Development Services Stormwater Treatment Facility Checklist

Transcription

1 Develpment Services Strmwater Treatment Facility Checklist Infrmatin This checklist has been created by the City t assist the design engineer in preparing a Strmwater Treatment Facility (STF) reprt and plans. Be advised the belw infrmatin is nt all-inclusive; therefre, the City has the right t require additinal infrmatin based n the scpe f each prject. Submittal Requirements 1. Final Strmwater Treatment Facility Reprt 2. Strmwater Treatment Facility Plans a. Single Lt Develpment Prjects: include STF plan sheets in the site civil plan set b. Subdivisin Prjects: include STF plan sheets in the strmwater public imprvement plan set. 3. Signed cpy f the Strmwater Treatment Cvenant 4. Signed cpy f the Strmwater Treatment Agreement 5. Strmwater Management Easements (submitted nce easement lcatins have been finalized) Final Strmwater Treatment Reprt Requirements Sectin I: Backgrund Brief histry f prject Written r graphical inventry f natural resurces n the site. List f impacts t existing streams and/r bdies f water, and permits required by state and federal agencies prir t cnstructin Identificatin f Ht Spts Sils Infrmatin gathered frm sils reprt (if required) Data regarding nature, strength and permeability Subsurface cnditins and sil bring results Recmmendatin fr grading and cnstructin prcedures Recmmendatin f the suitability f the sils fr the prpsed use Sectin II: Design and Cnstructin Level f Service Calculatins Summary f the STF Why was the STF selected fr this site Hw des the STF functin What benefit des the STF prvide Design calculatins fr each STF 11 x 17 inch cpies f the STF plans sheets apprved by the City Itemized cnstructin cst estimate fr each STF Cnstructin Schedule fr each STF Fr Single Lt Develpments, the STFs shall nt be cnstructed until the building and site imprvements are cmplete, unless therwise apprved by the City Fr Subdivisin Develpments, the STFs shall nt be cnstructed until 90% f the tributary area fr the STF is stabilized, unless therwise apprved by the City City Hall, Jhnsn Drive, Shawnee, KS Page 1 f 7

2 Prvide infrmatin n hw each STF will be prtected frm runff, ersin, and cnstructin traffic during installatin Sectin III: Maintenance and Repair Descriptin f maintenance respnsibilities the prpsed STFs will impse n Landwners List f maintenance and replacement csts and timeframes Prjected yearly maintenance cst utlined Ptential replacements csts f each STF Anticipated life expectancy fr each STF Maintenance and Repair Plan fr each STF List respnsible party fr nging maintenance bligatins (i.e. Landwner, HOA, BOA etc); include statement that subsequent Landwners are respnsible fr cntinued maintenance. Schedule f required maintenance fr each STF Detailed maintenance and repair prcedures, state if specialized equipment and/r training is necessary Landscape Management Plan prepared by a Registered Landscape Architect List and pictures f invasive species t be remved and hw Instructins n yearly maintenance requirements fr landscaping Prcedures fr replacing dead landscaping General Plan Requirements The belw items are required t be shwn n the plans, regardless f the type f STFs being utilized: Treatment area fr each STF identified with a dashed line and acreage called ut STF Setbacks are shwn and meet City standards 10-feet frm Right-f-Way 20-feet frm existing r prpsed prperty line 60-feet frm residential structures and 20-feet frm nnresidential structures Level f Service calculatins prvided in a table frmat matching the MARC BMP Manual Engineering calculatins prvided in table frmat; methd t design each type f STF shuld reflect the design example prvided in the MARC BMP Manual Cnstructin ntes and cnstructin phasing plan fr each STF Lcatin and dimensins f all Strmwater Management Easements (SMEs) and/r Tracts that will cntain a STF Grading Plan with bttm and verflw elevatins called ut, and cnturs shwn in ne ft increments Lcatins f STF infrmatinal signs called ut and a detail f the sign is prvided Landscaping Plan Plan view f prpsed plantings and seeding areas Planting schedule with planting seasn fr each species prvided Perclatin test results STF Specific Plan Requirements Native Vegetatin, Value Rating = 9.25 Rain Garden, Value Rating = 9.0 Minimum 20 frm WQv pl t building fundatin Filter strip f grass, except as nted belw Filter strip f river rck at least 12-inches wide fr flws entering frm paved areas Overflw path r structure prvided City Hall, Jhnsn Drive, Shawnee, KS Page 2 f 7

