Storm water management assessment memorandum

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Page 7 of 20 Storm Water Management System Assessment Orono Truck Station III. Existing Conditions The Orono Truck Station storm water management system was inspectetl on January 20th(east pond) and March 4th (west pond). Skies were cloudy and temperatures were in the low 30's at the time of the first inspection, antl skies were cloudy and temperatures were in the teens at the time of the second visit. A follow-up inspection was performed on June 11th to observe those aspects of the storm water management system that were untler snow and ice cover. The purpose of these inspections was to evaluate the existing vegetation, runoff sources, inlet and outlet contlitions and pond condition (including a determination of the depth of accumulated sediment). Photographs taken during the inspection are included in the Appendix of this report. Vegetation Due to snow cover at the time of MFRA's first site visit, a thorough review of the vegetation could not be completed. At the follow-up inspection, it was observed that the east pond area is almost completely covered with cattails. Cattails typically do not grow in water deeper than 2 feet, and the maturity of these plants intlicates that the permanent water level of the pond is consistently at or below 2 feet. The west pond is also densely covered with cattails, which is not abnormal for a wetland with shallow standing water. Buckthorn was noted in the west pond surround. Both cattails and buckthorn are considered an invasive species and could be removed; however, their presence does not affect the ponds' performances. Additionally, the "Storm Water Pond Inspection" prepared by HDR in 2005 noted the need for a vegetated buffer to be reestablished near the northeast corner of the east pond. At the time of the inspection, it appeared as though this maintenance issue had been resolved and a lack of vegetated buffer was not observed. Table 1 lists the plant material that was visible at the time of the inspection, most of which is appropriate in a storm water pond.