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<br />Prepared by: Bolton & Menk, Inc. MCM 3: ILLICIT DISCHARGE DETECTION AND ELIMINATION PLAN <br />Orono SWPPP ǀ 0C1.126140 Page 4 <br />discharge observed at the outfall has a distinct or unique characteristic that can <br />allow field crews to quickly determine the type of activity or non-point source that <br />is generating the discharge. The investigator shall identify likely sources near the <br />reported discharge location by reviewing land use and drainage system maps. The <br />investigator shall then conduct a visual survey of the drainage area to confirm the <br />source of the discharge. The following table lists some potential causes of <br />reported discharges. <br />Table 7-1 – Common Discharges and Potential Sources <br />Observed Discharge Potential Causes <br />Clogging Sediment · Construction activity without proper erosion and <br />sediment controls <br />· Roadway sanding operations <br />· Outdoor work areas or material storage areas <br />Thick Algae Growth · Fertilizer leak or spill <br />· Landscaping operations <br />· Hydroseeding following construction <br />· Failing or leaking septic system <br />Oil · Refueling operations <br />· Vehicle or machinery maintenance activities <br />Sudsy Discharge · Power washing of buildings <br />· Vehicle or equipment washing operations <br />· Mobile cleaning crew dumping <br />· Laundry or Cleaner <br />· Household greywater discharge <br />Clogged Grease · Restaurant sink drain connection to stormwater <br />system <br />Sewage · Failing or leaking septic systems <br /> <br />d) Storm System Investigation – Storm system investigations shall be used when the <br />source of discharge observed at the outfall cannot be quickly attributed to a <br />certain type of activity or non-point source generating the discharge. This method <br />involves progressive investigation at manholes in the storm drain network to <br />narrow down the location where the illegal discharge is entering the drainage <br />system. Field crews shall work progressively upstream from the outfall and <br />inspect manholes until indicators reveal the discharge is no longer present. For <br />particularly large storm drain systems, major branches of the system shall be <br />identified, and the downstream manhole of the branch shall be investigated to <br />reduce area that must be investigated. Storm system investigation shall include <br />the following steps: <br />· Consult the drainage system map and identify the major branches. <br />· Starting from the outfall, observe the next upstream manhole or <br />junction to see if there is evidence of polluted discharge. Field crews <br />are looking for the presence of flow during dry weather, foul odors, <br />colors or stained deposits, oily sheen, floatable materials, and/or <br />other unusual observations. <br />· Repeat observations at each upstream manhole or junction until a <br />junction is found with no evidence of discharge.