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

stability, and to assure structure performance.• The need for erosion protection should beevaluated at all bridge crossings of watercourses.Utility CrossingsUtility crossings, if properly constructed, haveno inherent impact on channel stability sincethey are typically buried beneath the channelor extended overhead. Direct impacts onchannel stability can occur during utility constructiondue to disturbance of bank andfloodplain vegetation. Where vegetation isremoved, the underlying soils are more vulnerableto erosion and scour. If floods occurbefore the vegetation is reestablished, erosionof the construction alignment may occur andinitiate erosion of adjacent channel reaches.The following guidelines for utility constructionin the floodplain and erosion hazard zoneare recommended:• Bank and floodplain vegetation removedor damaged during construction shouldbe replaced immediately. Irrigation,inspection, and maintenance may berequired to assure survival of the replacementvegetation.• Underground utilities should be buriedbelow the 100-year general scour depth inthe main channel plus the long-term scourdepth. Utility lines have been damageddue to exposure by long-term scour onnumerous streams in Arizona.• Where the potential for lateral movementexists, underground utilities should beburied at the same depth in the overbankareas or erosion hazard zone as in themain channel, to prevent exposure aftermovement of the main channel.• Support structures for overhead utilitiesshould not be located within the floodplainor erosion hazard zone. Where thelength of the span requires that support39structures be constructed within the floodplainor erosion hazard zone, the structuresshould be designed using the 100-year general scour plus long-term scour inthe main channel burial depth. No structuresshould be placed in the main channel.Aesthetic Design GuidelinesAesthetic guidelines are developed as a tool tobe used by planners and designers to incorporateaesthetic quality into their design that issensitive and consistent with the natural environment.As part of the North Peoria ADMP,landscape character themes are developedthat could be incorporated into the design offlood control management alternatives. Specificthemes developed are a Mountain Themewith a Mining Theme Overlay, and a PlainsTheme with a Native American or RanchingTheme Overlay. Design guidelines and examplesare present in the North Peoria ADMP,Technical Data Notebook, Attachment 4,Landscape Character and Visual AssessmentReport. The following general design guidelinesare offered:Structural Erosion Protection MeasuresStructural erosion protection measures canconsist of a variety of engineered materials.Most common types of engineered materialsused in Maricopa County are rock filled wirebaskets (gabion mattress, Reno Mattress),gunite and soil cement. Structural erosionprotection measures could be aestheticallyenhanced by designing them to blend in color,texture and form with the surrounding environmentand desired landscape charactertheme. Treatments include selection of materialto provide the desired color and texture,artificially coloring material, and treatment offreshly excavated native material with Eoniteor a similar aging product.ChannelsChannel alignments and side slopes should beconsistent with natural channels in the area.Alignments should be sinuous and side slopesshould vary in the angle of slope.