Mayor and City Council
October 21, 2026

Meyers Creek Drainage Study
Preliminary Design Report
Preliminary Design Report:

MEYERS CREEK DRAINAGE STUDY
City of San Bernardino, San Bernardino County, California April 1, 2026
Prepared for:

City of San Bernardino
201 North “E” Street
San Bernardino, CA 92401
Prepared by:

Q3 Consulting
27051 Towne Centre Drive, Suite 270
Foothill Ranch, CA 92610
Contact : Remi Candaele, P.E.
[email protected]
949.259.6441
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Table of Contents
1 Introduction ...................................................................................................................... 1-5

1.1 Context ..................................................................................................................... 1-5

1.2 Objectives ................................................................................................................. 1-6

1.3 Watershed Setting ..................................................................................................... 1-7

1.4 Flood Insurance Rate Map ........................................................................................ 1-10

1.5 Previous Studies ...................................................................................................... 1-10

1.6 Project Alternatives .................................................................................................. 1-11 2 Hydrology Studies ........................................................................................................... 2-14

2.1 Hydrology Approach ................................................................................................ 2-14

2.2 Rainfall .................................................................................................................... 2-15

2.3 Results .................................................................................................................... 2-16 3 Hydraulics ...................................................................................................................... 3-19

3.1 Hydraulic Approach ................................................................................................. 3-19

3.2 Results .................................................................................................................... 3-22 4 Preliminary Engineer’s Estimate of Probable Costs ........................................................... 4-24

4.1 Alternative 1 – Backbone Storm Drain ....................................................................... 4-24

4.2 Alternative 2 – Improved Channel ............................................................................. 4-26 5 Sedimentation and Scour ................................................................................................ 5-31

5.1 Sediment Size ......................................................................................................... 5-31

5.2 Conceptual Sediment and Debris Yield .................................................................... 5-33

5.3 Field Observations ................................................................................................... 5-36

5.4 Review of Historical Aerials ...................................................................................... 5-36

5.5 Future Studies ......................................................................................................... 5-37 6 Permitting and Environmental Constraints Constructability Assessment ........................... 6-38

6.1 Approach ................................................................................................................ 6-38

6.2 Alternative 1 – Backbone Storm Drain ....................................................................... 6-38

6.3 Alternative 2 – Improved Channel ............................................................................. 6-40 7 Constructability Assessment ........................................................................................... 7-44

7.1 Alternative 1 – Backbone Storm Drain ....................................................................... 7-44

7.2 Alternative 2 – Improved Channel ............................................................................. 7-45 8 Project Timeline .............................................................................................................. 8-48

8.1 Alternative 1 – Backbone Storm Drain ....................................................................... 8-48 Meyers Creek Drainage Study
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8.2 Alternative 2 – Improved Channel ............................................................................. 8-48 9 Summary of Findings ....................................................................................................... 9-50 10 References .................................................................................................................... 10-52 11 Technical Appendices ................................................................................................... 11-53 Appendix A: Hydrologic Soil Group Map ............................................................................. 11-54 Appendix B: Land Use Map ................................................................................................ 11-55 Appendix C: Hydrology Maps ............................................................................................. 11-56 Appendix D: Hydrology Results .......................................................................................... 11-57 Appendix E: Proposed Alternative Conceptual Plans .......................................................... 11-58 Appendix F: HEC-RAS Model Results – 100-YR 24-Hour Event ............................................. 11-59 Appendix G: Preliminary Engineer’s Estimate of Probable Costs for Proposed Channel Improvements 11-60
Appendix H: Preliminary Engineer’s Estimate of Probable Costs for Proposed Storm Drain ... 11-61 Appendix I: NOAA Atlas 14 Precipitation Intensity Duration and Depth Data ....................... 11-62 Appendix J: FEMA FIRM Map ............................................................................................. 11-63 Appendix K: Precast Arched Waterway............................................................................... 11-64 Appendix L: Tract Maps ..................................................................................................... 11-65 Appendix M: As-Builts ........................................................................................................ 11-66 Appendix N: Environmental Constraints Analysis ............................................................... 11-67 Appendix O: Sedimentation and Scour ............................................................................... 11-68 Tables and Figures
Table 1-1 Meyers Creek Watershed Land Uses ............................................................................ 1-8 Table 2-1: SCAG Database Classifications to San Bernardino Hydrology Manual Classification .. 2-14 Table 2-2 Water-Year Rainfall Statistics (Gilbert Street USGS) .................................................... 2-16 Table 2-3 Rainfall Intensity Data ............................................................................................... 2-16 Table 2-4 Rainfall Depth Data .................................................................................................. 2-16 Table 2-5 Existing Condition Rational Method Results - Clearwater ........................................... 2-17 Table 2-6 SAUH AES Results for Existing Condition Upper Tributaries ........................................ 2-17 Table 2-7 Proposed Condition Rational Method Hydrology for Alternative 1 – Backbone Storm Drain .............................................................................................................................................. 2-18 Table 2-8 Proposed Condition Unit Hydrograph Method for Alternative 2 – Improved Channel .... 2-18 Table 3-1 Manning’s N for Land Cover ....................................................................................... 3-20 Table 3-2 HEC-RAS Boundary Condition Methods ..................................................................... 3-21 Table 3-3 WSPG Storm Drain Sizing Results .............................................................................. 3-23 Table 3-4 HEC-RAS Results, 100-year Storm Event ................................................................... 3-23 Table 4-1: Anticipated O&M Costs ............................................................................................ 4-26 Table 4-2 Parcel Acquisition Costs ........................................................................................... 4-28 Meyers Creek Drainage Study
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Table 4-3: Anticipated O&M Costs ............................................................................................ 4-30 Table 5-1: Conceptual Sediment Yield Estimates ...................................................................... 5-35 Table 5-2: Conceptual Sediment Yield Estimates – Tributaries A and B Only to Proposed Debris Basin ...................................................................................................................................... 5-35 Table 7-1 Potential Right-of-Way Acquisition ............................................................................. 7-47 Table 8-1 Conceptual Timeline for Alternative 1 ........................................................................ 8-49 Table 8-2 Conceptual Timeline for Alternative 2 ........................................................................ 8-49 Table 9-1 Comparison Table – Alternative 1 vs. Alternative 2 ..................................................... 9-51 Figure 1-1 Vicinity Map ............................................................................................................... 1-6 Figure 1-2 Watershed Setting ..................................................................................................... 1-9 Figure 1-3 Project Alternatives ................................................................................................. 1-13 Figure 5-1 Particle Size Distribution of Meyers Creek Bed Sediment Samples (November 2023) . 5-32 Meyers Creek Drainage Study
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1 Introduction

1.1 Context
The City of San Bernardino has tasked Q3 Consulting to perform an assessment of the Meyers Canyon Drainage system and develop a conceptual alignment to improve Meyers Canyon. The drainage area is classified as online E-11 of the County of San Bernardino (County)’s Comprehensive Storm Drain Plan (CSDP) No. 7. Six Tracts have recently been developed within the drainage area, including Tracts 16502, 16533, 17329, 17367, 20150, and 20539 (Appendix L:). The Meyers Canyon drainage system crosses successively W Meyers Road and Belmont Avenue W before its confluence with the unimproved Cable Creek. Downstream of the existing confluence and North Little League Drive, Cable Creek has been improved to an engineered channel with a soft bottom and hardened banks, environmental mitigation, and other conveyance considerations. Cable Creek is owned and maintained by the County of San Bernardino Flood Control District (District).

The hydrology study of Meyers Creek extends from its headwaters to its point of confluence with Cable Creek. The original focused study, dated July 2025,evaluates conceptual drainage improvements from 500’ north of Meyers Road to the confluence with Cable Creek. The updated focused study was extended to approximately 1,500’ upstream of Meyers Road at the request of the District to incorporate an inline debris basin.

Currently, Meyers Creek is channelized as an earthen, unlined, trapezoidal channel from approximately 200 feet upstream of the Meyers Road crossing to 200 feet downstream of the lowwater crossing at Belmont Avenue. The channel presents a steep longitudinal slope averaging 4.1- percent. Upstream of Meyers Road, the current course of Meyers Creek may have been altered from its historical path or could diLer from the anticipated course in the vicinity of parcels APN#026106101 and APN#034811112 due to berming resulting from grading activities by the local private residents.

Existing drainage infrastructure along Meyers Road includes an existing 48-inch RCP which conveys stormwater flows from Tracts 17329 and 20539. The 48-inch RCP facility is designed to convey up to 243 cfs and runs southbound under Little League Drive until it reaches Meyers Road where it turns westbound towards Meyers Creek. The 48-inch RCP expands to a 81-inch RCP and receives flows from two CMP risers and a curb inlet along Meyers Road. The RCP expands to a 87-inch diameter before out letting to Meyers Creek downstream of the Meyers Road Culvert. These improvements were completed in 1991 and the As-Builts are included in Appendix M:.

The low-water crossing of Meyers Creek at Belmont Avenue was improved in 2007 by replacing the failing double 36-inch CMP with a double 36-inch RCP culvert was added at Belmont Avenue. The Meyers Road concrete box culvert was improved to be 10’ x 7.5’ and receives flow from two catch basins to the west of the culvert. The culvert has significant blockage (~20%) at the downstream side Meyers Creek Drainage Study
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due to vegetation and accumulated sediments. Two catch basins were constructed just north of where Little League Drive crosses over Cable Creek. Both Culverts outlet to Cable Creek.

Figure 1-1 Vicinity Map

1.2 Objectives
The preparation of the Preliminary Design Study is motivated by several factors, including:

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- The increase in frequency and volume of stormwater runoL flows to Meyers Creek resulting from the development of Tracts 17329 and 20539;
- Eliminating emergency maintenance operations from City StaL to remove significant sediment accumulation in the 87-inch RCP, Meyers Creek downstream of Meyers Road, and in adjacent streets. Evidence of sediment-laden flows in the Meyers Rd Storm Drain and adjacent street has been documented over time. Significant deposition of fine sediment (silt) resulted in the partial to full clogging of Meyers Rd Storm both in 2006 and 2010. - Providing flood protection and an eLective drainage system to the local residents.

1.3 Watershed Setting
Meyers Creek is a tributary to Cable Creek. The watershed tributary to Cable Creek Channel consists of approximately 10.7 square miles lying to the east of Cajon Canyon Wash, and includes Cable Canyon, Ames Canyon, Hopper Canyon, Meyers Canyon and Meecham Canyon. Ground elevation in the watershed varies from approximately 5,600 feet at the Monument Peak to approximately 1,550 feet at the confluence of Cable Creek and Devil Creek Diversion Channel. Slopes in the upper, northeast, watershed can exceed 30% while the terrain exhibits milder slopes in the southwest (2% to 6% grades).

Upstream of the confluence with Meyers Creek, the upper Cable Creek watershed encompasses 6.5 square miles of tributary area. An inline spreading grounds with a total storage capacity of 993 acrefeet was constructed by the District to provide 415 acre-feet of detention volume and 578 acre-feet of sediment and debris accumulation.

Downstream of Little League Drive, Cable Creek was improved by the District as a trapezoidal channel with grouted riprap lined side slopes, a 40-foot bottom width, and an overall depth of 12 feet.

Upstream of Little League Drive, the District, California Department of Water Resources (DWR), and the Santa Ana Watershed Project Authority (SAWPA) have partnered to create a debris and detention basin at the existing Cable Creek spreading grounds. The proposed project will provide long-term flood protection,
The Meyers Creek subwatershed is part of the Lytle Creek system, characterized by steep, sedimentprone hillsides draining onto alluvial fan deposits. Meyers Creek contributes approximately 811 acres of tributary area to Cable Creek at Little League Drive. The composition of Meyers Creek with respect to land use has shifted in recent years due to the large residential developments currently in construction along the eastern side of the subwatershed. The undeveloped region of the watershed contained eLective slopes of 5% on average. Cable Creek contributes as a mid-slope tributary, draining mountainous slopes via a canyon reach into Lytle Creek. Its watershed includes headwater catchments, with significant runoL and sediment delivery during peak storms (Appendix C:) as discussed further in Section 2 of this report.

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Land use in the area primarily consists of single-family dwellings units, schools, parks, and streets (SCAG, 2012). The specific designation for residential density has been updated since the 2012 general plan from general residential to low density. Several parcels in the north western section of the watershed were switched from general residential(1110) to rural residential (1150) in SCAG classifications. Large sections of the residential development from the southeastern portion of the watershed went from general residential (1110) to rural residential (1150). As a conservative estimate of density, 5-7 dwelling units per acre (as classified in the San Bernardino Hydrology Manual) was utilized in the rational method analysis. Impervious area was calculated using the inverse of the parcels to account for roadways.

Table 1-1 Meyers Creek Watershed Land Uses
Classification
2012 General
Plan SCAG
2019 General
Plan SCAG
1110-Single Family
Residential 45.3% 32.8%
1150-Rural Residential 0.0% 12.6%
1240-Public Facilities 0.5% 0.6%
1430-Utility Facilities 0.1% 0.0%
1800-Open Space and
Recreation 51.3% 51.3%
Impervious 2.8% 2.7%
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Figure 1-2 Watershed Setting
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1.4 Flood Insurance Rate Map
The existing Federal Emergency Management Agency (FEMA) map was used to determine if the project site is located within the limits of the 100-year floodplain. Review of the existing FEMA Flood Insurance Rate Map (FIRM), panel 06071C7930J indicates that the vicinity of Meyers Creek is mapped in a Flood Designation Zone A, which indicates that the vicinity of the project extents fall within the 100-year floodplain. Refer to Appendix J.

No detailed mapping study was performed by FEMA, the City, or the District.

1.5 Previous Studies
No detailed studies have been prepared by the City or the District to evaluate the Meyers Creek subwatershed. However, several regional studies have been performed in its vicinity, which provide some indication as.

The District prepared a Comprehensive Storm Drain Plan (CSDP) Number 7 for the Cable Creek-Lytle Creek watershed (1982). Meyers Creek Channel is referenced as Project No. 7-E11. The existing storm drain lateral along Meyers Road is referenced as Project No. 7-E12, which was completed by the City in 1991. Approximately 1,800 feet upstream of Meyers Road, the District identifies two potential debris basins to be implemented in the West Fork (subwatershed A) and East Fork of Meyers Creek (subwatershed B), respectively. These debris basins are referenced as Project No. 7-E10. The CSDP No.7 references a concrete-lined facility for Meyers Creek Channel from the upper debris basins to the its confluence with Cable Creek. Specifically, a trapezoidal concrete-lined channel (8- foot bottom and 7-foot tall) is proposed between the proposed debris basin and Meyers Road to convey a 100-year peak discharge of 1,574 cfs. Downstream of Meyers Road, a U-shaped concretelined channel (10-foot bottom and 8-foot tall) is proposed to convey 1,974 cfs. Construction costs were estimated at $1.2 Million in 1982, or $4.3 Million in today’s value adjusted per the ENR Construction Cost Index (1982: 3,705 ; 2025: 13,200).

CM Engineering Associates (1986) prepared a drainage study for Bailey Canyon for the District. Bailey Canyon is the next downstream tributary to Cable Creek from Meyers Creek. The goal was to establish the alignment and configuration of the ultimate facility for Bailey Canyon Channel consistent with the District’s Comprehensive Storm Drain Plan Project No. 7-E14 and E-14A. The report identifies that highly debris laden flows are anticipated from the mountainous drainage area of 525 acres. A high-level hydrology delineation and hydrology study is included, which determined 349 acres of tributary drainage area for the Meyers Creek subwatershed at Meyers Road. Using the rational method, the study computed peak discharges of 636 cfs and 993 cfs for the 10- and 100-year storm events, respectively.

The District performed the Cable Creek Drainage Study (1994) to analyze the conditions of the Cable Creek watershed and make recommendations for improvements to the Cable Creek mainstem system from the mouth of Cable Creek Canyon to its confluence with Devil Creek Diversion Channel.

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Based on an evaluation of the watershed, basin topography, site conditions, and discussions with the County and City StaL, three main recommendations were made: (1) a detention basin is proposed for implementation within the existing Cable Creek Spreading Grounds, eLectively reducing to 100-year peak discharge from 10,830 cfs down to 5,675 cfs ; (2) due to extremely steep topography of the watershed, the implementation of debris basins within each canyon was deemed undesirable. Instead, an extension of the existing levee system along Cable Creek was recommended; and (3) downstream of the detention basin, the District has the required right-of-way to improve the existing channel to a grouted riprap trapezoidal channel section.

1.6 Project Alternatives
Q3 presented two conceptual project alternatives to the City in April 2024. The two project alternatives evaluated in this Project Design Report (PDR) include Alternative 1(Backbone Storm Drain) and Alternative 2 (Improved Channel).

1.6.1 Alternative 1 (Backbone Storm Drain)
The first alternative consists of constructing 2,300 linear feet of backbone storm drain under Little League Drive from Meyers Road to its discharge to Cable Creek east of Little League Drive. Two storm drain laterals are proposed, one 72-inch RCP along Meyers Road to replace the existing westbound (reversed) 81-inch RCP, and an 84-inch RCP along Belmont Avenue. The backbone storm drain would begin at the intersection with Meyers Road as a 7’x6’ RCB. Its size would increase progressively to 11’x7’ RCB with the confluence with the Belmont Avenue lateral storm drain and as the longitudinal slope becomes milder downstream. The outlet to Cable Creek would include wingwalls and an energy dissipation feature, such as riprap apron, velocity rings, and an impact basin. The ultimate configuration would be determined during final engineering.

Standard catch basin inlets and street curb inlets are proposed at the intersections of Little League Drive with Belmont Avenue and Meyers Road, respectively. Similar standard catch basins and street curb inlets are not suLicient to capture a significant portion of the overtopping flows from Meyers Creek that may occur at Meyers Road and Belmont Avenue during major flood events. Instead, Alternative 1 relies on a series of longitudinal drop channels placed at strategic locations within the northside (westbound) parkway. A series of longitudinal, rectangular, open inletss would be 8-feet wide and up to 50-foot long. The longitudinal, rectangular, inlets would be surrounded by cable railing or covered with grated inlets for fall prevention and divert captured flows to the storm drain laterals. Should the Alternative be retained by the City, the dimensions and configuration of the longitudinal, rectangular drop channels would be determined during final engineering. Preliminary design plan and profiles are included in Appendix E:.

1.6.2 Alternative 2 (Improved Channel)
The second alternative consists of improving the existing Meyers Creek channel to its ultimate condition to convey the 100-year peak discharge. Upon receiving direction from the District, the proposed channel configuration follows the District’s Standard Plan (S.P.) 192E for a concrete-lined Meyers Creek Drainage Study
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channel section. The proposed channel would consist of both concrete-lined bottom and side slopes. The proposed channel includes two dikes on both sides of the channel, allowing for future maintenance, consistent with the District S.P. 100.

An inline debris basin is proposed upstream the channel improvements at the confluence of Meyers Creek tributaries A (west) and B (east). The debris basin is designed to capture approximately 29.9 acre-feet of debris from tributaries A and B. Maintenance access ramps around the perimeter and to the bottom of the basin are included in the concept and connect for ingress/egress with the abandoned City road of Meyers Road. A low-flow tower and an inline spillway allow for the basin to fully drain. Side slopes, spillway, and upstream transition structures will be protected with rock slope protection. The spillway configuration allows for the full 100-year discharge to overtop and run down the channel.

The proposed concrete-lined channel would pick up flows from the proposed debris basin approximately 1,500’ north of Meyers Road. Downstream of the basin spillway, the concrete-lined channel would begin with a 40’ bottom wide section allowing the channel to capture all flows and transitioning the proposed channel to a 12’ bottom width. Downstream of Belmont Avenue, the bottom width increases to 30’ as the longitudinal slope flattens to 0.5%. The channel dikes transition progressively until they meet the existing grade.

The existing crossings at Meyers Road and Belmont Avenue would be improved to convey the full 100- year, clear, peak discharge. Notably:
- The existing 10’ x 7.5’ RCB culvert at the Meyers Road crossing would be replaced with a precast arch culvert (32’ span by 11’ 0 ¾” rise).
- The existing double 36” RCP culvert would be replaced with another precast arch culvert (32’ span by 11’ 0 ¾” rise).

Preliminary plans and profiles for this alternative are included in Appendix E:.

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Figure 1-3 Project Alternatives
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2 Hydrology Studies

2.1 Hydrology Approach
Hydrologic computations were performed to determine peak discharge runoL from the tributary watershed at strategic locations along the proposed Alternatives. The hydrologic analysis was conducted in accordance with the 1986 San Bernardino County Hydrology Manual and its 2010 Hydrology Manual Addendum. The Hydrology Manual Addendum specifies the use of NOAA Atlas 14 rainfall values for hydrologic analyses.

The 1986 San Bernardino County Hydrology Manual limits the applicability of the rational method to drainage areas smaller than 640 acres. The limitation assumes that rainfall is distributed uniformly over the entire drainage area under that threshold. The Meyers Creek subwatershed (811 acres) is of elongated shape exhibiting significant topographic relief, thus reducing the likelihood of uniform rainfall patterns. For this reason, the unit hydrograph method was used to size the proposed concrete-lined channel (Alternative 2). The rational method was, however, used to size the local infrastructure, such as storm drains, catch basins, and other local drainage features, notably in Alternative 1.

A watershed delineation was carried out using available topographic data, aerial imagery from Google Earth, and an understanding of the location of existing culverts. The following topographic information was utilized:
- USGS Lidar 1 Meter Contours for San Bernardino (2022) - USGS NED 1/3 arc-second Contours for San Bernardino (2022) A 10-foot composite Digital Elevation Model (DEM) was compiled and used as the basis for delineation. GIS watershed delineation tools were employed to generate drainage catchments and flow paths, in accordance with the guidelines set forth in the San Bernardino County Hydrology Manual (1986). Drainage areas were further refined based on observations made during our site reconnaissance on November 10, 2022 and November 29, 2023.The longest flowpath through the watershed is roughly 13,500 feet with an elevation drop of 2,577 feet.

Land uses within the watershed were translated from the SCAG classifications to the classifications utilized in the San Bernardino Hydrology Manual. As discussed in Section 1, the residential land uses were translated to 5-7 Dwellings per acre as a conservative approach considering future development in the watershed.

Table 2-1: SCAG Database Classifications to San Bernardino Hydrology Manual Classification SCAG Database Classes San Bernardino Hydrology Manual Classes 1110-Single Family Residential 5-7 Dwellings per acre
1150-Rural Residential 5-7 Dwellings per acre
1240-Public Facilities School
1430-Utility Facilities Natural Good Cover, “Meadows”
1800-Open Space and Recreation Public Park or Shrub/Scrub Meyers Creek Drainage Study
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The single area unit hydrographs were computed using the land uses identified in the National Land Cover Database (2016). Since the development is expected to mitigate an increase in flows, the existing land cover for the development region is appropriate for use in the hydrologic calculations.

2.1.1 Rational Method
The addendum to the San Bernardino County Hydrology Manual states that the correct antecedent moisture condition (AMC) should be used depending on if the watershed falls within a designated arid region. Refer to Addendum Figure ADD-1. The entire Meyers Creek subwatershed falls within the AMCIII region. Antecedent Moisture Condition (AMC) II was used for the 10-year storm and AMC III was used for the 100-year storm.

2.1.2 Single Area Unit Hydrographs
Due to the limits on rational method hydrology as discussed in Section 2.1, unit hydrographs were developed for the upper tributaries to Meyers Creek. A map of the tributary areas is included in The hydrologic results from the UH computations were then input to a rational method analysis for the downstream portion of the Meyers Creek Watershed prior to its confluence with Cable Creek. Unit hydrographs were created for Upper Tributaries A (West Meyers Creek), B (East Meyers Creek), and E (Tracts No. 17329 and 20150). Additional Single Area Unit Hydrographs were computed for the watershed at the Meyers Road crossing, Belmont Avenue crossing, Meyers Road Storm Drain at Meyers Road and Little League Drive, and confluence with Cable Creek. These hydrographs were utilized for sizing the proposed channel in Alternative 2. Tables, figures, and equations for low rates, yield fraction, loss fraction, and curve numbers were derived from the San Bernardino County Hydrology Manual. Loss rates were calculated for each soil type, land use and AMC within each watershed and an area average loss rate was calculated for each overall watershed for the 10, 100, and 500-year storm events.

Hydrologic computations were performed using the proprietary AES software.

2.2 Rainfall
Daily rainfall data are available on the USGS website for the Gilbert Street Precipitation Gage Station in the City of San Bernardino (USGS Station ID#340742117161701). Available daily rainfall records span from October 2005 to January 2024. To support our assessment, water-year summaries were generated for Water Year 2005 through 2023. Total rainfall in inches and maximum daily rainfall in inches are summarized in Error! Reference source not found..

The wettest water-year on record is 2023 (October 2022 – September 2023) with a total of 25.72 inches. Other above average water-years include 2010, 2011, 2017, and 2019. The highest daily rainfall is 3.46 inches on November 21, 2013. Conversely, water-years 2006, 2007, 2018, and 2021 were relatively dry.

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Table 2-2 Water-Year Rainfall Statistics (Gilbert Street USGS) Water-Year 2006 2007 2008 2009 2010 2011 2012 2013 2014 Total Rainfall (inch) 3.2 4.33 13.7 10.1 17.8 23.5 9.01 9.52 12.42 Daily Max Rainfall
(inch)

2.2 0.9 2.6 1.76 1.98 3.2 1.66 2.04 3.46
Water-Year 2015 2016 2017 2018 2019 2020 2021 2022 2023 Total Rainfall (inch) 11.09 8.84 21.57 6.81 19.85 12.55 8.19 10.99 25.72 Daily Max Rainfall
(inch)

1.81 1.49 2.07 1.96 3.34 1.57 1.63 2.33 2.47
The District’s Hydrology Manual Addendum (2010) requires the use of NOAA Atlas 14 rainfall values when completing hydrologic analyses for the 10-, 100-, and 500-year storms. Complete data sets from NOAA are included in Appendix I:. Table 2-3 and Table 2-4 summarize the rainfall intensityduration and depth-duration statistics per NOAA Atlas 14, respectively. Due to the larger distribution of rainfall patterns within the watershed, the rainfall used for hydrologic analysis varied slightly across the subareas and tributaries.

Table 2-3 Rainfall Intensity Data
Rainfall Duration 10–yr. Intensity
(in/hr.)
100-yr Intensity
(in/hr.)
500-yr Intensity
(in/hr.)
5-min 4.39 7.08 9.61
15-min 2.54 4.09 5.56
30-min 1.89 3.04 4.15
1-hr 1.43 2.31 3.17
2-hr 1.0 1.57 2.14
3-hr 0.60 0.91 1.74
Table 2-4 Rainfall Depth Data
Rainfall Duration 10-yr Depth (in) 100-yr Depth (in) 500-yr Depth (in) 5-min 0.39 0.62 0.80
30-min 1.00 1.62 2.08
1-hr 1.53 2.46 3.17
3-hr 2.70 4.15 5.24
6-hr 3.94 5.97 7.47
24-hr 7.89 12.0 15.0

2.3 Results

2.3.1 Existing Condition
The table below shows the results of the existing rational method study. Complete results and output are included in Appendix C: and Appendix D:. The results for the single area unit hydrographs used Meyers Creek Drainage Study
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for the existing rational method are below. The lag time was not included in the rational method input because the flow was specified as a constant source flow, code 16, rather than a user specified flow, code 7, to avoid AES software issues.

