Loading...
HomeMy WebLinkAbout1991-044-03/05/1991-CONSTRUCTION EROSION CONTROL CONSTRUCTION STANDARDS STORM DRAINAGE DESIGN CRITERIA RESOLUTION 91- 44 OF THE COUNCIL OF THE CITY OF FORT COLLINS AMENDING THE "STORM DRAINAGE DESIGN CRITERIA AND CONSTRUCTION STANDARDS" BY THE ADDITION OF CONSTRUCTION EROSION CONTROL CRITERIA WHEREAS, pursuant to Section 26-544 of the Code of the City, the City Council , by Resolution No. 84-41, adopted the Storm Drainage Design Criteria and Construction Standards; and WHEREAS, the Council is committed to the enhancement and protection of existing lands, streams, lakes, wetlands and rivers that may be impacted by sediment-laden wind and runoff resulting from construction activities; and WHEREAS, the Council has established a goal of maintaining and enhancing the quality of the natural environment of the City and has determined that revisions to the Code relating to storm water quality will serve as a needed step in achieving this goal ; and WHEREAS, the Council has determined that an important element in protecting the quality of storm water is the implementation of erosion control criteria; and WHEREAS, the Council has determined that it is in the best interests of the citizens of the City that the Storm Drainage Design Criteria and Construction Standards be amended by the addition of detailed criteria for the control of erosion on construction sites. NOW, THEREFORE, BE IT RESOLVED BY THE COUNCIL OF THE CITY OF FORT COLLINS that the "Construction Erosion Control Criteria" attached hereto and shown in shaded print be, and the same hereby are, accepted, approved and adopted as an amendment and addition to Sections 2, 8 and 10 of the City's Storm Drainage Design Criteria and Sections 1 and 11 of the City's Storm Drainage Construction Standards. Passed and adopted at a regular meeting of the Council of the City of Fort Collins held this 5th day of March, A.D. 1991 . Mayor ATTEST:: �M.yo_ cA i City Clerk "E: Shaded portions are new text. SECTION 2. DOCUMENTATION 2.Z preliminary Submittal Requirements - Drainage, and., Erosion Control' Preliminary reports,: subdivision plats and P.U.D. plans submitted to the City prior to the Planning and Zoning Board meetings must include the following storm drainage and erosion control information in addition to the requirements of the Planning Department. * A11 drawings 1.11shall 'be 24" x 36" in Isize. A General: Location Map shall he provided in suffic.ent data tb identify drainage flow entering and leaving the development and general drainage patterns. The map should be at a scale.,sufficient to show the path of all drainage from the upper end of any off-site 'basiris to major drainagewaysv The map shalt identify, any major construction development, irrigation ditches, existing; detention facilities, culverts; storm severs.):: along the `entire' ath p of drainage. * Existing and proposed contours at two foot intervals,:: closer;: if needed, to accurately show grading and drainage patterns. The icontours should extend at least 550 feet from all project boundaries, .further, if necessary, to show, the drainage relationship with adjacent property * .; All existing vegetation accurately located. All prominent features accurately 3epicted. Prominent features include streams, canals, ponds, wetlands major utilities overhead electric lines or underground utilities that cannot be practically relocated), etc. * Soils information of the site shall be presented:' Discussion shall .include rainfall and ', wind erodibil,ity problems, Zim.x tin g characteristics and suitability of the. soils for development . Information shall be presented concerning conceptual plans for controlling wind. and rainfall erosion, and the effectiveness of establishing vegetation. * Proposed landscaping: berms, planters, shrub Beds, trees,:; etc. * Proposed building ,footprints, parking lots, sidewalks and. streets.. * AZl 100 ': year. floodplain and floodway, boundaries and:'haaa flood elevation lines clearly labeled To :the extent possible, this also :applies to detention areas 1.ar nearby irrigation canals:! * All watercourses, rivers, or creeks which infringe upon the property or which are located within 150 feet adjacent to the property must be shown on the plans. January 1991 2-1 DESIGN CRITERIA * All drainage ways, streets, arroyos, dry gullies, diversion ditches spillways, reservoirs, etc., which may be incorporated into the storm drainage system for the property shall be