northwest Hydraulic Consultants Inc. (nhc)
SUBJECT: Panther Creek Watershed Rehabilitation Memo, Tukwila to Renton Improvement
Project
This memorandum describes hydrologic modeling and analyses within the Springbrook Creek
basin conducted by nhc as part of Task AC of Work Order Y-9573 for the I-405 Project Team’s
(STATE’s) Tukwila to Renton Improvement Project (TRIP). The purpose of this work was to
assess potential hydrologic impacts to the Panther Creek Wetland and Springbrook Creek
tributaries as a result of altered land use, detention, and diversions under the proposed Master
Plan conditions.
The work described in this memorandum is similar in concept to previous work done by nhc
under Task AB of UCO Agreement Y8534 – Part II: Support of Nickel Project Downstream
Analysis. Baseline conditions and several land use and detention pond alternatives were
simulated and compared to provide an evaluation of hydrologic impacts of the proposed
alternatives. The STATE is developing proposals for numerous improvement projects along the
I-405 and SR-167 corridors. nhc has developed a suite of HSPF models to represent these
different scenarios. The modeling and analysis done by nhc in support of the Tukwila to Renton
Improvement Project is reported in three separate technical memorandums: “Implementation
Plan” which addresses near term highway improvements, “Master Plan” which addresses longer
term highway improvements, and “Panther Creek Watershed Rehabilitation” which describes
hydrologic analyses as related to the Panther Creek Watershed.
HSPF Modeling Scenarios Developed for Master Plan Analysis
Numerous conveyance system and land-use alternatives have been previously modeled in the
Springbrook Creek basin. A subset of these has been selected for inclusion in the TRIP
hydrologic analyses. These include:
Basin Land-use (non Project areas): Full build-out condition as per the flood insurance
study model (nhc, 2003)
Renton Village Shopping Center Conveyance System: Proposed improved condition
as per the ESGRWP modeling (nhc, 1996)
Panther Creek Flow Routing: Current condition with the primary flow path to the
Panther Creek Wetland, and a secondary flow path to SW 34th Street, as described in
nhc Part II report (nhc, June 2006), and proposed condition with all flow directed into the
Panther Creek Wetland
SW 19th Street Outlet from Rolling Hills Creek/Panther Creek Wetland: Existing
condition and a modified condition reflecting the “compromise conditions” as described
in nhc’s Panther Creek Wetland Hydrologic Analysis report (nhc, February 2006)
December 22, 2006 nhc 2
SW 23rd Street Outlet from Panther Creek Wetland: Existing condition and a modified
condition developed for this study to mitigate increased peak flows in Springbrook Creek
resulting from increased flows via the SW 19th Street system. The design of the modified
condition is conceptual only and not currently reflected in the STATE’s Master Plan
scenario
SW 34th Street Outlet from Panther Creek/Panther Creek Wetland: Existing condition
as described in nhc’s Part II report (nhc, June 2006)
Table 1 summarizes the land use and conveyance characteristics of the different HSPF models
developed by nhc under this work assignment. With so many alternative land-use and
conveyance scenarios it is problematic, if not impossible, to fully describe each scenario with a
brief name. Therefore, for purposes of this project, each combination of project elements (land-
use and conveyance system characteristics) is referred to simply by the scenario numbers as
shown in Table 1. The Master Plan analyses were conducted using scenarios 1, 2, 7, and 8.
None of the scenarios described in this memo are exactly identical to any of the scenarios
modeled previously in the “Panther Creek Wetland Supplemental Hydrologic Analysis” memo
(nhc, February 2006). Changes in model set up include adjustments in drainage areas, the
option of directing all of Panther Creek to the Panther Creek Wetland, and a modified SW 23rd
St channel outlet.
Exhibits A and B provide schematics of the HSPF subbasin layout and routing assumptions
under the baseline conditions, scenarios 1 and 2, respectively. Exhibits C and D show the
subbasin layout under the Master Plan conditions (scenarios 7 and 8) including the Threshold
Discharge Area (TDA) subbasins and flow routing corresponding to the STATE’s proposed
detention. The schematics only depict the Springbrook Creek system and key tributaries north
of SW 43rd St / S 180th St. Additional upstream reaches and subbasins were modeled but
because these are not affected by the Master Plan proposal they are not shown on the
schematics.
Representation of Subbasins and Flow Control Facilities under Master Plan Conditions
Subbasin boundaries delineated for the HSPF model of the Springbrook Creek basin sometimes
correspond to the centerline of a highway (I-405 and SR-167). While it is known that local
drainage systems along these highways sometimes divert runoff from one side of the highway
to the other, these minor transfers were not field investigated or reflected in the original HSPF
modeling conducted for this basin. When evaluating land-use changes at the scale of the TRIP
improvements, it is more important to consider these minor connections and their effect on
basin tributary acreage. To account for these connections without fully reworking the basin
land-use analysis (which was beyond the scope of this study) the subbasin acreages for several
basins in the baseline scenarios (1 & 2) were adjusted to transfer grass land cover from one
subbasin to an adjacent subbasin. The amount of grass land cover transferred was set equal to
the area of new impervious surface that will be built and directed to the receiving subbasin
under the Master Plan (as this is the area identified by the STATE as currently draining to that
location due to the highway drainage systems). Since the Master Plan includes the largest
increase in impervious surface areas, these land adjustments are suitable to be used for the
Implementation Plan also. The adjustments in grass area by subbasin are summarized in Table
2.
The Master Plan land use includes the baseline conditions described above with changes made
to account for the STATE’s planned roadway improvements. The first step in developing the
Master Plan land use was to convert existing grass areas to impervious area. Next, a portion of
the new and existing impervious area in some subbasins was transferred to subbasin 101 to
represent direct discharge to the Panther Creek Wetland (Table 3 and Exhibits C and D). The
December 22, 2006 nhc 3
diversion acreages were computed using GIS analysis of the STATE’s design and represent
areas where the proposed grade allows the highway runoff to be directed into the wetland. As
per discussions with Alan Black, additional impervious area from TDA S3 was also assumed to
direct discharge to the Panther Creek Wetland. This area corresponds to the impervious area in
subbasins 17, 25, and 107b that exceeds the mitigation capacity of the proposed pond in TDA
S3 in subbasin 17.
The STATE provided nhc with designs for four TDA flow control facilities for use in the Master
Plan modeling. In the HSPF model, runoff from the TDA areas was first routed to a reach with
stage-storage-discharge characteristics matching the characteristics of the respective TDA flow
control facility. The outflow from these reaches was then directed to the reach representing the
subbasin encompassing the TDA. The detention pond for TDA S1 is located in HSPF subbasin
7 which enters Springbrook Creek downstream of SW 19th St. There are two flow control vaults
in TDA S2, both located in subbasin 103 (which discharges to Rolling Hills Creek at I-405). The
detention pond for TDA S3 is located in subbasin 17 (and discharges to the SW 23rd St
Channel).
The modeled changes in impervious area, flow diversions to the Panther Creek Wetland, and
flow control facilities representing the Master Plan are summarized in Table 3. Table 4 and
Table 5 provide a land use breakdown for the Baseline and Master Plan Scenarios,
respectively. Only basins where changes were made for the Master Plan scenarios are shown
in these tables.
Downstream Flow Analysis
nhc performed downstream analyses to summarize the hydrologic differences between the
baseline and Master Plan scenarios. Peak flows and flow durations were evaluated at locations
a-f below to evaluate compliance with King County’s Level 3 flow control criteria. Additional
analyses at locations g and h below were performed to evaluate impacts to the Panther Creek
Wetland.
a. Comparison of flow peaks and durations in the Thunder Hills Creek tributary
downstream of I-405 (Reach 115)
b. Comparison of flow peaks and durations in the Rolling Hills Creek tributary at I-405
downstream of the Renton Village Shopping Center (Reach 103)
c. Comparison of flow peaks and durations at the upstream and downstream ends of the
SW 19th Street drainage system (i.e. the northern outlet from the Panther Creek
Wetland) (Reaches 102-1 and 11)
d. Comparison of flow peaks and durations at the upstream and downstream ends of the
SW 23rd Street channel (i.e. the central outlet from the Panther Creek Wetland)
(Reaches 101 and 17)
e. Comparison of flow peaks and durations at the upstream, and downstream end of the
SW 34th Street drainage system (i.e. the southern outlet from the Panther Creek
Wetland). (Reaches 105-1 and 25)
f. Comparison of flow peaks and durations in Springbrook Creek downstream of the SW
19th Street tributary (i.e. downstream of the northernmost project impact) (Reach 7)
December 22, 2006 nhc 4
g. Evaluation of hydroperiod impacts in the Panther Creek wetland based on a comparison
of the existing and proposed conditions stage durations (Reach 101)
h. Comparison of average monthly flows from Panther Creek into the south end of the
Panther Creek Wetland (Reach 106-1 in Scenarios 1 and 7, Reach 107 on Scenarios 2
and 8)
The Level 3 standard is the most stringent flow control standard in common use in King County
and is intended to mitigate potential stream channel erosion and wetland water level changes
resulting from development projects. When evaluating flow durations, the Level 3 criteria
requires that no more than 50% of the flow levels evaluated between ½ the 2-year through the
50-year flow show any increase in flow durations. The Level 3 standard also requires that the 2-
year, 10-year, and 100-year peak flows be maintained at or below their predevelopment level.
The Level 3 standard is intended to ensure that receiving drainage systems are not adversely
hydrologically impacted by a development project.
Peak Flow and Stage Analysis
Peak flow frequency analysis was performed by extracting simulated annual maximum hourly
flows and fitting these with theoretical distributions using the methodology described in WRC
Bulletin 17B. Locations where the theoretical fit was poor were fit by hand. Table 6 compares
the peak flow quantiles for the four scenarios evaluated in the Master Plan analysis. To
establish compliance with the Level 3 standard the 2-year, 10-year, and 100-year peaks flows
should be maintained at or below the baseline level. Figures 1-10 display the peak flow and
stage frequency data and the fitted theoretical distributions. The flow frequency quantiles
estimated from these fitted distributions are provided in Table 6.
Flow and Stage Duration Analysis
The results of the flow and stage duration analyses are provided in Tables 9-28 and Figures 11-
30. The odd numbered tables (9, 11, 13…27) compare the results of Master Plan scenarios 7
and 8 to baseline scenario 1. The even numbered tables (10, 12, 14…28) compare Master Plan
scenarios 7 and 8 with baseline scenario 2.
In the flow duration tables (Tables 9-26), columns were added to indicate compliance, or lack
thereof, with the Level 3 criteria. The first added column counts the number of times that flow
durations exceed the baseline between ½ of the 2-year and the 50-year flow. A “1” indicates
that the flow duration exceeds the baseline and a “0” indicates that the flow duration is below
the baseline (blank cells indicate rows outside the limits of the evaluation). To demonstrate
compliance with the Level 3 criteria flow durations no more than half of the flow levels can show
an increase in flow durations relative to the baseline condition. The second added column
displays the percentage change in flow duration at each level. The Level 3 criterion requires that
none of the flow duration increases exceed 10%. At the bottom of each compliance column is a
summary of whether the Level 3 criteria has been achieved or not for that location and scenario.