Table 2-5 Existing Condition Rational Method Results - Clearwater Node Location Q10(CFS) Q100(CFS)
108 US Meyers Creek/ Meyers Rd 941 1738
109 DS Meyers Creek/ Meyers Rd 980 1809
111 US Meyers Creek/ Belmont Rd 1248 2267
112 DS Meyers Creek/ Belmont Rd 1248 2267
115 US Cable Creek 1268 2308
116 DS Cable Creek 1310 1284
Table 2-6 SAUH AES Results for Existing Condition Upper Tributaries Watershed Area(acres) Q10(CFS) Q100(CFS) Q500(CFS)
A 186 276 538 702
B 341 577 1064 1356
E 135 305 432 689

2.3.2 Alternative 1 - Backbone Storm Drain
Results from the HEC-RAS model (Refer to Section 3) were used to determine discharge overtopping at the Meyers Road and Belmont Avenue crossings, resulting from the undersized culverts. Complete results from HEC-RAS are included in Section 3.2 for the proposed storm drain. The HEC-RAS peak flow was subtracted from the existing condition rational method peak flow to size the storm drain system accordingly. The as-built, Tract No. 17329-1 Storm Drain Improvements by Allard Engineering was used to obtain the existing 100-year design flows and pipe sizing at the Little League Drive and Meyers Road junction.

Table 2-7 summarizes the peak discharge results for Alternative 1. Overtopping peak discharges reaching Meyers Road and Belmont Avenue are identified. Because the low-water crossing at Belmont Avenue is only four feet lower than the adjacent left bank, significant volumes of floodwaters overtop at Belmont Avenue. Both lateral storm drains are sized to convey the 521 and 729 CFS coming from Meyers Creek at Meyers and Belmont Road, respectively.

The final ultimate section of the Backbone Storm Drain under Little League Drive is a 11’x7’ RCB, which would be able to convey 1821 CFS. Refer to WSPG calculations under Section 3.

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Table 2-7 Proposed Condition Rational Method Hydrology for Alternative 1 – Backbone Storm Drain Node Location Q10(CFS) Q100(CFS)
703 (HEC-RAS Captured by Meyers
Rd Lateral Storm Drain)
Meyers Creek/ Meyers Rd 153 521
707 Little League Rd/ Meyers Rd 446 1021
804 (HEC-RAS Captured by
Belmont Ave Lateral Storm Drain)
Meyers Creek/ Belmont Rd 446 1022
709 Little League/ Belmont Rd 430 729
711 DS Cable Creek 915 1821

2.3.3 Alternative 2 – Improved Channel
Table 2-8 summarizes the peak discharge results for Alternative 2. All flows are contained within the channel, as the channel will be improved to meet the District’s standards.

Table 2-8 Proposed Condition Unit Hydrograph Method for Alternative 2 – Improved Channel Location Q500 – Clearwater (CFS)
US Meyers Creek/ Meyers Rd
Concentration Point A
2401.4
US Meyers Creek/ Belmont Rd
Concentration Point B
3151.4
Confluence Cable Creek
Concentration Point D
3148.6
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3 Hydraulics

3.1 Hydraulic Approach

3.1.1 Existing Condition
The goal of the hydraulic analyses is to define the flood plain limits based on the depths derived from the hydraulic model. Along with the flood plain limits, the hydraulic model will help determine where floodwaters overtop Meyers Creek and how those overtopping floodwaters travel through the downstream neighborhood. The peak, volume, and velocities of floodwaters will also be quantified to help sit and size proposed drainage improvements that meet the City drainage criteria.

A two-dimensional, unsteady-state hydraulic model was created with HEC-RAS Version 6.3 (USACE, 2023) to model the flood event throughout the floodplain. DiLerent stimulations were created for existing and ultimate condition channel and storm drain, for the 10-, 100-, and 500-year storms. The downstream control was set to Base Flood Elevation of 1786 feet NAVD88 in Cable Creek, as referenced on FEMA DFIRM Panel #0607137930J.

A separate existing condition model was built assuming a 20% blockage at the Meyers Rd crossing in the existing condition. Clearwater hydraulics were performed only. The intent is to model and evaluate the current conveyance obstruction caused by accumulated debris, sediment, and overgrown vegetation inside and at the downstream outlet of the crossing culvert.

Water depth, velocity, and water surface elevation result maps were created in RAS Mapper. Several assumptions were made to build the HEC-RAS hydraulic models, including:

3.1.1.1 Topographic Mapping
United States Geological Survey (USGS), Southern California Wildfires 1-meter, Zone 5 LiDAR, MayOctober 2018. The limits of the model tie-in to the FEMA-designated floodplain of Cable Creek. The topographic mapping was also converted from meters to feet.

3.1.1.2 2D Mesh
2D flow areas were created as part of the geometry of the existing and proposed conditions in the hydraulic models, respectively. The model extends from approximately 1,200 linear feet upstream of W Meyers Road to the confluence of Meyers Creek with Cable Creek. The cell size for both 2D flow areas were set to 30 feet by 30 feet. Break lines were incorporated as barriers or controls of flows in the hydraulic model.

3.1.1.3 Hydraulic Roughness
A range of n-values from .016-0.15 were applied for the entire extent of the 2D flow area (NCLD, 2016).

Infiltration was not considered as the soils are saturated during a 100-year event.

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Table 3-1 Manning’s N for Land Cover
Nation Land Cover Data Class Manning’s n
Shrub-Scrub 0.05
Grassland-Herbaceous 0.04
Developed, Open Space 0.035
Evergreen Forest 0.15
Mixed Forest 0.12
Developed, High Intensity 0.016
Developed, Low Intensity 0.08
Developed, Medium Intensity 0.12

3.1.1.4 Model Boundary Conditions
Multiple boundary conditions were set, including stage hydrographs, flow hydrographs, normal depth, and precipitation for the watershed. Unsteady flow hydrographs were applied at the upstream boundaries, including Meyers Creek West Tributary A (US BC Trib A) and Meyers Creek East Tributary B (US BC Trib B). The Meyers Creek DS stage hydrograph was applied at the downstream boundary of Meyers Creek since the FEMA DFIRM map for Cable Creek only references the steady-state Base Flood Elevation. The stage hydrograph was built using the UH results and derived from WSPG.

Other boundary conditions at the east and west side of the 2D domain are set to normal depth of the channel from the friction slope since the East-West streets are sloped at approximately 0.5%.

A rain-on-grid approach was applied to the entire 2D domain using a hyetograph built from NOAA Atlas 14 rainfall statistics. The hyetograph was built using HEC-HMS.

Downstream boundary conditions were taken from the stage hydrograph at Meyers Creek and critical depth calculated from the slope of 0.0186 foot/foot at Cable Creek downstream of Little League Drive.

The initial water surface elevation across the entire 2D domain was set at 1765.85 feet.

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Table 3-2 HEC-RAS Boundary Condition Methods
Storage/ 2D Flow Areas Boundary Condition
Meyers Creek DS Stage Hydrograph
BC Trib B Flow Hydrograph
US BC Trib A Flow Hydrograph
Tract16420 SD Flow Hydrograph
East DS Normal Depth
East Project Boundary Normal Depth
Little League DS Normal Depth
DS Normal Depth
West Project Boundary Normal Depth

3.1.1.5 Unsteady Flow Analysis Settings
The unsteady flow computations were initially run using the Energy Equation to set up the model and address any major instabilities. The final models were run using the Full Dynamic Wave or Full Momentum equations in accordance with HEC-RAS User Manual Ch 8. The 100-year run has a simulation time window of 24 hours. The computation time step was set to 0.5 second and the output time intervals were set to every 5 minutes.

3.1.1.6 Culvert Modeling
Culverts were modeled as 1D hydraulic structures connected within the 2D grid. The hydraulic structures were set up in the middle of the 2D flow areas using the SA/2D Area Connection Data Editor. Culvert inlets and outlets connect automatically to cells at the upstream and downstream ends. Meyers Road has a 10x7.5 feet RCB with flared wingwalls and 77 feet long with a weir length of 78 feet. The Belmont Ave crossing has two 36-inch RCP with a groove end entrance 61 feet long with a weir length of 107 feet. The 100 feet long 36-inch diameter culvert is modeled to carry street flow into the creek at the Meyers Road crossing. The proposed swale is modeled as 1641 feet long 84” RCP down Little League Drive

3.1.2 Alternative 1 – Backbone Storm Drain
WSPG is a steady-state hydraulic model used to compute gradually varied flow profiles in open channels and closed conduits, which is supported by the District and the City. WSPG models were developed based on the alignments included in the proposed design for alternative 1 and utilizing the rational method peak 100-year flow rates calculated for the proposed storm drain system. The results of these runs were used to size the system to convey the 100-year event flows without flooding. Overtopping flows at Belmont Avenue and Meyers Road calculated in the existing condition HEC-RAS model were added to the system where catch basins were proposed to prevent flooding during the 100-year event as part of the rational method analysis.

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The tailwater elevation is set to the FEMA’s BFE elevation of 1786, and the hydraulic grade line was kept 2 feet below the existing ground elevation for the 100-year peak discharge. Only the main storm drain, and laterals were modeled, disregarding the majority of the subarea flows from the catch basins. The invert of the laterals was set to 0.5-2 feet above the main pipeline elevation to avoid hydraulic jumps.

3.1.3 Alternative 2 – Improved Channel
The methodology employed to evaluate the existing conditions are similar to that used in evaluating the improved channel, i.e. a HEC-RAS2D model. Inputs for the model were derived using the Single Area Unit Hydrograph model described in the Hydrology section of this report and identified as Upper Tributaries A and B. The SAUH at Concentration Point E was also utilized as an input for the model.

The proposed condition HEC-RAS2D model does not include the debris basin, as the basin dynamics may not be fully modeled.

Preliminary concrete-lined channel cross sections were determined through Hydraulic Toolbox with the 100-yr storm event flows and confirmed with the results from the HEC-RAS 2D modeling. The channel grading upstream of the Meyers Road Culvert was sized to carry the flow tributary to the culvert. Additionally, the channel expands gradually to capture the maximum flow through Meyers Canyon and minimize flooding along the road adjacent to the creek. The HEC-RAS 2D model was used to determine the necessary outlet dimensions required to maximize capture of flows through Meyers Canyon. The same size culverts at Meyers Road and at Belmont Avenue were incorporated.

Constant channel grading was also used for the approximate 400’ reach downstream of the Belmont Avenue crossing.

The slope of the channel was controlled by the required channel inverts at the crossings. The CONSPAN precast arch waterway, or approved equivalent, rises approximately 11’. Using a minimum cover of 4’ and a 1’ concrete thickness for the culvert wall, the invert for the upstream end of both crossings was found so that the existing street profile could be maintained. A 0.5% slope for both culverts set the downstream invert and starting station elevation for the downstream section of the channel profile.

The reach downstream of the Belmont culvert sloped at 0.5% to the existing ground. The upstream end of the proposed channel matches the existing ground before dropping four feet within a grade control structure. The channel continues at constant slope to the invert at the culvert.

3.2 Results

3.2.1 Existing Condition
Model Results for the existing condition with and without a blockage at Meyers Road are included in in Appendix F:. The results are included in the summary table in Section 3.2.4.

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3.2.2 Alternative 1: Backbone Storm Drain
The main pipes carrying the overland flow at Meyers and Belmont Rd will be 72” and 84” RCP’s which connect to the RCB along Little League Drive that transitions from a 7’x6’ to 9’x7’ to 11’x7’ RCB and outlets into Cable Creek. The hydraulic grade line is well below the 2 feet of cover from the existing ground.

Table 3-3 WSPG Storm Drain Sizing Results
Location Pipe/ Box Size
Meyers Rd from Meyers Creek to Little League Dr 6’ RCP
Meyers Rd from Magnolia Ave to Little League Dr 6’ RCP
Little League from Meyers Rd to Belmont Rd 7’x6’ RCB
Belmont Rd from Meyers Creek to Little League Dr 7’ RCP Little League from Belmont Rd to Cable Creek 9’x7’ RCB to 11’x7’ RCB

3.2.3 Alternative 2: Improved Channel
Proposed channel alignments, profiles, and typical cross sections are included in the conceptual design plans. Exhibits illustrating the eLects of the proposed channel and culverts calculated in HEC-RAS 2D are included in Appendix F: and flow rates and volumes are included in Section 3.2.4.

3.2.4 2D Model Results Summary
HEC-RAS 2D models of the existing and proposed channel condition showed an increase in flow within the channel with the proposed improvements. Clearing the vegetation and debris within the existing culvert had minor aLects on overtopping and increased the flow in the channel by approximately 20 CFS in comparison to the over 1,700 CFS increase in flow seen with the proposed channel improvements.

Table 3-4 HEC-RAS Results, 100-year Storm Event
Existing (20%
Blockage)
Existing (No
Blockage)
Proposed Channel
ID Scenarios Max Q
(cfs)
V
(acre/ft)
Max Q
(cfs)
V
(acre/ft)
Max Q
(cfs)
V
(acre/ft)
4 US Meyers Creek/
Meyers Rd
1438 445 1438 445 1912 416
7 DS Meyers Creek/
Meyers Rd
971 428 1117 438 1956 515
2 US Meyers Creek/
Belmont Rd
1618 535 1688 540 2485 645
16 DS Meyers Creek/
Belmont Rd
658 360 678 361 2401 647
11 US Little League 177 18 176 18 18 1.9
12 DS Little League 614 95 601 93 65 8
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4 Preliminary Engineer’s Estimate of Probable Costs

4.1 Alternative 1 – Backbone Storm Drain

4.1.1 Methods
Anticipated Construction Costs
The preliminary engineer’s assessment of probable costs for demolition and construction considers the following general items for the proposed storm drain:
• Demolition of portions of the existing storm drain, outlet structure, and roadway sections.

Demolition costs include cutting and removing asphalt and base above the proposed alignment and the existing alignment that will need to be removed. Existing storm drains sections at the intersection of Little League Drive and Meyers Road and along Meyers Road from Little League Drive to Meyers Creek will be sawcut and removed. Demolished RCP will need to be oL hauled along with trenched soils that cannot be used for backfilling; • Construction of RCP, RCB, and appurtenances;
• Construction of Rectangular Channels and Catch Basins; • Construction of transition structures, junctions, and manholes; • Construction of an outlet structure.

A preliminary engineer’s estimate of probable costs is prepared for the preferred design using recent bids from Riverside County and San Bernardino County projects of similar scope and size, quotes received from vendors, and RS means of construction cost data. Given that the proposed project is evaluated at a schematic design level only, the estimate is based on the following assumptions:
• Design and construction contingency of 20% to capture all design aspects that have not been detailed in the preliminary design;
• Final engineering design and engineer’s support during construction phase (10%) • Construction staking (5%)
• CEQA Planning and Permitting (1.5%)
• Agency Project Management (5%)
• Construction Administration (10%)
• Contractor’s General Conditions and General Requirements (20%) • Contractor’s Overhead and Profit (8%)
• Contractor’s Insurance and Bonds (2%)
• Escalation assumes that construction activities will start in January 2026 and will last 12 months.

A mid-point construction date is in July 2026. Escalation is based on an annual inflation rate of 5%.
• Soil remediation, independent inspections are not included.

Anticipated Operation and Maintenance Costs
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Under Alternative 1, the proposed backbone storm drain facility would be constructed within the City’s street right-of-way. The long-term maintenance of the backbone storm drain facility would be handled by the City.

Anticipated operation and maintenance cost estimates are based on general routine maintenance costs of storm drain and channel facilities publicly disclosed by San Bernardino County Flood Control District, Orange County Public Works, and Los Angeles County Department of Public Works as part of the maintenance contracts. Routine operation and maintenance activities include:
• Inspection and cleaning of the transition structures, junction, and manholes; • Inspection and cleaning of the rectangular channels with grated inlets/ fall prevention railing and catch basins during dry-weather and wet-weather seasons; • Major sediment removal of the backbone storm drain and its laterals; • (If necessary) Inspect and repair/repaint storm drain stenciling at catch basins; • Long-term repairs such as major structural repairs and/or rehabilitation are not included since the facilities would be new when constructed. Major rehabilitation is anticipated on a 25- to 50- year cycle only.

4.1.2 Right-of-Way Acquisition
Under Alternative 1, the proposed storm drain configuration remains within the ultimate City’s rightof-way, except at its outlet where the project would require an encroachment permit from the District. Along W. Meyers Road and Belmont Ave, the construction of the rectangular channel inlets would likely require either dedication of the ultimate right-of-way or a temporary construction encroachment permit from the private owners. No encroachment of the privately-owned parcels is anticipated.

Preliminary engineer’s estimates of probable costs do not include any right-of-way acquisition costs.

4.1.3 Environmental Mitigation
Refer to Section 6.1.2. Impacts are limited to the outlet in Cable Creek. The project is not anticipated to cause substantial adverse impacts requiring riparian mitigation. No costs for riparian mitigation are included.

4.1.4 Total Construction Cost
Total capital costs are anticipated to be $25.0 million.

4.1.5 Anticipated Operation and Management Cost
Detailed anticipated O&M costs are presented in Table 4-1.

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Table 4-1: Anticipated O&M Costs
Maintenance Activity and Description Frequency Annual
Costs
Junction and Transition Structures:
- Sediment and trash is evacuated through an access/
inspection manhole.
- Maintain record of inspections for the life of the system. - For accumulated sediment and debris, cleanout solids
exceeding 6 inches of build up, remove sediment and
debris.
- Inspect for standing water within 48 hours of heavy rain events to ensure proper drainage.

Twice a year during
wet season,
including
inspection just
before the wet
season.
$18,000
Catch Basins:
- Sediment and trash is evacuated through an access/
inspection manhole.
- Maintain record of inspections for the life of the system. - For accumulated sediment and debris, cleanout solids
exceeding 6 inches of build up, remove sediment and
debris.
- Inspect for standing water within 48 hours of heavy rain events to ensure proper drainage downstream.

Twice a year during
wet season,
including
inspection just
before the wet
season
$12,000
TOTAL $30,000

4.2 Alternative 2 – Improved Channel

4.2.1 Methods
Anticipated Construction Costs
The preliminary engineer’s assessment of probable costs for demolition and construction considers the following general items for the proposed channel improvements:
• Demolition of portions of the existing storm drain and outlet structure • Demolition of roadway sections
• Grading of debris basin
• Grading of trapezoidal channel
• Installation of precast arched culverts at Meyers Road and Belmont Avenue • Reconstruction of catch basins, curb and gutters, and sidewalks • Construction of spillway and outlet works for the debris basin • Construction of an outlet structure
• Construction of access road and access gates
• Construction of chain link fencing along project perimeter • Lining of basin slopes with rip rap and protection fabric • Lining of channel slopes with concrete lining
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A preliminary engineer’s estimate of probable costs is prepared for the preferred design using recent bids from San Bernardino County and Riverside County projects of similar scope and size, quotes received from vendors, and RS means of construction cost data. Given that the proposed project is evaluated at a schematic design level only, the estimate is based on the following assumptions:
• Design and construction contingency of 20% to capture all design aspects that have not been detailed in the preliminary design;
• Final engineering design and engineer’s support during construction phase (10%) • Construction Staking (5%)
• CEQA Planning and Permitting (5%)
• Agency Project Management (5%)
• Construction Administration (10%)
• Contractor’s General Conditions and General Requirements (20%) • Contractor’s Overhead and Profit (8%)
• Contractor’s Insurance and Bonds (2%)
• Escalation assumes that construction activities will start in July 2026 and will last 18 months. A mid-point construction date is in March 2027. Escalation is based on an annual inflation rate of 5%.
• Soil remediation and independent inspections are not included.

Anticipated Operation and Maintenance Costs
Meyers Creek Channel is referenced as Project No. 7-E11 in the District’s CSDP Number 7. The intent is for the City to transfer ownership of the ultimate channel facility (Alternative 2) upon construction to the District. Under Alternative 2, the District will be the responsible stakeholder for the long-term operation and maintenance (O&M) of the proposed ultimate channel facility.

Anticipated operation and maintenance cost estimates are based on general routine maintenance costs of storm drain and channel facilities publicly disclosed by San Bernardino County Flood Control District, Orange County Public Works, and Los Angeles County Department of Public Works as part of the maintenance contracts. Routine operation and maintenance activities include:
• Inspection and cleaning of the transition structures, junction, and manholes; • Major sediment removal of the channel facility;
• (If necessary) Inspect and repair/repaint storm drain stenciling at catch basins; • Minor structural repairs of the connections
• Inspection, clearing and repair of the access roads and ramps, and vegetation abatement of the channel facility;
• Annual regulatory compliance (MS4, 408) for the channel facility; • Long-term repairs such as major structural repairs and/or rehabilitation are not included since the facilities would be new when constructed. Major rehabilitation is anticipated on a 25- to 50- year cycle only.

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4.2.2 Right-of-Way Acquisition
The proposed channel improvements cross ten diLerent parcels as shown in Appendix E:. Right of way acquisition costs were calculated by assessing existing costs per acre for nearby undeveloped parcels for sale. Since the best available parcel data varied slightly from the county assessor’s area values, the total cost of parcels was calculated by multiplying the per acre cost by the County Assessor’s parcel area. Then a ratio of the parcel areas required over the total parcel areas developed in GIS was used to find the total cost of parcel acquisition by parcel. The sum of these costs was used for the total cost of parcel acquisition.

All parcels within the right of way of the proposed earthen channel are privately owned. The total area acquisition is 7.91 AC as measured with the best available parcel data.

Using an average per acre land cost of $500,000/AC, the total cost of parcel acquisition is approximately $4,710,000. The total parcel value including areas not required for the right of way is approximately $28,715,000.

Table 4-2 Parcel Acquisition Costs
APN Area (AC)
Area Required for Proposed
Right-of-Way (AC)
Percent Area
Required (%)
Assessors
Area (AC)
Partial Cost
026106101 5.05 0.95 19% 4.50 $425,276
026106106 1.64 0.01 1% 1.65 $4,533
026106107 1.81 0.18 10% 1.81 $87,391
026106109 1.03 0.33 32% 1.02 $161,778
026106128 0.36 0.11 30% 0.36 $54,137
026113102 3.77 0.80 21% 3.87 $409,071
026113103 20.51 0.50 2% 19.83 $241,114
034820112 1.39 0.10 7% 1.39 $48,837
034811119 1.36 0.95 70% 1.36 $475,223
034811120 12.01 3.99 33% 15.14 $2,516,478
034811112 10.17 0.89 9% 6.50 $285,705
Sum 59.08 7.91 - 57.43 $4,709,543

4.2.3 Environmental Mitigation
Refer to Section 6.2.2. Several potential environmental impacts have been identified and potential associated mitigation costs evaluated.

The Aquatic Resource Delineation (ECORP, 2024) delineated 0.835 acre of streambed and 0.624 acre of associated riparian habitat within the channel limits. Assuming a 4:1 mitigation ratio for stream channelization, the project would be required to repair 3.3 acres of riparian streambed under the Section 1600 agreement. Unit costs may vary from $150,000 to $500,000 per acre of mitigation. As Meyers Creek Drainage Study
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part of the improvements, mitigation to the habitat for local, native, species such as the San Bernardino Kangaroo Rat (SBKR) would be provided.

No aquatic resource delineation has been performed for the limits of the proposed debris basin, as the scope of the work was extended to incorporate a debris basin upon consultation with the District.

However it is anticipated that mitigation will be required for the extents of disturbance of the basin, or 3.6 acres. Should the Improved Channel alternative be retained, a supplemental aquatic resource delineation should be performed during final design and include the area to be impacted by the proposed debris basin
Long-term permitting, monitoring, and report may cumulate to $50,000 to $150,000.

4.2.4 Total Capital Cost
The anticipated capital cost for the project is estimated at $64.1 million.

4.2.5 Anticipated Operation and Management Cost
Anticipated O&M costs would include the removal of debris and sediment from the debris basin, cleaning of outlet structure from the debris basin, maintenance of catch basins and two Precast Waterways, or approved equivalent, two times per year. The maintenance access for the precast Waterways and channel will be determined during the final engineering. Detailed anticipated O&M costs are presented in Table 4-1.

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Table 4-3: Anticipated O&M Costs
Maintenance Activity and Description Frequency Annual
Costs
Routine Inspection and Cleaning:
- Visual inspections for debris, sediment buildup, and
structural integrity.
- Cleaning of inlets, manholes, and pipe systems using
vacuum trucks or flushing.
- Sediment and trash is evacuated.
- Maintain record of inspections for the life of the system. - Inspect for standing water within 48 hours of heavy rain events to ensure proper drainage.

Twice a year
during wet
season,
including
inspection just
before the wet
season.
$10,000
Debris Basin:
- Sediment and debris remvoval, offhauling, and disposal at designated facilities.
- Vegetation management, including removal of invasive
plants, trimming, and disposal.
- Structural repairs, as needed, of spillway and rock slope protection.
- Maintain record of inspections for the life of the system.

Twice a year
during wet
season,
including
inspection just
before the wet
season
$100,000
Catch Basins and Culverts:
- Sediment and trash is evacuated through an access/
inspection manhole.
- Maintain record of inspections for the life of the system. - For accumulated sediment and debris, cleanout solids
exceeding 6 inches of build up, remove sediment and
debris.

Twice a year
during wet
season,
including
inspection just
before the wet
season
$12,000
Vegetation & Access Road Maintenance
- Sediment and trash is evacuated through an access/
inspection manhole.
- Grading or resurfacing access roads.
- Repairing gates, fences, and signage to deter illegal dumping or trespassing.
- Mowing, herbicide application, and brush clearance for fire and vector control.
- Maintain record of maintenance activities for the life of the system.

Annually $25,000
TOTAL $147,000
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5 Sedimentation and Scour

5.1 Sediment Size
The NRCS Web Soil Survey defines a typical geologic profile in the upper Meyers Creek Subwatershed as gravelly loamy sand (Ramona Greenfield formations) from 0 to 36 inches, which transitions to fine gravelly sand from 36 to 70 inches. Loamy sand generally has a moderate potential for erosion. The typical geological profile is consistent with the visual observations made by Q3 StaL during the November 27, 2023, site visit.

Meyers Creek Tributary with exposed soil profile
along thalweg (November 2023)
Exposed soil profile of Meyers Creek
(November 2023)
Q3 StaL performed sediment sampling at four locations in the Meyers Creek subwatershed. All samples were collected using industry-standard protocols in the main stem of Meyers Creek at locations of interest. Samples were sent to Diaz-Yourman and Associates (DYA) for geotechnical testing, including five sieve analyses and one hydrometer (#200 sieve).

One sample was collected at the headwall outlet of the Meyers Rd Storm Drain (84” RCP) into Meyers Creek. The sediment composition and gradation appear much finer than the representative profile in Meyers Creek. Three other samples were collected in the mainstem of Meyers Creek. Limited erosion is apparent on the bed and banks of Meyers Creek due to the natural, established, vegetation, and coarse-grained bed materials that form an armoring layer.

Results from the sieve analysis reveal that:

1. All three samples in the mainstem of Meyers Creek returned consistent particle size distributions. The D50 is approximately 1.2 mm and is characterized as poorly graded sand with gravel (SP). Bed sediment includes between 14 and 31% of gravel (larger than 5mm). All three samples contained less than 1% of silt/clay (#200 sieve or smaller).

2. The soil deposit sample collected at the outlet of the Meyers Rd Storm Drain exhibits a D50 of 0.25 mm. The soil sample is classified as poorly graded sand with silt (SP-SM).

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90% of the materials are classified as coarse to fine sand. 10% of the sampled materials passed the #200 sieve and are classified as clay or silt.

Figure 5-1 Particle Size Distribution of Meyers Creek Bed Sediment Samples (November 2023) A separate memorandum was prepared by Q3 Consulting to evaluate the source of mud and debris flows that discharged onto North Little League Drive and W Meyers Road after the November 7-8, 2022 storm event. Significant amounts of mud were observed past Belmont Ave next to the parking lot of Little League Drive. The particle size distribution results indicate that the finer sediments Meyers Creek Drainage Study
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collected at the headwall of the 84” RCP could originate from the construction activities at Tract No. 17329, from the catastrophic failure of Detention Basin 2, or from historical deposits of the former agricultural operations upstream of the Meyers Rd Storm Drain. Refer to 0.