designated. * All irrigation ditches, laterals and structures shall be shown. * All required on-site detention areas, including notes indicating the approximate area and volume of the facility. * All plans shall include a note indicating the proposed outlet for the storm drainage from the property, including the name of the drainage way (where appropriate) , the downstream conditions (developed, available drainage ways, etc.) and any downstream restrictions, such as an embankment which may cause flooding. �.2 .F,�nal Subm '�tal Requ,ire�te�tts All analyses and designs of storm drainage systems within the City limits of Fort Collins shall be submitted to the Development Center for review and must obtain the city Engineer's written approval prior to any phase of construction. Submittals shall consist of two parts: (1) Six copies of an engineering drawing or set of drawings containing the information required in Section 2 .1 .1 "Engineering Drawings" of these specifications; and (2) Two copies of a report supplementing such drawings as described in Section 2 .1 .2 "Drainage and Erosion Control Reports" . In the case of storm drainage required for all subdivisions, including planned unit developments, engineering drawings described above shall be incorporated into the utility plans accompanied by the supplemental drainage and erosion control report when such utility plans are submitted to the Development Center for the City Engineer's review and approval . 2 .2 .1 Engineering Drawings All drawings shall be prepared by a licensed engineer and shall be on a reproducible medium of one or more sheets with an outer dimension of twenty four by thirty six (24 X 36) inches. Please 'note tilta tea.ribi tlaa grading plan and erosion control plan can be Combined: 2 .2< 2.1 Drainage The drawing shall contain the following information: * The name of the subdivision or project. JANUARY 1991 2-2 DESIGN CRITERIA * The date of preparation, the scale and symbol designating true north. * The boundary lines of the subdivision or project, right of way lines of streets, easements and other rights of way, irrigation ditches, detention ponds, watercourses, and lot lines, with accurate bearings and distances. * Designations of all streets and other rights of way, including dimensions and names of such streets. * The location and dimensions of any easements . * The boundary lines of all floodways and floodplains . * Existing and proposed contours at two foot intervals. * The location, size and type of all storm sewers. * The location, size and type of all inlets, crosspans, manholes, and other storm sewer appurtenances. * Profile views for all subsurface drainage facilities showing their size, slope, lengths, cover and relationship with existing utilities . * The location, size and type of all culverts, including box culverts, and of all open channels, including irrigation ditches with profile views where applicable. * The location, size and type of all existing utilities. * Cross-sectional views of all open channels, including irrigation ditches, trickle channels, spillway structures, etc. These views shall include applicable water surface elevations such as the 100- year storm depth, 2-year storm depth, and irrigation operating level . * Detention ponds shall show capacity, discharge, and high water level . * Water surface profiles for all open channels * F?fnishetl ' por. and :.<grade 'at inundation elevatzo�ss of alb .txuxld�ngs ; In zes zdentiax d.0 e2 pm nts aXsu pxavide lot corner elevatons Spot, e :e�ratians sal 3a critiea3 far: proper drainage: : (e g� inlets:; crosspans, spillways :; inlets/outlets of manholes culverts, and storm sewers) .; JANUARY 1991 2-3 DESIGN CRITERIA * Drainage subbasins ' and concentrat34n points for the developed site clearly delineated and labeled A; summary table of site hydrology,. including offsite flows entering the site, fcr the minor_and ma�4r .design. storm.:, * 1i tah le, ar chart showing. a. Grass ' I platted area xn .acres (includes R.O W, area) b. Gamposxte ratacnal srrrrotf cae€ficzent for the gross azea,. based on thexactual;sxte.plan, not the zoning. c. Net platted area in acres (excludes d. ;Composite runoff coefficient or, net area (based on ,site plan) . e. 