The flow and stage duration figures display two x-axes; the x-axis on the bottom shows the
exceedence probabilities as listed in the corresponding tables while the upper x-axis displays
the exceedence probability translated into average hours per year. To read the flow duration
figures, select a flow of interest from the Y axis and trace right, across to the point plotted for the
scenario of interest, then trace up or down to find the average hours per year (upper axis) or
exceedence probability (lower axis) corresponding to that flow.
December 22, 2006 nhc 5
Panther Creek Wetland Stage Hydrographs and Inflows from Panther Creek
In addition to the peak stage frequency analysis and stage duration analysis, an analysis of the
average monthly and daily stage for Panther Creek W etland was performed. The 10th, 50th, and
90th percentiles were computed from the monthly and daily stage data. This analysis is
presented in the form of daily stage hydrographs displayed in Figure 31 and tabulated monthly
results in Table 7. Average monthly inflows from Panther Creek into Panther Creek Wetland are
tabulated in Table 8.
Discussion of Results
The key questions to be addressed by the hydrologic analysis of the alternatives include:
1) What happens to Panther Creek Wetland water surface elevations compared to existing
conditions?
2) What is the impact on flood flows in the 23rd Street channel and how might this affect
backwater conditions in the East Valley stormwater drainage system?
3) What happens to the peak flows in Springbrook Creek downstream of the SW 19th Street
tributary?
4) Are King County’s Level 3 flow control criteria met at locations evaluated by this study?
Each of these questions is addressed below.
1) What happens to Panther Creek Wetland water surface elevations compared to existing
conditions?
Relative to baseline conditions, the impacts to wetland stages are anticipated to be small except
during large storm events. The impacts to peak wetland stages are displayed in Figure 10 and
Table 6. The estimated 100-year peak stages under scenario 1 and scenario 8 are 18.6 and
19.4 feet, respectively. The primary reason for this increase is the modified outlet from the
Panther Creek Wetland to the SW 23rd St. channel incorporated in Scenario 8. With the modified
outlet the wetland stores water slightly longer during large events to help mitigate downstream
peak flow increases in the SW 23rd St channel and in Springbrook Creek. The increase in 100-
year peak stage caused by the Master Plan improvements without the modified outlet is only 0.1
feet (as can be seen by comparing Scenario 7 with Scenario 1).
While the modeling indicates that the peak stages in the wetland will increase, higher stages will
not be maintained for an extended period of time. The stage duration analyses are shown in
Tables 27 & 28 and Figures 29 & 30. The Master Plan scenarios (7 and 8) begin to show
deviations from the baseline conditions for events with less than a 15% chance of exceedence.
That means that 85% of the time there will be no change in wetland stage. It is not until the near
0.1% exceedence level that the deviation in wetland stage exceeds one inch.
The wetland stage hydrographs provide a seasonal context to the wetland stage impacts. They
also demonstrate that change in wetland elevation averaged over a longer period of time shows
minimal change. The daily wetland stage hydrographs are shown in Figure 31 and a tabular
monthly summary is provided in Table 7. The most significant changes relative to the baseline
condition are shown at the 10% chance exceedence level during the fall and winter months.
However, the maximum change in average monthly water level is still less than half an inch.
2) What is the impact on flood flows in the 23rd Street channel and how might this affect
backwater conditions in the East Valley stormwater drainage system?
December 22, 2006 nhc 6
Flood flow frequency plots and tabulated quantiles for the upstream and downstream ends of
the SW 23rd St channel are shown in Figures 5 and 6 and Table 6. Implementing the
compromise outlet condition at the SW 19th Street outlet and the modified outlet to SW 23rd
Street (Scenario 2) increases the peak flow at lower recurrence intervals (4 cfs increase at the
2-year level) but decreases the peaks flows during the larger events (25 cfs decrease at the
100-year level). If only the Master Plan modifications are made (Scenario 7), increases to the
peak flow at the downstream end 23rd St channel are in the range of 2 to 7 cfs between the 2-
year and 100-year return period. Implementing both the wetland outlet modification and the
Master Plan modifications (Scenario 8) results in slightly larger peak flows up to the 5-year
recurrence interval but reduces the peaks for less frequent return intervals.
A backwater analysis of the East Valley Road drainage system assuming a constant tailwater
condition for the 23rd St channel was performed by RW Beck as part of 2004 East Side Green
River Watershed Plan. The analysis suggests that there are flooding issues at the 25 and 100
year levels (Mike Giseburt, 8/18/2006). As described above, scenarios 2 and 8 reduce peak
flows in the SW 23rd St channel above the 5–year level. These reductions could help reduce the
likelihood of flooding in the East Valley drainage system.
Tables 17-20 and Figures 19-22 display flow duration information for flows in the 23rd St
channel. Table 17 compares flow durations at the Central Panther Creek Wetland Outlet for
scenarios 1, 7, and 8 using scenario 1 as the baseline. Scenario 7 shows a consistent pattern of
increased flow durations, while scenario 8 shows that flow durations for flows up to about 100
cfs will be increased but the duration of higher flows will be reduced. At this location, 100 cfs
corresponds to about a 5-year event. Thus flows below about the 5-year level are expected to
increase in the East Valley drainage system with the duration of higher flows being reduced if
the proposed modifications to the SW 19th and SW 23rd St outlets are implemented.
3) What happens to the peak flows in Springbrook Creek downstream of the SW 19th Street
tributary?
Peak flows in Springbrook Creek downstream of the SW 19th Street Tributary is quite sensitive
to changes in the outlets from Panther Creek Wetland and less sensitive to land-use changes
proposed under the Master Plan. The flood flow frequency results for Springbrook Creek are
shown in Figure 9 and Table 6. With implementation of the Master Plan (scenario 7) the 100-
year peak flows at this location are predicted to increase to 1396 cfs from 1395 cfs (scenario 1).
The 100 year peak flow under either Scenarios 2 or 8 is 1387 cfs. The reduction as compared to
scenarios 1 and 7 is a result of the modified outlet from the Panther Creek Wetland to the SW
23rd St channel. Preliminary runs which did not include the modified wetland outlet indicated that
downstream flows would increase mainly due to the coincidence of peak flows from the SW 19th
system (under compromise conditions) with the peaks in Springbrook Creek.
4) Are King County’s Level 3 flow control criteria met at locations evaluated in this study?
Evaluating whether King County’s Level 3 flow control criteria are met at a given location
requires pre- and post-development scenarios. In addition to the development of the Master
Plan project, this study also looks at different flow management scenarios. So depending upon
which two scenarios are compared, the effects of the project development, flow management
options, or both will be highlighted. Baseline scenario 1 represents pre-development conditions
with no flow management changes. Baseline scenario 2 represents pre-development conditions
with multiple flow management changes throughout the basin. Scenarios 7 and 8 modify
scenarios 1 and 2 respectively with post-development Master Plan conditions. Comparing
December 22, 2006 nhc 7
scenario 1 to 7 and scenario 1 to 8 provide the most meaningful comparisons when evaluating
Level 3 flow control compliance.
Level 3 flow control is met at all of the locations evaluated in this study with the exceptions
described below:
SW 19th St System/North Panther Creek Wetland Outlet - With the proposed
modifications to the North Panther Creek Wetland outlet (Scenario 8) flows in this conveyance
system will exceed pre-development flows. These flow increases will not pose an increased
flooding risk based on knowledge of additional capacity in the SW 19th street system.
SW 23rd St System/ Central Panther Creek Wetland Outlet- Without the proposed
modification to the Central Panther Creek Wetland outlet (Scenario 7) there will be a slight
(<1%) increase in flows due to direct discharges to the wetland. With the proposed change to
the central outlet (Scenario 8) the 2-year peak will be exceeded but the 100-year peak will be
reduced as described in the SW 23rd St channel flooding discussion above.
Springbrook Creek downstream of SW 19th St. – Without the wetland outlet modifications
(Scenario 7) the 100-year peak flow in Springbrook Creek downstream of SW 19th St will
increase by about 1 cfs. This is not a significant increase but does constitute a violation of the
Level 3 flow control standard.
The flow duration component of the Level 3 flow control standard is primarily intended to reduce
channel and streambank erosion rates. The locations of interest in this study are very low
gradient systems and many are pipe systems which make erosion less likely or irrelevant.
Thus, in this study, a violation of the flow duration component of the Level 3 standards is not
anticipated to be problematic.
Conclusions
Implementing the Master Plan land-use and detention changes alone (Scenario 7) would result
in slightly higher peak stages in the Panther Creek Wetland and peak flows in the SW 23rd St
channel and Springbrook Creek downstream of SW 19th Street. Implementing the additional
wetland outlet modifications at SW 19th St and SW 23rd St. (Scenarios 2 and 8) has the potential
to help reduce flooding in the East Valley drainage system along the SW 23rd St. channel and
reduce peak flows in Springbrook Creek downstream of SW 19th St. During large events,
wetland water levels in the Panther Creek Wetland will be somewhat higher than under the
baseline conditions but these increases will be short lived and more typical wetland stages will
not be affected. Level 3 flow control standards are not met at some locations in the Springbrook
system. However, when considering the basin as a whole, the Level 3 violations may be
reasonable when they do not pose additional local flooding risks but provide a benefit elsewhere
in the system.
December 22, 2006 nhc 8
References
Northwest Hydraulic Consultants, June 13th 2006. Part II, Support the Nickel Improvement
Project Downstream Analyses, letter report prepared for I-405 Team
Northwest Hydraulic Consultants, February 17th 2006. Panther Creek Wetland Supplemental
Hydrologic Analysis, letter report prepared for I-405 Team
Northwest Hydraulic Consultants, 2003. Hydrologic Analysis for Floodplain Mapping Study of
Springbrook Creek, King County, Washington, report prepared for City of Renton
Northwest Hydraulic Consultants, March 1996. East Side Green River Watershed Hydrologic
Analysis, report prepared for R.W. Beck and City of Renton
e-mail from Alan Black (7/12/2006) Personal communication regarding diversions from TDA
S3 to Panther Creek Wetland which exceeded TDA S3 detention capacity.
e-mail from Mike Giseburt (8/18/2006) Personal communication regarding flooding issues
associated with the SW 23rd St System.