5.2 Conceptual Sediment and Debris Yield

5.2.1 Approach, methodologies, and assumptions
The USACE Los Angeles District Debris Method (USACE, 2000) consists of a set of predictive equations expressing the single event unit debris yield of a watershed as a function of physiographic, hydrologic, and meteorologic parameters. These predictive equations were developed by multiple regression analyses of single event debris data observed in the San Gabriel Ranges of southern California.

As defined in this method, the “total debris yield” is the total debris outflow from a watershed measurable at a specific concentration point for a specified event. It may include clay, silt, sand, gravel, boulders, tree stumps, and other organic materials. The “debris production” is the gross erosion within a watershed while the “debris yield” is the quantity of debris actually delivered to a concentration point of interest. The entire debris production of the watershed may not necessarily reach its outlet because it is stored temporarily within the watershed due to the lack of transporting capacity of the conveyance system.

There are five empirical equations that were derived on the basis of watershed size ranging from 0.1 to 200 square miles. The multiple regression analyses indicated that the unit debris yield (DY) for a watershed is highly correlated with the following basin parameters: relief ratio (RR) analogous to watershed slope, drainage area (A), unit peak flow (Q), and the non-dimensional fire factor (FF).

Equation 2 is usually applied to drainages 3 to 10 square miles in area. Equation 1, which is a function of precipitation rather than runoL, is used for basins 0.1 to 3; however, if frequency discharge information is available, Equation 2 may be used for areas less than 3 square miles (USACE, 2002).

Equation 2 was applied herein to the drainages of interest less than 3 square miles in size since frequency discharge information was available; thus, Equation 2 was applied to every subbasin:
logDY = 0.85logQ + 0.53logRR + 0.04logA + 0.22FF
where:
• DY = unit debris yield (yd3/mi2),
• RR = relief ratio (feet/mile),
• A = drainage area (acres),
• FF = non-dimensional fire factor, and
• Q = unit peak flow (cfs/mi2)
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5.2.2 Limitations
The general limitations related to the applications of the USACE Los Angeles District Debris Method in the prediction of debris yield are as follows: (1) geographic constraints, (2) drainage area constraints, (3) topographic constraints, (4) frequency constraints, and (5) input constraints. The frequency and input constraints pertain to small events less than 20-percent annual chance and low runoL or precipitation. Since the recurrence interval in this study is 100-year, only the geographic, drainage area and topographic constraints remain. This method is intended to be used for the estimation of debris yield mainly from coastal-draining mountainous watersheds located in southern California. Since the predictive equations were derived from data observed in the San Gabriel Range, the use of these equations for watershed conditions diLerent from those of the San Gabriel Range must be specifically addressed. The method is applicable only to watersheds with areas ranging from

0.1 to 200 square miles and with a high proportion of their total area in steep, mountainous terrain.

The use of this method to compute debris yields for watersheds in mild-sloped valley areas with a high percentage of piedmonts and alluvial fans or valley fill areas may result in estimates that are higher than actual yield. If the sediment transport capacity is less than the statistical debris method results, the sediment transport capacity governs the debris yield.

5.2.3 Adjustment-Transposition (A-T) factor
The use of predictive equations developed from data pertaining to watersheds, which historically demonstrate extremely high unit yields will result in overestimates of debris yields when applied to areas with less erosional activity. Recognizing this limitation, and the importance of uncertain geomorphic and geologic parameters, the USACE Los Angeles District developed an AdjustmentTransposition (A-T) factor. Using Table B-1 of the Los Angeles District Debris Method manual, the resulting A-T factor was computed to 0.65.

Due to the potential risk of wildfires occurring in this region, the Fire Factor (FF) used in the analysis of each subbasin was assigned a minimum value of 4.5 based on fire factor (Tables A-1 and A-2; USACE, 2000).

5.2.4 Computational results
Debris yield calculations were performed for the entire watershed, assuming that all debris and sediments would reach Meyers Creek. However, debris basins will be constructed. There are also several natural planforms that may help capture sediments and act as debris barriers. Further investigations should be performed during final engineering. Refer to Table 5-1 and Table 5-2.

The conceptual debris basin has a storage capacity of 29.9 acre-feet, which would capture 27% of the anticipated debris from a 10-year event. The conceptual design includes ingress/egress maintenance access routes to ensure that larger debris can be removed on a regular basis.

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subbasin drainage
area {sq
mi}
relief
ratio
{ft/mi}
fire
factor
for 4
years
since
100%
Wildfire
A-T
factor
Max 1-Hr
100-Yr
Precipitation
{in}
1-percent annual chance storm
Qp
{cfs}
qp
{cfs/mi2}
flood
volume
{ac-ft}
debris
yield
{ac-ft}
bulked
volume
{ac-ft}
bulking
factor
Qp,bulked
{cfs}
debris
yield
{cu-yd}
Meyers
Creek

1.254 1889 4.5 0.65 2.31 2,316 1,847 623 254.7 878 1.41 3,263 410,909 Max 1-Hr 10-
Yr
Precipitation
{in}
10-percent annual chance storm
Qp
{cfs}
qp
{cfs/mi2}
flood
volume
{ac-ft}
debris
yield
{ac-ft}
bulked
volume
{ac-ft}
bulking
factor
Qp,bulked
{cfs}
debris
yield
{cu-yd}

1.43 1,373 1,095 353 163.3 516 1.46 2,008 263,409
Table 5-1: Conceptual Sediment Yield Estimates
subbasin drainage
area {sq
mi}
relief
ratio
{ft/mi}
fire
factor
for 4
years
since
100%
Wildfire
A-T
factor
Max 1-Hr
100-Yr
Precipitation
{in}
1-percent annual chance storm
Qp
{cfs}
qp
{cfs/mi2}
flood
volume
{ac-ft}
debris
yield
{ac-ft}
bulked
volume
{ac-ft}
bulking
factor
Qp,bulked
{cfs}
debris
yield
{cu-yd}
Meyers
Creek

0.936 1889 4.5 0.65 2.31 2,070 2,212 496 170.8 667 1.34 2,783 275,596 Max 1-Hr 10-
Yr
Precipitation
{in}
10-percent annual chance storm
Qp
{cfs}
qp
{cfs/mi2}
flood
volume
{ac-ft}
debris
yield
{ac-ft}
bulked
volume
{ac-ft}
bulking
factor
Qp,bulked
{cfs}
debris
yield
{cu-yd}

1.43 1,234 1,318 286 110.1 396 1.38 1,709 177,548
Table 5-2: Conceptual Sediment Yield Estimates – Tributaries A and B Only to Proposed Debris Basin Meyers Creek Drainage Study
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5.3 Field Observations
Sediment sampling along the mainstem of Meyers Creek indicates a median particle size (D₅₀) of approximately 1.2 mm, classified as poorly graded sand with gravel (SP), and containing less than 1% fines (silt and clay). This grain size distribution typically suggests high mobility and a susceptibility to entrainment during moderate storm events, particularly in steep-sloped channels. However, field observations reveal that the downstream channel segment, which was graded over 35 years ago with a slope of approximately 2%, exhibits minimal signs of headcutting, scouring, or bank erosion. Side slopes remain intact with less than 6 inches of incision, suggesting long-term geomorphic stability under current flow and sediment regimes.

This apparent contradiction between theoretical mobility and observed stability implies that the channel has reached a state of dynamic equilibrium, where sediment transport capacity is roughly balanced with sediment supply. The coarse fraction (14–31% gravel) may act as a natural armoring layer, protecting the bed from incision despite the steep slope and non-cohesive material.

Additionally, low sediment input from the upstream watershed, intermittent flow conditions, and vegetation reinforcement along the banks may contribute to the long-term persistence of the earthen channel geometry. This finding supports the viability of maintaining an open-channel solution in some areas, with minimal hard armoring, provided that hydraulic and sediment conditions are preserved during design modifications.

5.4 Review of Historical Aerials
Aerial imagery and topographic maps obtained from the U.S. Geological Survey (USGS) EROS Data Center were reviewed for multiple time points, including July 1952, November 1967, May 1970, August 1975, December 1980, October 1986, April 1994, and March 2008. Prior to October 1986, the Meyers Creek drainage functioned as an active, braided alluvial fan system, distributing stormwater and sediment across a wide depositional area from Meyers Creek Road downslope to its confluence with Cable Creek. Overbank flow dispersal and sediment deposition were visually evident across successive decades, with flow paths meandering but remaining largely confined west of Little League Road. The aerial patterns confirm a historically dynamic system with moderate to high sediment mobility, typical of ephemeral channels in the San Bernardino foothills.

Following the onset of residential development around October 1986, the downstream segment of Meyers Creek was engineered into an unlined trapezoidal channel, extending from West Meyers Road to the Cable Creek floodplain. This channelization eLort introduced longitudinal confinement, reduced lateral flow dispersion, and formalized the drainage path through developed land. Since that time, aerial imagery shows minimal lateral migration or incision, and the channel banks appear to have maintained their integrity, suggesting the reach has stabilized over the past 35 years. This observed long-term stability despite a relatively steep channel slope (~2%) and non-cohesive bed material, which supports the field-based interpretation that the creek is operating under dynamic equilibrium conditions, balancing sediment transport and supply across typical storm events.

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Refer to 0 for aerial photographs.

5.5 Future Studies
Should Alternative 2 be pursued and alternative lining options be considered, further sediment transport investigations are recommended during the final design phase. This should include detailed cross-sectional surveys to document current channel geometry and slope, sediment transport modeling using field-calibrated parameters, and critical shear stress calculations to identify reaches that may exceed mobility thresholds under proposed flow conditions.

The sediment transport models should be based on functions that handle coarse, non-cohesive bed material (D₅₀ ≈ 1.2 mm sand + gravel), episodic high flows, and steep gradients (longitudinal slope >2%). The following sediment transport models/functions should be evaluated:
• Meyer-Peter Müller (MPM) for baseline bedload behavior • Wilcock-Crowe for gradation-aware modeling (if platform allows) • Engelund-Hansen if suspended load or total transport is needed for sandy reaches Where necessary, localized grade control structures or bed armoring can be designed to stabilize transitions or outlet structures. Additionally, establishing a monitoring program during and after construction can ensure that channel adjustments remain within acceptable limits and that the existing dynamic balance is not unintentionally disrupted.

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6 Permitting and Environmental Constraints
Constructability Assessment

6.1 Approach
ECORP prepared an Environmental Constraints Analysis to compare, identify, and assess anticipated environmental constraints for the two proposed alternatives (May 2025). The analysis reviewed subject sections of the California Environmental Quality Act (CEQA) Initial Study (IS) checklist to identify potential environmental constraints for the purposes of this PDR. The findings are preliminary only and are not intended to replace a full CEQA analysis, should an alternative be selected.

Overall, both alternatives would require the need to further study Air Quality, Biological Resources, Cultural Resources, Energy, Geology, Greenhouse Gas, Land Use and Planning, Noise, Transportation, and Tribal Cultural Resources. A summary of the recommendations and findings are presented herein. A full copy of the Environmental Constraints Analysis can be found under Appendix N.

6.2 Alternative 1 – Backbone Storm Drain

6.2.1 Air Quality & Greenhouse Gas Emissions
Construction would generate temporary emissions from equipment and dust, but operational emissions are negligible due to the passive nature of stormwater infrastructure. A streamlined Air Quality and GHG Emissions Assessment is recommended during CEQA to ensure significance thresholds (e.g., SCAQMD) are not exceeded. Permitting requirements would include:
• CEQA Air Quality/GHG technical memo
• Conformance with South Coast AQMD thresholds
• Dust control measures (per SCAQMD Rule 403)

6.2.2 Biological Resources
There are limited impacts due to the alignment being within the right-of-way. While within the street right-of-way, the critical habitat of the San Bernardino Kangaroo Rat (SBKR) could overlap with parts of the alignment and may still require trapping and agency consultation. Permitting requirements would include:
• Biological Resources Assessment
• Focused surveys: SBKR, nesting birds, special-status plants • For the outlet to Cable Creek: CDFW 1600 Streambed Alteration Agreement, Section 404 for the WOTUS, and Section 401 WQ Certification
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6.2.3 Cultural & Tribal Cultural Resources
Multiple previous studies exist within a mile of the proposed project. Two studies encompass portions of the proposed project alignment, including the Cultural Resources Assessment for the Verdemont Heights Towne Center Project (2006) and the Cultural Resource Survey and Clearance for an AT&T Fiberoptic Communication Cable Re-Route from San Bernardino Northwest to San Bernardino National Forest Boundary (1988). The records search determined that 19 previously recorded resources are located within a mile of the Project Area. Of those 19 resources, 18 are historic-period resources and one is of an undermined age. One resource, the historic-period Cable Creek Levy, falls within the proposed storm drain alignment. Permitting requirements would include:
• CEQA cultural resources report
• AB 52 Tribal Consultation
• Inadvertent discovery procedures in specs
• Section 106 consultation (if federal funding or permit triggers)

6.2.4 Energy
Temporary construction-related fuel use; negligible operational energy demand. A streamlined energy/GHG assessment is recommended to demonstrate minimal long-term impact. • No specific permits are anticipated. However, the preparation of a CEQA GHG/energy memorandum is anticipated.

6.2.5 Geology, Soils, & Paleontology
The project is not located within the Alquist-Priolo Zone. Some ground disturbance may aLect paleontological resources. Both a geotechnical evaluation and a paleo records search are recommended. Requirements would include:
• Site-specific geotechnical report (required for design) • Paleontological records search & mitigation plan

6.2.6 Hydrology & Water Quality
The proposed alignment is mostly located in a FEMA-designated Flood Hazard Zone X, or outside of the 1% annual probability floodplain. At the discharge location into Cable Creek, the project would encroach onto Zone AE of Cable Creek with the banks being protected by levees.

The project would disturb more than one acre of area and be subject to both the Construction General Permit and post-construction MS4 Permit requirements. Anticipated requirements include:
• SWPPP + NPDES General Construction Permit (State Water Board) • For the outlet in Cable Creek: Section 401 WQ Certification Meyers Creek Drainage Study
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6.2.7 Land Use & Planning
No changes are required since the proposed alignment falls within the built in existing right-of-way.

6.2.8 Noise
Construction noise may impact nearby residents; project is exempt from local noise ordinance if mitigated. A focused construction noise analysis is recommended. Anticipated requirements include:
• Noise technical report
• Compliance with construction hours (7 AM–8 PM)

6.2.9 Transportation & TraLic
Long segments of road trenching need phased closures. The preparation of TraLic Control Plans is recommended to maintain emergency access and minimize disruption. Refer to Section 7.1.5.

6.2.10 Other Resources
Other resources, including Aesthetics, Agriculture, Hazards, Recreation, Utilities, Population, Mineral Resources, and Wildfire were reviewed. No significant constraints were identified as the proposed alignment avoids scenic highways, parks, and utilities. The project is neither located in active agricultural zones or near mineral resources.

6.3 Alternative 2 – Improved Channel

6.3.1 Air Quality & Greenhouse Gas Emissions
Construction would generate temporary emissions from equipment and dust, but operational emissions are negligible due to the passive nature of stormwater infrastructure. A streamlined Air Quality and GHG Emissions Assessment is recommended during CEQA to ensure significance thresholds (e.g., SCAQMD) are not exceeded. Permitting requirements would include:
• CEQA Air Quality/GHG technical memo
• Conformance with South Coast AQMD thresholds
• Dust control measures (per SCAQMD Rule 403)

6.3.2 Biological Resources
The channel improvements would impact existing moderate to dense patches of disturbed vegetation, including the California buckwheat scrub and scale broom scrub, which present moderate-quality habitat for special status species.

Should Alternative 1 be selected, the impacts of the alignment on several sensitive species should be evaluated, notably for the San Bernardino Kangaroo Rat (SBKR), the Crotch bumble bee, the coastal California gnatcatcher, the arroyo toad, bats, and burrowing howls. Additional focused plant surveys should be performed for sensitive plant species such as Nevin’s barbery, slender- Meyers Creek Drainage Study
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horned spineflower, and Santa Ana River woollystar. All surveys shall be performed during the adequate season.

An aquatic resource delineation was performed in May 2024 for the extents of Alternative 2, which mapped a total of 0.237 acre of ephemeral drainage, 0.835 acre of streambed, and 0.624 acre of associated riparian habitat. No wetlands were observed nor are the existing aquatic features supporting wetland characteristics.

No aquatic resource delineation has been performed for the limits of the proposed debris basin, as the scope of the work was extended to incorporate a debris basin upon consultation with the District.

However, it is anticipated that mitigation will be required for the extents of disturbance of the basin, or 3.6 acres. Should the Improved Channel alternative be retained, a supplemental aquatic resource delineation should be performed during final design and include the area to be impacted by the proposed debris basin.

Meyers Creek is a non-navigable and non-relatively permanent water. Meyers Creek does not appear to support any surface-water related interstate commerce. It does not appear to meet the current definition of Waters of the US and is not likely to be considered jurisdictional under Section 404 of the Clean Water Act.

However, Meyers Creek would likely be considered Waters of the State. The area mapped as streambed at Meyers Creek and its riparian habitat would likely be regulated under Section 1600 of the California Fish and Game Code. Permitting requirements would include:
• Section 7 Consultation with USFWS (if federal nexus, e.g., via Army Corps) • CDFW 1600 Streambed Alteration Agreement
• Section 401 WQ Certification
• Biological Resources Assessment
• Focused surveys: SBKR, nesting birds, bats, gnatcatcher, arroyo toad, special-status plants during the Spring-Summer seasons
• For the outlet to Cable Creek: CDFW 1600 Streambed Alteration Agreement, Section 404 for the WOTUS, and Section 401 WQ Certification

6.3.3 Cultural & Tribal Cultural Resources
Multiple previous studies exist within a mile of the proposed project. One study covers portions of the proposed project alignment, including the Cultural Resources Assessment for the Verdemont Heights Towne Center Project (2006). The records search determined that 19 previously recorded resources are located within a mile of the Project Area. Permitting requirements would include:
• CEQA cultural resources report
• AB 52 Tribal Consultation
• Inadvertent discovery procedures in specs
• Section 106 consultation (if federal funding or permit triggers) Meyers Creek Drainage Study
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6.3.4 Energy
Temporary construction-related fuel use; negligible operational energy demand. A streamlined energy/GHG assessment is recommended to demonstrate minimal long-term impact. • No specific permits are anticipated. However, the preparation of a CEQA GHG/energy memorandum is anticipated.

6.3.5 Geology, Soils, & Paleontology
The project is not located within the Alquist-Priolo Zone. Some ground disturbance may aLect paleontological resources. Both a geotechnical evaluation and a paleo records search are recommended. Requirements would include:
• Site-specific geotechnical report (required for design) • Paleontological records search & mitigation plan

6.3.6 Hydrology & Water Quality
The proposed alignment is mostly located in a FEMA-designated Flood Hazard Zone A, or within a 1% annual probability floodplain. Channelization would reduce the footprint of the FEMAdesignated floodplain and remove flooding impacts on adjacent properties.

The project would disturb more than one acre of area and be subject to both the Construction General Permit and post-construction MS4 Permit requirements. Anticipated requirements include:
• SWPPP and Notice of Intent under the Construction General Permit (State Water Board) • For the outlet in Cable Creek: Section 401 WQ Certification

6.3.7 Land Use & Planning
Acquisition of privately-owned would be required. The City may need to review its General Plan and Zoning, depending on the outcome of the acquisition process. Anticipated requirements include:
• CEQA documentation should review and reflect any land use changes, if deemed applicable.

6.3.8 Noise
Construction noise may impact nearby residents; project is exempt from local noise ordinance if mitigated. A focused construction noise analysis is recommended. Anticipated requirements include:
• Noise technical report
• Compliance with construction hours (7 AM–8 PM)

6.3.9 Transportation & TraLic
Full closure of W. Meyers Road and Belmont Avenue would be required, which would trigger rerouting and coordination with local residents.

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Long segments of road trenching need phased closures. The preparation of TraLic Control Plans is recommended to maintain emergency access and minimize disruption. Refer to Section 7.1.5.

6.3.10 Other Resources
Other resources, including Aesthetics, Agriculture, Hazards, Recreation, Utilities, Population, Mineral Resources, and Wildfire were reviewed. No significant constraints were identified as the proposed alignment avoids scenic highways, parks, and utilities. The project is neither located in active agricultural zones or near mineral resources.

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7 Constructability Assessment

7.1 Alternative 1 – Backbone Storm Drain

7.1.1 Earthwork
Alternative 1 would result in approximately 32,500 cubic-yard of soil excavation during construction, of which 12,000 cubic-yard would be potentially reused as backfill and the delta (20,500 cubic-yard) to be hauled oL locally. Dependent on the geotechnical report, native soils may be allowed as backfill for trench repair. The impacts of earth moving operations should be evaluated during the CEQA process.

7.1.2 TraLic Impacts
Within the project area, Little League Drive is classified as a secondary arterial and Meyers Road is classified as a collector. Belmont Avenue east of Little League Drive is considered a collector while the portion to the west of Little League Drive is considered a local street. The proposed project alignment will significantly limit traLic flow through Little League Drive.

The conceptual storm drain alignment is oLset by 2 feet from the street centerline of Little League Drive. Assuming that the trench width would range from 11 feet to 15 feet, the alignment should allow for one travel lane of traLic in each direction, except at intersection and near the outlet to Cable Creek. Additionally, both intersections of Belmont Avenue and Meyers Road with Little League drive will need to be closed for cold milling of the full intersection. Construction at the intersection of W.

Meyers Road should be specifically reviewed to preserve limited access to Verdemont Estates as closing W. Meyers Road would result in a significant detour for the residents of over 100 parcels and 65 private homes.

The academic school year will also need to be considered as the project borders North Verdemont Elementary School. Primary drop-oL/pick-up zones are avoided with the current project boundaries.

Access to the Little League Baseball Complex on Little League Drive will be restricted during construction. However, access to the facility is possible from the north and south ends of the block and can be considered for construction.

Residential access will also be aLected by construction and require additional consideration. A traLic control plan indicating detour routes and temporary traLic conditions should be prepared.

7.1.3 Utility Interference and Existing Infrastructure
Significant portions of the existing 81” and 87” RCP storm drain along W. Meyers Road would need to be removed and the three existing catch basins would need to be retrofitted for the new storm drain alignment which is sloped in the opposite direction of the existing alignment. Additionally, two CMP risers on the north side of Meyers Road would be demolished to allow for construction of the proposed rectangular channels and catch basins. The proposed alteration to the 48-inch RCP lateral Meyers Creek Drainage Study
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alignment on Meyers Road would require demolition of a portion of the existing 48-inch RCP and protection of an 8-inch sewer, 12-inch drinking water, and telephone/communication lines.

Alternative storm drain alignments should be evaluated during final engineering. Currently, the proposed 9’x7’ RCB facility is aligned between the Natural Gas line and the 8-inch sewer line between the Belmont Ave. intersection and the Cable Creek outlet. Relocation of the 8-inch sewer line is unlikely. However, crossing of the 10-inch sewer line should be considered in the final storm drain alignment to avoid conflicts. To remain conservative, a line item for the relocation of the 8-inch sewer line is included in the cost estimate.

7.1.4 Required Easements
The proposed storm drain crosses through two parcels, Assessor Parcel Numbers #026113291 and 026117218, owned by the City of San Bernardino and San Bernardino Flood Control District, respectively. An easement would be required from the District.

Along W. Meyers Road and Belmont Ave, the construction of the grated channel inlets would likely require either dedication of the ultimate right-of-way or a temporary construction encroachment permit from the private owners. The location and configuration of the grated channel inlet should be coordinated with the anticipated location of future driveways, access roads, pedestrian path-oftravel, and utilities. No encroachment of the privately-owned parcels is anticipated.

No acquisition is anticipated.

7.2 Alternative 2 – Improved Channel

7.2.1 Earthwork
Proposed channel improvements would require significant cutting and filling to grade the proposed cross sections. The conceptual grading anticipates approximately 138,000 cubic-yard of earthwork cuts and 12,000 cubic-yard of fill. Of those earthwork quantities, 98,000 cubic-yard of cuts are anticipated for the debris basin. The costs and logistics and associated costs of oL-hauling operations should be further considered during final engineering.

7.2.2 TraLic Impacts
Channel construction will block traLic from flowing across Meyers Creek through Meyers Road and a small portion of Belmont Avenue. A number of homes’ sole access route to Little League Drive is Belmont Avenue. As discussed previously, Little League drive is classified as a secondary arterial, Meyers Road is classified as a collector, and Belmont Avenue east of Little League drive is considered a collector while the portion to the west of Little League Drive is considered a local street. Temporary access will need to be provided for the following APNs: 026112112, 026113101, 034811112, 034811119, 034811120, 034811122, and 034811123.

Currently, Meyers Road is the only access to Verdemont Estates, the development to the northwest of the Meyers Road crossing. Future development could provide alternative access for Verdemont Meyers Creek Drainage Study
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Estates during construction on Meyers Road, however, with the current roadways, temporary access development will be required during construction. No current CAL TRANS right-of-way allows for convenient extension of West Meyers Road into the town Devore Heights.

7.2.3 Utility Interference and Existing Infrastructure
Multiple utilities, including a 16-inch water line, an encased 4-inch AT&T cable, a telephone and electric bank conduit, and a 3-inch plastic natural gas line, cross Meyers Creek at the existing W.

Meyers Road culvert. All these utilities will need to be replaced after demolition and reconstruction of the existing road and culvert. The relocation of those lines will require coordination as they appear to service the homes that are to the west of the crossings.

Coordination with SCE will also be required as an existing electrical pole is located at the northeast corner of the W. Meyers Road culvert and would require protection in place or relocation. Current conceptual plans allow potentially suLicient spacing for protection; however, the potential utility conflict should be addressed further in final design.

At the Belmont Avenue crossing, there appears to be no underground utilities based on existing asbuilts. However, an existing pole located at the northwest side of the Meyers Creek crossing, which would require protection in place or relocation. Current conceptual plans allow potentially suLicient spacing for protection; however, the potential utility conflict should be addressed further in final design.

All utility findings should be verified during final engineering by obtaining confirmation from all utility purveyors.

7.2.4 Required Easements
The proposed alignment runs through privately-owned parcels. It is anticipated that the project may require right-of-way acquisition from 11 separate parcels, as shown in Appendix E:. A total of 7.91 AC will need to be acquired for the proposed design right-of-way.

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Table 7-1 Potential Right-of-Way Acquisition
APN Area (AC)
Area Required for Proposed Right-of-Way
(AC)
Percent Area
Required (%)
026106101 5.05 0.95 19%
026106106 1.64 0.01 1%
026106107 1.81 0.18 10%
026106109 1.03 0.33 32%
026106128 0.36 0.11 30%
026113102 3.77 0.80 21%
026113103 20.51 0.50 2%
034820112 1.39 0.10 7%
034811119 1.36 0.95 70%
034811120 12.01 3.99 33%
034811112 10.17 0.89 9%
Sum 59.08 7.91 -
To do so, the District and the City would need to follow the following process, consistent with both state laws (California Government Code and Eminent Domain Law) and local city ordinances and procedures:
• A Preliminary Engineering Report and Parcel Impact Study are prepared to determine which properties will be aLected.
• A fair mark value appraisal
• A first written oLer
• Negotiation, including Eminent Domain, if deemed necessary. • City Council Authorization
Negotiation with multiple owners could be lengthy and result in the preparation of a resolution of necessity or more.

