Laserfiche WebLink
<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />1 <br />I <br /> <br />dissolved phosphorus + nitrogen. The area of the <br />proposed site plan which will be grassed and <br />assumedly have the assimilative capacity of grassy <br />marshland is approximately 1.12 acres. Properly <br />maintained for optimum assimilation at 20 #/acre, <br />the site is therefore theoretically capable of re- <br />moving 1.12 x 20 or 22.4 #/year. It follows that <br />th t t b t' d th 't 10.69 + 5.55 <br />e wa er mus e re a1ne on e Sl e 22.4 <br />or 73% of the time in order to complete assimila- <br />tion to take place. The previously discussed storm <br />water quantity calculations do not reflect that <br />this requirement is likely to be met. <br /> <br />A considerable amount of the potential pollutant to <br />the site lies in asphalt oils, sediment, and float- <br />ing materials. It is notable that the proposed <br />action includes inverted weirs with very low "flow <br />through" velocities to remove these pollutants and <br />retain them on the site. <br /> <br />The Rice Creek Watershed District has reviewed the <br />plan and method of treatment (the three retention <br />ponds) and feels that the system will adequately <br />treat the 16.24# of nutrients. (See Appendix D) <br /> <br />In order to make the treatment ponds operate it <br />will be necessary to maintain them as grassy marshes. <br />The vegetation must be allowed to thrive and algae <br />must be preserved. In addition, maximum water vol- <br />umes must be retained whenever possible. It does <br />not appear, as a result of the quantity calculations <br />previously discussed, that all the water will be <br />retained for adequate treatment except in cases of <br />very small storms. Most of the pollutants will be <br /> <br />I <br />I <br /> <br />V-5 <br />