U.S. Water Resource Council, “Guidelines for Determining Flood Flow frequency,” Bulletin 17
B, 1981
Table 1 Project Elements in Scenarios to Be Simulated with the HSPF Model Scenario ExistingImplementation PlanMaster Plan Yes No Unimproved ImprovedDiverted To PCWExisting (2006)To SW 34th (pre 2006) Existing Optimized Compromise Existing Modified ExistingOptimized/ Compromise1 xx x x x x2 xx xx x x3 x x x x x x x4 x x x xx x x5 x x x x x x x6 x x x xx x x7 x x x x x x x8 x x x xx x xNotes:Full Buildout Conditions Land-useWSDOT Land-use 2Basin Land-use (except WSDOT) 15 Panther Creek Flows indicates whether the flows in Panther Creek at the South end of the PCW are to be modeled as current conditions, as modeled prior to 2005, or as fully diverted to the PCW 1 Basin Land-use includes all areas not included in the Tukwila to Renton Improvement Project2 WSDOT Land-use referes to all areas where land cover will be converted by the Tukwila to Renton Improvement Project3 WSDOT Detention indicates if the TRIP project is to have detention facilities or proposes direct discharge4 Renton Village Storm Drain System indicates whether the model scenario is to assume the current, flood prone state of the conveyance system through renton Village or an improved condition SW 34th Street Outlet from PCW 8Panther Creek Flows 5SW 19th Street Outlet from PCW 6SW 23rd Street Outlet from PCW 76 SW 19th Street Outlet from Panther Creek Wetland indicates whether the model scenario is to assume the current condition, the flooding optimized condition or the compromise condition as per nhc's 2006 PCW analysis7 SW 23rd Street Outlet from Panther Creek Wetland indicates whether the model scenario is to assume the existing condition or the modified condition. The modified condition was developed during the current analysis and is applied when the SW 19th St outlet is modeled as the compromised condition. 8 SW 34th Street Outlet from Panther Creek Wetland indicates whether the model scenario is to assume the current condition or the flooding optimized/compromise condition as per nhc's 2006 PCW analysis Renton Village Storm Drain System 4WSDOT Detention 3
Table 2 Land Use Adjustments in Baseline Scenarios 1 and 2 Subbasins with increases in Grass area (acres)7101103107B6.52 3.39 0.29 0.25Subbasins with reductions in Grass area (acres)5 11 17 19 25-3.86 -1.64 -2.51 -1.48 -0.98 Table 3 Land Use Changes and Diversions for Master Plan Scenarios 7 and 8 Subbasin5 7 11 17 25 101 103 103A 103B 103C 107BTDA SubtotalsTDA S1 0.79 12.74 0.49 14.02TDA S2 7.61 6.52 14.88 2.84 2.19 34.04TDA S31.068.414.965.490.2520.17HSPF subtotals0.79 12.74 8.67 8.41 4.96 12.01 15.37 2.84 2.19 0.00 0.25Subbasin5 7 11 17 25 101 103 103A 103B 103C 107BTDA SubtotalsTDA S22.15 9.993.192.050.2517.64TDA S3 5.59 4.9610.55Subbasin57111725101103103A103B103C107BTDA S1 Pond 14.02TDA S2 (1) Vault6.34TDA S2 (2) Vault5.84TDA S3 Pond2.82TDA S2(1) also detains 1.3 acres of till-grassGrass Area Converted to Impervious Area under Master Plan (acres)Existing and New Impervious Area Which Direct Discharges to Panther Creek Wetland under Master Plan (acres)An additional 6.88 acres of existing and new impervious area from TDA S2 already fell within subbasin 101 which drains to the PCWImpervious Area Detained by Flow Control Facilites (acres)
Table 4 Land Use Acreages in Basins where Master Plan will have an Impact, Baseline Scenarios 1 and 2 SubbasinPERLND 13PERLND 23PERLND 31PERLND 41PERLND 51PERLND 62PERLND 72IMPLND 11S59.05 111.71 49.78 19.24 74.40 351.81 615.99S7 8.08 0.09 17.43 63.97 89.57S9 0.55 14.03 68.38 82.96S11 17.54 4.17 54.33 76.04S17 37.07 0.02 3.85 153.09 194.03S19 14.69 0.01 19.31 127.34 161.35S25 1.56 28.02 5.24 180.92 215.74P10118.96 243.85 67.10 0.74 9.07 175.07 514.79P103 1.63 2.18 0.43 14.73 113.01 131.98P103A2.04 31.12 0.09 1.47 27.43 62.15P103B8.43 114.27 0.16 2.86 0.11 126.49 252.32P103C29.17 272.94 0.74 0.10 2.00 161.20 466.15P107B3.156.79 0.54 0.2738.9649.71Impervious Total AreaOutwash Grass WetlandAlluvium ForestAlluvium GrassTill Forest Till GrassOutwash Forest Table 5 Land Use Acreages in Basins where Master Plan will have an Impact, Master Plan Scenarios 7 and 8 SubbasinPERLND 13PERLND 23PERLND 31PERLND 41PERLND 51PERLND 62PERLND 72IMPLND 11S59.05 111.71 49.78 19.24 73.61 352.60 615.99S7 8.08 0.09 4.69 62.69 75.55S9 0.55 14.03 68.38 82.96S11 13.04 60.85 73.89S17 32.51 0.02 153.09 185.62S19 14.69 0.01 19.31 127.34 161.35S25 1.56 28.02 0.29 180.92 210.79P10118.96 231.84 67.10 0.74 9.07 215.01 542.73P103 0.33 1.54 0.43 106.21 108.51P103A2.04 28.28 0.09 1.47 27.07 58.96P103B8.43 112.08 0.16 2.86 0.11 126.63 250.27P103C29.17 272.94 0.74 0.10 2.00 161.20 466.15P107B3.15 6.79 0.54 0.02 38.96 49.46TDA S1 14.02 14.02TDA S2 (1) 1.30 6.34 7.64TDA S2 (2) 5.84 5.84TDA S3 2.822.82Impervious Total AreaTill Forest Till GrassOutwash ForestOutwash Grass WetlandAlluvium ForestAlluvium Grass
Table 6 Peak Flow and Stage Quantiles Comparison - Master Plan Scn 1 Scn 2 Scn 7 Scn 8 Scn 1 Scn 2 Scn 7 Scn 8 Scn 1 Scn 2 Scn 7 Scn 8Thunder Hills Creek44.4 44.4 44.4 44.4 88.8 88.8 88.8 88.8 125 125 125 125Rolling Hills Creek at I-405101 101 99 99 202 202 199 199 281 281 276 276North Panther Creek Wetland Outlet26.3 33.6 26.0 33.3 52.7 67.2 52.0 66.7 67.6 78.3 66.8 77.8SW 19th St channel, downstream end31.1 34.3 31.4 34.4 62.1 68.5 62.8 68.9 69.7 75.6 70.3 76.2Central Panther Creek Wetland Outlet41.5 43.5 45.0 44.5 83.0 87.0 90.0 89.0 140 122 142 124SW 23rd St channel, downstream end45.0 44.8 45.5 45.0 90.0 89.5 91.0 90.0 152 146 154 147South Panther Creek Wetland Outlet13.4 3.0 13.4 3.0 26.8 6.0 26.8 6.0 33.7 8.5 33.7 8.5SW 34th St channel, downstream end18.3 18.1 18.3 18.1 36.5 36.1 36.5 36.1 37.7 36.5 37.7 36.5Springbrook Creek downstream of SW 19th St.359 365 360 366 718 730 720 733 1006 1012 1008 1013Panther Creek Wetland Stage (feet)8.3 8.4 8.3 8.4 16.6 16.7 16.6 16.8 17.5 17.9 17.6 18.010-year1/2 the 2-year 2-year Scn 1 Scn 2 Scn 7 Scn 8 Scn 1 Scn 2 Scn 7 Scn 8Thunder Hills Creek156 156 156 156 169 169 169 169Rolling Hills Creek at I-405347 347 341 341 375 375 369 369North Panther Creek Wetland Outlet80.9 86.2 80.0 85.7 86.7 89.2 85.7 88.7SW 19th St channel, downstream end75.6 80.3 76.0 81.2 78.0 82.0 78.3 83.0Central Panther Creek Wetland Outlet154 131 156 133 157 132 159 134SW 23rd St channel, downstream end166 147 168 148 168 148 169 149South Panther Creek Wetland Outlet38.4 10.8 38.4 10.8 40.2 11.8 40.2 11.8SW 34th St channel, downstream end38.1 37.0 38.1 37.0 38.2 37.3 38.2 37.3Springbrook Creek downstream of SW 19th St.1275 1272 1277 1272 1395 1387 1396 1387Panther Creek Wetland Stage (feet)18.3 18.9 18.4 19.0 18.6 19.3 18.7 19.450-year 100-year all flows in cfs
Table 7 Panther Creek Wetland Percentiles of Monthly Stage Data Month Scn 1 Scn 2 Scn 7 Scn 8 Scn 1 Scn 2 Scn 7 Scn 8 Scn 1 Scn 2 Scn 7 Scn 8OCT 15.02 15.03 15.04 15.05 14.42 14.42 14.43 14.43 14.07 14.07 14.06 14.06NOV 15.36 15.37 15.38 15.39 14.83 14.83 14.84 14.84 14.28 14.28 14.28 14.28DEC 15.42 15.43 15.43 15.45 14.90 14.90 14.90 14.91 14.48 14.47 14.48 14.48JAN 15.43 15.44 15.44 15.46 14.88 14.88 14.88 14.88 14.42 14.42 14.41 14.41FEB 15.34 15.35 15.35 15.36 14.84 14.84 14.84 14.84 14.43 14.43 14.42 14.42MAR 15.18 15.18 15.19 15.20 14.76 14.76 14.77 14.77 14.39 14.39 14.39 14.39APR 14.97 14.97 14.98 14.98 14.56 14.56 14.56 14.56 14.27 14.27 14.26 14.27MAY 14.76 14.76 14.76 14.76 14.32 14.32 14.31 14.32 14.18 14.18 14.18 14.18JUN 14.71 14.71 14.71 14.72 14.23 14.22 14.22 14.22 14.13 14.13 14.13 14.13JUL 14.46 14.46 14.46 14.46 14.14 14.14 14.14 14.14 14.08 14.08 14.08 14.08AUG 14.57 14.57 14.58 14.58 14.11 14.11 14.10 14.10 14.06 14.06 14.05 14.05SEP 14.75 14.75 14.76 14.76 14.12 14.12 14.12 14.12 14.05 14.05 14.05 14.0510% Chance Exceedance Percentile 50% Chance Exceedance Percentile 90% Chance Exceedance Percentile Wetland elevations in feet Table 8 Average Monthly Inflows from Panther Creek into Panther Creek Wetland (water years 1949-2001) Month Scn 1 Scn 2 Scn 7 Scn 8OCT 1.82 2.06 1.82 2.06NOV 4.55 5.20 4.55 5.20DEC 5.32 5.98 5.32 5.98JAN 5.41 6.02 5.41 6.02FEB 4.47 4.93 4.47 4.93MAR 3.27 3.50 3.27 3.50APR 1.84 1.99 1.84 1.99MAY 0.83 0.88 0.83 0.88JUN 0.71 0.77 0.71 0.77JUL 0.38 0.40 0.38 0.40AUG 0.49 0.55 0.49 0.55SEP 0.75 0.84 0.75 0.84 Flows in cfs