In addition, temporary construction easements would be required from a total of 11 parcel owners to grade the proposed channel dikes to the existing ground.

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8 Project Timeline
For each alternative, a conceptual implementation timeline was prepared based on projects of similar scope and size. Funding for either alternative has not been secured to date. Timeline is provided for informational purposes only and may be updated as funding and additional information becomes available.

8.1 Alternative 1 – Backbone Storm Drain
The critical path for Alternative 1 begins with CEQA compliance, including technical studies and AB 52 tribal consultation, which is expected to take 6 to 12 months. Following CEQA clearance, the project will require regulatory permitting—particularly a CDFW Streambed Alteration Agreement and water quality certification from the Regional Water Board—alongside final design development and coordination with utility agencies. Right-of-way access and easement agreements must be secured in parallel with design. Once design and permits are finalized, the project can proceed to bidding and construction, which is anticipated to last approximately 12 months and will involve significant road closures and utility coordination. Refer to timeline in next page.

8.2 Alternative 2 – Improved Channel
Alternative 2 would require ROW acquisition from 11 parcels (~7.9 acres), subject to fair market valuation and City Council approval. CEQA compliance, AB 52 tribal consultation, and regulatory permitting (CDFW 1600, RWQCB 401, SWRCB NPDES) may take 18-36 months to complete, with additional time for consultation with USFWS if SBKR habitat is confirmed. ROW acquisition could proceed in parallel but may extend 18-60 months depending on negotiations and need for eminent domain. The construction phase may last up to 18 months.

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Table 8-1 Conceptual Timeline for Alternative 1
Task Duration
Year 1 Year 2 Year 3 Year 4 Year 5
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Grant Funding Application / Project Financing 18 months Final Design & Utility Coordination 18 months Environmental Permitting 12 months Community Outreach 27 months Procurement / Construction Bid 6 months Construction 12 months Final Walk and Closeout 3 months Table 8-2 Conceptual Timeline for Alternative 2
Task Duration
Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Grant Funding Application / Project Financing 18 months Right-of-Way Acquisition 48 months Final Design & Utility Coordination 30 months Environmental Permitting 30 months Community Outreach 39 months Procurement / Construction Bid 6 months Construction 18 months Final Walk and Closeout 3 months Meyers Creek Drainage Study
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9 Summary of Findings
This Preliminary Design Report for the Meyers Creek Drainage Study evaluates two conceptual alternatives to address chronic flooding, sedimentation, and drainage ineLiciencies in the Meyers Creek subwatershed in the City of San Bernardino. Both alternatives—the construction of a backbone storm drain (Alternative 1) and the improvement of the existing creek channel (Alternative 2)—were developed to accommodate the 100-year peak discharge while minimizing downstream impacts to Cable Creek and the surrounding community. Hydrologic and hydraulic modeling confirmed that each alternative would significantly improve stormwater conveyance and reduce flooding at Meyers Road and Belmont Avenue, with variations in right-of-way requirements, environmental constraints, and long-term maintenance responsibilities.

The analysis determined that both alternatives would require CEQA compliance and agency permitting, though Alternative 2 involves more extensive biological surveys, habitat mitigation, and private property acquisition. Cost estimates for construction and permitting range from approximately $25.3 million for Alternative 1 to $64.1 million for Alternative 2, with higher anticipated long-term maintenance costs for the channel facility. TraLic impacts, utility conflicts, and constructability challenges vary, with Alternative 1 requiring staged road trenching and Alternative 2 resulting in full road closures during culvert replacement. Ultimately, both alternatives oLer eLective drainage solutions but diLer in their implementation pathways, permitting timelines, and operational ownership.

A summary matrix was prepared to summarize the findings identified under this PDR. Refer to Table Table 9-1.

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Table 9-1 Comparison Table – Alternative 1 vs. Alternative 2 Category Alternative 1 – Backbone Storm
Drain
Alternative 2 – Improved Channel
Drainage Approach Subsurface RCB with drop inlets
and laterals
Engineered concrete-lined open
channel with upstream 29.9 acrefeet debris basin
Conveyance
Capacity
100-year flows intercepted via
storm drain
100-year flows fully contained
within channel
Construction Cost ~$25.0 million ~$64.1 million
Right-of-Way
Needs
Minimal (mostly within City ROW;
minor easements at outlets)
Significant (11 parcels, ~7.9 acres
of acquisition)
Environmental
Impacts
Limited (mostly within disturbed
ROW)
Higher (riparian/streambed
impacts, SBKR habitat)
Mitigation
Requirements
Outlet to Cable Creek may require
1600/401 agreements
Full stream alteration mitigation +
SBKR consultation
Permitting
Timeline
12–18 months 18–36 months (longer if SBKR
consultation required)
Constructability Trenching in roadways; staged
closures; utility conflicts
Major grading; full road closures;
culvert replacement
Traffic Impacts Moderate (intersection closures,
detours)
High (full closures at Meyers &
Belmont Roads)
O&M
Responsibility
City of San Bernardino County Flood Control District
(post-dedication)
Annual O&M Cost ~$30,000 ~$147,000
Utility Conflicts Conflicts with sewer, gas, water,
telecom lines
Full utility relocation at two
crossings
Agency
Coordination
City + CDFW/RWQCB/SWRCB +
District
City + CDFW/RWQCB + potential
USFWS (SBKR) + District
Meyers Creek Drainage Study
Preliminary Design Report
10-52 Q3 Consulting
10 References
SBCFCD, 1986, Hydrology Manual, San Bernardino County, August.

SBCFCD, San Bernardino County Flood Control District Standard Plats.

Public Works Standards, In., Standard Plans for Public Works Construction (2021 Edition) USACE, 2022, River Analysis System, HEC-RAS, Version 6.5, Hydrologic Engineering Center, U.S.

Army Corps of Engineers (USACE), Davis, California, March.

Advanced Engineering Software, 2015, Flood Routing Analysis using County Hydrology Manual of San Bernardino (1986).

Advanced Engineering Software, 2015, Rational Method Hydrology Computer Program Package (Reference: 1986 San Bernardino Co. Hydrology Criterion).

Advanced Engineering Software, 2015, CH1.

NRCS, 2019, Soil Survey Geographic (SSURGO) Database for San Bernardino County, California, Natural Resources Conservation Service.

USGS, 2018, Lidar: Southern California Wildfires.

USDA, 2022, NAIP 4-Band 8 Bit Imagery: California.

SCAG, 2021, 2019 Annual Land Use.

SCAG, 2021, 2012 Annual Land Use.

USGS, 2019, National Land Cover Database (NLCD).

Meyers Creek Drainage Study
Preliminary Design Report
11-53 Q3 Consulting
11 Technical Appendices
Meyers Creek Drainage Study
Preliminary Design Report
Q3 Consulting
Appendix A: Hydrologic Soil Group Map
A-1
Meyers Creek Drainage Study
Preliminary Design Report
Q3 Consulting
Appendix B: Land Use Map
B-1
Meyers Creek Drainage Study
Preliminary Design Report
Q3 Consulting
Appendix C: Hydrology Maps
Consulting
27051 Towne Centre Drive, Suite 270
Foothill Ranch, CA 92610
949.259.6770
FOR CITY OF SAN BERNADINO APR 2024
BENCH MARK: PREPARED BY:

NAVD 88
CCS ZONE 5,NAD83
FIGURE
Table 1:

Feet
0 500 1000
Consulting
27051 Towne Centre Drive, Suite 270
Foothill Ranch, CA 92610
949.259.6770
FOR CITY OF SAN BERNADINO APR 2024
BENCH MARK: PREPARED BY:

NAVD 88
CCS ZONE 5,NAD83
FIGURE
Table 1:

Feet
0 500 1000
C-3
C-4
Meyers Creek Drainage Study
Preliminary Design Report
11-56 Q3 Consulting
Appendix D: Hydrology Results
10YR-FUTURE-STORMDRAIN.docx Page 1 of 17
____________________________________________________________________________ ****************************************************************************

RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
(Reference: 1986 SAN BERNARDINO CO. HYDROLOGY CRITERION) (c) Copyright 1983-2015 Advanced Engineering Software (aes) Ver. 22.0 Release Date: 07/01/2015 License ID 1673
Analysis prepared by:

************************** DESCRIPTION OF STUDY ************************** * HYDROLOGY STUDY - MEYERS CREEK - PROPOSED STORM DRAIN * * RATIONAL METHOD - 10YR *
* 04/15/2024 *
************************************************************************** FILE NAME: 10MEYSD.DAT
TIME/DATE OF STUDY: 15:35 07/23/2024
============================================================================ USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
============================================================================ --*TIME-OF-CONCENTRATION MODEL*--
USER SPECIFIED STORM EVENT(YEAR) = 100.00
SPECIFIED MINIMUM PIPE SIZE(INCH) = 12.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.90 *USER-DEFINED TABLED RAINFALL USED*
NUMBER OF [TIME,INTENSITY] DATA PAIRS = 6
1) 5.00; 4.390
2) 15.00; 2.540
3) 30.00; 1.890
4) 60.00; 1.430
5) 120.00; 1.000
6) 360.00; 0.598
*ANTECEDENT MOISTURE CONDITION (AMC) II ASSUMED FOR RATIONAL METHOD* *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING

WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n)
=== ===== ========= ================= ====== ===== ====== ===== ======= 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0312 0.167 0.0150 2 18.0 13.0 0.020/0.020/0.050 0.50 1.50 0.0312 0.125 0.0150 3 22.0 17.0 0.020/0.020/0.050 0.67 2.00 0.0312 0.167 0.0150 4 25.0 20.0 0.020/0.020/0.050 0.67 2.00 0.0312 0.167 0.0150 5 30.0 25.0 0.020/0.020/0.050 0.67 2.00 0.0312 0.167 0.0150 6 19.0 14.0 0.020/0.020/0.050 0.67 2.00 0.0312 0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS:

Meyers Creek – Proposed Storm Drain 2024

1. Relative Flow-Depth = 0.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)

2. (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S)
*SIZE PIPE WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*
*USER-SPECIFIED MINIMUM TOPOGRAPHIC SLOPE ADJUSTMENT NOT SELECTED **************************************************************************** FLOW PROCESS FROM NODE 700.00 TO NODE 701.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
>>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< ============================================================================ INITIAL SUBAREA FLOW-LENGTH(FEET) = 990.00
ELEVATION DATA: UPSTREAM(FEET) = 2001.00 DOWNSTREAM(FEET) = 1888.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20
SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.407
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.945
SUBAREA Tc AND LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS Tc
LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN (MIN.)

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 1.43 0.98 0.500 32 9.48

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 0.35 0.57 0.500 69 9.48
COMMERCIAL A 0.16 0.98 0.100 32 7.41
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.90
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.467
SUBAREA RUNOFF(CFS) = 6.15
TOTAL AREA(ACRES) = 1.94 PEAK FLOW RATE(CFS) = 6.15
**************************************************************************** FLOW PROCESS FROM NODE 701.00 TO NODE 702.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1888.00 DOWNSTREAM(FEET) = 1872.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 208.00 CHANNEL SLOPE = 0.0769 CHANNEL FLOW THRU SUBAREA(CFS) = 6.15
FLOW VELOCITY(FEET/SEC) = 6.15 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.56 Tc(MIN.) = 7.97
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 702.00 = 1198.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 702.00 TO NODE 702.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ Meyers Creek – Proposed Storm Drain 2024

MAINLINE Tc(MIN.) = 7.97
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.840
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.62 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 1.18 0.57 0.500 69
COMMERCIAL A 0.04 0.98 0.100 32
COMMERCIAL C 0.08 0.57 0.100 69
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.71
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.475
SUBAREA AREA(ACRES) = 1.92 SUBAREA RUNOFF(CFS) = 6.06
EFFECTIVE AREA(ACRES) = 3.86 AREA-AVERAGED Fm(INCH/HR) = 0.38 AREA-AVERAGED Fp(INCH/HR) = 0.80 AREA-AVERAGED Ap = 0.47 TOTAL AREA(ACRES) = 3.9 PEAK FLOW RATE(CFS) = 12.03
**************************************************************************** FLOW PROCESS FROM NODE 702.00 TO NODE 703.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1872.00 DOWNSTREAM(FEET) = 1860.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 320.00 CHANNEL SLOPE = 0.0375 CHANNEL FLOW THRU SUBAREA(CFS) = 12.03
FLOW VELOCITY(FEET/SEC) = 5.07 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 1.05 Tc(MIN.) = 9.02
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 703.00 = 1518.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 703.00 TO NODE 703.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 9.02
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.646
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 2.63 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 0.72 0.57 0.500 69
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.89
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
SUBAREA AREA(ACRES) = 3.35 SUBAREA RUNOFF(CFS) = 9.66
EFFECTIVE AREA(ACRES) = 7.21 AREA-AVERAGED Fm(INCH/HR) = 0.41 AREA-AVERAGED Fp(INCH/HR) = 0.84 AREA-AVERAGED Ap = 0.48 Meyers Creek – Proposed Storm Drain 2024

TOTAL AREA(ACRES) = 7.2 PEAK FLOW RATE(CFS) = 21.01
**************************************************************************** FLOW PROCESS FROM NODE 703.00 TO NODE 704.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1860.00 DOWNSTREAM(FEET) = 1858.20 CHANNEL LENGTH THRU SUBAREA(FEET) = 152.00 CHANNEL SLOPE = 0.0118 CHANNEL FLOW THRU SUBAREA(CFS) = 21.01
FLOW VELOCITY(FEET/SEC) = 3.30 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.77 Tc(MIN.) = 9.79
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 704.00 = 1670.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 704.00 TO NODE 704.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 9.79
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.504
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 1.62 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" B 0.11 0.75 0.500 56
COMMERCIAL A 0.40 0.98 0.100 32
COMMERCIAL B 0.16 0.75 0.100 56
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.96
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.402
SUBAREA AREA(ACRES) = 2.29 SUBAREA RUNOFF(CFS) = 6.43
EFFECTIVE AREA(ACRES) = 9.50 AREA-AVERAGED Fm(INCH/HR) = 0.40 AREA-AVERAGED Fp(INCH/HR) = 0.87 AREA-AVERAGED Ap = 0.46 TOTAL AREA(ACRES) = 9.5 PEAK FLOW RATE(CFS) = 26.51
**************************************************************************** FLOW PROCESS FROM NODE 704.00 TO NODE 704.00 IS CODE = 16 ---------------------------------------------------------------------------- >>>>>USER SPECIFIED CONSTANT SOURCE FLOW AT NODE<<<<<
============================================================================ USER-SPECIFIED CONSTANT SOURCE FLOW = 153.30(CFS)
USER-SPECIFIED AREA ASSOCIATED TO SOURCE FLOW = 96.60(ACRES) * CUMULATIVE SOURCE FLOW DATA: FLOW(CFS) = 153.30 AREA(AC.) = 96.60 * SUMMED DATA: FLOW(CFS) = 179.81 TOTAL AREA(ACRES) = 106.10 **************************************************************************** FLOW PROCESS FROM NODE 704.00 TO NODE 705.00 IS CODE = 31 Meyers Creek – Proposed Storm Drain 2024

---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1858.20 DOWNSTREAM(FEET) = 1858.10 FLOW LENGTH(FEET) = 115.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 87.0 INCH PIPE IS 65.5 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 5.39
ESTIMATED PIPE DIAMETER(INCH) = 87.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 179.81
PIPE TRAVEL TIME(MIN.) = 0.36 Tc(MIN.) = 10.14
* TOTAL SOURCE FLOW(CFS) = 153.30
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 705.00 = 1785.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 705.00 TO NODE 705.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 10.14
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.438
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 1.12 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 2.40 0.57 0.500 69
COMMERCIAL A 0.44 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.70
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.456
SUBAREA AREA(ACRES) = 3.96 SUBAREA RUNOFF(CFS) = 11.11
EFFECTIVE AREA(ACRES) = 13.46 AREA-AVERAGED Fm(INCH/HR) = 0.38 AREA-AVERAGED Fp(INCH/HR) = 0.82 AREA-AVERAGED Ap = 0.46 TOTAL AREA(ACRES) = 13.5 PEAK FLOW RATE(CFS) = 37.06
* SOURCE FLOW DATA: FLOW(CFS) = 153.30 AREA(ACRES) = 96.6 * SUMMED DATA: FLOW(CFS) = 190.36 TOTAL AREA(ACRES) = 110.1 **************************************************************************** FLOW PROCESS FROM NODE 705.00 TO NODE 706.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1858.10 DOWNSTREAM(FEET) = 1858.00 FLOW LENGTH(FEET) = 77.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 81.0 INCH PIPE IS 63.7 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 6.31
ESTIMATED PIPE DIAMETER(INCH) = 81.00 NUMBER OF PIPES = 1 Meyers Creek – Proposed Storm Drain 2024

PIPE-FLOW(CFS) = 190.36
PIPE TRAVEL TIME(MIN.) = 0.20 Tc(MIN.) = 10.35
* TOTAL SOURCE FLOW(CFS) = 153.30
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 706.00 = 1862.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 706.00 TO NODE 706.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 10.35
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.401
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN
COMMERCIAL A 0.07 0.98 0.100 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.69 0.98 0.500 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.463
SUBAREA AREA(ACRES) = 0.76 SUBAREA RUNOFF(CFS) = 2.02
EFFECTIVE AREA(ACRES) = 14.22 AREA-AVERAGED Fm(INCH/HR) = 0.38 AREA-AVERAGED Fp(INCH/HR) = 0.83 AREA-AVERAGED Ap = 0.46 TOTAL AREA(ACRES) = 14.2 PEAK FLOW RATE(CFS) = 38.63
* SOURCE FLOW DATA: FLOW(CFS) = 153.30 AREA(ACRES) = 96.6 * SUMMED DATA: FLOW(CFS) = 191.93 TOTAL AREA(ACRES) = 110.8 **************************************************************************** FLOW PROCESS FROM NODE 706.00 TO NODE 707.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1858.00 DOWNSTREAM(FEET) = 1856.00 FLOW LENGTH(FEET) = 86.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 48.0 INCH PIPE IS 36.4 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 18.77
ESTIMATED PIPE DIAMETER(INCH) = 48.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 191.93
PIPE TRAVEL TIME(MIN.) = 0.08 Tc(MIN.) = 10.42
* TOTAL SOURCE FLOW(CFS) = 153.30
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 707.00 = 1948.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 707.00 TO NODE 707.00 IS CODE = 16 ---------------------------------------------------------------------------- >>>>>USER SPECIFIED CONSTANT SOURCE FLOW AT NODE<<<<<
============================================================================ USER-SPECIFIED CONSTANT SOURCE FLOW = 254.41(CFS)
Meyers Creek – Proposed Storm Drain 2024

USER-SPECIFIED AREA ASSOCIATED TO SOURCE FLOW = 134.80(ACRES) * CUMULATIVE SOURCE FLOW DATA: FLOW(CFS) = 407.71 AREA(AC.) = 231.40 * SUMMED DATA: FLOW(CFS) = 446.34 TOTAL AREA(ACRES) = 245.62 **************************************************************************** FLOW PROCESS FROM NODE 707.00 TO NODE 708.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1856.00 DOWNSTREAM(FEET) = 1833.00 FLOW LENGTH(FEET) = 578.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 60.0 INCH PIPE IS 44.7 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 28.43
ESTIMATED PIPE DIAMETER(INCH) = 60.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 446.34
PIPE TRAVEL TIME(MIN.) = 0.34 Tc(MIN.) = 10.76
* TOTAL SOURCE FLOW(CFS) = 407.71
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 708.00 = 2526.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 708.00 TO NODE 708.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 10.76
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.324
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.82 0.98 0.500 32
SCHOOL A 3.02 0.98 0.600 32
COMMERCIAL A 1.23 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.463
SUBAREA AREA(ACRES) = 5.07 SUBAREA RUNOFF(CFS) = 13.11
EFFECTIVE AREA(ACRES) = 19.29 AREA-AVERAGED Fm(INCH/HR) = 0.40 AREA-AVERAGED Fp(INCH/HR) = 0.87 AREA-AVERAGED Ap = 0.46 TOTAL AREA(ACRES) = 19.3 PEAK FLOW RATE(CFS) = 50.75
* SOURCE FLOW DATA: FLOW(CFS) = 407.71 AREA(ACRES) = 231.4 * SUMMED DATA: FLOW(CFS) = 458.46 TOTAL AREA(ACRES) = 250.7 **************************************************************************** FLOW PROCESS FROM NODE 708.00 TO NODE 709.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ Meyers Creek – Proposed Storm Drain 2024

ELEVATION DATA: UPSTREAM(FEET) = 1833.00 DOWNSTREAM(FEET) = 1828.00 FLOW LENGTH(FEET) = 96.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 57.0 INCH PIPE IS 43.6 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 31.53
ESTIMATED PIPE DIAMETER(INCH) = 57.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 458.46
PIPE TRAVEL TIME(MIN.) = 0.05 Tc(MIN.) = 10.81
* TOTAL SOURCE FLOW(CFS) = 407.71
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 709.00 = 2622.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 709.00 TO NODE 709.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:

TIME OF CONCENTRATION(MIN.) = 10.81
RAINFALL INTENSITY(INCH/HR) = 3.31
AREA-AVERAGED Fm(INCH/HR) = 0.40
AREA-AVERAGED Fp(INCH/HR) = 0.87
AREA-AVERAGED Ap = 0.46
EFFECTIVE STREAM AREA(ACRES) = 19.29
TOTAL STREAM AREA(ACRES) = 19.29
PEAK FLOW RATE(CFS) AT CONFLUENCE = 50.75
* SOURCE FLOW DATA: FLOW(CFS) = 407.71 AREA(ACRES) = 231.4 * SUMMED DATA: FLOW(CFS) = 458.46 TOTAL AREA(ACRES) = 250.7 **************************************************************************** FLOW PROCESS FROM NODE 709.00 TO NODE 709.00 IS CODE = 10 ---------------------------------------------------------------------------- >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 <<<<< ============================================================================ ***MEMORY FUNCTION CAN NOT BE ACCESSED - PROCESS IGNORED.*** **************************************************************************** FLOW PROCESS FROM NODE 800.00 TO NODE 801.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
>>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< ============================================================================ INITIAL SUBAREA FLOW-LENGTH(FEET) = 284.00
ELEVATION DATA: UPSTREAM(FEET) = 1863.00 DOWNSTREAM(FEET) = 1851.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20
SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.016
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 4.017
SUBAREA Tc AND LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS Tc
Meyers Creek – Proposed Storm Drain 2024

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN (MIN.)

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.44 0.98 0.500 32 7.02
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
SUBAREA RUNOFF(CFS) = 1.40
TOTAL AREA(ACRES) = 0.44 PEAK FLOW RATE(CFS) = 1.40
**************************************************************************** FLOW PROCESS FROM NODE 801.00 TO NODE 802.00 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1851.00 DOWNSTREAM(FEET) = 1843.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 194.00 CHANNEL SLOPE = 0.0412 CHANNEL BASE(FEET) = 20.00 "Z" FACTOR = 2.000
MANNING'S FACTOR = 0.030 MAXIMUM DEPTH(FEET) = 5.00
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.674
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.64 0.98 0.500 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 2.31
TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 1.74 AVERAGE FLOW DEPTH(FEET) = 0.07 TRAVEL TIME(MIN.) = 1.85 Tc(MIN.) = 8.87
SUBAREA AREA(ACRES) = 0.64 SUBAREA RUNOFF(CFS) = 1.84
EFFECTIVE AREA(ACRES) = 1.08 AREA-AVERAGED Fm(INCH/HR) = 0.49 AREA-AVERAGED Fp(INCH/HR) = 0.98 AREA-AVERAGED Ap = 0.50 TOTAL AREA(ACRES) = 1.1 PEAK FLOW RATE(CFS) = 3.10
END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.08 FLOW VELOCITY(FEET/SEC.) = 1.90
LONGEST FLOWPATH FROM NODE 800.00 TO NODE 802.00 = 478.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 802.00 TO NODE 803.00 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1843.00 DOWNSTREAM(FEET) = 1838.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 128.00 CHANNEL SLOPE = 0.0391 CHANNEL BASE(FEET) = 20.00 "Z" FACTOR = 2.000
MANNING'S FACTOR = 0.030 MAXIMUM DEPTH(FEET) = 5.00
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.486
Meyers Creek – Proposed Storm Drain 2024

SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.73 0.98 0.500 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 4.08
TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 2.10 AVERAGE FLOW DEPTH(FEET) = 0.10 TRAVEL TIME(MIN.) = 1.02 Tc(MIN.) = 9.89
SUBAREA AREA(ACRES) = 0.73 SUBAREA RUNOFF(CFS) = 1.97
EFFECTIVE AREA(ACRES) = 1.81 AREA-AVERAGED Fm(INCH/HR) = 0.49 AREA-AVERAGED Fp(INCH/HR) = 0.98 AREA-AVERAGED Ap = 0.50 TOTAL AREA(ACRES) = 1.8 PEAK FLOW RATE(CFS) = 4.88
END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.11 FLOW VELOCITY(FEET/SEC.) = 2.20
LONGEST FLOWPATH FROM NODE 800.00 TO NODE 803.00 = 606.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 803.00 TO NODE 804.00 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1838.00 DOWNSTREAM(FEET) = 1833.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 173.00 CHANNEL SLOPE = 0.0289 CHANNEL BASE(FEET) = 20.00 "Z" FACTOR = 2.000
MANNING'S FACTOR = 0.030 MAXIMUM DEPTH(FEET) = 5.00
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.262
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 1.57 0.98 0.500 32
COMMERCIAL A 0.27 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.97
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.441
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 7.23
TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 2.38 AVERAGE FLOW DEPTH(FEET) = 0.15 TRAVEL TIME(MIN.) = 1.21 Tc(MIN.) = 11.10
SUBAREA AREA(ACRES) = 1.84 SUBAREA RUNOFF(CFS) = 4.69
EFFECTIVE AREA(ACRES) = 3.65 AREA-AVERAGED Fm(INCH/HR) = 0.46 AREA-AVERAGED Fp(INCH/HR) = 0.98 AREA-AVERAGED Ap = 0.47 TOTAL AREA(ACRES) = 3.7 PEAK FLOW RATE(CFS) = 9.21
END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.17 FLOW VELOCITY(FEET/SEC.) = 2.62
Meyers Creek – Proposed Storm Drain 2024

LONGEST FLOWPATH FROM NODE 800.00 TO NODE 804.00 = 779.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 804.00 TO NODE 804.00 IS CODE = 16 ---------------------------------------------------------------------------- >>>>>USER SPECIFIED CONSTANT SOURCE FLOW AT NODE<<<<<
============================================================================ USER-SPECIFIED CONSTANT SOURCE FLOW = 430.00(CFS)
USER-SPECIFIED AREA ASSOCIATED TO SOURCE FLOW = 271.54(ACRES) * CUMULATIVE SOURCE FLOW DATA: FLOW(CFS) = 430.00 AREA(AC.) = 271.54 * SUMMED DATA: FLOW(CFS) = 439.21 TOTAL AREA(ACRES) = 275.19 **************************************************************************** FLOW PROCESS FROM NODE 804.00 TO NODE 805.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1833.00 DOWNSTREAM(FEET) = 1832.00 FLOW LENGTH(FEET) = 87.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 75.0 INCH PIPE IS 56.4 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 17.75
ESTIMATED PIPE DIAMETER(INCH) = 75.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 439.21
PIPE TRAVEL TIME(MIN.) = 0.08 Tc(MIN.) = 11.18
* TOTAL SOURCE FLOW(CFS) = 430.00
LONGEST FLOWPATH FROM NODE 800.00 TO NODE 805.00 = 866.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 805.00 TO NODE 805.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 11.18
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.247
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 2.34 0.98 0.500 32
COMMERCIAL A 0.31 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.453
SUBAREA AREA(ACRES) = 2.65 SUBAREA RUNOFF(CFS) = 6.69
EFFECTIVE AREA(ACRES) = 6.30 AREA-AVERAGED Fm(INCH/HR) = 0.45 AREA-AVERAGED Fp(INCH/HR) = 0.98 AREA-AVERAGED Ap = 0.46 TOTAL AREA(ACRES) = 6.3 PEAK FLOW RATE(CFS) = 15.85
* SOURCE FLOW DATA: FLOW(CFS) = 430.00 AREA(ACRES) = 271.5 * SUMMED DATA: FLOW(CFS) = 445.85 TOTAL AREA(ACRES) = 277.8 Meyers Creek – Proposed Storm Drain 2024

