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Kerry Lyons
5 years ago
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35 ATTACHMENT J CONCEPTUAL MITIGATION PLAN

36 Attachment J Conceptual Mitigation Plan (1) Mitigation Objectives of the proposed mitigation include: Compensate for ecological functions of ephemeral drainage channels and wetlands to be impacted; Maintain existing stream flows downstream of the project area; Maintain or improve water quality through on-site drainages, detention/retention features and storm water best management practices (BMPs); Enhance vegetation species diversity through planting of native woody and herbaceous plant species; Create open water and temporarily inundated aquatic/wetland habitat that benefits wildlife species and increase vegetation diversity. Structural Features Proposed on-site mitigation includes construction of detention and retention ponds and drainage channels to maintain downstream surface water flows around the impact area. The detention/retention ponds would be designed to detain water during storm events and slowly release the water downstream until the normal pool elevation is reached; thus, a significant area of the ponds will function as temporarily inundated wetlands. The constructed drainage system would consist of earthen channels 25 to 50 feet wide that would convey surface drainage around the impact area where it will flow off site to tributaries of Nash Creek, which eventually drains to the Guadalupe River. The proposed constructed channels and detention ponds are intended to protect downstream water quality while maintaining existing flows through the project area. Table 1 provides a summary of proposed drainage channels and ponds to be constructed and to be incorporated into the mitigation plan. Table 1. Summary of proposed structural mitigation features. 1 Feature Type Earthen Drainage Channel Earthen Drainage Channel Length within Project Area (feet) Width (feet) Area of Channel (acres) 5, , Created Natural 3, Drainage TOTAL 13, J-1

37 Feature ID Feature Type 2 Size Normal Pool (acres) Pond 1 Detention 2.3 Pond 2 Retention 12.9 Pond 3 Detention/ 2.0 Sedimentation Pond 5 Habitat 2.2 TOTAL Information based on conceptual designs subject to modification. 2 Ponds 1 and 3 would be seasonally inundated; not designed to permanently hold water Revegetation Post Oak Clean Green, Inc. is in consultation with the Texas Parks and Wildlife Department (TPWD) on species selection and design of the proposed mitigation to provide enhanced habitat values to native wildlife species. It is proposed to plant a diverse mix of high quality late successional native hardwood trees and other native species. Table 2 provides a list of species being considered for planting of mitigation areas and project buffer areas requiring revegetation or enhancement. This list includes native species that have been observed in the project area. Table 2. Proposed revegetation species. Scientific Name Common Name Native (N) or Introduced (I) Grasses and Grass-like Plants Andropogon gerardii Big bluestem N Andropogon glomeratus Bushy bluestem N Bouteloua curtipendula Sideoats grama N Buchloe dactyloides Buffalograss N Chasmanthium latifolium Inland seaoats N Cynodon dactylon Bermudagrass I Chloris spp. Windmill grass N Dichanthelium oligosanthes Rosette grass N Elymus canadensis Canada wildrye N Panicum anceps Beaked panicgrass N Panicum virgatum Switchgrass N Setaria sp. Bristlegrass N Sorghastrum nutans Indiangrass N Tripsacum dactyloides Eastern gamagrass N Cyperus spp. Flatsedge N Eliocharis montevidensis Spikerush N Juncus spp. Rush N J-2

38 Scientific Name Common Name Native (N) or Introduced (I) Forbs Asclepias tuberosa Butterfly weed N Cassia fasciculata Partridge pea N Coreopsis tinctoria Plains coreopsis N Helianthus annuus Annual sunflower N Hydrocotyle umbellata Pennywort N Liatris spp. Gayfeather N Ludwigia spp. Water primrose N Lupinus texensis Bluebonnets N Marsilea spp. Water clover N Phyla incisa Frogfruit N Polygonum pensylvanicum Smartweed N Polygonum hydropiperoides Smartweed N Rudbeckia hirta Black-eyed Susan N Sagittaria spp. Arrowhead N Salvia farinacea Mealy blue sage N Verbesina virginica Frostweed N Xanthium strumarium Cocklebur N Trees, Shrubs and Vines Acer negundo Box-elder N Amorpha fruticosa False indigo N Carya illinoiensis Pecan N Cephalanthus occidentalis Buttonbush N Cornus drummondii Roughleaf dogwood N Crataegus sp. Hawthorn N Fraxinus pennsylvanica Green ash N Gleditsia triacanthos Honey locust N Ilex decidua Possumhaw N Maclura pomifera Bois d arc N Morus rubra Red mulberry N Platanus occidentalis Sycamore N Populus deltoides Cottonwood N Prunus serotina Black cherry N Ptelea trifoliata Wafer ash N Rubus trivialis Dewberry N Quercus stellata Post oak N Salix nigra Black willow N Sideroxylon lanuginosum Gum bumelia N Ulmus crassifolia Cedar elm N J-3