Table 9. Flow Duration Evaluation - Thunder Hills CreekScenario 1 Baseline - Master Plan MemoWindow of EvaluationScenario 1 Baseline1/2 2-yr (cfs) 44.450-yr (cfs)156.2Cutoff Flowcfs4645924645924645920.0 99.6800 463123 99.68 46312399.68 4631237.9 3.0956 14382 3.0956 143823.0956 1438215.9 1.2484 5800 1.2484 58001.2484 580023.8 0.6171 2867 0.6171 28670.6171 286731.7 0.3534 1642 0.3534 16420.3534 164239.7 0.2103 977 0.2103 9770.2103 97747.6 0.1315 611 0.1315 611 0 0% 0.1315 611 0 0%55.5 0.0809 376 0.0809 376 0 0% 0.0809 376 0 0%63.5 0.0482 224 0.0482 224 0 0% 0.0482 224 0 0%71.4 0.0321 149 0.0321 149 0 0% 0.0321 149 0 0%79.3 0.0220 102 0.022 102 0 0% 0.022 102 0 0%87.3 0.0136 63 0.0136 63 0 0% 0.0136 63 0 0%95.2 0.0080 37 0.007964 37 0 0% 0.007964 37 0 0%103.1 0.0050 23 0.0049506 23 0 0% 0.0049506 23 0 0%111.1 0.0039 18 0.0038744 18 0 0% 0.0038744 18 0 0%119.0 0.0024 11 0.0023677 11 0 0% 0.0023677 11 0 0%126.9 0.0013 6 0.0012915 6 0 0% 0.0012915 6 0 0%134.9 0.0006 3 0.0006457 3 0 0% 0.0006457 3 0 0%142.8 0.0004 2 0.0004305 2 0 0% 0.0004305 2 0 0%150.7 0.0002 1 0.0002152 1 0 0% 0.0002152 1 0 0%158.7 0.0000 0 0 00 0Max Value158.651158.651PassPass158.651PassPassBaseline - Scn 1 Scn 7Exceedance Probability CountExceedance Probability CountTimes ExceededScn 7- Level III CompliancePercent ChangeScn 8 Scn 8- Level III ComplianceExceedance Probability CountTimes ExceededPercent Change
Table 10. Flow Duration Evaluation - Thunder Hills CreekScenario 2 Baseline - Master Plan MemoWindow of EvaluationScenario 2 Baseline1/2 2-yr (cfs) 44.450-yr (cfs)156.2Cutoff Flowcfs4645924645924645920.0 99.6800 463123 99.68 46312399.68 4631237.9 3.0956 14382 3.0956 143823.0956 1438215.9 1.2484 5800 1.2484 58001.2484 580023.8 0.6171 2867 0.6171 28670.6171 286731.7 0.3534 1642 0.3534 16420.3534 164239.7 0.2103 977 0.2103 9770.2103 97747.6 0.1315 611 0.1315 611 0 0% 0.1315 611 0 0%55.5 0.0809 376 0.0809 376 0 0% 0.0809 376 0 0%63.5 0.0482 224 0.0482 224 0 0% 0.0482 224 0 0%71.4 0.0321 149 0.0321 149 0 0% 0.0321 149 0 0%79.3 0.0220 102 0.022 102 0 0% 0.022 102 0 0%87.3 0.0136 63 0.0136 63 0 0% 0.0136 63 0 0%95.2 0.0080 37 0.007964 37 0 0% 0.007964 37 0 0%103.1 0.0050 23 0.0049506 23 0 0% 0.0049506 23 0 0%111.1 0.0039 18 0.0038744 18 0 0% 0.0038744 18 0 0%119.0 0.0024 11 0.0023677 11 0 0% 0.0023677 11 0 0%126.9 0.0013 6 0.0012915 6 0 0% 0.0012915 6 0 0%134.9 0.0006 3 0.0006457 3 0 0% 0.0006457 3 0 0%142.8 0.0004 2 0.0004305 2 0 0% 0.0004305 2 0 0%150.7 0.0002 1 0.0002152 1 0 0% 0.0002152 1 0 0%158.7 0.0000 0 0 00 0Max Value158.651158.651PassPass158.651PassPassScn 8- Level III ComplianceBaseline - Scn 2 Scn 7 Scn 7- Level III Compliance Scn 8CountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 11. Flow Duration Evaluation - Rolling Hills Creek at I-405Scenario 1 Baseline - Master Plan MemoWindow of EvaluationScenario 1 Baseline1/2 2-yr (cfs) 101.050-yr (cfs)347.2Cutoff Flowcfs4645924645924645920.0 99.8500 463901 99.86 46392699.86 46392617.7 2.9994 13935 2.968 137892.968 1378935.5 1.3315 6186 1.3029 60531.3029 605353.2 0.6804 3161 0.6606 30690.6606 306971.0 0.3900 1812 0.3788 17600.3788 176088.7 0.2310 1073 0.2221 10320.2221 1032106.4 0.1468 682 0.1401 651 0 -5% 0.1401 651 0 -5%124.2 0.0880 409 0.0837 389 0 -5% 0.0837 389 0 -5%141.9 0.0504 234 0.048 223 0 -5% 0.048 223 0 -5%159.6 0.0323 150 0.0297 138 0 -8% 0.0297 138 0 -8%177.4 0.0202 94 0.0192 89 0 -5% 0.0192 89 0 -5%195.1 0.0138 64 0.0121 56 0 -13% 0.0121 56 0 -13%212.9 0.0095 44 0.007964 37 0 -16% 0.007964 37 0 -16%230.6 0.0052 24 0.0049506 23 0 -4% 0.0049506 23 0 -4%248.3 0.0037 17 0.0034439 16 0 -6% 0.0034439 16 0 -6%266.1 0.0026 12 0.0021524 10 0 -17% 0.0021524 10 0 -17%283.8 0.0011 5 0.000861 4 0 -20% 0.000861 4 0 -20%301.6 0.0006 3 0.0004305 2 0 -33% 0.0004305 2 0 -33%319.3 0.0004 2 0.0004305 2 0 0% 0.0004305 2 0 0%337.0 0.0002 1 0.0002152 1 0 0% 0.0002152 1 0 0%354.8 0.0000 0 0 00 0Max Value354.771349.951PassPass349.951PassPassBaseline - Scn 1 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceCountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 12. Flow Duration Evaluation - Rolling Hills Creek at I-405Scenario 2 Baseline - Master Plan MemoWindow of EvaluationScenario 2 Baseline1/2 2-yr (cfs) 101.050-yr (cfs)347.2Cutoff Flowcfs4645924645924645920.0 99.8500 463901 99.86 46392699.86 46392617.7 2.9994 13935 2.968 137892.968 1378935.5 1.3315 6186 1.3029 60531.3029 605353.2 0.6804 3161 0.6606 30690.6606 306971.0 0.3900 1812 0.3788 17600.3788 176088.7 0.2310 1073 0.2221 10320.2221 1032106.4 0.1468 682 0.1401 651 0 -5% 0.1401 651 0 -5%124.2 0.0880 409 0.0837 389 0 -5% 0.0837 389 0 -5%141.9 0.0504 234 0.048 223 0 -5% 0.048 223 0 -5%159.6 0.0323 150 0.0297 138 0 -8% 0.0297 138 0 -8%177.4 0.0202 94 0.0192 89 0 -5% 0.0192 89 0 -5%195.1 0.0138 64 0.0121 56 0 -13% 0.0121 56 0 -13%212.9 0.0095 44 0.007964 37 0 -16% 0.007964 37 0 -16%230.6 0.0052 24 0.0049506 23 0 -4% 0.0049506 23 0 -4%248.3 0.0037 17 0.0034439 16 0 -6% 0.0034439 16 0 -6%266.1 0.0026 12 0.0021524 10 0 -17% 0.0021524 10 0 -17%283.8 0.0011 5 0.000861 4 0 -20% 0.000861 4 0 -20%301.6 0.0006 3 0.0004305 2 0 -33% 0.0004305 2 0 -33%319.3 0.0004 2 0.0004305 2 0 0% 0.0004305 2 0 0%337.0 0.0002 1 0.0002152 1 0 0% 0.0002152 1 0 0%354.8 0.0000 0 0 00 0Max Value354.771349.951PassPass349.951PassPassBaseline - Scn 2 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceCountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 13. Flow Duration Evaluation - North Panther Creek Wetland OutletScenario 1 Baseline - Master Plan MemoWindow of EvaluationScenario 1 Baseline1/2 2-yr (cfs) 26.350-yr (cfs)80.9Cutoff Flowcfs4645924645924645920.0 100.0000 464584 100 46458599.99 4645524.5 10.4300 48460 10.46 4858810.61 492768.9 6.3398 29454 6.3062 292986.6067 3069413.3 4.6243 21484 4.575 212555.2214 2425817.8 3.7198 17282 3.6699 170504.4381 2061922.2 3.1288 14536 3.0782 143013.8888 1806726.7 2.6669 12390 2.6143 12146 0 -2% 2.0745 9638 0 -22%31.1 1.1309 5254 1.0982 5102 0 -3% 1.0911 5069 0 -4%35.5 0.2049 952 0.1965 913 0 -4% 0.6541 3039 1219%40.0 0.1089 506 0.1035 481 0 -5% 0.503 2337 1362%44.4 0.0555 258 0.0521 242 0 -6% 0.3756 1745 1576%48.8 0.0282 131 0.025 116 0 -11% 0.2774 1289 1884%53.3 0.0127 59 0.0123 57 0 -3% 0.1838 854 11347%57.7 0.0077 36 0.0066725 31 0 -14% 0.1055 490 11261%62.2 0.0043 20 0.0036591 17 0 -15% 0.0493 229 11045%66.6 0.0026 12 0.0025829 12 0 0% 0.022 102 1750%71.0 0.0013 6 0.0012915 6 0 0% 0.0073182 34 1467%75.5 0.0011 5 0.0010762 5 0 0% 0.0021524 10 1100%79.9 0.0004 2 0.0002152 1 0 -50% 0.0012915 6 1200%84.3 0.0000 0 0 0 0.0006457 388.8 0.0000 0 0 00 0Max Value82.76181.831PassPass88.781FailFailBaseline - Scn 1 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceCountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 14. Flow Duration Evaluation - North Panther Creek Wetland OutletScenario 2 Baseline - Master Plan MemoWindow of EvaluationScenario 2 Baseline1/2 2-yr (cfs) 33.650-yr (cfs)86.2Cutoff Flowcfs4645924645924645920.0 99.9900 464554 100 46458599.99 4645524.5 10.5000 48781 10.38 4820910.52 488969.0 6.6105 30712 6.2562 290666.5651 3050113.5 5.2489 24386 4.5427 211055.1897 2411118.0 4.4805 20816 3.6393 169084.4174 2052322.4 3.9286 18252 3.0508 141743.8688 1797426.9 2.0439 9496 2.5879 120231.9895 924331.4 1.0790 5013 0.9029 41951.0422 484235.9 0.6666 3097 0.1866 867 0 -72% 0.6444 2994 0 -3%40.4 0.5123 2380 0.0975 453 0 -81% 0.4923 2287 0 -4%44.8 0.3778 1755 0.0486 226 0 -87% 0.3635 1689 0 -4%49.3 0.2779 1291 0.0241 112 0 -91% 0.2658 1235 0 -4%53.8 0.1832 851 0.0121 56 0 -93% 0.1752 814 0 -4%58.3 0.1007 468 0.0064573 30 0 -94% 0.0956 444 0 -5%62.8 0.0467 217 0.0034439 16 0 -93% 0.0448 208 0 -4%67.2 0.0209 97 0.0023677 11 0 -89% 0.0189 88 0 -9%71.7 0.0062 29 