Drainage Overview - Maricopa County Department of Transportation
Drainage Overview - Maricopa County Department of Transportation Drainage Overview - Maricopa County Department of Transportation
channel slopes at the base of the White Tank Mountains can result in high flow velocities with the energy to move significant volumes of sediment and debris during floods. The SVADMP analyzed several alternatives for mitigating the flood hazards of the alluvial fans including structural and non-structural strategies. The result of the alternatives evaluation process was to recommend large in-line detention basins at the apex of each alluvial fan together with downstream corridors protected by levees. The detention basins were designed to outlet 10 percent of the 100-year inflow volume from each alluvial fan. The corridors were designed to act as regional flood control trunk systems and were sized to include local drainage as well as sediment from adjacent watershed areas. Numerous drop structures would be constructed as part of the wash corridors. A conceptual cross-section of the leveed corridor and the location of the recommended flood control improvements are included in Appendix TM3-07. The Deer Valley Parkway alignment will almost certainly cross the proposed leveed drainage corridor associated with alluvial fan #2. Similar to typical wash crossings, the final design of this crossing will need to accommodate the hydraulic design and sediment load anticipated within the corridor, including the effect of contraction and expansion of flows at the structure. 3.4.4 Scour and Sedimentation Transport and distribution of sediment within the study area are significantly impacted by the CAP canal according to the Wittmann Area Drainage Master Study Update (ADMSU) Geomorphic and Sedimentation Analysis Report (FCDMC, 2005). The CAP canal is located upstream of the eastern portion of the study area and traverses the western portion of the study area. Concrete drainage over-chutes convey storm runoff and sediment across the canal upstream of and within the study area. Typically, sediment is deposited upstream of the over-chutes and scour occurs downstream of the over-chutes. According to the Wittmann ADMSU Sedimentation Report, all of the areas upstream of the CAP canal within the 100-year floodplain should be considered to be depositional hazard areas. The report also identified several sedimentation problems that are common with roadways, including the following: � Undersized bridges or culverts can cause significant deposition to occur upstream of the roadway and erosion to occur downstream of the roadway; � Gathering numerous washes into a single wash to reduce bridge construction costs can disrupt existing drainage patterns and have significant impacts downstream; and � Trapping of debris can have a major impact on the ability of culverts and bridges to adequately convey runoff and sediment. Alluvial fans are built up from sediment that drops out of flood waters when flows start to spread out at the base of mountains. Therefore, excessive sedimentation can be expected in active alluvial fan areas. 3.4.5 Lateral Erosion Bank erosion from flood events is another critical concern for potential Deer Valley Parkway infrastructure. Most of the soils in the study area are composed of sands and noncohesive materials that water can easily erode. Avulsions can readily occur where some 091337137, 2011-018, TT005 Maricopa County Department of Transportation Technical Memorandum 3 Deer Valley Parkway Feasibility Study Drainage Overview 15 April 2012
change in the terrain, manmade or natural, causes water to abandon a previously established channel in favor of a new drainage path. An example of an existing avulsion within the study area is shown in Figures GR-96 and GR-97 in Appendix TM3-08, taken from the Wittmann ADMSU Geomorphic and Sedimentation Analysis Report (FCDMC, 2005). The historic flowpath of 5 West Wash has been redirected by the power line access road. Avulsions like this could lead to downstream developed areas or infrastructure receiving unexpected increases in flood flows. Deer Valley Parkway should minimize changes to existing flow paths as much as possible and provide adequate structural protection of the roadway at all wash crossing locations. Erosion hazard zones were delineated for Trilby Wash, Iona Wash, Iona Wash (West Split), and 1 West Wash as part of the Wittmann ADMSU Geomorphic and Sedimentation Analysis Report. The erosion hazard delineations are included in Appendix TM3-08. The portions of Trilby Wash, Iona Wash, and Iona (West Split) Wash from Pinnacle Peak Road to the confluence near the Beardsley Road alignment were identified to have particularly high erosion hazard potential. The 1 West Wash has an area of high erosion hazard potential from Pinnacle Peak Road to McMicken Dam. Wherever possible, care must be taken to locate foundations and structures outside of the erosion hazard zones that have been delineated for Trilby Wash, Iona Wash, Iona Wash (West Split) and 1 West Wash. These drainage systems are highly dynamic and have a history of rapidly changing channels. 3.5 Potentially Impacted Existing Drainage Structures 3.5.1 CAP Canal The CAP canal is located upstream of the eastern end of the study area and crosses through the western end of the study area. The location of the CAP canal is shown in Figure 5. Many of the contributing watershed hydrographs are modified by the CAP canal due to significant storage along the upstream dikes protecting the canal. Drainage runoff crosses the canal at select locations via culverts, over-chutes, or siphons. There are four culverts crossing the CAP canal east of US 60 CAP canal near 243 that convey flow to washes that cross US 60 and drain through the study area. Four concrete over-chutes west of US 60 are located upstream of the study area. One additional concrete over-chute conveys 5 West Wash across the CAP canal within the Deer Valley Parkway study area. The Deer Valley Parkway alignment may need to cross the CAP canal at the western end of the study area. If that is the case, it is recommended that the parkway be located far enough north such that the impacts to the floodplain upstream of the canal are minimized. If the Deer Valley Parkway alignment is located immediately downstream of the CAP canal, additional scour protection may need to be considered. rd Avenue alignment 091337137, 2011-018, TT005 Maricopa County Department of Transportation Technical Memorandum 3 Deer Valley Parkway Feasibility Study Drainage Overview 16 April 2012
