04-14-1980 Council Minutes - Laserfiche WebLink

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,, ' Page 37 . Metropolitan Waste Control Commission � April 10 , 1980 Page Four This discharge standard can be met by minor plant modifications . The construction of an interceptor would result in an even . greater nonpoint phosphorous discharge into Lake Minnetonka. The lakeshore around Lare r9inneton}:a has been urbanized years ago because of the attraction of the lake as a recreational ' facility. Away from the lake , most of the area in the cities of Orono, t�7innetrista , Indepenaence and Medina are rural in nature. If one builds an interceptor across this rural area , then laterals will be extended someday from that interceptor forcing dense urbanization of the property in order to pay for the cost of the installation of the trunks and laterals . The Harza study shows that this sort of urbanization will lead to the pollution of the watersned and Lake Minnetonka because of the increased phosp}�orous load which would be in the surface water runoff. It is a well known fact, with which everyone agrees , that the amount of phosphorous increases with urbanization. When urban development occurs , the function of the natural drainageways and filtr�tion system is adversely affected in three ways: The speed and quantity of the storm water runoff are increased , and the absorption ability of the land is eliminated with hardcover (houses, driveways , roads , etc. ) . This increase in the speed and quantity of storm water runoff causes the third adverse effect, which is the increase of the amount of nutrients which are contained in the storm water runoff which now has less time in the natural marsh filtration system to be purified before entering the lake. Nutrients contained in dying vege�ation, lawn fertilizers , and from other urban sources are discharged into the lake faster and in greater guantities as the level of urbanization increases . The Hickok report entitled "Storm �9ater Impact Investigation ' for the Metropolitan Council , " November, 1972 , revised February, 1973 , shows that in an urbanized area, as much as 3 . 68 pounds of phosphorous per acre is generated versus . 3 pounds per acre of discharge in a two acre minimum lot size zone. When you install trunks and laterals around the lake, it is very expensive , as high as $12 ,000 per unit, and therefore you force intense urbanization with the resulting adverse environmental effect. This cycle is best shown in the attached chart.