0.0012915 6 0 -79% 0.0058116 27 0 -7%76.2 0.0022 10 0.0006457 3 0 -70% 0.0019372 9 0 -10%80.7 0.0011 5 0.0002152 1 0 -80% 0.000861 4 0 -20%85.2 0.0006 3 0 0 0 -100% 0.0006457 3 0 0%89.7 0.0000 0 0 00 0Max Value89.66181.831PassPass88.781PassPassBaseline - Scn 2 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceCountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 15. Flow Duration Evaluation - SW 19th St channel, downstream endScenario 1 Baseline - Master Plan MemoWindow of EvaluationScenario 1 Baseline1/2 2-yr (cfs) 31.150-yr (cfs)75.6Cutoff Flowcfs4645924645924645920.0 99.9800 464509 99.99 46454799.99 4645524.3 11.2700 52340 11.31 5254511.46 532328.5 6.9622 32346 6.9566 323207.202 3346012.7 5.2031 24173 5.1807 240695.6906 2643817.0 4.1587 19321 4.1411 192394.8279 2243021.2 3.4955 16240 3.468 161124.2106 1956225.4 2.9833 13860 2.9598 137513.3378 1550729.7 2.4794 11519 2.4402 113371.9983 928433.9 1.2447 5783 1.3336 6196 1 7% 1.215 5645 0 -2%38.1 0.5519 2564 0.6156 2860 112%0.8388 3897 152%42.3 0.3093 1437 0.3483 1618 113%0.6363 2956 1106%46.6 0.1924 894 0.2137 993 111%0.5069 2355 1163%50.8 0.1362 633 0.1483 689 1 9% 0.4143 1925 1204%55.0 0.0766 356 0.0867 403 113%0.325 1510 1324%59.3 0.0349 162 0.0403 187 115%0.2187 1016 1527%63.5 0.0164 76 0.0187 87 114%0.1464 680 1795%67.7 0.0041 19 0.0049506 23 121%0.0603 280 11374%72.0 0.0017 8 0.0019372 9 113%0.0198 92 11050%76.2 0.0009 4 0.000861 4 0.0038744 1880.4 0.0002 1 0.0002152 1 0.0010762 584.7 0.0000 0 0 00 0Max Value80.62181.151FailFail84.661FailFailBaseline - Scn 1 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceCountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 16. Flow Duration Evaluation - SW 19th St channel, downstream endScenario 2 Baseline - Master Plan MemoWindow of EvaluationScenario 2 Baseline1/2 2-yr (cfs) 34.350-yr (cfs)80.3Cutoff Flowcfs4645924645924645920.0 99.9900 464552 99.99 46454799.99 4645524.3 11.4200 53036 11.31 5254511.46 532328.5 7.2175 33532 6.9566 323207.202 3346012.7 5.7214 26581 5.1807 240695.6906 2643817.0 4.8653 22604 4.1411 192394.8279 2243021.2 4.2461 19727 3.468 161124.2106 1956225.4 3.3268 15456 2.9598 137513.3378 1550729.7 1.9744 9173 2.4402 113371.9983 928433.9 1.1965 5559 1.3336 61961.215 564538.1 0.8201 3810 0.6156 2860 0 -25% 0.8388 3897 1 2%42.3 0.6261 2909 0.3483 1618 0 -44% 0.6363 2956 1 2%46.6 0.5004 2325 0.2137 993 0 -57% 0.5069 2355 1 1%50.8 0.4113 1911 0.1483 689 0 -64% 0.4143 1925 1 1%55.0 0.3209 1491 0.0867 403 0 -73% 0.325 1510 1 1%59.3 0.2129 989 0.0403 187 0 -81% 0.2187 1016 1 3%63.5 0.1386 644 0.0187 87 0 -86% 0.1464 680 1 6%67.7 0.0549 255 0.0049506 23 0 -91% 0.0603 280 1 10%72.0 0.0174 81 0.0019372 9 0 -89% 0.0198 92 114%76.2 0.0030 14 0.000861 4 0 -71% 0.0038744 18 129%80.4 0.0009 4 0.0002152 1 0.0010762 584.7 0.0000 0 0 00 0Max Value83.93181.151PassPass84.661FailFailBaseline - Scn 2 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceCountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 17. Flow Duration Evaluation - Central Panther Creek Wetland OutletScenario 1 Baseline - Master Plan MemoWindow of EvaluationScenario 1 Baseline1/2 2-yr (cfs) 41.550-yr (cfs)154.0Cutoff Flowcfs4645924645924645920.0 100.0000 464592 100 46459299.99 4645408.0 13.5100 62758 13.86 6439314.02 6511416.1 5.5035 25569 5.8044 269676.036 2804324.1 2.6098 12125 2.8147 130773.0375 1411232.2 1.3831 6426 1.5226 70741.7021 790840.2 0.7650 3554 0.8481 39400.988 459048.2 0.4660 2165 0.5129 2383 110%0.6027 2800 129%56.3 0.3031 1408 0.3358 1560 111%0.41 1905 135%64.3 0.2088 970 0.2269 1054 1 9% 0.297 1380 142%72.4 0.1578 733 0.1739 808 110%0.2331 1083 148%80.4 0.1242 577 0.1356 630 1 9% 0.1937 900 156%88.4 0.0999 464 0.1113 517 111%0.1375 639 138%96.5 0.0827 384 0.0913 424 110%0.0964 448 117%104.5 0.0689 320 0.0749 348 1 9% 0.0562 261 0 -18%112.5 0.0555 258 0.0622 289 112%0.0325 151 0 -41%120.6 0.0450 209 0.0502 233 111%0.0142 66 0 -68%128.6 0.0265 123 0.0299 139 113%0.0040896 19 0 -85%136.7 0.0133 62 0.0157 73 118%0 0 0 -100%144.7 0.0052 24 0.0060268 28 117%0 0 0 -100%152.7 0.0011 5 0.0019372 9 180%0 0 0 -100%160.8 0.0000 0 0 00 0Max Value158.941160.781FailFail133.281PassFailBaseline - Scn 1 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceCountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 18. Flow Duration Evaluation - Central Panther Creek Wetland OutletScenario 2 Baseline - Master Plan MemoWindow of EvaluationScenario 2 Baseline1/2 2-yr (cfs) 43.550-yr (cfs)131.0Cutoff Flowcfs4645924645924645920.0 99.9900 464540 100 46459299.99 4645408.0 13.6800 63550 13.86 6439314.02 6511416.1 5.7311 26626 5.8044 269676.036 2804324.1 2.8171 13088 2.8147 130773.0375 1411232.2 1.5547 7223 1.5226 70741.7021 790840.2 0.8831 4103 0.8481 39400.988 459048.2 0.5478 2545 0.5129 2383 0 -6% 0.6027 2800 110%56.3 0.3685 1712 0.3358 1560 0 -9% 0.41 1905 111%64.3 0.2665 1238 0.2269 1054 0 -15% 0.297 1380 111%72.4 0.2144 996 0.1739 808 0 -19% 0.2331 1083 1 9%80.4 0.1769 822 0.1356 630 0 -23% 0.1937 900 1 9%88.4 0.1233 573 0.1113 517 0 -10% 0.1375 639 112%96.5 0.0885 411 0.0913 424 1 3% 0.0964 448 1 9%104.5 0.0499 232 0.0749 348 150%0.0562 261 113%112.5 0.0286 133 0.0622 289 1117%0.0325 151 114%120.6 0.0116 54 0.0502 233 1331%0.0142 66 122%128.6 0.0024 11 0.0299 139 11164%0.0040896 19 173%136.7 0.0000 0 0.0157 730 0144.7 0.0000 0 0.0060268 280 0152.7 0.0000 0 0.0019372 90 0160.8 0.0000 0 0 00 0Max Value132.361160.781PassFail133.281FailFailExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeExceedance Probability CountBaseline - Scn 2 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceTimes ExceededPercent Change
Table 19. Flow Duration Evaluation - SW 23rd St channel, downstream endScenario 1 Baseline - Master Plan MemoWindow of EvaluationScenario 1 Baseline1/2 2-yr (cfs) 45.050-yr (cfs)166.0Cutoff Flowcfs4645924645924645920.0 99.9900 464527 100 46459299.99 4645278.4 14.5800 67747 14.9 6920315.02 6978616.9 6.4519 29975 6.7214 312276.8966 3204125.3 3.3354 15496 3.5343 164203.714 1725533.7 1.8627 8654 1.997 92782.1808 1013242.1 1.1001 5111 1.1959 55561.3435 624250.6 0.6673 3100 0.7355 3417 110%0.8444 3923 127%59.0 0.4384 2037 0.4824 2241 110%0.5691 2644 130%67.4 0.3164 1470 0.3485 1619 110%0.4137 1922 131%75.8 0.2391 1111 0.2617 1216 1 9% 0.3224 1498 135%84.3 0.1879 873 0.2062 958 1 10% 0.2533 1177 135%92.7 0.1332 619 0.1468 682 110%0.1795 834 135%101.1 0.1033 480 0.1111 516 1 8% 0.1223 568 118%109.5 0.0758 352 0.0818 380 1 8% 0.0816 379 1 8%118.0 0.0547 254 0.0598 278 1 9% 0.042 195 0 -23%126.4 0.0405 188 0.0446 207 110%0.0222 103 0 -45%134.8 0.0282 131 0.0314 146 111%0.0094707 44 0 -66%143.2 0.0189 88 0.0209 97 110%0.0025829 12 0 -86%151.7 0.0086 40 0.0096859 45 113%0 0 0 -100%160.1 0.0017 8 0.0034439 16 1100%0 0 0 -100%168.5 0.0000 0 0 00 0Max Value167.211168.511FailFail150.341FailFailBaseline - Scn 1 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceCountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 20. Flow Duration Evaluation - SW 23rd St channel, downstream endScenario 2 Baseline - Master Plan MemoWindow of EvaluationScenario 2 Baseline1/2 2-yr (cfs) 44.850-yr (cfs)147.0Cutoff Flowcfs4645924645924645920.0 99.9900 464527 100 46459299.99 4645278.4 14.7000 68305 14.9 6920315.02 6978616.9 6.6265 30786 6.7214 312276.8966 3204125.3 3.5031 16275 3.5343 164203.714 1725533.7 2.0179 9375 1.997 92782.1808 1013242.1 1.2346 5736 1.1959 55561.3435 624250.6 0.7777 3613 0.7355 3417 0 -5% 0.8444 3923 1 9%59.0 0.5155 2395 0.4824 2241 0 -6% 0.5691 2644 110%67.4 0.3758 1746 0.3485 1619 0 -7% 0.4137 1922 110%75.8 0.2901 1348 0.2617 1216 0 -10% 0.3224 1498 111%84.3 0.2322 1079 0.2062 958 0 -11% 0.2533 1177 1 9%92.7 0.1621 753 0.1468 682 0 -9% 0.1795 834 111%101.1 0.1126 523 0.1111 516 0 -1% 0.1223 568 1 9%109.5 0.0758 352 0.0818 380 1 8% 0.0816 379 1 8%118.0 0.0381 177 0.0598 278 157%0.042 195 110%126.4 0.0202 94 0.0446 207 1120%0.0222 103 1 10%134.8 0.0088 41 0.0314 146 1256%0.0094707 44 1 7%143.2 0.0019 9 0.0209 97 1978%0.0025829 12 133%151.7 0.0000 0 0.0096859 450 