Presentation on theme: "Impervious Surfaces By: Carl Nielsen, Alex MacLean, Jessie Kerr, Danielle Duffy, & Kayleigh Hursh."— Presentation transcript:
1 Impervious SurfacesBy: Carl Nielsen, Alex MacLean, Jessie Kerr, Danielle Duffy, & Kayleigh Hursh
2 What They Are?Impervious surfaces are mainly constructed surfaces - rooftops, sidewalks, roads, and parking lots - covered by impenetrable materials such as asphalt, concrete, brick, and stone. These materials seal surfaces, repel water and prevent precipitation and melt water from infiltrating soils. Soils compacted by urban development are also highly impervious.Materials like cement, asphalt, roofing, and compacted soil prevent percolation of runoff into the ground. The amount of impervious surface grows with increasing urbanization.
3 General InformationWater, the universal solvent, picks up pollutants as it moves across the land's surface, including fertilizers, pesticides, automobile emissions and other human byproducts. Soil particles, dislodged by the impact from raindrops hitting the ground and from sites cleared of vegetation, are carried to waterways with the moving storm water. This increases the transfer of pollutants to waterways and moves fertile soils from the land to creeks, rivers and bays.
4 Statistics Land Use Impervious Cover % Forest 1% 1% Urban/Suburban Open Land3% Low Density Residential (0.5 units/acre) 12% Low Density Residential (1 units/acre)20% Medium Density Residential (2 units/acre)25% Medium Density Residential (3 units/acre)30% Medium Density Residential (4 units/acre)38% High Density Residential (5-7 units/acre)40% Multifamily Townhouse (>7 units per acre)65% Commercial85% Parking – Unpaved90% Roads/Paved Parking100% Statistics
5 What to expect when just 10% of a watershed is covered with impervious surfaces: Increased pollutantsIncreased erosion, leading to loss of trees and vegetation along the banks (at 8% to 10% impervious surface coverage, streams double in the size of the bed due to the increased volume)The temperature of the stream can increase which can badly effect many biological processes.
6 Continued:Decreased woody debris, a crucial habitat element for aquatic insects.Decrease in substrate quality.Decrease in insect and fish diversity. At 12% imperviousness, trout and other sensitive species can no longer survive in the stream.
7 Local DataWhile studying Mill Creek we observed that the water was murky. This could be a direct affect of impervious surfaces located around Mill Creek. The surfaces allow particles to run into the stream causing the water to become dark and turbid.
8 Data Continued:Also while collecting data at Mill Creek we noticed that the banks of the creek were very eroded which could have been caused by impervious surfaces. When impervious surfaces are in abundance the run off water flow is very fast and powerful which can erode the banks of the creek.High alkalinity in Musselman water data means that impervious surfaces could be causing runoff with lots of local minerals to flow into the water.
9 Interesting FactsWhen it rains, about 5% of the rain water runs off wooded areas and about 95% of the rain water runs off a parking lot. This all happens during only a mere one inch storm.1,361 gallons of water runs off a one-acre wooded area while 25,800 gallons of water runs off a one-acre parking lot.
13 Aggregate GradationAggregate is defined as a collective term for sand, gravel, and crushed minerals.When aggregate is mixed with asphalt as a median, it can be used to create a slightly more porous road or surface.This mix allows water to infiltrate at a much great rate than existing dirt roads.It allows excess runoff move to its edges and into existing drainage systems.
14 Continued:The cleaner than dirt surface makes runoff water less turbid.Though it is not recommended for high traffic areas this type off rode would be very beneficial to small back roads that are normally around rivers, and streams.
15 Cost of Aggregate Gradation A regular road is about $5.04 per square meter.Aggregate Gradation costs about $15-$30.Though this type of road may be almost three to six times more expensive then the cost of a regular road, in the end we believe the benefits will be far more valuable. Having a healthy watershed could bring the cost of having to filter or clean water down immensely.
16 Conclusions Our conclusions are very simple, but very important. Impervious surfaces have a huge affect on watershed quality. They can be the cause of increases pollutants and bed erosion. With such things going on the population of the streams or rivers can decrease. With these pollutants in the stream we are also costing ourselves more money. We have to spend extra money to purify the water we like to collect from our watershed for the running water we use in our homes and the drinking water we buy. By cleaning our watershed we can save money and creatures alike.
17 "Impervious Surfaces - Bay Pressures - Chesapeake Bay Program "Impervious Surfaces - Bay Pressures - Chesapeake Bay Program." Chesapeake Bay Program - A Watershed Partnership. Web. 13 Apr <"Impervious Surfaces in the Chesapeake Bay Watershed - The Woods Hole Research Center." The Woods Hole Research Center - Home Page. Web. 13 Apr <"Land Development - Maps - Chesapeake Bay Program." Chesapeake Bay Program - A Watershed Partnership. Web. 13 Apr <"Land Development - Photos - Chesapeake Bay Program." Chesapeake Bay Program - A Watershed Partnership. Web. 10 Apr <"Mill Creek West Virginia." Google Maps. Web. 12 Apr <Bibliography
18 Bibliography Continued: "Statewide Indicators." Maryland Department of Natural Resources. Web. 13 Apr <"Stormwater and Streams." Prince William Conservation Alliance. Web. 12 Apr <"What Is an Impervious Surface?" Chesapeake Bay and Mid-Atlantic from Space. Web. 13 Apr <