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'�G�hOA S�C710N: Fd�:��' �+�� Ct��L �� a7�: - - 12/I3/7fi ORIGINATING �EPT.�pIV.: :�P�aiS nvD Rc:C�7f1P�t�'i�aTID��S P�Jt�LIC �10E?;;S �E�� No.: �r�nn o�sc�iPr+on�� PEiASE I REP�RT OId THE IiVFILTRA7I0Pd/IPdFLOid .4 �- _ �F� Af�ALYS I S c QEP7. HEAD APPROVAE.. �� '!-/ MGR. REVIEtVEfl/RECOMi�vfE�:�S: �'�� - ;;. A� On h9ay 17, 1976, the counci 1 authori zed the fi rm of Bani ster, Short, El l i ott, I-len-- drickson & Associates, in con�unc.tiari witn DDnahue an�.Assac�aies, io und�r�ake the first phas� o�' a study to determine th� ex�ent of infiltration and infiow in the ciiy's sanitary sewer system. This fiirs� phas� is novl compTeted and work is beginni�g on Rhase �. The aceompanying repori indicates tne �h�vretical �xtent of this problem basec� on histor�cal records and 1975 in p�rtic�iar. As was feared ►ihen we decided ta begin this project, an extensive a�ount of infil- trat�on and inflow apparently exists as part af the volume of se«age going to the Pletroplitan 'n�aste Control Commission fflr treatment purposes. Phase 1 es�ima�es �hat in 19�5, approximately 800 million gallons, ar aimost half v� the totai voiume, is the resul� of ir�filtra�ion and in�'iow. All infiltratian and inf7ow wyl1, of caurse, never be remaved �ram the system; but hapeful7y, approxi�nateiy 40� cauld be eliminat�d thraugh prop�r� action. Us3ny. this 40� goa3, it is estima�ed �hat it �rill �ost approximately $900,000 ove r= the next few years to locate and rehabilitate t�flse port�ons of the system, wi�ich are practica� and resu�t in �ost savings. These expense5, however, would be recovered within 1� years through savings in reduced i�l�tro Waste Commission fees, becaUSe of the reduction ir� overa�ll flo�r.. Rhase 2 of the study, as me�t7oned before, is now being initiated. Inc3uded in th�s phase are: ' 1} Estimates for base f7ow ca��itions-in each of the 2� su5 systern� which are bezng created to analyze ti�e city. 2} Fiow monitoring in each of ti�e 2e sub systems. 3} R�su1t�.of each o� these sub systems will be analysed and a deter- rii na�i on made to see i f Phase 3 snou7 d be under�ak�r�. Thi s thi rd pt�ase woul d cor�- sist of detailed field investigations in those sub areas which are suspect as a result o�f tf�e manitorin.� and wou7d ap�ear to be cast effective. i'i�e sc}zedul e+�oNr cal 1 s for Phase 2 to b� done _duri ng the s�r� ng vf next y�ar; and a good �artion of Pi�ase 3 completed hefore tne end o� the year, if it is si�own to be the proper step ta take . 7ize co+�nci 1 wi 1 i b� app�ai sed of ti�e si tuati on pri or to ��e wark bei ng under�aken i n f�hase 3, This re.port is to provide tf�Q counci� �vith �nformatian as to the sta�us of the over- a7i study.and no� action is necessary a-t this tim�. �