0160.1 0.0000 0 0.0034439 160 0168.5 0.0000 0 0 00 0Max Value149.371168.511PassFail150.341FailFailBaseline - Scn 2 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceCountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 21. Flow Duration Evaluation - South Panther Creek Wetland OutletScenario 1 Baseline - Master Plan MemoWindow of EvaluationScenario 1 Baseline1/2 2-yr (cfs) 13.450-yr (cfs)38.4Cutoff Flowcfs4645924645924645920.0 100.0000 464592 99.99 46455099.99 4645501.9 4.9370 22937 4.9359 229321.7346 80593.7 3.0592 14213 3.0592 142130.3018 14025.6 2.0091 9334 2.0086 93320.0547 2547.4 1.4094 6548 1.4094 6548 0.0088249 419.3 1.0323 4796 1.0323 4796 0.0015067 711.1 0.7667 3562 0.7665 3561 0.0002152 113.0 0.5803 2696 0.5799 26940 014.8 0.4516 2098 0.4514 2097 0 0% 0 0 0 -100%16.7 0.3577 1662 0.3577 1662 0 0% 0 0 0 -100%18.5 0.2729 1268 0.2729 1268 0 0% 0 0 0 -100%20.4 0.2068 961 0.2068 961 0 0% 0 0 0 -100%22.2 0.1489 692 0.1489 692 0 0% 0 0 0 -100%24.1 0.1031 479 0.1031 479 0 0% 0 0 0 -100%25.9 0.0585 272 0.0585 272 0 0% 0 0 0 -100%27.8 0.0321 149 0.0321 149 0 0% 0 0 0 -100%29.6 0.0174 81 0.0174 81 0 0% 0 0 0 -100%31.5 0.0069 32 0.0068878 32 0 0% 0 0 0 -100%33.4 0.0022 10 0.0021524 10 0 0% 0 0 0 -100%35.2 0.0009 4 0.000861 4 0 0% 0 0 0 -100%37.1 0.0000 0 0 00 0Max Value37.06137.061PassPass11.961PassPassBaseline - Scn 1 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceCountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 22. Flow Duration Evaluation - South Panther Creek Wetland OutletScenario 2 Baseline - Master Plan MemoWindow of EvaluationScenario 2 Baseline1/2 2-yr (cfs) 3.050-yr (cfs)10.8Cutoff Flowcfs4645924645924645920.0 100.0000 464592 99.99 46455099.99 4645501.9 1.7355 8063 4.9359 229321.7346 80593.7 0.3022 1404 3.0592 14213 1912%0.3018 1402 0 0%5.6 0.0547 254 2.0086 9332 13574%0.0547 254 0 0%7.4 0.0088 41 1.4094 6548 115871%0.0088249 41 0 0%9.3 0.0015 7 1.0323 4796 168414%0.0015067 7 0 0%11.1 0.0002 1 0.7665 3561 0.0002152 113.0 0.0000 0 0.5801 26950 014.8 0.0000 0 0.4516 20980 016.7 0.0000 0 0.3577 16620 018.5 0.0000 0 0.2729 12680 020.4 0.0000 0 0.2068 9610 022.2 0.0000 0 0.1489 6920 024.1 0.0000 0 0.1031 4790 025.9 0.0000 0 0.0585 2720 027.8 0.0000 0 0.0321 1490 029.6 0.0000 0 0.0174 810 031.5 0.0000 0 0.0068878 320 033.4 0.0000 0 0.0021524 100 035.2 0.0000 0 0.000861 40 037.1 0.0000 0 0 00 0Max Value11.96137.061FailFail11.961PassPassBaseline - Scn 2 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceCountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 23. Flow Duration Evaluation - SW 34th St channel, downstream endScenario 1 Baseline - Master Plan MemoWindow of EvaluationScenario 1 Baseline1/2 2-yr (cfs) 18.350-yr (cfs)38.1Cutoff Flowcfs4645924645924645920.0 92.0700 427766 89.87 41752789.75 4169691.9 8.8869 41288 8.8615 411707.1962 334333.8 6.2730 29144 6.2618 290924.8765 226565.7 4.8363 22469 4.8288 224343.7493 174197.6 3.8940 18091 3.8856 180523.0302 140789.5 3.2525 15111 3.2465 150832.5166 1169211.4 2.7966 12993 2.7932 129772.1242 986913.3 2.4531 11397 2.4495 113801.8065 839315.2 2.1681 10073 2.1671 100681.5319 711717.1 1.9402 9014 1.9378 90031.3078 607619.0 1.7433 8099 1.7413 8090 0 0% 1.1356 5276 0 -35%20.9 1.5958 7414 1.5937 7404 0 0% 0.9811 4558 0 -39%22.8 1.4550 6760 1.4531 6751 0 0% 0.8625 4007 0 -41%24.7 1.2277 5704 1.2247 5690 0 0% 0.6649 3089 0 -46%26.6 1.0515 4885 1.0504 4880 0 0% 0.5213 2422 0 -50%28.5 0.9075 4216 0.9053 4206 0 0% 0.4092 1901 0 -55%30.4 0.7101 3299 0.7092 3295 0 0% 0.2622 1218 0 -63%32.3 0.4557 2117 0.4539 2109 0 0% 0.1061 493 0 -77%34.3 0.3805 1768 0.3797 1764 0 0% 0.0734 341 0 -81%36.2 0.2299 1068 0.229 1064 0 0% 0.023 107 0 -90%38.1 0.0000 0 0 00 0Max Value38.06238.052PassPass37.221PassPassBaseline - Scn 1 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceCountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 24. Flow Duration Evaluation - SW 34th St channel, downstream endScenario 2 Baseline - Master Plan MemoWindow of EvaluationScenario 2 Baseline1/2 2-yr (cfs) 18.150-yr (cfs)37.0Cutoff Flowcfs4645924645924645920.0 91.9200 427067 89.87 41752789.75 4169691.9 7.2250 33567 8.8628 411767.1977 334403.8 4.8903 22720 6.2625 290954.8776 226615.7 3.7553 17447 4.829 224353.7493 174197.6 3.0341 14096 3.8862 180553.0306 140809.5 2.5186 11701 3.2469 150852.5166 1169211.4 2.1272 9883 2.7934 129782.1244 987013.3 1.8102 8410 2.4495 113801.8067 839415.2 1.5353 7133 2.1673 100691.5319 711717.1 1.3104 6088 1.9383 90051.3082 607819.0 1.1369 5282 1.7413 8090 153%1.1356 5276 0 0%20.9 0.9822 4563 1.5939 7405 162%0.9813 4559 0 0%22.8 0.8631 4010 1.454 6755 168%0.8627 4008 0 0%24.7 0.6668 3098 1.2252 5692 184%0.6651 3090 0 0%26.6 0.5230 2430 1.0506 4881 1101%0.5217 2424 0 0%28.5 0.4100 1905 0.9053 4206 1121%0.4094 1902 0 0%30.4 0.2643 1228 0.7094 3296 1168%0.2637 1225 0 0%32.3 0.1068 496 0.4539 2109 1325%0.1061 493 0 -1%34.2 0.0736 342 0.3797 1764 1416%0.0734 341 0 0%36.1 0.0230 107 0.2318 1077 1907%0.023 107 0 0%38.1 0.0000 0 0 00 0Max Value37.22138.052FailFail37.221PassPassBaseline - Scn 2 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceCountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 25. Flow Duration Evaluation - Springbrook Creek downstream of SW 19th St.Scenario 1 Baseline - Master Plan MemoWindow of EvaluationScenario 1 Baseline1/2 2-yr (cfs) 358.850-yr (cfs)1274.7Cutoff Flowcfs4645924645924645920.1 100.0000 464591 100 464591100 46459163.7 15.4500 71769 15.5 7201015.5 72024127.3 7.9373 36876 7.9706 370317.9627 36994191.0 4.6445 21578 4.6746 217184.6673 21684254.6 2.8104 13057 2.8294 131452.8466 13225318.3 1.7252 8015 1.7435 81001.7452 8108381.9 1.1126 5169 1.1259 5231 1 1% 1.1042 5130 0 -1%445.5 0.7189 3340 0.7297 3390 1 1% 0.7157 3325 0 0%509.2 0.4572 2124 0.4677 2173 1 2% 0.4755 2209 1 4%572.8 0.2846 1322 0.2908 1351 1 2% 0.299 1389 1 5%636.4 0.1754 815 0.1782 828 1 2% 0.1855 862 1 6%700.1 0.1108 515 0.1132 526 1 2% 0.1167 542 1 5%763.7 0.0717 333 0.073 339 1 2% 0.0764 355 1 7%827.3 0.0482 224 0.0486 226 1 1% 0.0508 236 1 5%891.0 0.0316 147 0.0323 150 1 2% 0.0342 159 1 8%954.6 0.0204 95 0.0207 96 1 1% 0.0213 99 1 4%1018.3 0.0110 51 0.0112 52 1 2% 0.011 51 0 0%1081.9 0.0050 23 0.0049506 23 0 0% 0.0055963 26 113%1145.5 0.0024 11 0.0025829 12 1 9% 0.0023677 11 0 0%1209.2 0.0013 6 0.0012915 6 0 0% 0.0012915 6 0 0%1272.8 0.0000 0 0 00 0Max Value1270112731FailPass12681FailFailBaseline - Scn 1 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III ComplianceCountExceedance Probability CountExceedance Probability CountTimes ExceededPercent ChangeTimes ExceededPercent ChangeExceedance Probability
Table 26. Flow Duration Evaluation - Springbrook Creek downstream of SW 19th St.Scenario 2 Baseline - Master Plan MemoWindow of EvaluationScenario 2 Baseline1/2 2-yr (cfs) 365.250-yr (cfs)1271.7Cutoff Flowcfs4645924645924645920.1 100.0000 464591 100 464591100 46459163.7 15.4500 71774 15.5 7201015.5 72024127.3 7.9205 36798 7.9706 370317.9627 36994191.0 4.6378 21547 4.6746 217184.6673 21684254.6 2.8289 13143 2.8294 131452.8466 13225318.3 1.7217 7999 1.7435 81001.7452 8108381.9 1.0915 5071 1.1259 5231 1 3% 1.1042 5130 1 1%445.5 0.7081 3290 0.7297 3390 1 3% 0.7157 3325 1 1%509.2 0.4664 2167 0.4677 2173 1 0% 0.4755 2209 1 2%572.8 0.2936 1364 0.2908 1351 0 -1% 0.299 1389 1 2%636.4 0.1810 841 0.1782 828 0 -2% 0.1855 862 1 2%700.1 0.1158 538 0.1132 526 0 -2% 0.1167 542 1 1%763.7 0.0760 353 0.073 339 0 -4% 0.0764 355 1 1%827.3 0.0506 235 0.0486 226 0 -4% 0.0508 236 1 0%891.0 0.0340 158 0.0323 150 0 -5% 0.0342 159 1 1%954.6 0.0209 97 0.0207 96 0 -1% 0.0213 99 1 2%1018.3 0.0108 50 0.0112 52 1 4% 0.011 51 1 2%1081.9 0.0056 26 0.0049506 23 0 -12% 0.0055963 26 0 0%1145.5 0.0024 11 0.0025829 12 1 9% 0.0023677 11 0 0%1209.2 0.0013 6 0.0012915 6 0 0% 0.0012915 6 0 0%1272.8 0.0000 0 0 00 0Max Value1265112731PassPass12681FailPassBaseline - Scn 2 Scn 7 Scn 7- Level III Compliance Scn 8 Scn 8- Level III CompliancePercent ChangeTimes ExceededPercent ChangeExceedance Probability CountTimes ExceededExceedance Probability CountExceedance Probability Count