'Onsite'detenton -Cu feetfacra 2aased on gross area: f. '!Drainage basins) . in whI.ch the project 2. .2. Eroszon Control' The drawing shall co} taro the folloVanq information:: * The namefol the! subdiuisxon or project«: The date of preparation,. die„ scale ens symbol designating true north * The boundary lines o the subdiuisian::oz protect; (; rzght of way lines: streets, easements and; athes rxhts of way, irrigation ditches, :: detention ponds,: we ercou.rses, and o . Itnesx with .accuzat Frearxngsand' distances * Desigl2atoXls of all streets and other z zghts of way, including dimensions f such streets The location and dimensions of and easements * Tie bodnaary, lines of aII :; floodways and floodpla 'ns * Sxistingand proposed contours at two foert intezvals. *,Th'e location of all storm sewer inlets ar?d outlets , .., .Drainage; �subtsasins € and € conce..... a (design}:?;points for� the developed site. * The location .and identification of ..a11 proposed structural and vegetatxve` eroszon control methods.: JANUARY 1991 2-4 DESIGN CRITERIA * A summary table of Ferformancei;Standards an3 Net; EFF values , for each mayor drainage basin.: * A summaryj.table Zisti.ng(,the eaaczty.of eac2 sedimentation. pond * Installation "cFiedule usang _standard B©r * Standard detail's of ; structural eros.Lan ... control methods * Technical €nol .rol * Technical; notes, for vegetatirre erasion control methods. ncZudricj soil preparation;: fertilizing, seed mzx, planting and mul'chi.ng. ....................... 2 .2 .2 Drainage and ErosionjControl{ Reports Supplemental reports shall contain the information and calculations supporting the detailed engineering drawings . Such information and calculations shall be presented in a neat and orderly fashion to facilitate review. All reports shall be stamped and signed by a licensed professional engineer and shall include a cover letter indicating the date, the name of the project or subdivision, the engineer or engineers designing the system, a statement of compliance with the Storm Drainage Design Criteria, and the Design Criteria publication date. 2 .2 .2 .1 Drainage Report The drainage report shall include an analysis of the area under consideration in reference to the zoning, historical and developed conditions, existing topography, contributing runoff from upstream area, control easements or features, and continuity with a master drainage plan or with the existing drainage. Natural drainage ways are to be used whenever possible; however, when any irrigation ditch is to be used as part of the storm drainage system, the drainage report shall include a thorough hydraulic engineering analysis demonstrating that such use is without unreasonable hazard. The report shall contain the hydrologic analysis including areas, storm frequencies, rainfall intensities,, runoff coefficients, times of concentration, adjustments for infrequent storms, and all runoff computation. JANUARY 1991 2-5 DESIGN CRITERIA if the Colorado Urban Hydrograph Procedure is used, the synthetic unit hydrographs derived shall also be included. Calculations of street flows for both initial and major storms shall be provided with regard to street encroachments, theoretical capacities and allowable gutter flows. Should storm sewers be required, the report shall include the calculations for the Rational Method for Sizing Storm Sewer Systems described in these specifications or an equivalent method. Engineering analyses of all culverts, open channels, and box culverts shall include the design criteria, computation and figures required in Section 6 "Culverts" and Section 7 "Open Channels" . For any detention facility design, the supplemental drainage report shall include a soils analysis and water table elevations. All calculations, mass diagrams, and/or hydrographs (methods used shall depend on the area of the basin to be analyzed) required to size the detention facility and determine its discharge shall also be included. Calculations for specific detention times shall be provided if required by the City Engineer. The volume calculations submitted shall be based on the formula stated in Section 9.2 "Storage Requirements" . Erasion, e nt . eperzt The erosion cantxvt x�paxt shalt .znc,Iude an anaIysxs t the `area usder.eonsxdsxatian in reference, to detielaped "coNalt oz�s, s�txtd a.."d rainfall .srodibi t , proposed a*Fas eros�az cantr+�l methods ... pzopased xaiafa�.� ezos,zar control me:thads ; Analysts of wsnd erasaan;aantrol shaI �nctute srr31 types:and idgntlxy ink maxluttm�rzxsheteerl d�.stances Por ttt8� s�bi3�v�SSEs2� ,o� �arrx�ec sorts wzthzn the project sha�2 be xdent Ue+ wibY regare7 to tl?e tP�ssd eradilzlatp ?zauss=ss x�eit��ied frame •=the w�,�e� erod,�blt:.