BEsT MANAGEMENT PRACTICEs HANDbooK - Tahoe BMP

2.2.2.3 SITE LIMITATIONS AND CONSTRAINTSProperties may have existing conditions that do not lend themselves toimplementing all of the BMPs required by TRPA.Identify potential site limitations/constraints:HIGH GROUND WATER AND BEDROCKThe presence of high ground water and shallow bedrock may limit the depthof infiltration BMPs. Indicators of seasonal high ground water include evidenceof surface water, riparian vegetation including willows, alders, and Lodgepolepines. A Soils/Hydrology Report will identify the depth to seasonal high watertable and the presence of bedrock and is recommended if there is the questionas to whether or not a site has these features.SLOW SOILS, LESS THAT 1“/HRSlow draining soils may be a constrained because they may require largesystems to infiltrate the design storm, particularly when they are combinedwith a large amount of impervious surface and shallow ground water orbedrock. A CHP test is recommended to verify the Ksat of the soil.UTILITIES AND INFRASTRUCTUREUtilities locations may be a constraint, depending on their location relative towhere collection, conveyance, and infiltration BMPs are scoped. Some utilitylocations may be obvious; however; you should always call USA DIG prior toany excavation to verify utility locations.RETAINING WALLS AND STEEP CUT AND FILL SLOPESIdentify retaining walls and steep cut and fill slopes, particularly those adjacentto driveways as they may prohibit the installation of an infiltration system.If it is determined that a project has a site constraint, alternative BMPs may beapproved by the permitting authority. By preserving natural drainage patterns,trees, native vegetation, riparian buffers, and wetlands, you may be able toconstruct smaller structural stormwater controls to cope with runoff fromyour site. You should aim to reduce the volume and velocity of the runoff andreduce the pollutants in the stormwater that does leave your site. 1313EPA, 2007, Developing your Stormwater Pollution Prevention Plan: A Guide for Construction SitesTRPA BMP HandbookCHAPTER 2: Site Analysis2012 Page 2-13