july-august 2007 - maricopa county,...

Study PurposeThe Flood Control District of Maricopa County (District), in association with the City of Phoenix (City), is conducting the Metro Phoenix Area Drainage Master Plan (Metro ADMP). The Metro ADMP is intended to quantify the extent of drainage and fl ooding problems within the study area and to develop proposed drainage plans to reduce fl ooding hazards. The City and the District will use these conceptual drainage plans to identify, defi ne, and budget future drainage improvement projects.

Purpose of the Public MeetingsThe purpose of this series of public meetings is twofold. The Metro ADMP study team will present the latest study developments, provide information on the alternative drainage measures, and solicit your comments regarding the proposed alternatives.

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PHOENIX

PARADISEVALLEY

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TEMPE

Cactus Road

Lower Buckeye Road

Bethany Home Road

Peoria Avenue

Thunderbird Road

Glendale Avenue

Dunlap Avenue

Northern Avenue

Buckeye Road

Indian School Road

Van Buren Street

Camelback Road

Broadway Road

Southern Avenue

McDowell Road

Thomas Road

27th

Aven

ue

32nd

Str

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24th

Str

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40th

Str

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7thS

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48th

Str

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16th

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7thAv

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35th

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19th

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Greenway Road

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Study areaExisting floodplain areas

Supervisor Mary Rose Wilcox, District 5; Supervisor Andy Kunasek, District 3; Supervisor Don Stapley, District 2

www.fcd.maricopa.gov

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JULY-AUGUST 2007

Project Area

Secondly, information on the preliminary re-delineation of the boundary for the Cave Creek fl oodplain will be provided. This re-delineation will be submitted to the Federal Emergency Management Agency (FEMA), and if approved, the revised boundary may result in a number of properties being removed from the existing fl oodplain.

Study Area The Metro ADMP study area is located mainly within the City of Phoenix; however, it includes small portions of the Cities of Scottsdale and Tempe along its eastern boundary. The study area is approximately 90 square miles and specifi cally covers the older developed part of Phoenix that is located south of the Arizona Canal and north of the Salt River, between Interstate 17 (I-17) and the Papago Buttes.

Study ProgressSince the August 2006 public meeting, the Metro ADMP study team has completed the following tasks:

Developed a rainfall-runoff computer model of existing hydrologic conditionsReviewed the Cave Creek fl oodplain between Grand Canal and the Salt River Assessed environmental issuesEvaluated multi-use opportunities within the study areaFormulated and analyzed potential drainage alternativesCoordinated the involvement of local agencies and groups

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Flood-Prone Areas The Metro ADMP study team has identifi ed several fl ood-prone areas. These areas were identifi ed by analyzing the existing hydrologic conditions within the study area, reviewing citizen input from previous public meetings, and investigating drainage complaints fi led with the City.

Cave Creek Floodplain – This area incorporates the Cave Creek fl oodplain and its adjacent areas. Due to the topography of the area, runoff from large storms can exceed the capacity of the storm drain system and fl ood low-lying areas.

Old Cave Creek Floodplain – The area downstream of the Arizona Canal was part of the Cave Creek fl oodplain before the U.S. Army Corps of Engineers constructed the Arizona Canal Diversion Channel (ACDC) to divert fl oodwaters. This area exhibits much of the same shallow fl ooding problems associated with the Cave Creek fl oodplain area.

Grand Canal – During large storms, when the storm drain system capacity is exceeded, runoff builds up on the north side of the elevated banks of the Grand Canal and fl oods adjacent residential and commercial properties.

Downtown – The downtown area is subject to substantial fl ood fl ows, as evidenced by the August 2005 fl ood that seriously disrupted the downtown area. Flooding problems in this area are largely due to the lack of open, undeveloped land that can absorb water.

Durango Curve (I-17 at Durango Street) – Most of the study area drains into this location upstream of the Durango curve. If the capacity of the storm drain system in this area is exceeded, ponding of stormwater behind the elevated I-17 roadway results in fl ooding of a number of homes and businesses.

Arcadia/Old Crosscut Canal Watershed – The Arcadia area is subject to fl ooding from Camelback Mountain runoff. In addition, several properties located in the Old Crosscut Canal Watershed downstream of the Arizona Country Club have a history of fl ooding.

Airport North – Substantial fl oodwater accumulation occurs along the north side of Sky Harbor Airport. Similar to the Cave Creek fl oodplain, this area is characterized by wide, shallow fl ooding that extends westward toward I-10. Once the capacity of the storm drain system is exceeded, runoff accumulates and results in a fl ooding hazard for low-lying properties.

