2008-11-25_PWETC_AgendaPacket - Laserfiche WebLink

Home

~nl~~° '~ ~C~L !feT!' ~-~ te~p €1~`~~c~s'a ' . o a StCot] `[~JT~L-3 Co~~ rKgT~' (~~p,~.~~5 ~' ~ Yom.? ;_~i,~ 're ~®~ ~`>~ l1S.ZI e e e li~o~~ ? KoTj' ~`~~'~~S Co~`i ~~S?~;I' n 1i~ ~~ ~rne~AYt~$.1~11k~!1~~1~~~5..~~ai!F"~PSL ~~a(S1~ d 1~`~~.~4 e ~676~0~ F~~ Co "~" ~7 ra~~~el~ 'boo ( tC~::~~co„ - a r~ ;_o".l? y~~~~ lei ~ A~i~iGt't° e~'1~Ti. 'oTe3-.a ~i ~'.~3~~' 1 ° . o$ ~~~:-~~Y~~ t • ~~5 (f''~u€R~.a'~ iT~C4C"~o °.Y% e ;l,'Lt*o~Y~'inrEfS~'~.[l~' [Uqj° to ; ~~ 1 ~ ;ems l~~, C~~I Cr~k. ~~`~ ~ ~ ~; ) `may ~o~, `; ~' s i6':sii'~~~'~~i ~`~ t~~.o74~'i ~r C lY p'S ~L .~9 D - . • c ~: `C o a ~ U~.r~ ~?c``~~ ~'~ ~~ Metropolitan Council ' ii _ ~ ~ Water Rewurces ~~ enter LRRB ~ ~,,,,~.t.rv~ ~. ~, Minnesota Pollution =~~ ~: ~~.~~r~r..._:. Control Agency r, `~~~II ii~ l~Y Ld? 4~~ tCt~£C~.t3' c~`5~=-~' ® GC°? Cj~r~ ~.~~ C~:~r I ~e~.2~~53P P7~~~57+~~ L~,_~i~~I3~~, ~r i ~'~ef~k~.I~ f~lte~~i} ~~!TA~~ ~~n) ~ C3C:~L`~"i ~ ` e ~ [a~ td1~1[`b~~5'1.Fk-`~f _.. • ff~L'~'I+`~i r r7 (0.2`~:~_d%/ L~Z+~ +~Z.~•~i~u1P ~4~.C®1R~~w~ .~~~ +~t.~T.~' tf~e~p~'~~~','~k.7~~ F;~ d ~~~.'~~ f ~ta.Fi"~~ZP~,~~ite'~.~i, [nlPt~Iyfl2n~l ~a`~ ~4x.~' (ltd) ~~L7~a e~d~a1 lX ,• G d r [r?P te7ele ~ r'F'a y~~X°'X, ;~ ~~X~~L~"dtrCt~~~ ~ ~@~.~c f~:~~BIGT0,1e'S[s7c~1~c2~ 04 tai ~1CTi ]_1 i ~ ' o(z~~t.1. + - ~ {~~~1 o=ar ~~~, ~~~ scl ~ ~ ~=~x~ a t~b7 cal IMPACTS OF STORMWATER INFILTRATION ON GROUNDWATER Contributed by Pete Weiss (weiss00$@umn.edu} Funded by Minnesota Pollution Control Agency Infiltration of stormwater, which is being more widely used across the country, can increase groundwater recharge, re- duce runoff peak flows and volumes, and reduce non-point source pollution. There has been, however, an increased concern in Minnesota that pollutants present in stormwater may contaminate groundwater. Thus, to understand the fate of infiltrated stormwater pollutants and better understand the risk of groundwater contamination, a literature review of scientific and engineering journals was undertaken. The review found that risk of contamination by heavy metals, hydrocarbons, and phosphate are typically very low. Met- als and hydrocarbons are usually removed in the first 2Q-50 cm of soil media or less and phosphate concentrations were found to be higher in groundwater than the infiltration water. The latter finding suggests that phosphates are leached from the soil into the infiltrating runoff. Bacteria and viruses were also found to be typically filtered by the infiltration media but under favorable conditions they can survive for extended periods of time and be mobile. Although the risk of ground- water contamination from the aforementioned contaminants is low, documented cases of contamination for each contam- inant do exist so care and long-term planning are essential to the preservation of groundwater resources. Karst areas and other areas where the subsurface has cracks and fissures can obviously increase the risk of groundwater contamination. Also, any system that utilizes subsurface in- jection increases the risk of groundwater contamination. Fi- nally, salts are not removed by any infiltration systems and in some cold weather climates, salt concentrations of ground- water and area lakes has been documented to be increasing. This is presumably due to application of salt to roadways during the winter months. With all pollutants, the risks of infiltration versus other means of stormwater management must be carefully weighed and considered. TO READ THE FULL REPORT go to: http://home. safl. umn.edu/bm ackay/pub/pr/pr515.pdf ~~ricunin.E:clu/ci~i~a_~t,cf~~~stc,~iriv,~atc,i~l~~niE~~.,sc~sn~~ nt