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8 <br /> Stormwater lmpacts from Solar Farms Page 2 <br /> March 14, 2012 <br /> she indicated that even some fixed solar panels could be installed that did not reduce <br /> the infiftration of precipitation. This would mean that depending upon design, the solar <br /> panels themselves would not be included in the impervious surface limit. This is <br /> important since much of Orange County has low impervious surface limits used to <br /> protect drinking water supplies. <br /> On the other hand, this does not mean that there is no impact. Due to the amount of <br /> clay found in most of the soils in Orange County, just about any disturbance can <br /> compact soil. Compacted soil will have reduced infiltration and it can be difficult to <br /> maintain vegetation. Most county soils are also highly erodible. Maintaining adequate <br /> ground cover is paramount to reducing sedimentation. <br /> Erosion Control/Stormwater Division staff discussed these issues and agree with the <br /> state that from a stormwater standpoint, solar farms could be installed and that the <br /> panels should not be considered in the impervious surFace calculations provided <br /> infiltration is not reduced. To assure this Erosion Control/Stormwater staff recommends <br /> the following: <br /> 1. Solar farms should not be considered agriculture and therefore exempt from <br /> these requirements unless the power generated is strictly being used by the bona <br /> fide farming operation only. <br /> 2. Proposed solar farms must have an approved erosion control and stormwater <br /> plan designed by a licensed PE. The plan must be submitted to the Erosion <br /> Control Division for review and approval. <br /> 3. Calculations must be provided that show that the infiltration of precipitation is not I <br /> reduced, the volume of runoff is not increased and that the peak rate is not <br /> increased between the pre and post development. If needed, structural <br /> stormwater BMPs should be installed to meet these requirements. <br /> 4. Stormwater nutrient load requirements for new development must be met; this <br /> includes the new Jordan/Falls Lake rule limits currently being considered for <br /> adoption. <br /> 5. Protection of soils during installation of the panels must be provided. This may <br /> include segregating topsoil, limiting access, minimizing vehicle traffic, etc. <br /> 6. Once the solar panels are installed, areas that were disturbed or possibly <br /> compacted should be tilled, seeded and mulched appropriately. This may include <br /> testing soils and providing amendments as necessary. <br /> 7. An operation and maintenance agreement must be filed which will include <br /> periodic inspections to show that areas remain vegetated and that BMPs are <br /> operating properly. This should be required even if no structural BMPs are <br /> needed to meet the stormwater standards. <br /> S:\5 Erosion Control and Water Quality�Erosion Control and Water Quality�Erosion Conh-ol Div\correspondence�2012\Harvey Solaz Memo <br /> 03142012.docx <br />