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Greenway Road

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19th

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35th

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7thA

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16th

Stre

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Thomas Road

McDowell Road

Southern Avenue

Broadway Road

Camelback Road

Van Buren Street

Indian School Road

Buckeye Road

Northern Avenue

Dunlap Avenue

Glendale Avenue

Thunderbird Road

48th

Stre

et

Peoria Avenue

Bethany Home Road

Lower Buckeye Road

Cactus Road

7thSt

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40th

Stre

et

24th

Stre

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32nd

Stre

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27th

Ave

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KeyStudy areaCave CreekOld Cave CreekGrand CanalDowntownDurango CurveArcadiaAirport NorthExisting floodplain areas

Map of Flood Prone Areas

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Palo VerdeGolf Course

EncantoGolf Course

Existingstorm drain

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7thA

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16tth

Stre

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19th

Ave

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27th

Ave

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Thomas Road

Buckeye Road

Van Buren Street

Northern Avenue

McDowell Road

Glendale Avenue

Dunlap Avenue

Camelback Road

Indian School Road

Bethany Home Road

KeyFlood-prone areaADOT drainage tunnelProposed storm drainProposed floodwater storage100-year floodplain

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OLD CAVE CREEK FLOODPLAIN ALTERNATIVES

Storm Drain Alternative

Provide a 10-year level of protection by increasing the capacity of the storm drain system from the existing 2-year design Construct new storm drains in 21st, 15th, 3rd,and Central AvenuesEstimated cost: $76 million

Storm Drain Alternative with Floodwater Storage at Palo Verde Golf Course

Provide a 10-year level of protection by increasing the capacity of the storm drain system from the existing 2-year design Construct new storm drains in 21st, 15th, 3rd, and Central AvenuesReconstruct Palo Verde Golf Course to provide fl oodwater storage and enhance the playability of the courseDrain golf course storage into the existing 15th Avenue storm drainEstimated cost: $82 million

Floodproofi ng Alternative

Elevate residences or provide protective berms around properties Estimated cost depends on the number of requests for assistance

No Action Alternative

No improvementsEstimated cost: none

CAVE CREEK FLOODPLAIN ALTERNATIVES


Storm drain improvements alone are not feasible for this area given constraints

Storm Drain Alternative with Floodwater Storage at Encanto Golf Course

Provide a 10-year level of protection by increasing the capacity of the storm drain system from the existing 2-year design Construct new storm drains in 18th, 15th,and 3rd AvenuesReconstruct Encanto Golf Course to provide fl oodwater storage and enhance the playability of the courseDrain golf course storage into the I-10 drainage systemEstimated cost: $79 million





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Cave Creek and Old Cave Creek Flood Prone Areas

GRAND CANAL ALTERNATIVES

Floodplain Property Acquisition Alternative

Acquire residences within the boundaries of the Grand Canal fl oodplainRemove residences and resell lots Require property owners of resold lots to elevate the lowest fl oor elevation above the canal bankEstimated cost: $79 million

Storage Basins/Parks Alternative

Acquire residences within the boundaries of the Grand Canal fl oodplainConstruct storage basins that would be developed into small parks/open spaces, creating a linear park system along the canalDrain storage basins into existing storm drain systemEstimated cost: $168 million





ARCADIA/OLD CROSSCUT CANAL WATERSHED ALTERNATIVES

New Storm Drain System – Camelback Road Alternative Provide a 10-year level of protection for the Arcadia/Old Crosscut Canal watershedConstruct new 10-year storm drains in Arcadia Drive; Lafayette Boulevard; and Camelback, Invergordon, and Thomas RoadsEstimated cost: $25 million

New Storm Drain System – Lafayette Interceptor Alternative Provide a 10-year level of protection for the Arcadia/Old Crosscut Canal watershedConstruct new 10-year storm drains in 56th Street, Arcadia Drive, Lafayette Boulevard, and Osborn and Thomas Roads, and a new 2-year storm drain in Camelback RoadEstimated cost: $26 million

Floodproofi ng AlternativeElevate residences or provide protective berms around properties Estimated cost depends on the number of requests for assistance



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Camelback Road

Gran d C anal

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16th

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19th

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Thomas Road

McDowell Road

Indian School Road

Bethany Home Road

KeyFlood-prone areaProposed basin100-year floodplain

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McDowell Road

Thomas Road

Indian School Road

Camelback Road

Lincoln Drive

64th

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56th

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ArizonaCanal

Old

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Arizona CanalDiversion Channel

KeyFlood-prone areaProposed storm drain100-year floodplain


Grand Canal Flood Prone Area

Arcadia/Old Crosscut Canal Flood Prone Area

DOWNTOWN ALTERNATIVES

Storm Drain Alternative North of Railroad

Provide a 10-year level of protection by increasing the capacity of the storm drain system from the existing 2-year design Use excess capacity of existing storm drains in 19th, 15th, and 11th Avenues and 7th, 12th, and 16th StreetsConstruct new storm drains in 3rd and 9th Avenues and Fillmore Street that drain runoff into the Arizona Department of Transportation’s (ADOT) existing drainage facility Estimated cost: $31 million

