North Peoria Area Drainage Master Plan - Flood Control District of ...

More documents

Recommendations

Info

• Collect hydrologic data - peak dischargerates, flow duration curve, mean andmonthly flow rates, annual flood series,flood history, climatic data, etc.• Measure channel planform characteristics– channel pattern, meander features, pooland riffle spacing, width, slope, periodicityof narrow and wide reaches.• Identify evidence of paleofloods.• Identify stream analogs on adjacent watersheds.• Evaluate tributary characteristics – drainagearea, slope, sediment type, sedimentyield, flow rates, location of confluence.• Assess impacts of tributaries and tributarysediment load on main channel morphology.• Apply applicable methodologies from theDistrict Piedmont Flood Hazard AssessmentManual (Draft, August 1998) to identifysurface ages and stability.• Perform stream classification.• Define stream reaches.Hydraulic and Empirical Analyses. Engineeringanalyses based on hydraulic data obtainedfrom a HEC-RAS model of the study reachwill be performed to assess the potential forbank erosion and scour. These analyses willbe used to determine whether a stream is stable,whether it is likely to experience bank erosionand/or scour, and what amount of lateralerosion is likely to occur. Where hydraulicdata are required, the computations will bebased on 2-, 10-, and 100-year reach-averagedhydraulic data. Specific tasks include the following:• Revision of HEC-RAS model as describedabove.• Define stream reaches using hydraulicdata and physical stream characteristics.• Determine reach-averaged hydraulic data.• Compute allowable velocity.• Compute scour depths (general, local, andlong-term).• Compute armoring potential & depth toarmor.• Compute equilibrium slope.• Compute reach sediment continuity relationships.• Apply lane relation to stream reaches.• Apply regime equations to stream reaches.• Apply hydraulic geometry relationships tostream reaches.• Apply empirical channel geometry relationshipsto stream reaches.• Apply appropriate regional lateral stabilityprediction methodologies – these mayinclude the AMAFCA Prudent Line,ADWR State Standard 5-96, King County(WA) methodology, Rosgen bank assessmenttechniques, etc.Impacts Analysis. The proposed developmentwill be modeled to assess the potential downstreamand upstream impacts, using the sameprocedures and methodologies listed above.Final ProductThe final product for these tasks will include amap showing the recommended erosion hazardzone boundaries and a final report. Thefinal report will include the following:• Discussion of assumptions and limitationsof methodologies.31
NORTH PEORIAAREA DRAINAGE MASTER PLAN• Discussion of how the results of the variousanalyses were combined with the sedimenttransport modeling results, sandand gravel mining impact assessmentanalysis, and were translated into the erosionhazard zone(s).• Recommendation for future updates ofhazard zone boundaries.• Recommendation for long-term monitoring.• Recommendations for how to modify theerosion hazard boundaries and/or underwhat conditions development can occurwithin the boundaries.Earthen Dams (Stock Tanks)There are a number of stock tanks in the NorthPeoria ADMP study area. Stock tanks typicallyconsist of a non-engineered earthen damof varying height placed across a watercourseto impound stormwater runoff. Vegetationtypically lines the impoundment area. Shoulddownstream areas become urbanized theseearthen dams would present a hazard. TheADWR Dam Safety Section, has legal jurisdictionover dams (embankments) which exceedcertain height and storage limits. ADWRdefines a jurisdictional dam as “either 25 feetor more in height or stores more than 50 acrefeet.If it is less than six feet in height regardlessof the storage capacity or does not storemore than 15-acre-feet regardless of height, itis not jurisdictional”. However even though astructure may not be considered jurisdictionalall dams (embankments) in an urban environmentare considered as having high hazardpotential.The structural integrity and safety of existingstock tanks shall be evaluated to access downstreamimpacts to existing or proposed developmentdue to a dam break. Criteria for thedesign and evaluation of dams can be foundin the book entitled “Design of Small Dams”,third edition (1987, Bureau of Reclamation). Aprofessional engineer registered under thelaws of Arizona, and having proficiency in32civil engineering as related to dam technology,shall conduct evaluation and/or designof an earthen structure.Retention/Detention FacilitiesAll detention/retention facilities incorporatedwithin new developments will be designed toretain the peak flow and volume of runofffrom the 100-year, 2-hour duration stormevent. In the special case when a detentiononly facility is allowed, the requirement toretain the 100-year 2-hour runoff volume maybe waived; however, the post-developmentpeak discharge leaving the site can not exceedpredevelopment conditions. In addition to the100-year event, the effects of more frequentevents (2- and 10- year events) of using adetention only facility must be determined.Standard Retention PracticeGuidelines for the standard practice of retainingthe volume of runoff from the 100-year, 2-hour event can be found in “Drainage Regulationsfor Maricopa County, Maricopa CountyDrainage Design Manual Volume II-Hydraulicsand City of Peoria Infrastructure DevelopmentGuidelines.In-stream, In-Line Detention BasinsIn-stream, in-line detention basins are stormwaterpeak reduction facilities, which could beemployed with authorization, from thereviewing agency, instead of the standardpractices of retaining the volume of runofffrom the 100-year, 2-hour event. The detentionfacility is typically located in a watercourseand functions only to reduce postdevelopment peak discharges. The facilitytypically consists of an encroachment into the100-year floodplain (possibly at a roadwaycrossing), an outlet structure sized to conveyrunoff from frequent events such that the naturalform and function of the watercourse isnot disturbed (sediment transport capabilitiesare maintained), and to impound runoff sufficiently,so that there enough storage providedto reduce peak discharges. The followingguidelines/consideration should beaddressed in the design of such a facility:
Page 2 and 3: TABLE OF CONTENTSPreface ..........
Page 4: PREFACEAt the request of the City o
Page 8 and 9: LIST OF TABLESTable 1: Regional and
Page 10 and 11: INTRODUCTIONThe natural physical ch
Page 12 and 13: minimize the effect of urbanization
Page 14 and 15: Peoria General PlanThe Peoria Gener
Page 16 and 17: HYDRAULICS8QQDPHG:DVK%LJ6SULQJHydra
Page 18 and 19: FLOOD AND EROSION HAZARD ZONESWith
Page 20 and 21: ing them before they are destroyed
Page 22 and 23: PUBLIC INVOLVEMENTAn integral part
Page 24 and 25: hard pan, typically less than two f
Page 26 and 27: Economic CriterionThe evaluation of
Page 28 and 29: Table 4Summary of Evaluation Result
Page 30 and 31: INTRODUCTIONRULES OF DEVELOPMENTCom
Page 32 and 33: Objective EH1.3Identify erosion haz
Page 34 and 35: the purpose of watershed and waterc
Page 36 and 37: the North Peoria ADMP. Users of the
Page 38 and 39: (short, constricted reaches), backw
Page 42 and 43: • Basin Outlet (Culvert). The bas
Page 44 and 45: Low Impact Structural AlternativeFo
Page 46 and 47: ack at the natural channel bed. In
Page 48 and 49: stability, and to assure structure
Page 50 and 51: developed for the Estrella Roadway,
Page 52 and 53: gabion mattressA gabion mattress is
Page 54 and 55: Maricopa County, August 21, 1993, H
Page 70 and 71: 100-year W.S. ElevationBufferFEMA 1
Page 72 and 73: NORTH PEORIA AREA DRAINAGE MASTER P
Page 74: 100-year W.S. ElevationFEMA 100-yea

North Peoria Area Drainage Master Plan - Flood Control District of ...

Create successful ePaper yourself

Delete template?

Save as template?