5.4. SR 11-13-2007 - Laserfiche WebLink

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~~ 1C'aS ~~ (~`r'O, 7 y~ ~t~ T~~~•~• • SOURCES OF POLLUTION SPREAD OF POLLU'TIO?V ~, ,~~w of ~1~~,~ ~l lAl l W V 1 Although industries and landfills today generally [f rain or surface ,water comes into P do a better job keeping chemical wastes out of contact with contaminated soff, Pnllutier= -- aS ~~ the groundwater, buried pollution from decades ago pollution can see into the ro :e Y t i~ hard t®get ~~t p g und- sourze can linger anal spread. It is far harder to detect than water. Liquid hazardous substances also surface water ollution. ~ .4 p can soak through the soil or rock into Plume ~~> AQUIFERS UNDER TFIE .METRO AREA _ ••••••-•• .the groundwater. Some pollutants do widens An aquifer is a layer of porous, not mix with the groundwater but pool a_s i# permeable rock saturated with water. Rock, gravel, sand --~I~~ i ', within the soil or bedrock, and can act as flov~rs Aquifers are replenished by surface :----• and soil deposited + ~ long-teen sources of contamination. water, but the process is slow, as is the ~ during the last ice age "`~.,-~ water movement through them. ~~~~''`' - _ The most heavily used aquifer in the ~ ~ "` Twin Cities area is the Prairie du Chien- ~~i`----.~ ~° ~ ~ _ Jordan. It consists mostly of sandy ~'`'~ ~ "" ~~`~~~ ~~ ~"----~-.. ` " " -, ... ,~;"` Dump site r ;' dolostone and Jordan sandstone at •-•••-•••• •- ~ AQUIFER ~`"--.~_ ;• depths of 100 to 400 feet. Other 1 FORMATION ~'~`~- _ ~ ~ - j _~- agiufers,typically separated by less- - -- _ _ ~ Remediation Private ar ,•.~ permeable layers, are the shallower • ~ ~- ~ well ~ municipal ,; ~ --.<„ jf' `-~-~- well `•~ Lake ~xr St. Peter Sandstone and the deeper ~ ~ -.,. :. - ~ ~ i0 ' • I ~`~--~.~ /r xiri+L-'" Franconia-Ironton-Galesville and the ~-•-• Less-porous ` '``-` _ -A I -~-.- = 0 ~'~~ d. Mount Simon-Hinckley, rock formation •-- Flowr of ~~ ~'"`- _ Note: Not to scale. Source: EPA; Star Tribune rese~ucli Star Tribune graphic by °illy Steve Clayton ~~ . ~ 7 groundwater _ _ ~ Nom."a ,--~ -- ~ .,' CLEANUP TECHNIQUES ~ - ~-.~~ "_ ~~ ~ ~ ~~°`~-~-_ ~ ~ ~ ~/ -~- ~ -~~ - ~~ ~,~ .:-..c , The first step is finding the source of pollution, often a dump, ••••-••••••-••••••••-••••--•••---•-•----•...••.-.. • ~- ' and removing chemicals and soil. From well sampling, hydro- ~'' `~ ,t ~~ ~'~ logrsts can tell if a pollution plume has spread in groundwater. ' `- ~` ''~~ Sometimes polluted groundwater is pumped out, treated to remove USING THE WATER -°•---•---•-•••--•••----•••--• ~ ' the contamination and then put back in the ground or surface water. Water supply managers look for well locations not affected by If contaminants are released slowly, large amounts of groundwater -•-' plumes of pollution If pollution is discovered in a drip..king need to be pumped to remove a small amount of contamination. water well, it often is abandoned. The water can be purified using Groundwater p:llutimn ~ar-~ Sometimes groundwater contamination is contained so that bacteria granular activated carbon filters or other methods. In-home filters can seep into, and Bonze#irree:s p~,~. in the soil can break it down. handle all the water used in a residence. under, Lakes and ri~rers i.