3 1-acre maximum treatment area 24- t 48-hur pnding time 6-inch maximum pnding depth Detailed crss-sectin: 24-inch minimum engineered sil mix f 1:1 sand/cmpst mix (if required based n perclatin test results) 6-inch planting sil layer cmpsed f tp sil r cmpst placed n tp f engineered sil mix 3 inches f shredded hardwd mulch placed n tp f planting sil layer Landscape plan Plant species are tlerant f perids f inundatin and drught and are native with deep rt systems (i.e. native wetland r mesic wetland species) Use f trees and shrubs is encuraged Infiltratin Basin, Value Rating = 9.0 Minimum 100 ft up-gradient frm building fundatin Minimum 10 ft dwn-gradient frm building fundatin Pretreatment prvided Emergency spillway shwn and designed t pass 1% strm Basin is placed ff-line f strm system Design Requirements 2-acre maximum treatment area 72-hur maximum pnding time 2-ft maximum pnding depth 3:1 length t width rati (r greater) 3:1 side slpes r flatter Infiltratin Trench, Value Rating = 9.0 Minimum 20 ft t building fundatin Observatin well prvided at center f trench 20-ft wide grass filter strip precedes trench Trench is placed ff-line f strm system 5-acre maximum treatment area 6 t 72-hur required detentin time Infiltratin rate f sil is between 0.5 t 2.0 inches/hur Sil has less than 40% clay cntent 3- t 8-ft trench depth 5% maximum slpe Detailed crss-sectin: 2-inch pea gravel filter layer Trench filled with 1.5 inch t 2.5 inch clean stne, n limestne r shale Filter fabric n all fur sides f clean stne Nt fr use in cmmercial and industrial develpments Biretentin, Value Rating = ft x 40 ft minimum dimensins Minimum 20 ft t building fundatin Pretreatment required, recmmend 10-ft minimum vegetated filter strip Overflw path r structure prvided City Hall, Jhnsn Drive, Shawnee, KS Page 3 f 7

4 Limits f pnding area and limits f BSM clearly defined Underdrain layut shwn 4-acre maximum treatment area Inflw velcity less than 3 ft/sec 12-inch maximum pnding depth Detailed crss-sectin 3 inches f shredded hardwd mulch placed n tp BSM 30-inch minimum BSM, refer t MARC BMP Manual fr specificatins 8-inch minimum gravel bed ver underdrain Filter fabric placed n tp f gravel bed 4:1 side slpes r flatter Underdrain Requirements: 4-inch minimum perfrated pipe 10-ft max lngitudinal spacing Minimum grade f 0.5% Transverse underdrains required if width is greater than 20 feet Cleanut prvided every 50 feet and at end f pipe runs Dwnstream cnnectin elevatin prvided Landscape plan Plant species are tlerant f perids f inundatin and drught and are native with deep rt systems (i.e. native wetland r mesic wetland species) Use f trees and shrubs are encuraged Permeable Pavement, Value Rating = 7.5 Limits f permeable pavement shwn Jint layut prvided (if required) Include mix design and technical specificatins in plan set, r prvide a cpy and reference them in the plan set Detailed crss-sectin Depth f aggregate called ut, required t be ¾ inch clean rck Pavement thickness called ut Filter fabric lcatin shwn Intake pipe and/r underdrain shwn Water surface elevatins fr WQv, 10%, 4%, and 1% strm events shwn Aggregate has 30% pen pre space with fractured surfaces Design area rati des nt exceed 3:1 (cntributing impervius area divided by pervius pavement area) Overflw path and structure prvided Extended Detentin Wetland, Value Rating = 7.0 Sediment frebay: separated by earthen berm, rip rap wall, r gabin wall 4-6 feet deep (hld 10% WQv) maintenance access prvided capacity t cntain 5 years f sediment inlet dissipatin prvided Micrpl: 4-6 feet deep (hld 10% WQv) Reverse slpe pipe r brad-crested weir fr utlet cntrl, placed 1-ft belw nrmal pl surface elevatin City Hall, Jhnsn Drive, Shawnee, KS Page 4 f 7