**************************************************************************** FLOW PROCESS FROM NODE 805.00 TO NODE 709.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1832.00 DOWNSTREAM(FEET) = 1830.00 FLOW LENGTH(FEET) = 148.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 72.0 INCH PIPE IS 56.3 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 18.80
ESTIMATED PIPE DIAMETER(INCH) = 72.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 445.85
PIPE TRAVEL TIME(MIN.) = 0.13 Tc(MIN.) = 11.31
* TOTAL SOURCE FLOW(CFS) = 430.00
LONGEST FLOWPATH FROM NODE 800.00 TO NODE 709.00 = 1014.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 709.00 TO NODE 709.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
>>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< ============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE:

TIME OF CONCENTRATION(MIN.) = 11.31
RAINFALL INTENSITY(INCH/HR) = 3.22
AREA-AVERAGED Fm(INCH/HR) = 0.45
AREA-AVERAGED Fp(INCH/HR) = 0.98
AREA-AVERAGED Ap = 0.46
EFFECTIVE STREAM AREA(ACRES) = 6.30
TOTAL STREAM AREA(ACRES) = 6.30
PEAK FLOW RATE(CFS) AT CONFLUENCE = 15.85
* SOURCE FLOW DATA: FLOW(CFS) = 430.00 AREA(ACRES) = 271.5 * SUMMED DATA: FLOW(CFS) = 445.85 TOTAL AREA(ACRES) = 277.8 ** CONFLUENCE DATA **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER SOURCE
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE FLOW 1 50.75 10.81 3.314 0.87( 0.40) 0.46 19.3 700.00
407.7
2 15.85 11.31 3.222 0.98( 0.45) 0.46 6.3 800.00
430.0

RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER SOURCE
Meyers Creek – Proposed Storm Drain 2024

NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE FLOW 1 66.41 10.81 3.314 0.89( 0.41) 0.46 25.3 700.00
407.7
2 65.00 11.31 3.222 0.89( 0.41) 0.46 25.6 800.00
430.0
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 66.41 Tc(MIN.) = 10.81
EFFECTIVE AREA(ACRES) = 25.31 AREA-AVERAGED Fm(INCH/HR) = 0.41 AREA-AVERAGED Fp(INCH/HR) = 0.89 AREA-AVERAGED Ap = 0.46 TOTAL AREA(ACRES) = 25.6
* CUMULATIVE SOURCE FLOW DATA: FLOW(CFS) = 837.71 AREA(AC.) = 502.9 * SUMMED DATA: FLOW(CFS) = 904.12 TOTAL AREA(ACRES) = 528.5 LONGEST FLOWPATH FROM NODE 700.00 TO NODE 709.00 = 2622.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 709.00 TO NODE 710.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1830.00 DOWNSTREAM(FEET) = 1789.00 FLOW LENGTH(FEET) = 1360.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 81.0 INCH PIPE IS 62.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 30.36
ESTIMATED PIPE DIAMETER(INCH) = 81.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 904.12
PIPE TRAVEL TIME(MIN.) = 0.75 Tc(MIN.) = 11.56
* TOTAL SOURCE FLOW(CFS) = 837.71
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 710.00 = 3982.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 710.00 TO NODE 710.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:

TIME OF CONCENTRATION(MIN.) = 11.56
RAINFALL INTENSITY(INCH/HR) = 3.18
AREA-AVERAGED Fm(INCH/HR) = 0.41
AREA-AVERAGED Fp(INCH/HR) = 0.89
AREA-AVERAGED Ap = 0.46
EFFECTIVE STREAM AREA(ACRES) = 25.31
TOTAL STREAM AREA(ACRES) = 25.59
PEAK FLOW RATE(CFS) AT CONFLUENCE = 66.41
* SOURCE FLOW DATA: FLOW(CFS) = 837.71 AREA(ACRES) = 502.9 * SUMMED DATA: FLOW(CFS) = 904.12 TOTAL AREA(ACRES) = 528.5 Meyers Creek – Proposed Storm Drain 2024

**************************************************************************** FLOW PROCESS FROM NODE 900.00 TO NODE 901.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
>>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< ============================================================================ INITIAL SUBAREA FLOW-LENGTH(FEET) = 533.00
ELEVATION DATA: UPSTREAM(FEET) = 1849.00 DOWNSTREAM(FEET) = 1828.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20
SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.153
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.992
SUBAREA Tc AND LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS Tc
LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN (MIN.)
SCHOOL A 0.77 0.98 0.600 32 9.69
PUBLIC PARK A 0.01 0.98 0.850 32 11.36
COMMERCIAL A 0.28 0.98 0.100 32 7.15
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.97
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.470
SUBAREA RUNOFF(CFS) = 3.37
TOTAL AREA(ACRES) = 1.06 PEAK FLOW RATE(CFS) = 3.37
**************************************************************************** FLOW PROCESS FROM NODE 901.00 TO NODE 902.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 5 USED)<<<<<
============================================================================ UPSTREAM ELEVATION(FEET) = 1828.00 DOWNSTREAM ELEVATION(FEET) = 1816.00 STREET LENGTH(FEET) = 341.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 25.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 5.73 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.31
HALFSTREET FLOOD WIDTH(FEET) = 7.39
AVERAGE FLOW VELOCITY(FEET/SEC.) = 3.89
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.19
STREET FLOW TRAVEL TIME(MIN.) = 1.46 Tc(MIN.) = 8.61
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 3.721
Meyers Creek – Proposed Storm Drain 2024

SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN
SCHOOL A 0.07 0.98 0.600 32
PUBLIC PARK A 1.08 0.98 0.850 32
COMMERCIAL A 0.52 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.606
SUBAREA AREA(ACRES) = 1.67 SUBAREA RUNOFF(CFS) = 4.71
EFFECTIVE AREA(ACRES) = 2.73 AREA-AVERAGED Fm(INCH/HR) = 0.54 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.55 TOTAL AREA(ACRES) = 2.7 PEAK FLOW RATE(CFS) = 7.82
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.33 HALFSTREET FLOOD WIDTH(FEET) = 8.76
FLOW VELOCITY(FEET/SEC.) = 4.09 DEPTH*VELOCITY(FT*FT/SEC.) = 1.36 LONGEST FLOWPATH FROM NODE 900.00 TO NODE 902.00 = 874.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 902.00 TO NODE 710.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 5 USED)<<<<<
============================================================================ UPSTREAM ELEVATION(FEET) = 1816.00 DOWNSTREAM ELEVATION(FEET) = 1789.00 STREET LENGTH(FEET) = 951.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 25.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 10.45 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.37
HALFSTREET FLOOD WIDTH(FEET) = 10.52
AVERAGE FLOW VELOCITY(FEET/SEC.) = 4.03
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.49
STREET FLOW TRAVEL TIME(MIN.) = 3.93 Tc(MIN.) = 12.55
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 2.994
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN
PUBLIC PARK A 1.42 0.98 0.850 32
COMMERCIAL A 0.95 0.98 0.100 32
Meyers Creek – Proposed Storm Drain 2024

SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.549
SUBAREA AREA(ACRES) = 2.37 SUBAREA RUNOFF(CFS) = 5.24
EFFECTIVE AREA(ACRES) = 5.10 AREA-AVERAGED Fm(INCH/HR) = 0.54 AREA-AVERAGED Fp(INCH/HR) = 0.98 AREA-AVERAGED Ap = 0.55 TOTAL AREA(ACRES) = 5.1 PEAK FLOW RATE(CFS) = 11.27
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.38 HALFSTREET FLOOD WIDTH(FEET) = 10.91 FLOW VELOCITY(FEET/SEC.) = 4.09 DEPTH*VELOCITY(FT*FT/SEC.) = 1.54 LONGEST FLOWPATH FROM NODE 900.00 TO NODE 710.00 = 1825.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 710.00 TO NODE 710.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
>>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< ============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE:

TIME OF CONCENTRATION(MIN.) = 12.55
RAINFALL INTENSITY(INCH/HR) = 2.99
AREA-AVERAGED Fm(INCH/HR) = 0.54
AREA-AVERAGED Fp(INCH/HR) = 0.98
AREA-AVERAGED Ap = 0.55
EFFECTIVE STREAM AREA(ACRES) = 5.10
TOTAL STREAM AREA(ACRES) = 5.10
PEAK FLOW RATE(CFS) AT CONFLUENCE = 11.27
** CONFLUENCE DATA **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER SOURCE
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE FLOW 1 66.41 11.56 3.176 0.89( 0.41) 0.46 25.3 700.00
407.7
1 65.00 12.06 3.084 0.89( 0.41) 0.46 25.6 800.00
430.0
2 11.27 12.55 2.994 0.98( 0.54) 0.55 5.1 900.00

0.0 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER SOURCE
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE FLOW 1 77.57 11.56 3.176 0.91( 0.43) 0.48 30.0 700.00
407.7
2 76.23 12.06 3.084 0.91( 0.43) 0.48 30.5 800.00
430.0
Meyers Creek – Proposed Storm Drain 2024

3 74.08 12.55 2.994 0.91( 0.43) 0.48 30.7 900.00

0.0 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 77.57 Tc(MIN.) = 11.56
EFFECTIVE AREA(ACRES) = 30.01 AREA-AVERAGED Fm(INCH/HR) = 0.43 AREA-AVERAGED Fp(INCH/HR) = 0.91 AREA-AVERAGED Ap = 0.48 TOTAL AREA(ACRES) = 30.7
* CUMULATIVE SOURCE FLOW DATA: FLOW(CFS) = 837.71 AREA(AC.) = 502.9 * SUMMED DATA: FLOW(CFS) = 915.28 TOTAL AREA(ACRES) = 533.6 LONGEST FLOWPATH FROM NODE 700.00 TO NODE 710.00 = 3982.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 710.00 TO NODE 711.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1789.00 DOWNSTREAM(FEET) = 1788.00 FLOW LENGTH(FEET) = 59.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 90.0 INCH PIPE IS 71.1 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 24.45
ESTIMATED PIPE DIAMETER(INCH) = 90.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 915.28
PIPE TRAVEL TIME(MIN.) = 0.04 Tc(MIN.) = 11.60
* TOTAL SOURCE FLOW(CFS) = 837.71
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 711.00 = 4041.00 FEET. ============================================================================ END OF STUDY SUMMARY:

TOTAL AREA(ACRES) = 30.7 TC(MIN.) = 11.60
EFFECTIVE AREA(ACRES) = 30.01 AREA-AVERAGED Fm(INCH/HR)= 0.43 AREA-AVERAGED Fp(INCH/HR) = 0.91 AREA-AVERAGED Ap = 0.476 PEAK FLOW RATE(CFS) = 77.57
* CUMULATIVE SOURCE FLOW DATA: FLOW(CFS) = 837.71 AREA(AC.) = 502.9 * SUMMED DATA: FLOW(CFS) = 915.28 TOTAL AREA(ACRES) = 533.6 ** PEAK FLOW RATE TABLE **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER SOURCE
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE FLOW 1 77.57 11.60 3.169 0.91( 0.43) 0.48 30.0 700.00
407.7
2 76.23 12.10 3.077 0.91( 0.43) 0.48 30.5 800.00
430.0
3 74.08 12.59 2.987 0.91( 0.43) 0.48 30.7 900.00

0.0 ============================================================================ ============================================================================

END OF RATIONAL METHOD ANALYSIS
100YR-FUTURE-STORMDRAIN.docx Page 1 of 17
____________________________________________________________________________ ****************************************************************************

RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
(Reference: 1986 SAN BERNARDINO CO. HYDROLOGY CRITERION) (c) Copyright 1983-2015 Advanced Engineering Software (aes) Ver. 22.0 Release Date: 07/01/2015 License ID 1673
Analysis prepared by:

************************** DESCRIPTION OF STUDY ************************** * HYDROLOGY STUDY - MEYERS CREEK - PROPOSED STORM DRAIN * * RATIONAL METHOD - 100 YEAR *
* 07/22/2024 *
************************************************************************** FILE NAME: 100MEYSD.DAT
TIME/DATE OF STUDY: 14:30 07/22/2024
============================================================================ USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
============================================================================ --*TIME-OF-CONCENTRATION MODEL*--
USER SPECIFIED STORM EVENT(YEAR) = 100.00
SPECIFIED MINIMUM PIPE SIZE(INCH) = 12.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.90 *USER-DEFINED TABLED RAINFALL USED*
NUMBER OF [TIME,INTENSITY] DATA PAIRS = 6
1) 5.00; 7.080
2) 15.00; 4.090
3) 30.00; 3.040
4) 60.00; 2.310
5) 120.00; 1.570
6) 360.00; 0.908
*ANTECEDENT MOISTURE CONDITION (AMC) III ASSUMED FOR RATIONAL METHOD* *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING

WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n)
=== ===== ========= ================= ====== ===== ====== ===== ======= 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0312 0.167 0.0150 2 18.0 13.0 0.020/0.020/0.050 0.50 1.50 0.0312 0.125 0.0150 3 22.0 17.0 0.020/0.020/0.050 0.67 2.00 0.0312 0.167 0.0150 4 25.0 20.0 0.020/0.020/0.050 0.67 2.00 0.0312 0.167 0.0150 5 30.0 25.0 0.020/0.020/0.050 0.67 2.00 0.0312 0.167 0.0150 6 19.0 14.0 0.020/0.020/0.050 0.67 2.00 0.0312 0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS:

Meyers Creek – Proposed Storm Drain 2024

1. Relative Flow-Depth = 0.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)

2. (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S)
*SIZE PIPE WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*
*USER-SPECIFIED MINIMUM TOPOGRAPHIC SLOPE ADJUSTMENT NOT SELECTED **************************************************************************** FLOW PROCESS FROM NODE 700.00 TO NODE 701.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
>>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< ============================================================================ INITIAL SUBAREA FLOW-LENGTH(FEET) = 990.00
ELEVATION DATA: UPSTREAM(FEET) = 2001.00 DOWNSTREAM(FEET) = 1888.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20
SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.407
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 6.360
SUBAREA Tc AND LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS Tc
LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN (MIN.)

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 1.43 0.74 0.500 52 9.48

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 0.35 0.27 0.500 86 9.48
COMMERCIAL A 0.16 0.74 0.100 52 7.41
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.65
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.467
SUBAREA RUNOFF(CFS) = 10.57
TOTAL AREA(ACRES) = 1.94 PEAK FLOW RATE(CFS) = 10.57
**************************************************************************** FLOW PROCESS FROM NODE 701.00 TO NODE 702.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1888.00 DOWNSTREAM(FEET) = 1872.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 208.00 CHANNEL SLOPE = 0.0769 CHANNEL FLOW THRU SUBAREA(CFS) = 10.57
FLOW VELOCITY(FEET/SEC) = 7.03 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.49 Tc(MIN.) = 7.90
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 702.00 = 1198.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 702.00 TO NODE 702.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ Meyers Creek – Proposed Storm Drain 2024

MAINLINE Tc(MIN.) = 7.90
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 6.213
SUBAREA LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.62 0.74 0.500 52

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 1.18 0.27 0.500 86
COMMERCIAL A 0.04 0.74 0.100 52
COMMERCIAL C 0.08 0.27 0.100 86
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.43
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.475
SUBAREA AREA(ACRES) = 1.92 SUBAREA RUNOFF(CFS) = 10.38
EFFECTIVE AREA(ACRES) = 3.86 AREA-AVERAGED Fm(INCH/HR) = 0.26 AREA-AVERAGED Fp(INCH/HR) = 0.54 AREA-AVERAGED Ap = 0.47 TOTAL AREA(ACRES) = 3.9 PEAK FLOW RATE(CFS) = 20.69
**************************************************************************** FLOW PROCESS FROM NODE 702.00 TO NODE 703.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1872.00 DOWNSTREAM(FEET) = 1860.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 320.00 CHANNEL SLOPE = 0.0375 CHANNEL FLOW THRU SUBAREA(CFS) = 20.69
FLOW VELOCITY(FEET/SEC) = 5.86 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.91 Tc(MIN.) = 8.81
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 703.00 = 1518.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 703.00 TO NODE 703.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 8.81
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 5.941
SUBAREA LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 2.63 0.74 0.500 52

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 0.72 0.27 0.500 86
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.64
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
SUBAREA AREA(ACRES) = 3.35 SUBAREA RUNOFF(CFS) = 16.94
EFFECTIVE AREA(ACRES) = 7.21 AREA-AVERAGED Fm(INCH/HR) = 0.29 AREA-AVERAGED Fp(INCH/HR) = 0.59 AREA-AVERAGED Ap = 0.48 Meyers Creek – Proposed Storm Drain 2024

TOTAL AREA(ACRES) = 7.2 PEAK FLOW RATE(CFS) = 36.69
**************************************************************************** FLOW PROCESS FROM NODE 703.00 TO NODE 704.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1860.00 DOWNSTREAM(FEET) = 1858.20 CHANNEL LENGTH THRU SUBAREA(FEET) = 152.00 CHANNEL SLOPE = 0.0118 CHANNEL FLOW THRU SUBAREA(CFS) = 36.69
FLOW VELOCITY(FEET/SEC) = 3.86 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.66 Tc(MIN.) = 9.47
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 704.00 = 1670.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 704.00 TO NODE 704.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 9.47
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 5.744
SUBAREA LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 1.62 0.74 0.500 52

RESIDENTIAL
"5-7 DWELLINGS/ACRE" B 0.11 0.42 0.500 76
COMMERCIAL A 0.40 0.74 0.100 52
COMMERCIAL B 0.16 0.42 0.100 76
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.72
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.402
SUBAREA AREA(ACRES) = 2.29 SUBAREA RUNOFF(CFS) = 11.24
EFFECTIVE AREA(ACRES) = 9.50 AREA-AVERAGED Fm(INCH/HR) = 0.29 AREA-AVERAGED Fp(INCH/HR) = 0.62 AREA-AVERAGED Ap = 0.46 TOTAL AREA(ACRES) = 9.5 PEAK FLOW RATE(CFS) = 46.66
**************************************************************************** FLOW PROCESS FROM NODE 704.00 TO NODE 704.00 IS CODE = 16 ---------------------------------------------------------------------------- >>>>>USER SPECIFIED CONSTANT SOURCE FLOW AT NODE<<<<<
============================================================================ USER-SPECIFIED CONSTANT SOURCE FLOW = 520.80(CFS)
USER-SPECIFIED AREA ASSOCIATED TO SOURCE FLOW = 177.91(ACRES) * CUMULATIVE SOURCE FLOW DATA: FLOW(CFS) = 520.80 AREA(AC.) = 177.91 * SUMMED DATA: FLOW(CFS) = 567.46 TOTAL AREA(ACRES) = 187.41 **************************************************************************** FLOW PROCESS FROM NODE 704.00 TO NODE 705.00 IS CODE = 31 Meyers Creek – Proposed Storm Drain 2024

---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1858.20 DOWNSTREAM(FEET) = 1858.10 FLOW LENGTH(FEET) = 115.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 132.0 INCH PIPE IS 102.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 7.14
ESTIMATED PIPE DIAMETER(INCH) = 132.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 567.46
PIPE TRAVEL TIME(MIN.) = 0.27 Tc(MIN.) = 9.74
* TOTAL SOURCE FLOW(CFS) = 520.80
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 705.00 = 1785.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 705.00 TO NODE 705.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 9.74
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 5.664
SUBAREA LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 1.12 0.74 0.500 52

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 2.40 0.27 0.500 86
COMMERCIAL A 0.44 0.74 0.100 52
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.43
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.456
SUBAREA AREA(ACRES) = 3.96 SUBAREA RUNOFF(CFS) = 19.49
EFFECTIVE AREA(ACRES) = 13.46 AREA-AVERAGED Fm(INCH/HR) = 0.26 AREA-AVERAGED Fp(INCH/HR) = 0.56 AREA-AVERAGED Ap = 0.46 TOTAL AREA(ACRES) = 13.5 PEAK FLOW RATE(CFS) = 65.46
* SOURCE FLOW DATA: FLOW(CFS) = 520.80 AREA(ACRES) = 177.9 * SUMMED DATA: FLOW(CFS) = 586.26 TOTAL AREA(ACRES) = 191.4 **************************************************************************** FLOW PROCESS FROM NODE 705.00 TO NODE 706.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1858.10 DOWNSTREAM(FEET) = 1858.00 FLOW LENGTH(FEET) = 77.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 126.0 INCH PIPE IS 94.4 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 8.43
ESTIMATED PIPE DIAMETER(INCH) = 126.00 NUMBER OF PIPES = 1 Meyers Creek – Proposed Storm Drain 2024

PIPE-FLOW(CFS) = 586.26
PIPE TRAVEL TIME(MIN.) = 0.15 Tc(MIN.) = 9.89
* TOTAL SOURCE FLOW(CFS) = 520.80
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 706.00 = 1862.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 706.00 TO NODE 706.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 9.89
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 5.618
SUBAREA LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN
COMMERCIAL A 0.07 0.74 0.100 52

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.69 0.74 0.500 52
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.74
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.463
SUBAREA AREA(ACRES) = 0.76 SUBAREA RUNOFF(CFS) = 3.61
EFFECTIVE AREA(ACRES) = 14.22 AREA-AVERAGED Fm(INCH/HR) = 0.26 AREA-AVERAGED Fp(INCH/HR) = 0.57 AREA-AVERAGED Ap = 0.46 TOTAL AREA(ACRES) = 14.2 PEAK FLOW RATE(CFS) = 68.52
* SOURCE FLOW DATA: FLOW(CFS) = 520.80 AREA(ACRES) = 177.9 * SUMMED DATA: FLOW(CFS) = 589.32 TOTAL AREA(ACRES) = 192.1 **************************************************************************** FLOW PROCESS FROM NODE 706.00 TO NODE 707.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1858.00 DOWNSTREAM(FEET) = 1856.00 FLOW LENGTH(FEET) = 86.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 72.0 INCH PIPE IS 56.7 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 24.68
ESTIMATED PIPE DIAMETER(INCH) = 72.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 589.32
PIPE TRAVEL TIME(MIN.) = 0.06 Tc(MIN.) = 9.95
* TOTAL SOURCE FLOW(CFS) = 520.80
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 707.00 = 1948.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 707.00 TO NODE 707.00 IS CODE = 16 ---------------------------------------------------------------------------- >>>>>USER SPECIFIED CONSTANT SOURCE FLOW AT NODE<<<<<
============================================================================ USER-SPECIFIED CONSTANT SOURCE FLOW = 431.20(CFS)
Meyers Creek – Proposed Storm Drain 2024

USER-SPECIFIED AREA ASSOCIATED TO SOURCE FLOW = 134.80(ACRES) * CUMULATIVE SOURCE FLOW DATA: FLOW(CFS) = 952.00 AREA(AC.) = 312.71 * SUMMED DATA: FLOW(CFS) = 1020.52 TOTAL AREA(ACRES) = 326.93 **************************************************************************** FLOW PROCESS FROM NODE 707.00 TO NODE 708.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1856.00 DOWNSTREAM(FEET) = 1833.00 FLOW LENGTH(FEET) = 578.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 81.0 INCH PIPE IS 61.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 34.83
ESTIMATED PIPE DIAMETER(INCH) = 81.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1020.52
PIPE TRAVEL TIME(MIN.) = 0.28 Tc(MIN.) = 10.22
* TOTAL SOURCE FLOW(CFS) = 952.00
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 708.00 = 2526.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 708.00 TO NODE 708.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 10.22
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 5.518
SUBAREA LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.82 0.74 0.500 52
SCHOOL A 3.02 0.74 0.600 52
COMMERCIAL A 1.23 0.74 0.100 52
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.74
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.463
SUBAREA AREA(ACRES) = 5.07 SUBAREA RUNOFF(CFS) = 23.61
EFFECTIVE AREA(ACRES) = 19.29 AREA-AVERAGED Fm(INCH/HR) = 0.28 AREA-AVERAGED Fp(INCH/HR) = 0.62 AREA-AVERAGED Ap = 0.46 TOTAL AREA(ACRES) = 19.3 PEAK FLOW RATE(CFS) = 90.85
* SOURCE FLOW DATA: FLOW(CFS) = 952.00 AREA(ACRES) = 312.7 * SUMMED DATA: FLOW(CFS) = 1042.85 TOTAL AREA(ACRES) = 332.0 **************************************************************************** FLOW PROCESS FROM NODE 708.00 TO NODE 709.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ Meyers Creek – Proposed Storm Drain 2024

ELEVATION DATA: UPSTREAM(FEET) = 1833.00 DOWNSTREAM(FEET) = 1828.00 FLOW LENGTH(FEET) = 96.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 78.0 INCH PIPE IS 58.9 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 38.80
ESTIMATED PIPE DIAMETER(INCH) = 78.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1042.85
PIPE TRAVEL TIME(MIN.) = 0.04 Tc(MIN.) = 10.26
* TOTAL SOURCE FLOW(CFS) = 952.00
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 709.00 = 2622.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 709.00 TO NODE 709.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:

TIME OF CONCENTRATION(MIN.) = 10.26
RAINFALL INTENSITY(INCH/HR) = 5.51
AREA-AVERAGED Fm(INCH/HR) = 0.28
AREA-AVERAGED Fp(INCH/HR) = 0.62
AREA-AVERAGED Ap = 0.46
EFFECTIVE STREAM AREA(ACRES) = 19.29
TOTAL STREAM AREA(ACRES) = 19.29
PEAK FLOW RATE(CFS) AT CONFLUENCE = 90.85
* SOURCE FLOW DATA: FLOW(CFS) = 952.00 AREA(ACRES) = 312.7 * SUMMED DATA: FLOW(CFS) = 1042.85 TOTAL AREA(ACRES) = 332.0 **************************************************************************** FLOW PROCESS FROM NODE 709.00 TO NODE 709.00 IS CODE = 10 ---------------------------------------------------------------------------- >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 <<<<< ============================================================================ ***MEMORY FUNCTION CAN NOT BE ACCESSED - PROCESS IGNORED.*** **************************************************************************** FLOW PROCESS FROM NODE 800.00 TO NODE 801.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
>>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< ============================================================================ INITIAL SUBAREA FLOW-LENGTH(FEET) = 284.00
ELEVATION DATA: UPSTREAM(FEET) = 1863.00 DOWNSTREAM(FEET) = 1851.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20
SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.016
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 6.477
SUBAREA Tc AND LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS Tc
Meyers Creek – Proposed Storm Drain 2024

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN (MIN.)