�ty .m located at ,the-ercf of :tlixs daeumenC JANUARY 1991 2-6 DESIGN CRITERIA Control of rainfall erosion shall be analyzed in a manner that clearly demonstrates an understanding of how temporary and permanent mitigation methods are used to control sediment. If temporary methods include use of sediment traps, calculations shall be included that verify the desired holding capacity. Included with the report shall be the Performance Standards as well as an analysis of the effectiveness to contain erosion from rainfall . All calculations shall be completed using standard forms SF-SA and SF-8B, respectively, included in these specifications. For establishment of dryland vegetation, discussion shall include soil types, seed mix, planting dates, and mulches. If temporary vegetation is utilized, a detailed discussion shall be provided to justify their use . An installation schedule shall be developed using standard form SF-SC that clearly delineates when all erosion control methods shall be implemented commencing with overlot grading through final build out. The installation schedule shall be the same as shown on the engineering drawings. 2 .3 Security Construction of the erosion control measures shown on the approved erosion control plan shall not begin without the Owner submitting proof of deposit of security to insure rehabilitation of the disturbed land. A performance bond, irrevocable letter of credit, or cash escrow, acceptable to the City of Fort Collins, and naming the City as the protected party, is required. The amount of-the security shall be based on one and one-half times the owner's estimate of the cost to install the approved measures, or one and one-half times the cost to vegetate the disturbed land to dryland grasses (see Table 7.1) based upon unit cost determined by the City's Annual Landscape Bid, whichever is greater. In no instance, shall the amount of security be less than $1, 000 . Should the pravis�ons':of the;appraised er©ssoa. control Zan not be ' complied 'With,.. the Cityi may call ,the. seeurzty In the event :that:tfxe City calls the security, it is nat the. City's fasten, to routinely a dffiinsstar the 'construction of the Measures` srhovm on the erosion control glans, however, tke City reserves the right to'enter ,upon the land!ta have the measures constructed and make 'repairs as necessary.; JANUARY 1991 2-7 DESIGN CRITERIA Such bond,. qas esercaw, of rrevocab a Zettex o credit, shag fCrther.,;guarantee the continued rrtaintenancex aic�' reglaeement of the u�easures for a per cd of ,ane agar aftex installation Qf truc.s tural 'measures and`: two years after insCallat2on :of vegetative measures,; Upcsu aarepta�zce :'by the' �.�ty :<o� the initial ;xnstal;iat2ars';; of the measures tie sscrttt2t shall tse redrxced. to as percent (25;�� o�,M tote act�xa ;cast cst suc7 measures, Any' bond,; cash escro�! or 2rrevaealxie Setter of credit shaZ.� be rslelssed LljoA cer.Ei.�Ycat�,atr tsy 'tke City that the required areasureis have ;been dompleted and,ma2zxtasned =n accordance,wi#^1x the„erosiazz contro.� plat 2 .� Appea.2s Pzoces The purpose of these criteria is to set forth certain rules and regulations -which provide some assurance that the health, safety, welfare and property of the City and citizens shall be safeguarded and protected through the proper control and drainage of storm and surface water; and, further, to assure that there shall be uniformity in performance with respect to design and construction of all drainage facilities. Consequently, any time that it can be shown that an alternate design analysis or procedure shall provide performance equal to or better than the suggested methods of design analysis, said alternate may be submitted to the p1reC.Goz aP. utfxty Services recommendation for his review and recmendation for approval . If the decision by the fireetoz of LTtiZit�? Servioe, is negative, the decision may be appealed to the Storm Drainage Board and further to the City Council . JANUARY 1991 2-8 DESIGN CRITERIA 'E: Shaded portions are new text. SECTION S. SEDIMENT CONTROL STANDARDS 8 .1. wind and Ra nfall' Erosion Control These Criteria shall apply to all land within the City of'Fcrzt Collins,: including any pub3ic. 2ands These Criteria sha13 apply to all facillblaa-aonstructed on :—rivate land, public right-of-way, easements: dedicated for : puls4xc use, private roads and to all privatey, publicly, and quasi-publicly owned and maintained facilities, excluding.: 