5 Trash racks prvided 12-ft safety bench prvided with slpes n steeper than 6:1 Wetlands: Varying water depths, very shallw (<6 inches) and mderately shallw (< 18-inches) Wetland planting mix r suitable sil materials Species are apprpriate fr time perids and depths f inundatin Vegetatin cvers 50% t 75% surface area Shape f EDW Flwpath 3 times greater than width f facility Undulated bttm Wedge shaped, narrwest at inlet and widest at utlet Overflw path and structure prvided Separate drain pipe with valve t drain permanent pl fr maintenance 40-hur release perid fr WQv 4:1 r flatter vegetated slpes Near-zer lngitudinal slpe t slw velcity Sand Filter, Value Rating = 6.0 Refer t Figures 8.10, 8.11 and 8.12 in the BMP Manual Sand cnfrms t ASTM C-33 r AASHTO M-6 ranging in size frm 0.02 t 0.04 inch Treat highly impervius stabilized areas nly (i.e. parking lts, rftps, etc) Wetland Swale, Value Rating = 6.5 Less than 2% lngitudinal slpe (prvide prfile t cnfirm) Check dams at intervals f every 50 t 100 feet Frebay prvided 5-acre maximum treatment area 24-hur drawdwn time 12-inch maximum strage depth 4 ft/sec maximum velcity during 50% strm Detailed Crss-Sectin: 2 t 8 ft bttm width 3:1 r flatter side slpes Seasnal high water table shwn WQv, 10% (residential), 4% (cmmercial) and 1% depths and elevatins shwn Bi-Swale, Value Rating = 6.5 Less than 4% lngitudinal slpe (prvide prfile t cnfirm) Check dams at intervals f every 50 t 100 feet Frebay prvided 5-acre maximum treatment area 40-hur drawdwn time 12-inch maximum strage depth 5 ft/sec maximum velcity during 50% strm Detailed Crss-Sectin: 2- t 8-ft bttm width City Hall, Jhnsn Drive, Shawnee, KS Page 5 f 7

6 3:1 r flatter side slpes 30-inch permeable sil layter ver 6-inch clean gravel layer 4-inch perfrated underdrain placed at bttm f swale and cvered with clean gravel WQv, 10% (residential), 4% (cmmercial), and 1% depths, and elevatins shwn Vegetated Filter Strip, Value Rating = 5.0 Shw limits f filter strip with hatch Dimensin inflw apprach length 1% t 6% grades acrss filter strip Runff enters and exits strip as sheet flw 130-ft maximum apprach length Inflw areas use Value Rating f 5.0 Extended Wet Detentin, Value Rating = 5.0 Sediment frebay: separated by earthen berm, rip rap wall, gabin wall 4 t 6 feet deep (hld 10% WQv) maintenance access prvided capacity t include strage fr 5 years f sediment inlet dissipatin required Permanent Pl: 4- t 6-ft ptimal depth, 12-ft maximum depth 10-ft minimum depth required t supprt aquatic life 3:1 r flatter side slpes belw littral bench WQv, 10%, 4%, and 1% depths, and elevatins shwn Emergency spillway prvided and sized t pass 1% strm Multiple stage utlet structure required if being used fr detentin Littral Bench 10-ft width minimum 6 t 12 inches belw permanent pl elevatin 6:1 r flatter side slpes Bench cmprises 25% t 50% permanent pl surface area Separate drain pipe with valve t drain permanent pl fr maintenance Flwpath length is 3 times greater than width f facility 1000-acre maximum treatment area 40-hur release perid fr WQv Native Vegetatin Swale, Value Rating = 4.0 Less than 2% lngitudinal slpe (prvide prfile t cnfirm) Check dams at intervals f every 50 t 100 feet Frebay prvided Shw limits f native plantings (reference Appendix A f BMP Manual fr apprved species) 5-acre maximum treatment area 4-inch maximum depth f flw fr WQv 100-ft minimum length f swale 1 ft/sec maximum velcity fr WQv 4 ft/sec maximum velcity during 50% strm Detailed Crss-Sectin: City Hall, Jhnsn Drive, Shawnee, KS Page 6 f 7

7 2- t 8-ft bttm width 3:1 r flatter side slpes Shw WQv, 10% (residential), 4% (cmmercial), and 1% water surface elevatins Extended Dry Detentin, Value Rating = 4.0 Sediment frebay: separated by earthen berm, rip rap wall, gabin wall 4 t 6 feet deep (hld 10% WQv) maintenance access prvided capacity t include strage fr 5 years f sediment inlet dissipatin required Basin: WQv, 10%, 4%, and 1% depths, and elevatins shwn Lw flw channel prvided 4:1 r flatter side slpes (3:1 if als used fr detentin) Emergency spillway prvided and sized t pass 1% strm Multiple stage utlet structure prvided if being used fr detentin Inlet and utlet lcated at ppsite ends f basin t avid shrt-circuiting 2 t 5 ft depth fr WQv 40-hur release perid fr WQv Turf Grass Swale, Value Rating = 3.0 Less than 2% lngitudinal slpe (prvide prfile t cnfirm) Check dams at intervals f every 50 t 100 feet 5-acre maximum treatment area 4-inch maximum depth f flw fr WQv 100-ft minimum length f swale 1 ft/sec maximum velcity fr WQv 4 ft/sec maximum velcity during 50% strm Detailed Crss-Sectin: 2 t 6 ft bttm width 3:1 r flatter side slpes Shw WQv, 10%(residential), 25% (cmmercial), and 1% water surface elevatins City Hall, Jhnsn Drive, Shawnee, KS Page 7 f 7