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.44 0.74 0.500 52 7.02
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.74
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
SUBAREA RUNOFF(CFS) = 2.42
TOTAL AREA(ACRES) = 0.44 PEAK FLOW RATE(CFS) = 2.42
**************************************************************************** FLOW PROCESS FROM NODE 801.00 TO NODE 802.00 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1851.00 DOWNSTREAM(FEET) = 1843.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 194.00 CHANNEL SLOPE = 0.0412 CHANNEL BASE(FEET) = 20.00 "Z" FACTOR = 2.000
MANNING'S FACTOR = 0.030 MAXIMUM DEPTH(FEET) = 5.00
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 6.013
SUBAREA LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.64 0.74 0.500 52
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.74
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 4.05
TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 2.08 AVERAGE FLOW DEPTH(FEET) = 0.10 TRAVEL TIME(MIN.) = 1.55 Tc(MIN.) = 8.57
SUBAREA AREA(ACRES) = 0.64 SUBAREA RUNOFF(CFS) = 3.25
EFFECTIVE AREA(ACRES) = 1.08 AREA-AVERAGED Fm(INCH/HR) = 0.37 AREA-AVERAGED Fp(INCH/HR) = 0.74 AREA-AVERAGED Ap = 0.50 TOTAL AREA(ACRES) = 1.1 PEAK FLOW RATE(CFS) = 5.48
END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.12 FLOW VELOCITY(FEET/SEC.) = 2.31
LONGEST FLOWPATH FROM NODE 800.00 TO NODE 802.00 = 478.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 802.00 TO NODE 803.00 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1843.00 DOWNSTREAM(FEET) = 1838.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 128.00 CHANNEL SLOPE = 0.0391 CHANNEL BASE(FEET) = 20.00 "Z" FACTOR = 2.000
MANNING'S FACTOR = 0.030 MAXIMUM DEPTH(FEET) = 5.00
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 5.763
Meyers Creek – Proposed Storm Drain 2024

SUBAREA LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.73 0.74 0.500 52
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.74
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 7.26
TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 2.55 AVERAGE FLOW DEPTH(FEET) = 0.14 TRAVEL TIME(MIN.) = 0.84 Tc(MIN.) = 9.41
SUBAREA AREA(ACRES) = 0.73 SUBAREA RUNOFF(CFS) = 3.54
EFFECTIVE AREA(ACRES) = 1.81 AREA-AVERAGED Fm(INCH/HR) = 0.37 AREA-AVERAGED Fp(INCH/HR) = 0.74 AREA-AVERAGED Ap = 0.50 TOTAL AREA(ACRES) = 1.8 PEAK FLOW RATE(CFS) = 8.78
END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.16 FLOW VELOCITY(FEET/SEC.) = 2.78
LONGEST FLOWPATH FROM NODE 800.00 TO NODE 803.00 = 606.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 803.00 TO NODE 804.00 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1838.00 DOWNSTREAM(FEET) = 1833.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 173.00 CHANNEL SLOPE = 0.0289 CHANNEL BASE(FEET) = 20.00 "Z" FACTOR = 2.000
MANNING'S FACTOR = 0.030 MAXIMUM DEPTH(FEET) = 5.00
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 5.470
SUBAREA LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 1.57 0.74 0.500 52
COMMERCIAL A 0.27 0.74 0.100 52
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.74
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.441
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 13.04
TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 2.95 AVERAGE FLOW DEPTH(FEET) = 0.22 TRAVEL TIME(MIN.) = 0.98 Tc(MIN.) = 10.38
SUBAREA AREA(ACRES) = 1.84 SUBAREA RUNOFF(CFS) = 8.52
EFFECTIVE AREA(ACRES) = 3.65 AREA-AVERAGED Fm(INCH/HR) = 0.35 AREA-AVERAGED Fp(INCH/HR) = 0.74 AREA-AVERAGED Ap = 0.47 TOTAL AREA(ACRES) = 3.7 PEAK FLOW RATE(CFS) = 16.82
END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.25 FLOW VELOCITY(FEET/SEC.) = 3.30
Meyers Creek – Proposed Storm Drain 2024

LONGEST FLOWPATH FROM NODE 800.00 TO NODE 804.00 = 779.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 804.00 TO NODE 804.00 IS CODE = 16 ---------------------------------------------------------------------------- >>>>>USER SPECIFIED CONSTANT SOURCE FLOW AT NODE<<<<<
============================================================================ USER-SPECIFIED CONSTANT SOURCE FLOW = 729.00(CFS)
USER-SPECIFIED AREA ASSOCIATED TO SOURCE FLOW = 249.00(ACRES) * CUMULATIVE SOURCE FLOW DATA: FLOW(CFS) = 729.00 AREA(AC.) = 249.00 * SUMMED DATA: FLOW(CFS) = 745.82 TOTAL AREA(ACRES) = 252.65 **************************************************************************** FLOW PROCESS FROM NODE 804.00 TO NODE 805.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1833.00 DOWNSTREAM(FEET) = 1832.00 FLOW LENGTH(FEET) = 87.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 90.0 INCH PIPE IS 70.4 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 20.12
ESTIMATED PIPE DIAMETER(INCH) = 90.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 745.82
PIPE TRAVEL TIME(MIN.) = 0.07 Tc(MIN.) = 10.46
* TOTAL SOURCE FLOW(CFS) = 729.00
LONGEST FLOWPATH FROM NODE 800.00 TO NODE 805.00 = 866.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 805.00 TO NODE 805.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 10.46
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 5.449
SUBAREA LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 2.34 0.74 0.500 52
COMMERCIAL A 0.31 0.74 0.100 52
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.74
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.453
SUBAREA AREA(ACRES) = 2.65 SUBAREA RUNOFF(CFS) = 12.19
EFFECTIVE AREA(ACRES) = 6.30 AREA-AVERAGED Fm(INCH/HR) = 0.34 AREA-AVERAGED Fp(INCH/HR) = 0.74 AREA-AVERAGED Ap = 0.46 TOTAL AREA(ACRES) = 6.3 PEAK FLOW RATE(CFS) = 28.95
* SOURCE FLOW DATA: FLOW(CFS) = 729.00 AREA(ACRES) = 249.0 * SUMMED DATA: FLOW(CFS) = 757.95 TOTAL AREA(ACRES) = 255.3 Meyers Creek – Proposed Storm Drain 2024

**************************************************************************** FLOW PROCESS FROM NODE 805.00 TO NODE 709.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1832.00 DOWNSTREAM(FEET) = 1830.00 FLOW LENGTH(FEET) = 148.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 87.0 INCH PIPE IS 69.8 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 21.36
ESTIMATED PIPE DIAMETER(INCH) = 87.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 757.95
PIPE TRAVEL TIME(MIN.) = 0.12 Tc(MIN.) = 10.57
* TOTAL SOURCE FLOW(CFS) = 729.00
LONGEST FLOWPATH FROM NODE 800.00 TO NODE 709.00 = 1014.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 709.00 TO NODE 709.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
>>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< ============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE:

TIME OF CONCENTRATION(MIN.) = 10.57
RAINFALL INTENSITY(INCH/HR) = 5.41
AREA-AVERAGED Fm(INCH/HR) = 0.34
AREA-AVERAGED Fp(INCH/HR) = 0.74
AREA-AVERAGED Ap = 0.46
EFFECTIVE STREAM AREA(ACRES) = 6.30
TOTAL STREAM AREA(ACRES) = 6.30
PEAK FLOW RATE(CFS) AT CONFLUENCE = 28.95
* SOURCE FLOW DATA: FLOW(CFS) = 729.00 AREA(ACRES) = 249.0 * SUMMED DATA: FLOW(CFS) = 757.95 TOTAL AREA(ACRES) = 255.3 ** CONFLUENCE DATA **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER SOURCE
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE FLOW 1 90.85 10.26 5.506 0.62( 0.28) 0.46 19.3 700.00
952.0
2 28.95 10.57 5.414 0.74( 0.34) 0.46 6.3 800.00
729.0

RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER SOURCE
Meyers Creek – Proposed Storm Drain 2024

NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE FLOW 1 119.46 10.26 5.506 0.65( 0.30) 0.46 25.4 700.00
952.0
2 118.20 10.57 5.414 0.65( 0.30) 0.46 25.6 800.00
729.0
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 119.46 Tc(MIN.) = 10.26
EFFECTIVE AREA(ACRES) = 25.41 AREA-AVERAGED Fm(INCH/HR) = 0.30 AREA-AVERAGED Fp(INCH/HR) = 0.65 AREA-AVERAGED Ap = 0.46 TOTAL AREA(ACRES) = 25.6
* CUMULATIVE SOURCE FLOW DATA: FLOW(CFS) = 1681.00 AREA(AC.) = 561.7 * SUMMED DATA: FLOW(CFS) = 1800.46 TOTAL AREA(ACRES) = 587.3 LONGEST FLOWPATH FROM NODE 700.00 TO NODE 709.00 = 2622.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 709.00 TO NODE 710.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1830.00 DOWNSTREAM(FEET) = 1789.00 FLOW LENGTH(FEET) = 1360.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 108.0 INCH PIPE IS 78.3 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 36.45
ESTIMATED PIPE DIAMETER(INCH) = 108.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1800.46
PIPE TRAVEL TIME(MIN.) = 0.62 Tc(MIN.) = 10.89
* TOTAL SOURCE FLOW(CFS) = 1681.00
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 710.00 = 3982.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 710.00 TO NODE 710.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:

TIME OF CONCENTRATION(MIN.) = 10.89
RAINFALL INTENSITY(INCH/HR) = 5.32
AREA-AVERAGED Fm(INCH/HR) = 0.30
AREA-AVERAGED Fp(INCH/HR) = 0.65
AREA-AVERAGED Ap = 0.46
EFFECTIVE STREAM AREA(ACRES) = 25.41
TOTAL STREAM AREA(ACRES) = 25.59
PEAK FLOW RATE(CFS) AT CONFLUENCE = 119.46
* SOURCE FLOW DATA: FLOW(CFS) = 1681.00 AREA(ACRES) = 561.7 * SUMMED DATA: FLOW(CFS) = 1800.46 TOTAL AREA(ACRES) = 587.3 Meyers Creek – Proposed Storm Drain 2024

**************************************************************************** FLOW PROCESS FROM NODE 900.00 TO NODE 901.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
>>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< ============================================================================ INITIAL SUBAREA FLOW-LENGTH(FEET) = 533.00
ELEVATION DATA: UPSTREAM(FEET) = 1849.00 DOWNSTREAM(FEET) = 1828.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20
SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.153
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 6.436
SUBAREA Tc AND LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS Tc
LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN (MIN.)
SCHOOL A 0.77 0.74 0.600 52 9.69
PUBLIC PARK A 0.01 0.74 0.850 52 11.36
COMMERCIAL A 0.28 0.74 0.100 52 7.15
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.74
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.470
SUBAREA RUNOFF(CFS) = 5.81
TOTAL AREA(ACRES) = 1.06 PEAK FLOW RATE(CFS) = 5.81
**************************************************************************** FLOW PROCESS FROM NODE 901.00 TO NODE 902.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 5 USED)<<<<<
============================================================================ UPSTREAM ELEVATION(FEET) = 1828.00 DOWNSTREAM ELEVATION(FEET) = 1816.00 STREET LENGTH(FEET) = 341.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 25.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 10.01 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.35
HALFSTREET FLOOD WIDTH(FEET) = 9.83
AVERAGE FLOW VELOCITY(FEET/SEC.) = 4.33
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.54
STREET FLOW TRAVEL TIME(MIN.) = 1.31 Tc(MIN.) = 8.47
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 6.044
Meyers Creek – Proposed Storm Drain 2024

SUBAREA LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN
SCHOOL A 0.07 0.74 0.600 52
PUBLIC PARK A 1.08 0.74 0.850 52
COMMERCIAL A 0.52 0.74 0.100 52
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.74
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.606
SUBAREA AREA(ACRES) = 1.67 SUBAREA RUNOFF(CFS) = 8.41
EFFECTIVE AREA(ACRES) = 2.73 AREA-AVERAGED Fm(INCH/HR) = 0.41 AREA-AVERAGED Fp(INCH/HR) = 0.74 AREA-AVERAGED Ap = 0.55 TOTAL AREA(ACRES) = 2.7 PEAK FLOW RATE(CFS) = 13.84
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.39 HALFSTREET FLOOD WIDTH(FEET) = 11.40 FLOW VELOCITY(FEET/SEC.) = 4.65 DEPTH*VELOCITY(FT*FT/SEC.) = 1.80 LONGEST FLOWPATH FROM NODE 900.00 TO NODE 902.00 = 874.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 902.00 TO NODE 710.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 5 USED)<<<<<
============================================================================ UPSTREAM ELEVATION(FEET) = 1816.00 DOWNSTREAM ELEVATION(FEET) = 1789.00 STREET LENGTH(FEET) = 951.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 25.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 18.77 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.43
HALFSTREET FLOOD WIDTH(FEET) = 13.64
AVERAGE FLOW VELOCITY(FEET/SEC.) = 4.58
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.97
STREET FLOW TRAVEL TIME(MIN.) = 3.46 Tc(MIN.) = 11.93
* 100 YEAR RAINFALL INTENSITY(INCH/HR) = 5.008
SUBAREA LOSS RATE DATA(AMC III):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN
PUBLIC PARK A 1.42 0.74 0.850 52
COMMERCIAL A 0.95 0.74 0.100 52
Meyers Creek – Proposed Storm Drain 2024

SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.74
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.549
SUBAREA AREA(ACRES) = 2.37 SUBAREA RUNOFF(CFS) = 9.81
EFFECTIVE AREA(ACRES) = 5.10 AREA-AVERAGED Fm(INCH/HR) = 0.41 AREA-AVERAGED Fp(INCH/HR) = 0.74 AREA-AVERAGED Ap = 0.55 TOTAL AREA(ACRES) = 5.1 PEAK FLOW RATE(CFS) = 21.11
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.44 HALFSTREET FLOOD WIDTH(FEET) = 14.33 FLOW VELOCITY(FEET/SEC.) = 4.71 DEPTH*VELOCITY(FT*FT/SEC.) = 2.09 LONGEST FLOWPATH FROM NODE 900.00 TO NODE 710.00 = 1825.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 710.00 TO NODE 710.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
>>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< ============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE:

TIME OF CONCENTRATION(MIN.) = 11.93
RAINFALL INTENSITY(INCH/HR) = 5.01
AREA-AVERAGED Fm(INCH/HR) = 0.41
AREA-AVERAGED Fp(INCH/HR) = 0.74
AREA-AVERAGED Ap = 0.55
EFFECTIVE STREAM AREA(ACRES) = 5.10
TOTAL STREAM AREA(ACRES) = 5.10
PEAK FLOW RATE(CFS) AT CONFLUENCE = 21.11
** CONFLUENCE DATA **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER SOURCE
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE FLOW 1 119.46 10.89 5.320 0.65( 0.30) 0.46 25.4 700.00
952.0
1 118.20 11.19 5.228 0.65( 0.30) 0.46 25.6 800.00
729.0
2 21.11 11.93 5.008 0.74( 0.41) 0.55 5.1 900.00

0.0 RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER SOURCE
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE FLOW 1 140.03 10.89 5.320 0.66( 0.32) 0.48 30.1 700.00
952.0
2 138.95 11.19 5.228 0.66( 0.32) 0.48 30.4 800.00
729.0
Meyers Creek – Proposed Storm Drain 2024

3 134.03 11.93 5.008 0.67( 0.32) 0.48 30.7 900.00

0.0 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 140.03 Tc(MIN.) = 10.89
EFFECTIVE AREA(ACRES) = 30.06 AREA-AVERAGED Fm(INCH/HR) = 0.32 AREA-AVERAGED Fp(INCH/HR) = 0.66 AREA-AVERAGED Ap = 0.48 TOTAL AREA(ACRES) = 30.7
* CUMULATIVE SOURCE FLOW DATA: FLOW(CFS) = 1681.00 AREA(AC.) = 561.7 * SUMMED DATA: FLOW(CFS) = 1821.03 TOTAL AREA(ACRES) = 592.4 LONGEST FLOWPATH FROM NODE 700.00 TO NODE 710.00 = 3982.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 710.00 TO NODE 711.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1789.00 DOWNSTREAM(FEET) = 1788.00 FLOW LENGTH(FEET) = 59.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 120.0 INCH PIPE IS 88.3 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 29.39
ESTIMATED PIPE DIAMETER(INCH) = 120.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1821.03
PIPE TRAVEL TIME(MIN.) = 0.03 Tc(MIN.) = 10.92
* TOTAL SOURCE FLOW(CFS) = 1681.00
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 711.00 = 4041.00 FEET. ============================================================================ END OF STUDY SUMMARY:

TOTAL AREA(ACRES) = 30.7 TC(MIN.) = 10.92
EFFECTIVE AREA(ACRES) = 30.06 AREA-AVERAGED Fm(INCH/HR)= 0.32 AREA-AVERAGED Fp(INCH/HR) = 0.66 AREA-AVERAGED Ap = 0.476 PEAK FLOW RATE(CFS) = 140.03
* CUMULATIVE SOURCE FLOW DATA: FLOW(CFS) = 1681.00 AREA(AC.) = 561.7 * SUMMED DATA: FLOW(CFS) = 1821.03 TOTAL AREA(ACRES) = 592.4 ** PEAK FLOW RATE TABLE **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER SOURCE
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE FLOW 1 140.03 10.92 5.310 0.66( 0.32) 0.48 30.1 700.00
952.0
2 138.95 11.23 5.218 0.66( 0.32) 0.48 30.4 800.00
729.0
3 134.03 11.96 4.998 0.67( 0.32) 0.48 30.7 900.00

0.0 ============================================================================ ============================================================================

END OF RATIONAL METHOD ANALYSIS
10YR-FUTURE-NOIMPROVEMENTS.docx Page 1 of 81
____________________________________________________________________________ ****************************************************************************

RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
(Reference: 1986 SAN BERNARDINO CO. HYDROLOGY CRITERION) (c) Copyright 1983-2015 Advanced Engineering Software (aes) Ver. 22.0 Release Date: 07/01/2015 License ID 1673
Analysis prepared by:

************************** DESCRIPTION OF STUDY ************************** * HYDROLOGY STUDY - MEYERS CREEK - FUTURE CONDITION - NO IMPROVEMENTS * * RATIONAL METHOD - 10YR *
* 04/15/2024 *
************************************************************************** FILE NAME: 10MEY4.DAT
TIME/DATE OF STUDY: 15:29 07/23/2024
============================================================================ USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
============================================================================ --*TIME-OF-CONCENTRATION MODEL*--
USER SPECIFIED STORM EVENT(YEAR) = 10.00
SPECIFIED MINIMUM PIPE SIZE(INCH) = 12.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.90 *USER-DEFINED TABLED RAINFALL USED*
NUMBER OF [TIME,INTENSITY] DATA PAIRS = 6
1) 5.00; 4.390
2) 15.00; 2.540
3) 30.00; 1.890
4) 60.00; 1.430
5) 120.00; 1.000
6) 360.00; 0.598
*ANTECEDENT MOISTURE CONDITION (AMC) II ASSUMED FOR RATIONAL METHOD* *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING

WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n)
=== ===== ========= ================= ====== ===== ====== ===== ======= 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0313 0.167 0.0150 2 18.0 13.0 0.020/0.020/0.050 0.50 1.50 0.0313 0.125 0.0150 3 25.0 20.0 0.020/0.020/0.050 0.67 2.00 0.0313 0.167 0.0150 4 30.0 25.0 0.020/0.020/0.050 0.67 2.00 0.0313 0.167 0.0150 5 22.0 17.0 0.020/0.020/0.050 0.67 2.00 0.0313 0.167 0.0150 6 19.0 14.0 0.020/0.020/0.050 0.67 2.00 0.0313 0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS:

Meyers Creek – Existing Condition 2024

1. Relative Flow-Depth = 0.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)

2. (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S)
*SIZE PIPE WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*
*USER-SPECIFIED MINIMUM TOPOGRAPHIC SLOPE ADJUSTMENT NOT SELECTED **************************************************************************** FLOW PROCESS FROM NODE 300.00 TO NODE 300.00 IS CODE = 7 ---------------------------------------------------------------------------- >>>>>USER SPECIFIED HYDROLOGY INFORMATION AT NODE<<<<<
============================================================================ USER-SPECIFIED VALUES ARE AS FOLLOWS:

TC(MIN.) = 22.27 RAINFALL INTENSITY(INCH/HR) = 2.22
EFFECTIVE AREA(ACRES) = 186.00
TOTAL AREA(ACRES) = 186.00 PEAK FLOW RATE(CFS) = 276.07 AREA-AVERAGED Fm(INCH/HR) = 0.52 AREA-AVERAGED Fp(INCH/HR) = 0.67 AREA-AVERAGED Ap = 0.78
NOTE: EFFECTIVE AREA IS USED AS THE TOTAL CONTRIBUTING AREA FOR ALL CONFLUENCE ANALYSES.
**************************************************************************** FLOW PROCESS FROM NODE 300.00 TO NODE 301.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 2018.00 DOWNSTREAM(FEET) = 1986.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 381.00 CHANNEL SLOPE = 0.0840 CHANNEL FLOW THRU SUBAREA(CFS) = 276.07
FLOW VELOCITY(FEET/SEC) = 18.80 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.34 Tc(MIN.) = 22.61
LONGEST FLOWPATH FROM NODE 300.00 TO NODE 301.00 = 381.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 301.00 TO NODE 301.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 22.61
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.210
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.70 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" B 0.69 0.75 0.500 56

RESIDENTIAL
"5-7 DWELLINGS/ACRE" D 1.69 0.47 0.500 75
Meyers Creek – Existing Condition 2024

COMMERCIAL A 0.02 0.98 0.100 32
COMMERCIAL B 0.03 0.75 0.100 56
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.65
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.493
SUBAREA AREA(ACRES) = 3.13 SUBAREA RUNOFF(CFS) = 5.33
EFFECTIVE AREA(ACRES) = 189.13 AREA-AVERAGED Fm(INCH/HR) = 0.52 AREA-AVERAGED Fp(INCH/HR) = 0.67 AREA-AVERAGED Ap = 0.78 TOTAL AREA(ACRES) = 189.1 PEAK FLOW RATE(CFS) = 287.82
**************************************************************************** FLOW PROCESS FROM NODE 301.00 TO NODE 302.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1986.00 DOWNSTREAM(FEET) = 1913.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 996.00 CHANNEL SLOPE = 0.0733 CHANNEL FLOW THRU SUBAREA(CFS) = 287.82
FLOW VELOCITY(FEET/SEC) = 17.79 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.93 Tc(MIN.) = 23.55
LONGEST FLOWPATH FROM NODE 300.00 TO NODE 302.00 = 1377.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 302.00 TO NODE 302.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 23.55
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.170
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 2.30 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" B 1.72 0.75 0.500 56

RESIDENTIAL
"5-7 DWELLINGS/ACRE" D 0.87 0.47 0.500 75
COMMERCIAL A 0.15 0.98 0.100 32
COMMERCIAL B 0.09 0.75 0.100 56
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.81
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.481
SUBAREA AREA(ACRES) = 5.13 SUBAREA RUNOFF(CFS) = 8.23
EFFECTIVE AREA(ACRES) = 194.26 AREA-AVERAGED Fm(INCH/HR) = 0.52 AREA-AVERAGED Fp(INCH/HR) = 0.67 AREA-AVERAGED Ap = 0.77 TOTAL AREA(ACRES) = 194.3 PEAK FLOW RATE(CFS) = 289.17
**************************************************************************** FLOW PROCESS FROM NODE 302.00 TO NODE 302.00 IS CODE = 10 ---------------------------------------------------------------------------- Meyers Creek – Existing Condition 2024

>>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 3 <<<<< ============================================================================ **************************************************************************** FLOW PROCESS FROM NODE 400.00 TO NODE 400.00 IS CODE = 7 ---------------------------------------------------------------------------- >>>>>USER SPECIFIED HYDROLOGY INFORMATION AT NODE<<<<<
============================================================================ USER-SPECIFIED VALUES ARE AS FOLLOWS:

TC(MIN.) = 22.65 RAINFALL INTENSITY(INCH/HR) = 2.21
EFFECTIVE AREA(ACRES) = 341.00
TOTAL AREA(ACRES) = 341.00 PEAK FLOW RATE(CFS) = 577.46 AREA-AVERAGED Fm(INCH/HR) = 0.30 AREA-AVERAGED Fp(INCH/HR) = 0.32 AREA-AVERAGED Ap = 0.95
NOTE: EFFECTIVE AREA IS USED AS THE TOTAL CONTRIBUTING AREA FOR ALL CONFLUENCE ANALYSES.
**************************************************************************** FLOW PROCESS FROM NODE 400.00 TO NODE 401.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1995.00 DOWNSTREAM(FEET) = 1961.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 578.00 CHANNEL SLOPE = 0.0588 CHANNEL FLOW THRU SUBAREA(CFS) = 577.46
FLOW VELOCITY(FEET/SEC) = 19.89 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.48 Tc(MIN.) = 23.13
LONGEST FLOWPATH FROM NODE 400.00 TO NODE 401.00 = 1955.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 401.00 TO NODE 401.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 23.13
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.188
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.39 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 0.10 0.57 0.500 69

RESIDENTIAL
"5-7 DWELLINGS/ACRE" D 5.71 0.47 0.500 75
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.50
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
SUBAREA AREA(ACRES) = 6.20 SUBAREA RUNOFF(CFS) = 10.80
EFFECTIVE AREA(ACRES) = 347.20 AREA-AVERAGED Fm(INCH/HR) = 0.30 Meyers Creek – Existing Condition 2024

AREA-AVERAGED Fp(INCH/HR) = 0.32 AREA-AVERAGED Ap = 0.94 TOTAL AREA(ACRES) = 347.2 PEAK FLOW RATE(CFS) = 588.85
**************************************************************************** FLOW PROCESS FROM NODE 401.00 TO NODE 302.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1961.00 DOWNSTREAM(FEET) = 1913.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 867.00 CHANNEL SLOPE = 0.0554 CHANNEL FLOW THRU SUBAREA(CFS) = 588.85
FLOW VELOCITY(FEET/SEC) = 19.42 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.74 Tc(MIN.) = 23.88
LONGEST FLOWPATH FROM NODE 400.00 TO NODE 302.00 = 2822.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 302.00 TO NODE 302.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 23.88
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.155
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 3.76 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" D 1.48 0.47 0.500 75
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.83
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
SUBAREA AREA(ACRES) = 5.24 SUBAREA RUNOFF(CFS) = 8.20
EFFECTIVE AREA(ACRES) = 352.43 AREA-AVERAGED Fm(INCH/HR) = 0.30 AREA-AVERAGED Fp(INCH/HR) = 0.33 AREA-AVERAGED Ap = 0.94 TOTAL AREA(ACRES) = 352.4 PEAK FLOW RATE(CFS) = 588.85
NOTE: PEAK FLOW RATE DEFAULTED TO UPSTREAM VALUE
**************************************************************************** FLOW PROCESS FROM NODE 302.00 TO NODE 302.00 IS CODE = 11 ---------------------------------------------------------------------------- >>>>>CONFLUENCE MEMORY BANK # 3 WITH THE MAIN-STREAM MEMORY<<<<< ============================================================================ ** MAIN STREAM CONFLUENCE DATA **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 588.85 23.88 2.155 0.33( 0.30) 0.94 352.4 400.00
LONGEST FLOWPATH FROM NODE 400.00 TO NODE 302.00 = 2822.00 FEET.

