Laserfiche WebLink
<br />. <br /> <br />. <br /> <br />D. <br /> <br />. <br /> <br />and color consistency of colored concrete mixes are generally quite varied <br />from truck to truck resulting in several different hues of color. Six inch <br />high curb is most common but four inch high could be considered as well. <br />(4" is considcred surmountablc even with the B type design), (4" would <br />not carry runoff as effectively as 6"resulting in some spillover into lawns.) <br /> <br />c. <br /> <br />Drainage <br />1. Surfacc Runoff: Normally handled by underground storm sewer, ditches <br />or a combination of both. Proper drainage design depends on street profile <br />grades and the relationship of adjacent land to the edge of street. In most <br />parts of Arden Hills, insufficient land exists adjacent to streets to allow for <br />ditches. Curb and gutter works best with storm sewer, however if a ditch <br />section is appropriate a flat concrete edge strip could be incorporated into <br />the street design to provide the edge stability for the bituminous while <br />allowing runoff to sheet flow into the adjacent ditch. Ditches are more <br />common throughout the City as means to carry runoff between lakes and <br />wetlands etc. Where adequate space exists, generally ditches are much <br />more economical to construct than storm sewer and ditches provide some <br />infiltration capacity to reduce the overall volume of runoff entering natural <br />water bodies. Many of the City's older streets have "flat areas" which <br />temporarily pond water instead of sheeting it out to the gutters or adjacent <br />ditches. Ponding water on streets is bad for the street integrity and may <br />cause unsafe driving conditions. Typically this deficiency in roadway <br />section is only fixable by reconstructing the street with a more pronounced <br />crown or profile grade - overlays may not be able to correct large flat <br />areas. <br />2. Water Quality: The basic premise of water quality enhancement in the <br />casc of urban runoff is to slow the rate of flow or infiltrate runoff into the <br />ground thereby allowing silts, pollutants, phosphorus etc. to settle out of <br />the runoff stream. Storm sewers tend to accelerate flow (however in a <br />controlled condition within pipes), therefore ponds or other means of <br />stilling the outfall of storm sewers should always be ineluded with the <br />design of storm sewer systems. Infiltration may occur from ditches, rain <br />gardens and ponds and should be utilized where feasible. Subsoil type is a <br />major factor in the effectiveness and rate of infiltration. Storm water <br />detention ponds generally provide the best "bang for the buck" relative to <br />water quality vs. capital cost (property acquisition exeluded). A number of <br />alternative structures are currently on the market which utilize hydraulic <br />principals to settle out pollutants from the runoff stream, however these <br />structures are quite expensive. <br /> <br />Other Considerations <br />1. Walks and Trails: The inelusion of sidewalks, on road and off road trails <br />should be considered with any proposed street improvement. The residents <br />of Arden Hills have generally supported trail development and asked for <br />additional expenditures in this area. Several existing streets within the City <br />