- Page 2 and 3: TABLE OF CONTENTS DRAINAGE OVERVIEW
- Page 4 and 5: 1. INTRODUCTION The Deer Valley Par
- Page 6 and 7: Figure 1 - Study Area 091337137, 20
- Page 8 and 9: Figure 2 - Area Drainage Studies 09
- Page 10 and 11: the portion of the study area withi
- Page 12 and 13: Figure 3 - Topography 091337137, 20
- Page 14 and 15: Two areas fall within Hydrologic So
- Page 16 and 17: Figure 5 - Regulatory Floodplains 0
- Page 20 and 21: 3.5.2 Sun Valley Parkway The Draina
- Page 22 and 23: 4. EXISTING HYDROLOGY Various hydro
- Page 24 and 25: Figure 6 - Offsite Hydrology Workma
- Page 26 and 27: (PMF) events were also calculated f
- Page 28 and 29: 5. SUMMARY AND CONCLUSIONS The purp
- Page 30 and 31: APPENDIX TM3-01 DATA COLLECTION SUM
- Page 32 and 33: AZGS = Arizona Geological Survey AD
- Page 34 and 35: AZGS = Arizona Geological Survey AD
- Page 36 and 37: Deer Valley �������
- Page 38 and 39: Deer Valley �������
- Page 40 and 41: Deer Valley �������
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- Page 60 and 61: APPENDIX TM3-04 SUBSIDENCE DOCUMENT
- Page 62 and 63: 03/08/2004 To 09/13/2010 Subsidence
- Page 64 and 65: Dixileta Dr Patton Rd Jomax Rd Happ
- Page 66 and 67: Photo 903: Bridge over 1 West Wash
change in the terrain, manmade or natural, causes water to abandon a previously established<br />
channel in favor <strong>of</strong> a new drainage path. An example <strong>of</strong> an existing avulsion within the<br />
study area is shown in Figures GR-96 and GR-97 in Appendix TM3-08, taken from the<br />
Wittmann ADMSU Geomorphic and Sedimentation Analysis Report (FCDMC, 2005). The<br />
historic flowpath <strong>of</strong> 5 West Wash has been redirected by the power line access road.<br />
Avulsions like this could lead to downstream developed areas or infrastructure receiving<br />
unexpected increases in flood flows. Deer Valley Parkway should minimize changes to<br />
existing flow paths as much as possible and provide adequate structural protection <strong>of</strong> the<br />
roadway at all wash crossing locations.<br />
Erosion hazard zones were delineated for Trilby Wash, Iona Wash, Iona Wash (West Split),<br />
and 1 West Wash as part <strong>of</strong> the Wittmann ADMSU Geomorphic and Sedimentation Analysis<br />
Report. The erosion hazard delineations are included in Appendix TM3-08. The portions<br />
<strong>of</strong> Trilby Wash, Iona Wash, and Iona (West Split) Wash from Pinnacle Peak Road to the<br />
confluence near the Beardsley Road alignment were identified to have particularly high<br />
erosion hazard potential. The 1 West Wash has an area <strong>of</strong> high erosion hazard potential<br />
from Pinnacle Peak Road to McMicken Dam.<br />
Wherever possible, care must be taken to locate foundations and structures outside <strong>of</strong> the<br />
erosion hazard zones that have been delineated for Trilby Wash, Iona Wash, Iona Wash<br />
(West Split) and 1 West Wash. These drainage systems are highly dynamic and have a<br />
history <strong>of</strong> rapidly changing channels.<br />
3.5 Potentially Impacted Existing <strong>Drainage</strong> Structures<br />
3.5.1 CAP Canal<br />
The CAP canal is located upstream <strong>of</strong><br />
the eastern end <strong>of</strong> the study area and<br />
crosses through the western end <strong>of</strong> the<br />
study area. The location <strong>of</strong> the CAP<br />
canal is shown in Figure 5. Many <strong>of</strong><br />
the contributing watershed hydrographs<br />
are modified by the CAP canal due to<br />
significant storage along the upstream<br />
dikes protecting the canal. <strong>Drainage</strong><br />
run<strong>of</strong>f crosses the canal at select<br />
locations via culverts, over-chutes, or<br />
siphons. There are four culverts<br />
crossing the CAP canal east <strong>of</strong> US 60<br />
CAP canal near 243<br />
that convey flow to washes that cross<br />
US 60 and drain through the study area. Four concrete over-chutes west <strong>of</strong> US 60 are<br />
located upstream <strong>of</strong> the study area. One additional concrete over-chute conveys 5 West<br />
Wash across the CAP canal within the Deer Valley Parkway study area. The Deer Valley<br />
Parkway alignment may need to cross the CAP canal at the western end <strong>of</strong> the study area.<br />
If that is the case, it is recommended that the parkway be located far enough north such that<br />
the impacts to the floodplain upstream <strong>of</strong> the canal are minimized. If the Deer Valley<br />
Parkway alignment is located immediately downstream <strong>of</strong> the CAP canal, additional scour<br />
protection may need to be considered.<br />
rd Avenue alignment<br />
091337137, 2011-018, TT005 <strong>Maricopa</strong> <strong>County</strong> <strong>Department</strong> <strong>of</strong> <strong>Transportation</strong><br />
Technical Memorandum 3 Deer Valley Parkway Feasibility Study<br />
<strong>Drainage</strong> <strong>Overview</strong> 16 April 2012
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