Meyers Creek – Existing Condition 2024

** MEMORY BANK # 3 CONFLUENCE DATA **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 289.17 23.55 2.170 0.67( 0.52) 0.77 194.3 300.00
LONGEST FLOWPATH FROM NODE 300.00 TO NODE 302.00 = 1377.00 FEET. ** PEAK FLOW RATE TABLE **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 874.33 23.55 2.170 0.43( 0.38) 0.88 541.8 300.00
2 875.49 23.88 2.155 0.43( 0.38) 0.88 546.7 400.00
TOTAL AREA(ACRES) = 546.7
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 875.49 Tc(MIN.) = 23.878
EFFECTIVE AREA(ACRES) = 546.70 AREA-AVERAGED Fm(INCH/HR) = 0.38 AREA-AVERAGED Fp(INCH/HR) = 0.43 AREA-AVERAGED Ap = 0.88 TOTAL AREA(ACRES) = 546.7
LONGEST FLOWPATH FROM NODE 400.00 TO NODE 302.00 = 2822.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 302.00 TO NODE 302.00 IS CODE = 12 ---------------------------------------------------------------------------- >>>>>CLEAR MEMORY BANK # 3 <<<<<
============================================================================ **************************************************************************** FLOW PROCESS FROM NODE 302.00 TO NODE 303.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1913.00 DOWNSTREAM(FEET) = 1870.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 942.00 CHANNEL SLOPE = 0.0456 CHANNEL FLOW THRU SUBAREA(CFS) = 875.49
FLOW VELOCITY(FEET/SEC) = 20.05 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.78 Tc(MIN.) = 24.66
LONGEST FLOWPATH FROM NODE 400.00 TO NODE 303.00 = 3764.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 303.00 TO NODE 303.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 24.66
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.121
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
Meyers Creek – Existing Condition 2024

"5-7 DWELLINGS/ACRE" A 1.03 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" B 2.02 0.75 0.500 56
COMMERCIAL A 0.25 0.98 0.100 32
COMMERCIAL B 1.63 0.75 0.100 56
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.82
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.347
SUBAREA AREA(ACRES) = 4.93 SUBAREA RUNOFF(CFS) = 8.16
EFFECTIVE AREA(ACRES) = 551.63 AREA-AVERAGED Fm(INCH/HR) = 0.38 AREA-AVERAGED Fp(INCH/HR) = 0.43 AREA-AVERAGED Ap = 0.87 TOTAL AREA(ACRES) = 551.6 PEAK FLOW RATE(CFS) = 875.49
NOTE: PEAK FLOW RATE DEFAULTED TO UPSTREAM VALUE
**************************************************************************** FLOW PROCESS FROM NODE 303.00 TO NODE 303.00 IS CODE = 10 ---------------------------------------------------------------------------- >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 <<<<< ============================================================================ **************************************************************************** FLOW PROCESS FROM NODE 500.00 TO NODE 501.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
>>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< ============================================================================ INITIAL SUBAREA FLOW-LENGTH(FEET) = 576.00
ELEVATION DATA: UPSTREAM(FEET) = 1975.00 DOWNSTREAM(FEET) = 1967.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20
SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 11.630
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.163
SUBAREA Tc AND LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS Tc
LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN (MIN.)

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 1.02 0.98 0.500 32 11.63

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 0.68 0.57 0.500 69 11.63

RESIDENTIAL
"5-7 DWELLINGS/ACRE" D 0.03 0.47 0.500 75 11.63
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.81
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
SUBAREA RUNOFF(CFS) = 4.32
TOTAL AREA(ACRES) = 1.74 PEAK FLOW RATE(CFS) = 4.32
**************************************************************************** FLOW PROCESS FROM NODE 501.00 TO NODE 502.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
Meyers Creek – Existing Condition 2024

============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1967.00 DOWNSTREAM(FEET) = 1919.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 797.00 CHANNEL SLOPE = 0.0602 CHANNEL FLOW THRU SUBAREA(CFS) = 4.32
FLOW VELOCITY(FEET/SEC) = 5.00 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 2.65 Tc(MIN.) = 14.28
LONGEST FLOWPATH FROM NODE 500.00 TO NODE 502.00 = 1373.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 502.00 TO NODE 502.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 14.28
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.672
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 2.13 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 1.29 0.57 0.500 69
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.82
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
SUBAREA AREA(ACRES) = 3.43 SUBAREA RUNOFF(CFS) = 6.97
EFFECTIVE AREA(ACRES) = 5.16 AREA-AVERAGED Fm(INCH/HR) = 0.41 AREA-AVERAGED Fp(INCH/HR) = 0.82 AREA-AVERAGED Ap = 0.50 TOTAL AREA(ACRES) = 5.2 PEAK FLOW RATE(CFS) = 10.53
**************************************************************************** FLOW PROCESS FROM NODE 502.00 TO NODE 503.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1919.00 DOWNSTREAM(FEET) = 1884.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 789.00 CHANNEL SLOPE = 0.0444 CHANNEL FLOW THRU SUBAREA(CFS) = 10.53
FLOW VELOCITY(FEET/SEC) = 5.33 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 2.47 Tc(MIN.) = 16.75
LONGEST FLOWPATH FROM NODE 500.00 TO NODE 503.00 = 2162.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 503.00 TO NODE 503.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 16.75
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.464
SUBAREA LOSS RATE DATA(AMC II):

Meyers Creek – Existing Condition 2024

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 2.64 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 2.67 0.57 0.500 69
COMMERCIAL C 0.26 0.57 0.100 69
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.77
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.481
SUBAREA AREA(ACRES) = 5.57 SUBAREA RUNOFF(CFS) = 10.50
EFFECTIVE AREA(ACRES) = 10.73 AREA-AVERAGED Fm(INCH/HR) = 0.39 AREA-AVERAGED Fp(INCH/HR) = 0.79 AREA-AVERAGED Ap = 0.49 TOTAL AREA(ACRES) = 10.7 PEAK FLOW RATE(CFS) = 20.06
**************************************************************************** FLOW PROCESS FROM NODE 503.00 TO NODE 503.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:

TIME OF CONCENTRATION(MIN.) = 16.75
RAINFALL INTENSITY(INCH/HR) = 2.46
AREA-AVERAGED Fm(INCH/HR) = 0.39
AREA-AVERAGED Fp(INCH/HR) = 0.79
AREA-AVERAGED Ap = 0.49
EFFECTIVE STREAM AREA(ACRES) = 10.73
TOTAL STREAM AREA(ACRES) = 10.73
PEAK FLOW RATE(CFS) AT CONFLUENCE = 20.06
**************************************************************************** FLOW PROCESS FROM NODE 600.00 TO NODE 601.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
>>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< ============================================================================ INITIAL SUBAREA FLOW-LENGTH(FEET) = 997.00
ELEVATION DATA: UPSTREAM(FEET) = 2302.00 DOWNSTREAM(FEET) = 2058.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20
SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 8.160
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.805
SUBAREA Tc AND LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS Tc
LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN (MIN.)

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 0.28 0.57 0.500 69 8.16

RESIDENTIAL
"5-7 DWELLINGS/ACRE" D 4.39 0.47 0.500 75 8.16
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.48
Meyers Creek – Existing Condition 2024

SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
SUBAREA RUNOFF(CFS) = 14.99
TOTAL AREA(ACRES) = 4.67 PEAK FLOW RATE(CFS) = 14.99
**************************************************************************** FLOW PROCESS FROM NODE 601.00 TO NODE 602.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 2058.00 DOWNSTREAM(FEET) = 1982.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 773.00 CHANNEL SLOPE = 0.0983 CHANNEL FLOW THRU SUBAREA(CFS) = 14.99
FLOW VELOCITY(FEET/SEC) = 8.70 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 1.48 Tc(MIN.) = 9.64
LONGEST FLOWPATH FROM NODE 600.00 TO NODE 602.00 = 1770.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 602.00 TO NODE 602.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 9.64
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.531
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.40 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 6.53 0.57 0.500 69

RESIDENTIAL
"5-7 DWELLINGS/ACRE" D 2.24 0.47 0.500 75
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.56
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
SUBAREA AREA(ACRES) = 9.17 SUBAREA RUNOFF(CFS) = 26.84
EFFECTIVE AREA(ACRES) = 13.84 AREA-AVERAGED Fm(INCH/HR) = 0.27 AREA-AVERAGED Fp(INCH/HR) = 0.53 AREA-AVERAGED Ap = 0.50 TOTAL AREA(ACRES) = 13.8 PEAK FLOW RATE(CFS) = 40.68
**************************************************************************** FLOW PROCESS FROM NODE 602.00 TO NODE 603.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1982.00 DOWNSTREAM(FEET) = 1916.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 788.00 CHANNEL SLOPE = 0.0838 CHANNEL FLOW THRU SUBAREA(CFS) = 40.68
FLOW VELOCITY(FEET/SEC) = 10.56 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) Meyers Creek – Existing Condition 2024

TRAVEL TIME(MIN.) = 1.24 Tc(MIN.) = 10.88
LONGEST FLOWPATH FROM NODE 600.00 TO NODE 603.00 = 2558.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 603.00 TO NODE 603.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 10.88
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.301
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 7.47 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 6.48 0.57 0.500 69

RESIDENTIAL
"5-7 DWELLINGS/ACRE" D 0.50 0.47 0.500 75
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.77
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
SUBAREA AREA(ACRES) = 14.45 SUBAREA RUNOFF(CFS) = 37.91 EFFECTIVE AREA(ACRES) = 28.29 AREA-AVERAGED Fm(INCH/HR) = 0.33 AREA-AVERAGED Fp(INCH/HR) = 0.66 AREA-AVERAGED Ap = 0.50 TOTAL AREA(ACRES) = 28.3 PEAK FLOW RATE(CFS) = 75.72
**************************************************************************** FLOW PROCESS FROM NODE 603.00 TO NODE 503.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1916.00 DOWNSTREAM(FEET) = 1884.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 544.00 CHANNEL SLOPE = 0.0588 CHANNEL FLOW THRU SUBAREA(CFS) = 75.72
FLOW VELOCITY(FEET/SEC) = 10.60 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.86 Tc(MIN.) = 11.74
LONGEST FLOWPATH FROM NODE 600.00 TO NODE 503.00 = 3102.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 503.00 TO NODE 503.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
>>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< ============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE:

TIME OF CONCENTRATION(MIN.) = 11.74
RAINFALL INTENSITY(INCH/HR) = 3.14
AREA-AVERAGED Fm(INCH/HR) = 0.33
Meyers Creek – Existing Condition 2024

AREA-AVERAGED Fp(INCH/HR) = 0.66
AREA-AVERAGED Ap = 0.50
EFFECTIVE STREAM AREA(ACRES) = 28.29
TOTAL STREAM AREA(ACRES) = 28.29
PEAK FLOW RATE(CFS) AT CONFLUENCE = 75.72
** CONFLUENCE DATA **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 20.06 16.75 2.464 0.79( 0.39) 0.49 10.7 500.00
2 75.72 11.74 3.143 0.66( 0.33) 0.50 28.3 600.00

RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 94.38 11.74 3.143 0.68( 0.34) 0.50 35.8 600.00
2 77.52 16.75 2.464 0.69( 0.34) 0.50 39.0 500.00
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 94.38 Tc(MIN.) = 11.74
EFFECTIVE AREA(ACRES) = 35.82 AREA-AVERAGED Fm(INCH/HR) = 0.34 AREA-AVERAGED Fp(INCH/HR) = 0.68 AREA-AVERAGED Ap = 0.50 TOTAL AREA(ACRES) = 39.0
LONGEST FLOWPATH FROM NODE 600.00 TO NODE 503.00 = 3102.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 503.00 TO NODE 303.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1884.00 DOWNSTREAM(FEET) = 1870.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 327.00 CHANNEL SLOPE = 0.0428 CHANNEL FLOW THRU SUBAREA(CFS) = 94.38
FLOW VELOCITY(FEET/SEC) = 9.65 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.56 Tc(MIN.) = 12.30
LONGEST FLOWPATH FROM NODE 600.00 TO NODE 303.00 = 3429.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 303.00 TO NODE 303.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 12.30
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.039
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS
Meyers Creek – Existing Condition 2024

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.91 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" B 0.65 0.75 0.500 56
COMMERCIAL B 0.05 0.75 0.100 56
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.88
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.489
SUBAREA AREA(ACRES) = 1.61 SUBAREA RUNOFF(CFS) = 3.78
EFFECTIVE AREA(ACRES) = 37.43 AREA-AVERAGED Fm(INCH/HR) = 0.34 AREA-AVERAGED Fp(INCH/HR) = 0.69 AREA-AVERAGED Ap = 0.50 TOTAL AREA(ACRES) = 40.6 PEAK FLOW RATE(CFS) = 94.38
NOTE: PEAK FLOW RATE DEFAULTED TO UPSTREAM VALUE
**************************************************************************** FLOW PROCESS FROM NODE 303.00 TO NODE 303.00 IS CODE = 11 ---------------------------------------------------------------------------- >>>>>CONFLUENCE MEMORY BANK # 1 WITH THE MAIN-STREAM MEMORY<<<<< ============================================================================ ** MAIN STREAM CONFLUENCE DATA **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 94.38 12.30 3.039 0.69( 0.34) 0.50 37.4 600.00
2 77.52 17.35 2.438 0.70( 0.35) 0.50 40.6 500.00
LONGEST FLOWPATH FROM NODE 600.00 TO NODE 303.00 = 3429.00 FEET. ** MEMORY BANK # 1 CONFLUENCE DATA **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 874.33 24.33 2.136 0.44( 0.38) 0.87 546.7 300.00
2 875.49 24.66 2.121 0.43( 0.38) 0.87 551.6 400.00
LONGEST FLOWPATH FROM NODE 400.00 TO NODE 303.00 = 3764.00 FEET. ** PEAK FLOW RATE TABLE **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 763.92 12.30 3.039 0.45( 0.38) 0.83 313.9 600.00
2 808.39 17.35 2.438 0.45( 0.38) 0.84 430.5 500.00
3 940.64 24.33 2.136 0.45( 0.38) 0.84 587.4 300.00
4 941.26 24.66 2.121 0.45( 0.38) 0.85 592.3 400.00
TOTAL AREA(ACRES) = 592.3
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 941.26 Tc(MIN.) = 24.661
EFFECTIVE AREA(ACRES) = 592.27 AREA-AVERAGED Fm(INCH/HR) = 0.38 AREA-AVERAGED Fp(INCH/HR) = 0.45 AREA-AVERAGED Ap = 0.85 TOTAL AREA(ACRES) = 592.3
LONGEST FLOWPATH FROM NODE 400.00 TO NODE 303.00 = 3764.00 FEET.

Meyers Creek – Existing Condition 2024

**************************************************************************** FLOW PROCESS FROM NODE 303.00 TO NODE 303.00 IS CODE = 12 ---------------------------------------------------------------------------- >>>>>CLEAR MEMORY BANK # 1 <<<<<
============================================================================ **************************************************************************** FLOW PROCESS FROM NODE 303.00 TO NODE 108.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1870.00 DOWNSTREAM(FEET) = 1855.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 219.00 CHANNEL SLOPE = 0.0685 CHANNEL FLOW THRU SUBAREA(CFS) = 941.26
FLOW VELOCITY(FEET/SEC) = 25.15 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.15 Tc(MIN.) = 24.81
LONGEST FLOWPATH FROM NODE 400.00 TO NODE 108.00 = 3983.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 108.00 TO NODE 108.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 24.81
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.115
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.03 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" B 0.37 0.75 0.500 56
COMMERCIAL B 0.12 0.75 0.100 56
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.76
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.409
SUBAREA AREA(ACRES) = 0.52 SUBAREA RUNOFF(CFS) = 0.84
EFFECTIVE AREA(ACRES) = 592.79 AREA-AVERAGED Fm(INCH/HR) = 0.38 AREA-AVERAGED Fp(INCH/HR) = 0.45 AREA-AVERAGED Ap = 0.84 TOTAL AREA(ACRES) = 592.8 PEAK FLOW RATE(CFS) = 941.26
NOTE: PEAK FLOW RATE DEFAULTED TO UPSTREAM VALUE
**************************************************************************** FLOW PROCESS FROM NODE 108.00 TO NODE 108.00 IS CODE = 10 ---------------------------------------------------------------------------- >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 2 <<<<< ============================================================================ **************************************************************************** FLOW PROCESS FROM NODE 100.00 TO NODE 101.00 IS CODE = 21 Meyers Creek – Existing Condition 2024

---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
>>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< ============================================================================ INITIAL SUBAREA FLOW-LENGTH(FEET) = 526.00
ELEVATION DATA: UPSTREAM(FEET) = 2130.00 DOWNSTREAM(FEET) = 2072.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20
SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 5.791
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 4.244
SUBAREA Tc AND LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS Tc
LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN (MIN.)

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.74 0.98 0.500 32 7.41
COMMERCIAL A 0.03 0.98 0.100 32 5.79
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.97
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.485
SUBAREA RUNOFF(CFS) = 2.61
TOTAL AREA(ACRES) = 0.77 PEAK FLOW RATE(CFS) = 2.61
**************************************************************************** FLOW PROCESS FROM NODE 101.00 TO NODE 102.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0370
STREET LENGTH(FEET) = 163.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 19.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 14.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 4.62 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.35
HALFSTREET FLOOD WIDTH(FEET) = 9.35
AVERAGE FLOW VELOCITY(FEET/SEC.) = 4.35
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.50
STREET FLOW TRAVEL TIME(MIN.) = 0.63 Tc(MIN.) = 6.42
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 4.128
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS
Meyers Creek – Existing Condition 2024

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.64 0.98 0.500 32
COMMERCIAL A 0.53 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.318
SUBAREA AREA(ACRES) = 1.17 SUBAREA RUNOFF(CFS) = 4.03
EFFECTIVE AREA(ACRES) = 1.94 AREA-AVERAGED Fm(INCH/HR) = 0.37 AREA-AVERAGED Fp(INCH/HR) = 0.98 AREA-AVERAGED Ap = 0.38 TOTAL AREA(ACRES) = 1.9 PEAK FLOW RATE(CFS) = 6.55
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.38 HALFSTREET FLOOD WIDTH(FEET) = 10.99 FLOW VELOCITY(FEET/SEC.) = 4.69 DEPTH*VELOCITY(FT*FT/SEC.) = 1.77 LONGEST FLOWPATH FROM NODE 100.00 TO NODE 102.00 = 689.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 102.00 TO NODE 103.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0810
STREET LENGTH(FEET) = 999.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 19.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 14.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 7.95 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.36
HALFSTREET FLOOD WIDTH(FEET) = 10.00
AVERAGE FLOW VELOCITY(FEET/SEC.) = 6.68
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 2.39
STREET FLOW TRAVEL TIME(MIN.) = 2.49 Tc(MIN.) = 8.91
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.667
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.18 0.98 0.500 32
COMMERCIAL A 0.59 0.98 0.100 32
COMMERCIAL B 0.12 0.75 0.100 56
Meyers Creek – Existing Condition 2024

SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.96
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.182
SUBAREA AREA(ACRES) = 0.89 SUBAREA RUNOFF(CFS) = 2.80
EFFECTIVE AREA(ACRES) = 2.83 AREA-AVERAGED Fm(INCH/HR) = 0.31 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.32 TOTAL AREA(ACRES) = 2.8 PEAK FLOW RATE(CFS) = 8.55
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.37 HALFSTREET FLOOD WIDTH(FEET) = 10.39 FLOW VELOCITY(FEET/SEC.) = 6.74 DEPTH*VELOCITY(FT*FT/SEC.) = 2.47 LONGEST FLOWPATH FROM NODE 100.00 TO NODE 103.00 = 1688.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 103.00 TO NODE 104.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0840
STREET LENGTH(FEET) = 680.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 19.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 14.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 10.58 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.38
HALFSTREET FLOOD WIDTH(FEET) = 11.32
AVERAGE FLOW VELOCITY(FEET/SEC.) = 7.19
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 2.77
STREET FLOW TRAVEL TIME(MIN.) = 1.58 Tc(MIN.) = 10.48
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.376
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 1.04 0.98 0.500 32
COMMERCIAL A 0.46 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.378
SUBAREA AREA(ACRES) = 1.49 SUBAREA RUNOFF(CFS) = 4.04
EFFECTIVE AREA(ACRES) = 4.33 AREA-AVERAGED Fm(INCH/HR) = 0.33 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.34 Meyers Creek – Existing Condition 2024

TOTAL AREA(ACRES) = 4.3 PEAK FLOW RATE(CFS) = 11.85
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.40 HALFSTREET FLOOD WIDTH(FEET) = 11.92 FLOW VELOCITY(FEET/SEC.) = 7.36 DEPTH*VELOCITY(FT*FT/SEC.) = 2.92 LONGEST FLOWPATH FROM NODE 100.00 TO NODE 104.00 = 2368.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 104.00 TO NODE 105.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0720
STREET LENGTH(FEET) = 152.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 19.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 14.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 15.12 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.43
HALFSTREET FLOOD WIDTH(FEET) = 13.67
AVERAGE FLOW VELOCITY(FEET/SEC.) = 7.35
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 3.17
STREET FLOW TRAVEL TIME(MIN.) = 0.34 Tc(MIN.) = 10.83
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.312
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 2.44 0.98 0.500 32
COMMERCIAL A 0.11 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.482
SUBAREA AREA(ACRES) = 2.55 SUBAREA RUNOFF(CFS) = 6.53
EFFECTIVE AREA(ACRES) = 6.88 AREA-AVERAGED Fm(INCH/HR) = 0.38 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.39 TOTAL AREA(ACRES) = 6.9 PEAK FLOW RATE(CFS) = 18.13
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.45 HALFSTREET FLOOD WIDTH(FEET) = 14.76 FLOW VELOCITY(FEET/SEC.) = 7.66 DEPTH*VELOCITY(FT*FT/SEC.) = 3.47 Meyers Creek – Existing Condition 2024

LONGEST FLOWPATH FROM NODE 100.00 TO NODE 105.00 = 2520.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 105.00 TO NODE 106.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0610
STREET LENGTH(FEET) = 146.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 19.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 14.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 23.66 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.50
HALFSTREET FLOOD WIDTH(FEET) = 17.00
AVERAGE FLOW VELOCITY(FEET/SEC.) = 7.68
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 3.83
STREET FLOW TRAVEL TIME(MIN.) = 0.32 Tc(MIN.) = 11.14
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.253
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 3.84 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" B 0.01 0.75 0.500 56
COMMERCIAL A 0.51 0.98 0.100 32
COMMERCIAL B 0.01 0.75 0.100 56
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.97
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.453
SUBAREA AREA(ACRES) = 4.37 SUBAREA RUNOFF(CFS) = 11.05
EFFECTIVE AREA(ACRES) = 11.25 AREA-AVERAGED Fm(INCH/HR) = 0.41 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.42 TOTAL AREA(ACRES) = 11.2 PEAK FLOW RATE(CFS) = 28.83
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.53 HALFSTREET FLOOD WIDTH(FEET) = 18.43 FLOW VELOCITY(FEET/SEC.) = 8.04 DEPTH*VELOCITY(FT*FT/SEC.) = 4.24 LONGEST FLOWPATH FROM NODE 100.00 TO NODE 106.00 = 2666.00 FEET.

Meyers Creek – Existing Condition 2024

**************************************************************************** FLOW PROCESS FROM NODE 106.00 TO NODE 107.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0460
STREET LENGTH(FEET) = 954.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 19.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 14.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 36.33 ***STREET FLOW SPLITS OVER STREET-CROWN***
FULL DEPTH(FEET) = 0.54 FLOOD WIDTH(FEET) = 19.00
FULL HALF-STREET VELOCITY(FEET/SEC.) = 7.12
SPLIT DEPTH(FEET) = 0.40 SPLIT FLOOD WIDTH(FEET) = 12.19 SPLIT FLOW(CFS) = 9.27 SPLIT VELOCITY(FEET/SEC.) = 5.53 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.54
HALFSTREET FLOOD WIDTH(FEET) = 19.00
AVERAGE FLOW VELOCITY(FEET/SEC.) = 7.12
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 3.83
STREET FLOW TRAVEL TIME(MIN.) = 2.23 Tc(MIN.) = 13.38
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.840
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 5.73 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" B 0.14 0.75 0.500 56
COMMERCIAL A 0.97 0.98 0.100 32
COMMERCIAL B 0.07 0.75 0.100 56
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.97
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.440
SUBAREA AREA(ACRES) = 6.91 SUBAREA RUNOFF(CFS) = 15.00
EFFECTIVE AREA(ACRES) = 18.15 AREA-AVERAGED Fm(INCH/HR) = 0.41 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.43 TOTAL AREA(ACRES) = 18.2 PEAK FLOW RATE(CFS) = 39.65
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.54 HALFSTREET FLOOD WIDTH(FEET) = 19.00 Meyers Creek – Existing Condition 2024

FLOW VELOCITY(FEET/SEC.) = 7.12 DEPTH*VELOCITY(FT*FT/SEC.) = 3.83 LONGEST FLOWPATH FROM NODE 100.00 TO NODE 107.00 = 3620.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 107.00 TO NODE 108.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ REPRESENTATIVE SLOPE = 0.2500
FLOW LENGTH(FEET) = 8.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 18.0 INCH PIPE IS 12.1 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 31.30
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 39.65
PIPE TRAVEL TIME(MIN.) = 0.00 Tc(MIN.) = 13.38
LONGEST FLOWPATH FROM NODE 100.00 TO NODE 108.00 = 3628.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 108.00 TO NODE 108.00 IS CODE = 11 ---------------------------------------------------------------------------- >>>>>CONFLUENCE MEMORY BANK # 2 WITH THE MAIN-STREAM MEMORY<<<<< ============================================================================ ** MAIN STREAM CONFLUENCE DATA **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 39.65 13.38 2.839 0.97( 0.41) 0.43 18.2 100.00
LONGEST FLOWPATH FROM NODE 100.00 TO NODE 108.00 = 3628.00 FEET. ** MEMORY BANK # 2 CONFLUENCE DATA **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 763.92 12.46 3.010 0.45( 0.38) 0.83 314.5 600.00
2 808.39 17.50 2.432 0.45( 0.38) 0.83 431.0 500.00
3 940.64 24.47 2.129 0.45( 0.38) 0.84 587.9 300.00
4 941.26 24.81 2.115 0.45( 0.38) 0.84 592.8 400.00
LONGEST FLOWPATH FROM NODE 400.00 TO NODE 108.00 = 3983.00 FEET. ** PEAK FLOW RATE TABLE **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 803.44 12.46 3.010 0.47( 0.38) 0.80 331.4 600.00
2 811.70 13.38 2.839 0.47( 0.38) 0.81 353.9 100.00
3 841.37 17.50 2.432 0.46( 0.38) 0.82 449.2 500.00
4 968.68 24.47 2.129 0.45( 0.38) 0.83 606.0 300.00
5 969.07 24.81 2.115 0.45( 0.38) 0.83 610.9 400.00
TOTAL AREA(ACRES) = 610.9
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

Meyers Creek – Existing Condition 2024

PEAK FLOW RATE(CFS) = 969.07 Tc(MIN.) = 24.807
EFFECTIVE AREA(ACRES) = 610.94 AREA-AVERAGED Fm(INCH/HR) = 0.38 AREA-AVERAGED Fp(INCH/HR) = 0.45 AREA-AVERAGED Ap = 0.83 TOTAL AREA(ACRES) = 610.9
LONGEST FLOWPATH FROM NODE 400.00 TO NODE 108.00 = 3983.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 108.00 TO NODE 108.00 IS CODE = 12 ---------------------------------------------------------------------------- >>>>>CLEAR MEMORY BANK # 2 <<<<<
============================================================================ **************************************************************************** FLOW PROCESS FROM NODE 108.00 TO NODE 109.00 IS CODE = 37 ---------------------------------------------------------------------------- >>>>>COMPUTE CULVERT TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED CULVERT SIZE<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0140
FLOW LENGTH(FEET) = 40.00 MANNING'S N = 0.014
Notes:

1. Reference: "Hydraulic Charts for the Selection of
Highway Culverts", Hydraulic Engineering Circular No. 5, December 1965, Federal Highway Administration.