Table 27. Stage Duration Evaluation - Panther Creek Wetland ElevationScenario 1 Baseline - Master Plan MemoCutoff Stageft46459246459246459213.7 100.00 464592 100.00 464592 100.00 46458614.0 99.90 464128 99.90 464138 99.90 46413814.3 68.23 316986 68.19 316799 68.21 31691014.5 50.17 233073 50.27 233572 50.28 23359014.8 31.94 148382 32.15 149389 32.25 14983115.0 14.30 66418 14.64 68024 14.80 6876315.3 5.92 27498 6.22 28899 6.45 2995315.6 2.23 10365 2.42 11237 2.62 1218515.8 0.92 4255 1.02 4743 1.17 545516.1 0.38 1761 0.42 1946 0.50 230516.3 0.16 729 0.17 804 0.23 107516.6 0.08 368 0.09 404 0.15 68816.8 0.05 235 0.06 258 0.10 46717.1 0.03 152 0.04 165 0.08 35017.4 0.02 87 0.02 98 0.05 23617.6 0.01 48 0.01 57 0.04 16917.9 0.01 24 0.01 27 0.03 11618.1 0.00 9 0.00 13 0.01 6818.4 0.00 3 0.00 4 0.01 3718.7 0.00 0 0.00 0 0.00 1618.9 0.00 0 0.00 0 0.00 0Max Value18.52118.6118.921Baseline - Scn 1 Scn 7 Scn 8Exceedance Probability CountExceedance Probability CountExceedance Probability Count
Table 28. Stage Duration Evaluation - Panther Creek Wetland ElevationScenario 2 Baseline - Master Plan MemoCutoff Stageft46459246459246459213.7 100.00 464586 100.00 464592 100.00 46458614.0 99.91 464185 99.90 464138 99.90 46413814.3 68.27 317196 68.19 316799 68.21 31691014.5 50.20 233222 50.27 233572 50.28 23359014.8 32.03 148804 32.15 149389 32.25 14983115.0 14.46 67179 14.64 68024 14.80 6876315.3 6.16 28604 6.22 28899 6.45 2995315.6 2.42 11257 2.42 11237 2.62 1218515.8 1.06 4924 1.02 4743 1.17 545516.1 0.45 2081 0.42 1946 0.50 230516.3 0.21 989 0.17 804 0.23 107516.6 0.13 613 0.09 404 0.15 68816.8 0.09 433 0.06 258 0.10 46717.1 0.07 320 0.04 165 0.08 35017.4 0.05 214 0.02 98 0.05 23617.6 0.03 144 0.01 57 0.04 16917.9 0.02 103 0.01 27 0.03 11618.1 0.01 56 0.00 13 0.01 6818.4 0.01 30 0.00 4 0.01 3718.7 0.00 10 0.00 0 0.00 1618.9 0.00 0 0.00 0 0.00 0Max Value18.86118.6118.921Baseline - Scn 2 Scn 7 Scn 8Exceedance Probability CountExceedance Probability CountExceedance Probability Count
Percent Chance Exceedance -Thunder Hills Ck-TRIP Scenario 01 -Thunder Hills Ck-TRIP Scenario 02 -Thunder Hills Ck-TRIP Scenario 07 -Thunder Hills Ck-TRIP Scenario 08Fit Type:Log Pearson III distribution using the method of Bulletin 17B, Gringorten Plotting PositionAnnual Peak Frequency AnalysisAnnual Flood Flow Frequency Analysis - Master Plan MemoDischarge (cfs)50.70.90.110.130.150.170.Figure 1Ret Period-->10025105219649010802050Thunder Hills Creek
Percent Chance Exceedance -Rolling Hills Ck at I405-TRIP Scenario 01 -Rolling Hills Ck at I405-TRIP Scenario 02 -Rolling Hills Ck at I405TRIP Scenario 07 -Rolling Hills Ck at I405-TRIP Scenario 08Fit Type:Log Pearson III distribution using the method of Bulletin 17B, Gringorten Plotting PositionAnnual Peak Frequency AnalysisAnnual Flood Flow Frequency Analysis - Master Plan MemoRolling Hills Creek at I-405Discharge (cfs)120.150.180.210.240.270.300.330.360.Figure 2Ret Period-->10025105219649010802050
Percent Chance Exceedance -N Panther out-TRIP Scenario 01 -N Panther out-TRIP Scenario 02 -N Panther out-TRIP Scenario 07 -N Panther out-TRIP Scenario 08Fit Type:Log Pearson III distribution using the method of Bulletin 17B, Gringorten Plotting PositionAnnual Peak Frequency AnalysisAnnual Flood Flow Frequency Analysis - Master Plan MemoNorth Panther Creek Wetland OutletDischarge (cfs)30.40.50.60.70.80.90.Figure 3Ret Period-->10025105219649010802050
Percent Chance Exceedance -SW 19th Trib-TRIP Scenario 01 -SW 19th Trib-TRIP Scenario 02 -SW 19th Trib-TRIP Scenario 07 -SW 19th Trib-TRIP Scenario 08Fit Type:Log Pearson III distribution using the method of Bulletin 17B, Gringorten Plotting PositionAnnual Peak Frequency AnalysisAnnual Flood Flow Frequency Analysis - Master Plan MemoSW 19th Street Drainage System, Downstream EndDischarge (cfs)53.57.61.65.69.73.77.81.85.Figure 4Ret Period-->10025105219649010802050Outliers
Percent Chance Exceedance -S Panther out-TRIP Scenario 01 -S Panther out-TRIP Scenario 02 -S Panther out-TRIP Scenario 07 -S Panther out-TRIP Scenario 08Fit Type:Log Pearson III distribution using the method of Bulletin 17B, Gringorten Plotting PositionAnnual Peak Frequency AnalysisAnnual Flood Flow Frequency Analysis - Master Plan MemoSouth Panther Creek Wetland OutletDischarge (cfs)0.10.20.30.40.Figure 7Ret Period-->10025105219649010802050Outliers
Percent Chance Exceedance -Sprbk D/S 19th trib-TRIP Scenario 01 -Sprbk D/S 19th trib-TRIP Scenario 02 -Sprbk D/S 19th trib-TRIP Scenario 07 -Sprbk D/S 19th trib-TRIP Scenario 08Fit Type:Log Pearson III distribution using the method of Bulletin 17B, Gringorten Plotting PositionAnnual Peak Frequency AnalysisAnnual Flood Flow Frequency Analysis - Master Plan MemoSpringbrook Creek Downstream of SW 19th St ChannelDischarge (cfs)400.600.800.1000.1200.1400.Figure 9Ret Period-->10025105219649010802050
Percent Chance Exceedance -Panther Ck Wtld-TRIP Scenario 01 -Panther Ck Wtld-TRIP Scenario 02 -Panther Ck Wtld-TRIP Scenario 07 -Panther Ck Wtld-TRIP Scenario 08Fit Type:Log Pearson III distribution using the method of Bulletin 17B, Gringorten Plotting PositionAnnual Peak Frequency AnalysisAnnual Peak Stage Frequency Analysis - Master Plan MemoPanther Creek Wetland StageStage (ft)15.16.17.18.19.Figure 10Ret Period-->10025105219649010802050Outliers
Percent Chance Exceedance-Thunder Hills Ck-TRIP Scenario 01 [1115]-Thunder Hills Ck-TRIP Scenario 07 [7115]-Thunder Hills Ck-TRIP Scenario 08 [8115]Flow Duration Analysis - Scn 1 Baseline - Master Plan MemoDischarge (cfs)0.20.40.60.80.100.120.140.160.Figure 11Hrs/Yr-->10001001010.0010.199.81994961090208050OutliersThunder Hills Creek
Percent Chance Exceedance-Thunder Hills Ck-TRIP Scenario 02 [2115]-Thunder Hills Ck-TRIP Scenario 07 [7115]-Thunder Hills Ck-TRIP Scenario 08 [8115]Flow Duration Analysis - Scn 2 Baseline - Master Plan MemoDischarge (cfs)0.20.40.60.80.100.120.140.160.Figure 12Hrs/Yr-->10001001010.0010.199.81994961090208050OutliersThunder Hills Creek
Percent Chance Exceedance-Rolling Hills Ck at I405-TRIP Scenario 01 [1103]-Rolling Hills Ck at I405TRIP Scenario 07 [7103]-Rolling Hills Ck at I405-TRIP Scenario 08 [8103]Flow Duration Analysis - Scn 1 Baseline - Master Plan MemoRolling Hills Creek at I-405Discharge (cfs)0.100.200.300.400.Figure 13Hrs/Yr-->10001001010.0010.199.91994961090208050Outliers
Percent Chance Exceedance-Rolling Hills Ck at I405-TRIP Scenario 02 [2103]-Rolling Hills Ck at I405TRIP Scenario 07 [7103]-Rolling Hills Ck at I405-TRIP Scenario 08 [8103]Flow Duration Analysis - Scn 2 Baseline - Master Plan MemoRolling Hills Creek at I-405Discharge (cfs)0.100.200.300.400.Figure 14Hrs/Yr-->10001001010.0010.199.91994961090208050Outliers
Percent Chance Exceedance-N Panther out-TRIP Scenario 01 [1102]-N Panther out-TRIP Scenario 07 [7102]-N Panther out-TRIP Scenario 08 [8102]Flow Duration Analysis - Scn 1 Baseline - Master Plan MemoNorth Panther Creek Wetland OutletDischarge (cfs)0.20.40.60.80.100.Figure 15Hrs/Yr-->10001001010.00199.9990.199.91994961090208050Outliers
Percent Chance Exceedance-N Panther out-TRIP Scenario 02 [2102]-N Panther out-TRIP Scenario 07 [7102]-N Panther out-TRIP Scenario 08 [8102]Flow Duration Analysis - Scn 2 Baseline - Master Plan MemoNorth Panther Creek Wetland OutletDischarge (cfs)0.20.40.60.80.100.Figure 16Hrs/Yr-->10001001010.00199.9990.199.91994961090208050Outliers
Percent Chance Exceedance-SW 19th Trib-TRIP Scenario 01 [1011]-SW 19th Trib-TRIP Scenario 07 [7011]-SW 19th Trib-TRIP Scenario 08 [8011]Flow Duration Analysis - Scn 1 Baseline - Master Plan MemoSW 19th Street Drainage System, Downstream EndDischarge (cfs)0.20.40.60.80.100.Figure 17Hrs/Yr-->10001001010.00199.9990.199.91994961090208050Outliers
Percent Chance Exceedance-SW 19th Trib-TRIP Scenario 02 [2011]-SW 19th Trib-TRIP Scenario 07 [7011]-SW 19th Trib-TRIP Scenario 08 [8011]Flow Duration Analysis - Scn 2 Baseline - Master Plan MemoSW 19th Street Drainage System, Downstream EndDischarge (cfs)0.20.40.60.80.100.Figure 18Hrs/Yr-->10001001010.00199.9990.199.91994961090208050Outliers
