BEsT MANAGEMENT PRACTICEs HANDbooK - Tahoe BMP

treatment. This will reduce the maintenance and increase the longevity ofdownstream systems.C. Nutrients: The primary nutrients of concern in the Lake Tahoe Regionare nitrogen and phosphorus because they contribute to algae growth inthe lake. Common sources of nutrients on large projects are fertilizers,animal waste, detergents, failing septic systems, atmospheric deposition,leaking sewage pipes, and spills/illicit discharges. Nutrient and sedimentloads are directly related because a significant fraction of nutrient loadsoccur as particulates or adsorbed on particles. 28D. Hydrocarbons (oil/grease): Parking lots, roads, automobile leaks,industrial areas, gas stations, improper disposal of motor oil, and illicitconnections to storm drain systems are all major contributors ofhydrocarbons from a project.E. Heavy Metals: Industrial areas, automobile brakes and tires, automobileleaks and emissions, metal roofs, and weathering of building andstructures are all major contributors of heavy metals from a project.F. Toxic Organics: Toxic organics such as pesticides and herbicidescommonly derive from lawn care, agricultural lands, industrial areas,illicit connections to storm drain systems and road salting and impropersalt storage.G. Organic Materials: Organic materials originate from leaves, grassclippings, and pine needles.H. Trash and Debris: Trash and debris may become a pollutant of concernthrough improper site management including waste management, openor uncovered dumpsters, and spills.ADJACENT PARCEL RUN-ON AND ENCROACHMENTWater running on a parcel from an adjacent property is a common issue andmay cause problems for the receiving parcel. Property owners are onlyrequired to treat stormwater runoff generated from their impervious surfaces;however run-on has the potential to cause erosion on the property or flow intoinstalled BMPs and exceed their capacity. Identify the source of the run-onwater such as an adjacent private property, county or city right of way, orupland, overland flows and determine the extent of the run-on. This shouldhelp determine a solution.2.3.2.2 COMPLEX ON-SITE HYDROLOGYIMPERVIOUS AND PERVIOUS AREASIdentify and measure the square feet of all impervious surfaces (e.g. rooftops,driveways, roads, patios). On sites with simple drainage areas, this may be donewith a tape measure or measuring wheel. On larger more complex sites withmultiple large drainage areas, engineering tools may be needed to accuratelyand efficiently measure impervious surfaces. It is critical to know the squarefeet of impervious surfaces to determine the volume of stormwater that needs28SWQIC, 2004, Formulating and Evaluating Alternatives, A-4, Pg. A-76,http://www.trpa.org/documents/Final_FEA.CHAPTER 2: Site AnalysisTRPA BMP HandbookPage 2-26 2012