39 Scientific Name Common Name Native (N) or Introduced (I) Ulmus Americana American elm N Vaccumium arboreum Farkleberry N Vitis sp. Grapevine N Figure J-1 illustrates the proposed conceptual mitigation plan. Proposed mitigation features (such as ponds and constructed stream channel) will include a minimum 25-foot wide riparian buffer area. Depending on the condition of existing vegetation communities in these areas, this riparian buffer may be enhanced through planting of native tree, shrub, and herbaceous species. J-4

40 ATTACHMENT K SECTION 401 WATER QUALITY CERTIFICATION INFORMATION

41 Attachment K Section 401 Certification Information (1) Prospective Permittee Information Permittee: Post Oak Clean Green, Inc Old Seguin-Luling Rd 6200 UTSA Blvd., Suite 102 Seguin, Texas San Antonio, Texas Agent: SWCA Environmental Consultants (SWCA) Contacts: Tom Funderburg (210) and Norman Funderburg Contact: Christine Westerman (2) TCEQ Tier II 401 Certification Questionnaire I. Impacts to surface water in the State, including wetlands A. What is the area of surface water in the State, including wetlands, that will be disturbed, altered or destroyed by the proposed activity? The project will result in disturbance of 0.34 acre of wetlands and 1.69 acres of ephemeral stream channels. B. Is compensatory mitigation proposed? If yes, submit a copy of the mitigation plan. If no, explain why not. Proposed conceptual mitigation plan is provided as Attachment J. C. Please complete the attached Alternatives Analysis Checklist. II. Disposal of waste materials A. Describe the methods for disposing of materials recovered from the removal or destruction of existing structures. Any materials recovered from the removal or destruction of existing structures would be disposed of off-site in an appropriate landfill facility. No such material would be discharged into wetlands or other water bodies. B. Describe the methods for disposing of sewage generated during construction. If the proposed work establishes a business or a subdivision, describe the method for disposing of sewage after completing the project. K-1

42 Port-a-potties would be used during project construction. At completion of construction, the operation would dispose of sewage via an approved on-site system or through local utilities. C. For marinas, describe plans for collecting and disposing of sewage from marine sanitation devices. Also, discuss provisions for the disposing of sewage generated from day-to-day activities. Not applicable. III. Water quality impacts A. Describe the methods to minimize the short-term and long-term turbidity and suspended solids in the waters being dredged and/or filled. Also, describe the type of sediment (sand, clay, etc.) that will be dredged or used for fill. During construction, fill would consist of native soil and subsoil materials excavated to develop the project site. The actual facility would include on-site water quality treatment systems including stormwater detention ponds. Project construction and operation will be in accordance with TPDES construction stormwater and industrial permits. B. Describe measures that will be used to stabilize disturbed soil areas, including: dredge material mounds, new levees or berms, building sites, and construction work areas. The description should address both short-term (construction related) and long-term (normal operation or maintenance) measures. Typical measures might include containment structures, drainage modifications, sediment fences, or vegetative cover. Special construction techniques intended to minimize soil or sediment disruption should also be described. Project construction and operation will be in accordance with TPDES construction stormwater and industrial permits. Details will be provided to TCEQ in the 401 certification submittal. C. Discuss how hydraulically dredged materials will be handled to ensure maximum settling of solids before discharging the decant water. Plans should include a calculation of minimum settling times with supporting data (Reference: Technical Report, DS-7810, Dredge Material Research Program, GUIDELINES FOR DESIGNING, OPERATING, AND MAINTAINING DREDGED MATERIAL CONTAINMENT AREAS). If future maintenance dredging will be required, the disposal site should be designed to accommodate additional dredged materials. If not, please include plans for periodically removing the dried sediments from the disposal area. Not applicable. D. Describe any methods used to test the sediments for contamination, especially when dredging in an area known or likely to be contaminated, such as downstream of municipal or industrial wastewater discharges. Not applicable, contaminated sediments are not anticipated to be encountered. K-2

43 Tier II Alternatives Analysis Checklist A project alternatives analysis is included in Attachment F. Additional detail on alternatives will be provided in the TCEQ Section 401 Certification submittal. Post Oak understands that this information is required to be submitted within 30 days of the public notice for the USACE Individual Permit Application request. K-3