Percent Chance Exceedance-Panther Ck Wtld-TRIP Scenario 01 [1101]-Panther Ck Wtld-TRIP Scenario 07 [7101]-Panther Ck Wtld-TRIP Scenario 08 [8101]Flow Duration Analysis - Scn 1 Baseline - Master Plan MemoCentral Panther Creek Wetland OutletDischarge (cfs)0.30.60.90.120.150.180.Figure 19Hrs/Yr-->100010010199.999990.00199.9990.199.91994961090208050Outliers
Percent Chance Exceedance-Panther Ck Wtld-TRIP Scenario 02 [2101]-Panther Ck Wtld-TRIP Scenario 07 [7101]-Panther Ck Wtld-TRIP Scenario 08 [8101]Flow Duration Analysis - Scn 2 Baseline - Master Plan MemoCentral Panther Creek Wetland OutletDischarge (cfs)0.30.60.90.120.150.180.Figure 20Hrs/Yr-->100010010199.999990.00199.9990.199.91994961090208050Outliers
Percent Chance Exceedance-SW 23rd Trib-TRIP Scenario 01 [1017]-SW 23rd Trib-TRIP Scenario 07 [7017]-SW 23rd Trib-TRIP Scenario 08 [8017]Flow Duration Analysis - Scn 1 Baseline - Master Plan MemoSW 23rd Street Drainage System, Downstream EndDischarge (cfs)0.30.60.90.120.150.180.Figure 21Hrs/Yr-->100010010199.999990.00199.9990.199.91994961090208050Outliers
Percent Chance Exceedance-SW 23rd Trib-TRIP Scenario 02 [2017]-SW 23rd Trib-TRIP Scenario 07 [7017]-SW 23rd Trib-TRIP Scenario 08 [8017]Flow Duration Analysis - Scn 2 Baseline - Master Plan MemoSW 23rd Street Drainage System, Downstream EndDischarge (cfs)0.30.60.90.120.150.180.Figure 22Hrs/Yr-->100010010199.999990.00199.9990.199.91994961090208050Outliers
Percent Chance Exceedance-S Panther out-TRIP Scenario 01 [1105]-S Panther out-TRIP Scenario 07 [7105]-S Panther out-TRIP Scenario 08 [8105]Flow Duration Analysis - Scn 1 Baseline - Master Plan MemoSouth Panther Creek Wetland OutletDischarge (cfs)0.10.20.30.40.Figure 23Hrs/Yr-->100010010199.999990.00199.9990.199.91994961090208050Outliers
Percent Chance Exceedance-S Panther out-TRIP Scenario 02 [2105]-S Panther out-TRIP Scenario 07 [7105]-S Panther out-TRIP Scenario 08 [8105]Flow Duration Analysis - Scn 2 Baseline - Master Plan MemoSouth Panther Creek Wetland OutletDischarge (cfs)0.10.20.30.40.Figure 24Hrs/Yr-->100010010199.999990.00199.9990.199.91994961090208050Outliers
Percent Chance Exceedance-SW 34th Trib-TRIP Scenario 01 [1025]-SW 34th Trib-TRIP Scenario 07 [7025]-SW 34th Trib-TRIP Scenario 08 [8025]Flow Duration Analysis - Scn 1 Baseline - Master Plan MemoSW 34th Street Drainage System, Downstream EndDischarge (cfs)0.10.20.30.40.Figure 25Hrs/Yr-->10001001010.0010.114961090208050Outliers
Percent Chance Exceedance-SW 34th Trib-TRIP Scenario 02 [2025]-SW 34th Trib-TRIP Scenario 07 [7025]-SW 34th Trib-TRIP Scenario 08 [8025]Flow Duration Analysis - Scn 2 Baseline - Master Plan MemoSW 34th Street Drainage System, Downstream EndDischarge (cfs)0.10.20.30.40.Figure 26Hrs/Yr-->10001001010.0010.114961090208050Outliers
Percent Chance Exceedance-Sprbk D/S 19th trib-TRIP Scenario 01 [1007]-Sprbk D/S 19th trib-TRIP Scenario 07 [7007]-Sprbk D/S 19th trib-TRIP Scenario 08 [8007]Flow Duration Analysis - Scn 1 Baseline - Master Plan MemoSpringbrook Creek Downstream of SW 19th St ChannelDischarge (cfs)0.200.400.600.800.1000.1200.1400.Figure 27Hrs/Yr-->100010010199.99990.00199.990.199.81994961090208050Outliers
Percent Chance Exceedance-Sprbk D/S 19th trib-TRIP Scenario 02 [2007]-Sprbk D/S 19th trib-TRIP Scenario 07 [7007]-Sprbk D/S 19th trib-TRIP Scenario 08 [8007]Flow Duration Analysis - Scn 2 Baseline - Master Plan MemoSpringbrook Creek Downstream of SW 19th St ChannelDischarge (cfs)0.200.400.600.800.1000.1200.1400.Figure 28Hrs/Yr-->100010010199.99990.00199.990.199.81994961090208050Outliers
Percent Chance Exceedance-Panther Ck Wtld-TRIP Scenario 01 [1100]-Panther Ck Wtld-TRIP Scenario 07 [7100]-Panther Ck Wtld-TRIP Scenario 08 [8100]Stage Duration Analysis - Scn 1 Baseline - Master Plan MemoPanther Creek Wetland StageStage (ft)13.14.15.16.17.18.19.Figure 29Hrs/Yr-->100010010199.999990.00199.9990.199.91994961090208050Outliers
Percent Chance Exceedance-Panther Ck Wtld-TRIP Scenario 02 [2100]-Panther Ck Wtld-TRIP Scenario 07 [7100]-Panther Ck Wtld-TRIP Scenario 08 [8100]Stage Duration Analysis - Scn 2 Baseline - Master Plan MemoPanther Creek Wetland StageStage (ft)13.14.15.16.17.18.19.Figure 30Hrs/Yr-->100010010199.999990.00199.9990.199.91994961090208050Outliers
Panther Creek Wetland StageAverage Daily Stage HydrographsPercentiles of Daily Data from Water Years 1949 to 2001DSN -Panther Ck Wtld-TRIP Scenario 01DSN -Panther Ck Wtld-TRIP Scenario 02DSN -Panther Ck Wtld-TRIP Scenario 07DSN -Panther Ck Wtld-TRIP Scenario 08Water YearOCTNOVDECJANFEBMARAPRMAYJUNJULAUGSEPStage (ft)14.014.314.614.915.215.5Figure 31 10% 50% 90%
Key
R 1
R 5
R 7
R 13
R 15
R 17
R 21
R 9
R 27
R 31
R 19
R 23
R 11
R 25
R 2 R 3 R 4
R 102-1
R 102-2
R 101
R 105-2
R 106-2
R 105-1
R 109
R 103
R 106-1
R 107
1 2
101
3
103b
103a
103c
103
R 114
17
25
27
4
5
107b
107a 109
1179
23a
23b
19
13
15
21
Main Branch Springbrook Ck
at City of Renton Boundary
S 180th St /SW 43rd St
R 115
R 113
Black River
Pump Station
19th St Channel /
North PCW Outlet
23rd St Channel /
Central PCW outlet
34th St Channel /
South PCW outlet
Rolling Hills Creek
Panther Creek
Alluvial Fan
Upper Panther Ck
At Talbot Rd
Reach
Subbasin
northwest hydraulic consultants Inc
Springbrook Creek HSPF Schematic-
Scenario 1
Tukwila to Renton Improvement Project
Date 12/21/2006 Exhibit A
Panther
Creek
Wetland
Key
R 1
R 5
R 7
R 13
R 15
R 17
R 21
R 9
R 27
R 31
R 19
R 23
R 11
R 25
R 2 R 3 R 4
R 102-1
R 102-2
R 101
R 105-2
R 105-1
R 109
R 103
R 107
1 2
101
3
103b
103a
103c
103
R 114
17
25
27
4
5
107b
107a 109
1179
23a
23b
19
13
15
21
Main Branch Springbrook Ck
at City of Renton Boundary
S 180th St /SW 43rd St
R 115
R 113
Black River
Pump Station
19th St Channel /
North PCW Outlet
23rd St Channel /
Central PCW outlet
34th St Channel /
South PCW outlet
Rolling Hills Creek
Upper Panther Ck
At Talbot Rd
Reach
Subbasin
northwest hydraulic consultants Inc
Springbrook Creek HSPF Schematic-
Scenario 2
Tukwila to Renton Improvement Project
Date 12/21/2006 Exhibit B
Panther
Creek
Wetland
Key
R 1
R 5
R 7
R 13
R 15
R 17
R 21
R 9
R 27
R 31
R 19
R 23
R 11
R 25
R 2 R 3 R 4
R 102-1
R 102-2
R 101
R 105-2
R 105-1
R 109
R 103
1 2
101
3
103b*
103a*
103c
103*
R 114
TDA
S2 (1)
TDA
S1
TDA
S3
17*
25*
27
4
5
107b*
107a 109
11*79
23a
23b
19
13
15
21
R 115
R 113
Black River
Pump Station
19th St Channel /
North PCW Outlet
23rd St Channel /
Central PCW outlet
34th St Channel /
South PCW outlet
Rolling Hills Creek
Panther Creek
Wetland
Reach
Subbasin
northwest hydraulic consultants Inc
Springbrook Creek HSPF Schematic-
Master Plan, Scenario 7
Tukwila to Renton Improvement Project
Date 12/21/2006 Exhibit C
R 120
R 220
R 300
Main Branch Springbrook Ck
at City of Renton Boundary
S 180th St /SW 43rd St
Panther
Creek
Wetland
R 230
TDA
S2 (2)
R 106-2
R 106-1
R 107
Panther Creek
Alluvial Fan
Upper Panther Ck
At Talbot Rd
* denotes subbasins where some impervious area was transferred to
subbasin 101 representing direct discharge to Panther Creek
Wetland, see Direct Discharge areas in Table 3
Key
R 1
R 5
R 7
R 13
R 15
R 17
R 21
R 9
R 27
R 31
R 19
R 23
R 11
R 25
R 2 R 3 R 4
R 102-1
R 102-2
R 101
R 105-2
R 105-1
R 109
R 107
1 2
101
3
TDA
S1
TDA
S3
17*
25*
27
4
5
107b*
107a 109
11*79
23a
23b
19
13
15
21
Black River
Pump Station
19th St Channel /
North PCW Outlet
23rd St Channel /
Central PCW outlet
34th St Channel /
South PCW outlet
Upper Panther Ck
At Talbot Rd
Panther Creek
Wetland
Reach
Subbasin
northwest hydraulic consultants Inc
Springbrook Creek HSPF Schematic-
Master Plan, Scenario 8
Tukwila to Renton Improvement Project
Date 12/21/2006 Exhibit D
R 120
R 300
Main Branch Springbrook Ck
at City of Renton Boundary
S 180th St /SW 43rd St
Panther
Creek
Wetland
* denotes subbasins where some impervious area was transferred to
subbasin 101 representing direct discharge to Panther Creek
Wetland, see Direct Discharge areas in Table 3
R 103
103b*
103a*
103c
103*
R 114
TDA
S2 (1)
R 115
R 113
Rolling Hills Creek
R 220 R 230
TDA
S2 (2)