2. INLET control for all Culvert Analysis.

3. Headwater depth is ASSUMED to be 3 FEET above the culvert soffit.

GIVEN BOX CULVERT HEIGHT(FEET) = 7.50
ESTIMATED BOX CULVERT BASEWIDTH(FEET) = 11.01
CULVERT-FLOW VELOCITY(FEET/SEC.) = 11.73
CULVERT-FLOW(CFS) = 969.07
CULVERT-FLOW TRAVEL TIME(MIN.) = 0.06 Tc(MIN.) = 24.86
LONGEST FLOWPATH FROM NODE 400.00 TO NODE 109.00 = 4023.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 109.00 TO NODE 109.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:

TIME OF CONCENTRATION(MIN.) = 24.86
RAINFALL INTENSITY(INCH/HR) = 2.11
AREA-AVERAGED Fm(INCH/HR) = 0.38
AREA-AVERAGED Fp(INCH/HR) = 0.45
AREA-AVERAGED Ap = 0.83
EFFECTIVE STREAM AREA(ACRES) = 610.94
TOTAL STREAM AREA(ACRES) = 610.94
PEAK FLOW RATE(CFS) AT CONFLUENCE = 969.07
**************************************************************************** Meyers Creek – Existing Condition 2024

FLOW PROCESS FROM NODE 200.00 TO NODE 201.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
>>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< ============================================================================ INITIAL SUBAREA FLOW-LENGTH(FEET) = 284.00
ELEVATION DATA: UPSTREAM(FEET) = 2072.00 DOWNSTREAM(FEET) = 2056.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20
SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 5.177
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 4.357
SUBAREA Tc AND LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS Tc
LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN (MIN.)

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.06 0.98 0.500 32 6.62
COMMERCIAL A 0.15 0.98 0.100 32 5.18
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.217
SUBAREA RUNOFF(CFS) = 0.80
TOTAL AREA(ACRES) = 0.22 PEAK FLOW RATE(CFS) = 0.80
**************************************************************************** FLOW PROCESS FROM NODE 201.00 TO NODE 202.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0810
STREET LENGTH(FEET) = 111.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 19.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 14.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 1.44 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.21
HALFSTREET FLOOD WIDTH(FEET) = 2.42
AVERAGE FLOW VELOCITY(FEET/SEC.) = 5.81
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.20
STREET FLOW TRAVEL TIME(MIN.) = 0.32 Tc(MIN.) = 5.50
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 4.298
SUBAREA LOSS RATE DATA(AMC II):

Meyers Creek – Existing Condition 2024

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.29 0.98 0.500 32
COMMERCIAL A 0.07 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.97
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.419
SUBAREA AREA(ACRES) = 0.37 SUBAREA RUNOFF(CFS) = 1.28
EFFECTIVE AREA(ACRES) = 0.58 AREA-AVERAGED Fm(INCH/HR) = 0.34 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.34 TOTAL AREA(ACRES) = 0.6 PEAK FLOW RATE(CFS) = 2.07
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.25 HALFSTREET FLOOD WIDTH(FEET) = 4.48
FLOW VELOCITY(FEET/SEC.) = 5.30 DEPTH*VELOCITY(FT*FT/SEC.) = 1.31 LONGEST FLOWPATH FROM NODE 200.00 TO NODE 202.00 = 395.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 202.00 TO NODE 203.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0900
STREET LENGTH(FEET) = 232.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 19.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 14.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 3.17 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.28
HALFSTREET FLOOD WIDTH(FEET) = 5.96
AVERAGE FLOW VELOCITY(FEET/SEC.) = 5.82
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.61
STREET FLOW TRAVEL TIME(MIN.) = 0.66 Tc(MIN.) = 6.16
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 4.175
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.48 0.98 0.500 32
COMMERCIAL A 0.17 0.98 0.100 32
Meyers Creek – Existing Condition 2024

SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.396
SUBAREA AREA(ACRES) = 0.64 SUBAREA RUNOFF(CFS) = 2.20
EFFECTIVE AREA(ACRES) = 1.23 AREA-AVERAGED Fm(INCH/HR) = 0.36 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.37 TOTAL AREA(ACRES) = 1.2 PEAK FLOW RATE(CFS) = 4.20
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.30 HALFSTREET FLOOD WIDTH(FEET) = 7.05
FLOW VELOCITY(FEET/SEC.) = 6.12 DEPTH*VELOCITY(FT*FT/SEC.) = 1.83 LONGEST FLOWPATH FROM NODE 200.00 TO NODE 203.00 = 627.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 203.00 TO NODE 204.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0810
STREET LENGTH(FEET) = 319.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 19.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 14.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 5.32 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.32
HALFSTREET FLOOD WIDTH(FEET) = 8.25
AVERAGE FLOW VELOCITY(FEET/SEC.) = 6.11
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 1.98
STREET FLOW TRAVEL TIME(MIN.) = 0.87 Tc(MIN.) = 7.03
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 4.015
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.43 0.98 0.500 32
COMMERCIAL A 0.23 0.98 0.100 32
COMMERCIAL B 0.01 0.75 0.100 56
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.97
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.356
SUBAREA AREA(ACRES) = 0.68 SUBAREA RUNOFF(CFS) = 2.24
EFFECTIVE AREA(ACRES) = 1.90 AREA-AVERAGED Fm(INCH/HR) = 0.36 Meyers Creek – Existing Condition 2024

AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.37 TOTAL AREA(ACRES) = 1.9 PEAK FLOW RATE(CFS) = 6.26
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.34 HALFSTREET FLOOD WIDTH(FEET) = 8.96
FLOW VELOCITY(FEET/SEC.) = 6.31 DEPTH*VELOCITY(FT*FT/SEC.) = 2.13 LONGEST FLOWPATH FROM NODE 200.00 TO NODE 204.00 = 946.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 204.00 TO NODE 205.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0780
STREET LENGTH(FEET) = 381.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 19.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 14.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 8.07 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.36
HALFSTREET FLOOD WIDTH(FEET) = 10.17
AVERAGE FLOW VELOCITY(FEET/SEC.) = 6.60
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 2.39
STREET FLOW TRAVEL TIME(MIN.) = 0.96 Tc(MIN.) = 7.99
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.836
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.87 0.98 0.500 32
COMMERCIAL A 0.29 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.97
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.399
SUBAREA AREA(ACRES) = 1.16 SUBAREA RUNOFF(CFS) = 3.61
EFFECTIVE AREA(ACRES) = 3.07 AREA-AVERAGED Fm(INCH/HR) = 0.37 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.38 TOTAL AREA(ACRES) = 3.1 PEAK FLOW RATE(CFS) = 9.57
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.38 HALFSTREET FLOOD WIDTH(FEET) = 10.99 Meyers Creek – Existing Condition 2024

FLOW VELOCITY(FEET/SEC.) = 6.85 DEPTH*VELOCITY(FT*FT/SEC.) = 2.59 LONGEST FLOWPATH FROM NODE 200.00 TO NODE 205.00 = 1327.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 205.00 TO NODE 206.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0840
STREET LENGTH(FEET) = 482.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 19.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 14.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 11.33 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.39
HALFSTREET FLOOD WIDTH(FEET) = 11.70
AVERAGE FLOW VELOCITY(FEET/SEC.) = 7.27
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 2.85
STREET FLOW TRAVEL TIME(MIN.) = 1.10 Tc(MIN.) = 9.10
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.632
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.79 0.98 0.500 32
COMMERCIAL A 0.40 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.365
SUBAREA AREA(ACRES) = 1.19 SUBAREA RUNOFF(CFS) = 3.51
EFFECTIVE AREA(ACRES) = 4.26 AREA-AVERAGED Fm(INCH/HR) = 0.37 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.37 TOTAL AREA(ACRES) = 4.3 PEAK FLOW RATE(CFS) = 12.52
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.40 HALFSTREET FLOOD WIDTH(FEET) = 12.19 FLOW VELOCITY(FEET/SEC.) = 7.47 DEPTH*VELOCITY(FT*FT/SEC.) = 3.00 LONGEST FLOWPATH FROM NODE 200.00 TO NODE 206.00 = 1809.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 206.00 TO NODE 207.00 IS CODE = 62 Meyers Creek – Existing Condition 2024

---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0600
STREET LENGTH(FEET) = 668.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 19.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 14.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 14.58 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.44
HALFSTREET FLOOD WIDTH(FEET) = 14.00
AVERAGE FLOW VELOCITY(FEET/SEC.) = 6.79
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 2.97
STREET FLOW TRAVEL TIME(MIN.) = 1.64 Tc(MIN.) = 10.74
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.329
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.98 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" B 0.02 0.75 0.500 56
COMMERCIAL A 0.53 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.97
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.361
SUBAREA AREA(ACRES) = 1.54 SUBAREA RUNOFF(CFS) = 4.12
EFFECTIVE AREA(ACRES) = 5.79 AREA-AVERAGED Fm(INCH/HR) = 0.36 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.37 TOTAL AREA(ACRES) = 5.8 PEAK FLOW RATE(CFS) = 15.47
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.44 HALFSTREET FLOOD WIDTH(FEET) = 14.32 FLOW VELOCITY(FEET/SEC.) = 6.90 DEPTH*VELOCITY(FT*FT/SEC.) = 3.07 LONGEST FLOWPATH FROM NODE 200.00 TO NODE 207.00 = 2477.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 207.00 TO NODE 208.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 6 USED)<<<<<
Meyers Creek – Existing Condition 2024

============================================================================ REPRESENTATIVE SLOPE = 0.0410
STREET LENGTH(FEET) = 664.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 19.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 14.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 17.08 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.48
HALFSTREET FLOOD WIDTH(FEET) = 16.13
AVERAGE FLOW VELOCITY(FEET/SEC.) = 6.12
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 2.94
STREET FLOW TRAVEL TIME(MIN.) = 1.81 Tc(MIN.) = 12.55
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 2.994
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.79 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" B 0.04 0.75 0.500 56
COMMERCIAL A 0.41 0.98 0.100 32
COMMERCIAL B 0.10 0.75 0.100 56
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.96
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.346
SUBAREA AREA(ACRES) = 1.35 SUBAREA RUNOFF(CFS) = 3.22
EFFECTIVE AREA(ACRES) = 7.14 AREA-AVERAGED Fm(INCH/HR) = 0.36 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.37 TOTAL AREA(ACRES) = 7.1 PEAK FLOW RATE(CFS) = 16.95
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.48 HALFSTREET FLOOD WIDTH(FEET) = 16.13 FLOW VELOCITY(FEET/SEC.) = 6.07 DEPTH*VELOCITY(FT*FT/SEC.) = 2.92 LONGEST FLOWPATH FROM NODE 200.00 TO NODE 208.00 = 3141.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 208.00 TO NODE 209.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ REPRESENTATIVE SLOPE = 0.1000
Meyers Creek – Existing Condition 2024

FLOW LENGTH(FEET) = 20.00 MANNING'S N = 0.013
DEPTH OF FLOW IN 15.0 INCH PIPE IS 10.9 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 17.80
ESTIMATED PIPE DIAMETER(INCH) = 15.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 16.95
PIPE TRAVEL TIME(MIN.) = 0.02 Tc(MIN.) = 12.56
LONGEST FLOWPATH FROM NODE 200.00 TO NODE 209.00 = 3161.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 109.00 TO NODE 109.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
>>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< ============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE:

TIME OF CONCENTRATION(MIN.) = 12.56
RAINFALL INTENSITY(INCH/HR) = 2.99
AREA-AVERAGED Fm(INCH/HR) = 0.36
AREA-AVERAGED Fp(INCH/HR) = 0.97
AREA-AVERAGED Ap = 0.37
EFFECTIVE STREAM AREA(ACRES) = 7.14
TOTAL STREAM AREA(ACRES) = 7.14
PEAK FLOW RATE(CFS) AT CONFLUENCE = 16.95
** CONFLUENCE DATA **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 803.44 12.52 2.999 0.47( 0.38) 0.80 331.4 600.00
1 811.70 13.44 2.829 0.47( 0.38) 0.81 353.9 100.00
1 841.37 17.56 2.429 0.46( 0.38) 0.82 449.2 500.00
1 968.68 24.53 2.127 0.45( 0.38) 0.83 606.0 300.00
1 969.07 24.86 2.113 0.45( 0.38) 0.83 610.9 400.00
2 16.95 12.56 2.991 0.97( 0.36) 0.37 7.1 200.00

RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 820.38 12.52 2.999 0.47( 0.38) 0.80 338.5 600.00
2 820.81 12.56 2.991 0.47( 0.38) 0.80 339.7 200.00
3 827.61 13.44 2.829 0.47( 0.38) 0.80 361.1 100.00
4 854.71 17.56 2.429 0.47( 0.38) 0.81 456.3 500.00
5 980.08 24.53 2.127 0.46( 0.38) 0.83 613.2 300.00
6 980.38 24.86 2.113 0.46( 0.38) 0.83 618.1 400.00
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 980.38 Tc(MIN.) = 24.86
Meyers Creek – Existing Condition 2024

EFFECTIVE AREA(ACRES) = 618.08 AREA-AVERAGED Fm(INCH/HR) = 0.38 AREA-AVERAGED Fp(INCH/HR) = 0.46 AREA-AVERAGED Ap = 0.83 TOTAL AREA(ACRES) = 618.1
LONGEST FLOWPATH FROM NODE 400.00 TO NODE 109.00 = 4023.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 109.00 TO NODE 110.00 IS CODE = 56 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 100.00 DOWNSTREAM(FEET) = 100.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 60.00 CHANNEL SLOPE = 0.0000 GIVEN CHANNEL BASE(FEET) = 12.00 CHANNEL FREEBOARD(FEET) = 1.0 "Z" FACTOR = 2.000 MANNING'S FACTOR = 0.030
*ESTIMATED CHANNEL HEIGHT(FEET) = 7.77
CHANNEL FLOW THRU SUBAREA(CFS) = 980.38
FLOW VELOCITY(FEET/SEC.) = 5.67 FLOW DEPTH(FEET) = 6.77 TRAVEL TIME(MIN.) = 0.18 Tc(MIN.) = 25.04
LONGEST FLOWPATH FROM NODE 400.00 TO NODE 110.00 = 4083.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 110.00 TO NODE 110.00 IS CODE = 10 ---------------------------------------------------------------------------- >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 2 <<<<< ============================================================================ **************************************************************************** FLOW PROCESS FROM NODE 700.00 TO NODE 701.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
>>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< ============================================================================ INITIAL SUBAREA FLOW-LENGTH(FEET) = 990.00
ELEVATION DATA: UPSTREAM(FEET) = 2001.00 DOWNSTREAM(FEET) = 1888.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20
SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 7.407
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.945
SUBAREA Tc AND LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS Tc
LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN (MIN.)

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 1.43 0.98 0.500 32 9.48

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 0.35 0.57 0.500 69 9.48
COMMERCIAL A 0.16 0.98 0.100 32 7.41
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.90
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.467
SUBAREA RUNOFF(CFS) = 6.15
Meyers Creek – Existing Condition 2024

TOTAL AREA(ACRES) = 1.94 PEAK FLOW RATE(CFS) = 6.15
**************************************************************************** FLOW PROCESS FROM NODE 701.00 TO NODE 702.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1888.00 DOWNSTREAM(FEET) = 1872.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 208.00 CHANNEL SLOPE = 0.0769 CHANNEL FLOW THRU SUBAREA(CFS) = 6.15
FLOW VELOCITY(FEET/SEC) = 6.15 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.56 Tc(MIN.) = 7.97
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 702.00 = 1198.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 702.00 TO NODE 702.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 7.97
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.840
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.62 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 1.17 0.57 0.500 69
COMMERCIAL A 0.04 0.98 0.100 32
COMMERCIAL C 0.08 0.57 0.100 69
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.71
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.475
SUBAREA AREA(ACRES) = 1.91 SUBAREA RUNOFF(CFS) = 6.03
EFFECTIVE AREA(ACRES) = 3.85 AREA-AVERAGED Fm(INCH/HR) = 0.38 AREA-AVERAGED Fp(INCH/HR) = 0.80 AREA-AVERAGED Ap = 0.47 TOTAL AREA(ACRES) = 3.9 PEAK FLOW RATE(CFS) = 12.00
**************************************************************************** FLOW PROCESS FROM NODE 702.00 TO NODE 703.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1872.00 DOWNSTREAM(FEET) = 1860.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 320.00 CHANNEL SLOPE = 0.0375 CHANNEL FLOW THRU SUBAREA(CFS) = 12.00
FLOW VELOCITY(FEET/SEC) = 5.07 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 1.05 Tc(MIN.) = 9.02
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 703.00 = 1518.00 FEET.

Meyers Creek – Existing Condition 2024

**************************************************************************** FLOW PROCESS FROM NODE 703.00 TO NODE 703.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 9.02
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.646
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 2.62 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" C 0.71 0.57 0.500 69
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.89
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.500
SUBAREA AREA(ACRES) = 3.33 SUBAREA RUNOFF(CFS) = 9.60
EFFECTIVE AREA(ACRES) = 7.18 AREA-AVERAGED Fm(INCH/HR) = 0.41 AREA-AVERAGED Fp(INCH/HR) = 0.84 AREA-AVERAGED Ap = 0.48 TOTAL AREA(ACRES) = 7.2 PEAK FLOW RATE(CFS) = 20.93
**************************************************************************** FLOW PROCESS FROM NODE 703.00 TO NODE 704.00 IS CODE = 52 ---------------------------------------------------------------------------- >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 1860.00 DOWNSTREAM(FEET) = 1858.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 134.00 CHANNEL SLOPE = 0.0149 CHANNEL FLOW THRU SUBAREA(CFS) = 20.93
FLOW VELOCITY(FEET/SEC) = 3.71 (PER LACFCD/RCFC&WCD HYDROLOGY MANUAL) TRAVEL TIME(MIN.) = 0.60 Tc(MIN.) = 9.63
LONGEST FLOWPATH FROM NODE 700.00 TO NODE 704.00 = 1652.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 704.00 TO NODE 704.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ MAINLINE Tc(MIN.) = 9.63
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.534
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 1.81 0.98 0.500 32

RESIDENTIAL
"5-7 DWELLINGS/ACRE" B 0.11 0.75 0.500 56
COMMERCIAL A 0.64 0.98 0.100 32
Meyers Creek – Existing Condition 2024

COMMERCIAL B 0.15 0.75 0.100 56
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.96
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.384
SUBAREA AREA(ACRES) = 2.71 SUBAREA RUNOFF(CFS) = 7.72
EFFECTIVE AREA(ACRES) = 9.89 AREA-AVERAGED Fm(INCH/HR) = 0.40 AREA-AVERAGED Fp(INCH/HR) = 0.87 AREA-AVERAGED Ap = 0.46 TOTAL AREA(ACRES) = 9.9 PEAK FLOW RATE(CFS) = 27.93
**************************************************************************** FLOW PROCESS FROM NODE 704.00 TO NODE 704.00 IS CODE = 10 ---------------------------------------------------------------------------- >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 3 <<<<< ============================================================================ **************************************************************************** FLOW PROCESS FROM NODE 1100.00 TO NODE 1101.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
>>USE TIME-OF-CONCENTRATION NOMOGRAPH FOR INITIAL SUBAREA<< ============================================================================ INITIAL SUBAREA FLOW-LENGTH(FEET) = 270.00
ELEVATION DATA: UPSTREAM(FEET) = 1873.00 DOWNSTREAM(FEET) = 1866.00 Tc = K*[(LENGTH** 3.00)/(ELEVATION CHANGE)]**0.20
SUBAREA ANALYSIS USED MINIMUM Tc(MIN.) = 5.925
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 4.219
SUBAREA Tc AND LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS Tc
LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN (MIN.)
COMMERCIAL A 0.16 0.98 0.100 32 5.92
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.97
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.100
SUBAREA RUNOFF(CFS) = 0.58
TOTAL AREA(ACRES) = 0.16 PEAK FLOW RATE(CFS) = 0.58
**************************************************************************** FLOW PROCESS FROM NODE 1101.00 TO NODE 1102.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 2 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0110
STREET LENGTH(FEET) = 269.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 18.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 13.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
Meyers Creek – Existing Condition 2024

STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.86 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.24
HALFSTREET FLOOD WIDTH(FEET) = 5.89
AVERAGE FLOW VELOCITY(FEET/SEC.) = 1.86
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.45
STREET FLOW TRAVEL TIME(MIN.) = 2.42 Tc(MIN.) = 8.34
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.772
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN

RESIDENTIAL
"5-7 DWELLINGS/ACRE" A 0.01 0.98 0.500 32
SCHOOL A 0.01 0.98 0.600 32
COMMERCIAL A 0.15 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.97
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.152
SUBAREA AREA(ACRES) = 0.17 SUBAREA RUNOFF(CFS) = 0.56
EFFECTIVE AREA(ACRES) = 0.33 AREA-AVERAGED Fm(INCH/HR) = 0.12 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.13 TOTAL AREA(ACRES) = 0.3 PEAK FLOW RATE(CFS) = 1.08
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.26 HALFSTREET FLOOD WIDTH(FEET) = 6.65
FLOW VELOCITY(FEET/SEC.) = 1.93 DEPTH*VELOCITY(FT*FT/SEC.) = 0.50 LONGEST FLOWPATH FROM NODE 1100.00 TO NODE 1102.00 = 539.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 1102.00 TO NODE 1103.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 2 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0100
STREET LENGTH(FEET) = 207.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 18.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 13.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 Meyers Creek – Existing Condition 2024

**TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 1.30 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.27
HALFSTREET FLOOD WIDTH(FEET) = 7.41
AVERAGE FLOW VELOCITY(FEET/SEC.) = 1.95
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.53
STREET FLOW TRAVEL TIME(MIN.) = 1.77 Tc(MIN.) = 10.11
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.444
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN
SCHOOL A 0.03 0.98 0.600 32
COMMERCIAL A 0.12 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.213
SUBAREA AREA(ACRES) = 0.15 SUBAREA RUNOFF(CFS) = 0.44
EFFECTIVE AREA(ACRES) = 0.48 AREA-AVERAGED Fm(INCH/HR) = 0.15 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.15 TOTAL AREA(ACRES) = 0.5 PEAK FLOW RATE(CFS) = 1.42
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.28 HALFSTREET FLOOD WIDTH(FEET) = 7.77
FLOW VELOCITY(FEET/SEC.) = 1.97 DEPTH*VELOCITY(FT*FT/SEC.) = 0.55 LONGEST FLOWPATH FROM NODE 1100.00 TO NODE 1103.00 = 746.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 1103.00 TO NODE 1104.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 2 USED)<<<<<
============================================================================ REPRESENTATIVE SLOPE = 0.0120
STREET LENGTH(FEET) = 173.00 CURB HEIGHT(INCHES) = 6.0
STREET HALFWIDTH(FEET) = 18.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 13.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.050
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0150 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 1.61 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.28
HALFSTREET FLOOD WIDTH(FEET) = 7.87
AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.18
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.62
Meyers Creek – Existing Condition 2024

STREET FLOW TRAVEL TIME(MIN.) = 1.32 Tc(MIN.) = 11.44
* 10 YEAR RAINFALL INTENSITY(INCH/HR) = 3.199
SUBAREA LOSS RATE DATA(AMC II):

DEVELOPMENT TYPE/ SCS SOIL AREA Fp Ap SCS

LAND USE GROUP (ACRES) (INCH/HR) (DECIMAL) CN
COMMERCIAL A 0.13 0.98 0.100 32
SUBAREA AVERAGE PERVIOUS LOSS RATE, Fp(INCH/HR) = 0.98
SUBAREA AVERAGE PERVIOUS AREA FRACTION, Ap = 0.100
SUBAREA AREA(ACRES) = 0.13 SUBAREA RUNOFF(CFS) = 0.37
EFFECTIVE AREA(ACRES) = 0.61 AREA-AVERAGED Fm(INCH/HR) = 0.14 AREA-AVERAGED Fp(INCH/HR) = 0.97 AREA-AVERAGED Ap = 0.14 TOTAL AREA(ACRES) = 0.6 PEAK FLOW RATE(CFS) = 1.69
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.29 HALFSTREET FLOOD WIDTH(FEET) = 8.02
FLOW VELOCITY(FEET/SEC.) = 2.21 DEPTH*VELOCITY(FT*FT/SEC.) = 0.63 LONGEST FLOWPATH FROM NODE 1100.00 TO NODE 1104.00 = 919.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 1104.00 TO NODE 1105.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ REPRESENTATIVE SLOPE = 0.0440
FLOW LENGTH(FEET) = 40.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 12.000
DEPTH OF FLOW IN 12.0 INCH PIPE IS 4.0 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 7.41
ESTIMATED PIPE DIAMETER(INCH) = 12.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1.69
PIPE TRAVEL TIME(MIN.) = 0.09 Tc(MIN.) = 11.53
LONGEST FLOWPATH FROM NODE 1100.00 TO NODE 1105.00 = 959.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 1105.00 TO NODE 1105.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:

TIME OF CONCENTRATION(MIN.) = 11.53
RAINFALL INTENSITY(INCH/HR) = 3.18
AREA-AVERAGED Fm(INCH/HR) = 0.14
AREA-AVERAGED Fp(INCH/HR) = 0.97
AREA-AVERAGED Ap = 0.14
EFFECTIVE STREAM AREA(ACRES) = 0.61
TOTAL STREAM AREA(ACRES) = 0.61
PEAK FLOW RATE(CFS) AT CONFLUENCE = 1.69
Meyers Creek – Existing Condition 2024

**************************************************************************** FLOW PROCESS FROM NODE 1105.00 TO NODE 1105.00 IS CODE = 7 ---------------------------------------------------------------------------- >>>>>USER SPECIFIED HYDROLOGY INFORMATION AT NODE<<<<<
============================================================================ USER-SPECIFIED VALUES ARE AS FOLLOWS:

TC(MIN.) = 14.55 RAINFALL INTENSITY(INCH/HR) = 2.62
EFFECTIVE AREA(ACRES) = 134.79
TOTAL AREA(ACRES) = 134.79 PEAK FLOW RATE(CFS) = 304.97 AREA-AVERAGED Fm(INCH/HR) = 0.26 AREA-AVERAGED Fp(INCH/HR) = 0.28 AREA-AVERAGED Ap = 0.92
NOTE: EFFECTIVE AREA IS USED AS THE TOTAL CONTRIBUTING AREA FOR ALL CONFLUENCE ANALYSES.
**************************************************************************** FLOW PROCESS FROM NODE 1105.00 TO NODE 1105.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
>>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< ============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE:

TIME OF CONCENTRATION(MIN.) = 14.55
RAINFALL INTENSITY(INCH/HR) = 2.62
AREA-AVERAGED Fm(INCH/HR) = 0.26
AREA-AVERAGED Fp(INCH/HR) = 0.28
AREA-AVERAGED Ap = 0.92
EFFECTIVE STREAM AREA(ACRES) = 134.79
TOTAL STREAM AREA(ACRES) = 134.79
PEAK FLOW RATE(CFS) AT CONFLUENCE = 304.97
** CONFLUENCE DATA **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 1.69 11.53 3.182 0.97( 0.14) 0.14 0.6 1100.00
2 304.97 14.55 2.623 0.28( 0.26) 0.92 134.8 1105.00

RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM Q Tc Intensity Fp(Fm) Ap Ae HEADWATER
NUMBER (CFS) (MIN.) (INCH/HR) (INCH/HR) (ACRES) NODE
1 300.41 11.53 3.182 0.28( 0.26) 0.92 107.4 1100.00
2 306.35 14.55 2.623 0.28( 0.26) 0.92 135.4 1105.00
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 306.35 Tc(MIN.) = 14.55
EFFECTIVE AREA(ACRES) = 135.40 AREA-AVERAGED Fm(INCH/HR) = 0.26 AREA-AVERAGED Fp(INCH/HR) = 0.28 AREA-AVERAGED Ap = 0.92 Meyers Creek – Existing Condition 2024