Storm Drain Alternative South of Railroad

Provide a 10-year level of protection by increasing the capacity of the storm drain system’s from the existing 2-year design Use excess capacity of existing storm drains in 15th, 11th, and 7th AvenuesConstruct new storm drains in 7th Avenue and 7th Street that drain runoff into the Salt RiverConstruct new storm drain in 3rd Avenue that drains runoff into ADOT’s existing drainage facility Estimated cost: $18 million


Not considered in this area



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Van Buren Street

Sky Harbor International Airport

Existingstorm drain

7thS

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Van Buren St

16th

Stre

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McDowell Road

7thA

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19th

Ave

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Buckeye Road

27th

Ave

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SR-202

24th

St

32nd

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Lower Buckeye Road

SR-202 Westbound

24th

Stre

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KeyFlood-prone areaProposed storm drainProposed floodwater storageADOT drainage tunnel100-year floodplain


DURANGO CURVE ALTERNATIVES

100-Year Collection System Alternative

Provide a 100-year level of protection for the Durango Curve areaConstruct a system of new large-diameter storm drains to collect fl oodwaters upstream of the Durango Curve Construct a new outlet double-barrel box culvert from the Durango Curve to the Salt RiverEstimated cost: $103 million

100-Year Collection System Alternative with Floodwater Storage at Durango Curve

Provide a 100-year level of protection for the Durango Curve areaConstruct a system of new large-diameter storm drains to collect fl oodwaters and drain them into a new multi-use fl oodwater storage basin at the Durango CurveConstruct a new 102-inch pipe to drain the storage basin into the Salt RiverEstimated cost: $77 million

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Downtown and “Durango Curve” Flood Prone Areas

100-Year Collection System Alternative with Floodwater Storage at Durango Curve and at the Union Pacifi c Railroad

Provide a 100-year level of protection for the Durango Curve areaConstruct a system of new large-diameter storm drains to collect fl oodwaters and drain them into two new multi-use fl oodwater storage basins: one at the Durango Curve and the other along the north side of the Union Pacifi c RailroadConstruct a new 102-inch pipe to drain the storage basins into the Salt RiverEstimated cost: $100 million





AIRPORT NORTH ALTERNATIVES


Provide a 10-year level of protection by increasing the capacity of the storm drain system from the existing 2-year design Construct new storm drain in Van Buren Street that drains runoff into ADOT’s existing drainage facility Intercept fl ows from the existing storm drains in 24th, 32nd, and 40th StreetsAllow the Aviation Department to utilize the residual capacity of these three existing storm drains to provide much needed storm drain capacity for the airportEstimated cost: $24 million


Not considered in this areaNo Action Alternative


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McDowell Road

Van Buren Street

Union Pacific Railroad

24th

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32nd

Stre

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40th

Stre

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Sky Harbor International Airport

KeyFlood-prone areaADOT drainage tunnelProposed storm drain100-year floodplain


Airport North Flood Prone Areas

Revision of Cave Creek Floodplain- Grand Canal to I-10 The Cave Creek fl oodplain review indicates that the average depth of fl oodwaters within the fl oodplain may not warrant a fl oodplain designation. In the area upstream of McDowell Road, fl oodwaters fl ow over a very wide area, spreading out between 19th Avenue and 7th Street. This wide, shallow fl ooding does not meet the criteria for a fl oodplain designation, which usually involves larger-scale, deeper fl ooding. The District’s study results indicate that the fl oodplain designation can be removed for the area between the Grand Canal and McDowell Road if the designation change is fi rst approved by FEMA. The overall fl ood risk for the area would not change without fl ood control measures being constructed regardless of whether or not the fl oodplain designation is removed. The drainage alternatives presented earlier in this handout are designed to reduce or alleviate the remaining fl ooding potential within the study area.

Next StepsThe Metro ADMP study team will complete the alternatives analysis, which will include descriptions, cost estimates, opportunities, and constraints of each alternative. Next, the District will schedule a workshop with the Metro ADMP study team to choose the recommended alternatives, incorporating comments received from the public meetings.

Once the recommended alternatives have been chosen, the Metro ADMP study team will further develop the recommended plan. These efforts will include preliminary engineering drawings of the elements of the plan, refi ned cost estimates for plan implementation, and graphic simulations of the more visible elements, such as reconfi guration of the golf courses and construction of new detention basins. The District will then schedule the fi nal series of public meetings to present the recommended plan to the public.

For More Information, contact:Afshin Ahouraiyan, P.E.Project ManagerFlood Control District of Maricopa County2801 W. Durango StreetPhoenix, AZ 85009Tel: 602-506-1501Fax: 602-506-4601E-mail: [email protected]

july-august 2007 - maricopa county,...

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