1. Emergency work 2. Residential lots Less than 10,060 square feet in dares except when constrnrctien !activities a:re. within 50 !feet of the outer limits of sensitiue : areas ' includusg floodplains, slopes, riparian cprridors, lakes„ irrigation ditches,, etc: In its interpretation and application, the Criteria shall be regarded as' the mitnimum requizetaents for the,protection of the public health, safety, and welfare of the 'residents of the City,' Whenever a provision of the".,';Criteria and' any other provisions of the City of Fort Gollins; Subdivisian 32egu1ation4 or, any kind (whether federal, state, .local or special. district) , ;contain 1.any applicable restrictions covering any of the same subject matter, whichever provisions impose higher standards or requirements shall govern. Alternatives to the provisions of `these1criteria may ke approved but the ;burden. of proof that the alternatives:: are equal or, letter ;'is the responsibility of the Japplicant Detailed information on ;eroslan control can be:, found'. in the Erosion Control Reference, Manual (Reference Manual) .; It is the Cty1s intention not to disturb the natural balance of watershed sedinentatlon and erosion nor require eroslo�t control, in excess of: the natural system.! Erosion control measuresmust be implemented:'on,::.eve:loping and redeveloping sites such: that the following; des.ign standards will be met!; A 1 . Dree7eling or during construction, temporary erosion control measures shall be installed such that ;the maz1M:0:r amount' of sediment-discharge by either wind or water erosion, shall not exceed :the historic sediment dlscharg due to the 10-year rainfall event, by mare than 1 percent.: JANUARY 1991 8-1 DESIGN CRITERIA Z After,':construction;: perman@n't erasion dontroV.measu s shall be instal Zed such that the mayrimum amount o sediment discharge, try either windwIlar water eraion,;; shal3 net exceed the historic sediment discharge . The G'txterxa and equations, if ;apFlied ccsrrectly, wiTi result in an eraripn eontro3; plan,,: whlch: meets the 'standards ; Constructictn: activities shalt comply wrth the appraised erosion contx+�.� plan« & 1..1 i�xnd Erasion Control' Winn @rosion shall be contra3led by ;use of structural andy'ar. vegetattve meth ets.; 8.11.1 Exclusions ....................................................................... Sites May be excluded ftam i�11R� erosiar control requirements if they meet at least one ar the following cziteria, l Thirty five percent oz . mare cf` ! �e unprotected surface is actattaed by coars r e sail paztcles greatQz than 2 m it die@ter ( .e. graze@l, .stAnes Z etc J .: 2 Sites of Yacre or less.:: � Sites withunshe3tered distances (distance Unbroken .by a Tv nd barrierl parallel xto the preuailing wind direction of less than the 'tvalues in Table 4 .1 .: .......1 pequizements all other sites shall be Protected from ;Wina erosion .by one! or more of the following: 1:. Live vegetation :evenly distril ed3ouer 3a� €af the: entire dist�xbed arrea.:;: 2'. Crop zesirlue evenly distzlbuted over 5n of :she entire disturbed area.: 3. . One half "r:ton/acre hay or straw i*ld prppezl y anchor@3. 4! Cne(half ton per ;acre paper pr wood iber hydraulic mulch,; applied according to manufacture r,s :specifications.;. JANUARY 1991 8-2 DESIGN CRITERIA 5 . Surface bindinq materials applied according to manufacturers: specifications= 6. Arough soil surface With ridges and wind barriers, both perpendicular to .the prevail, nq northwest 'wind direction A wind barrier weans a snow: fencetrees, shrubs, grasses, screens, natural terrain•,: or other. natural cr ';manmada s structure ,. which is greater than one ;toot high and causes wind-suspended sediment depos�t�or to occur. Barriers u'.ili be installed' in a( northeast to southwest direction with a maximum spacing a5 shown below. The most downwind barrier will be ,', placed inside the site boundary at a distance of no more than,10 times the barrier height::: Allowable Wind 'Barrier Soacina Maximum Barrier Wir_d Eredibility Zone" Soacina Low, 1Q0(3 Peet Moderate 200 feet High 50 'feet. Us 11 e the attached Wind Erodibili'ty Zone Map to determine which one the s.Lte ...... is in . Structural methods shall 1be inspected during 'Novemlaer and hfarch to ensure b4rrlerso.. are in placeand the soil between barriers' is raughenei. IP 3t1� vegetative ground . cover : hasiecome '. sufficiently established, the barriers may be removed;:; upon approval day the Cit�r of Fort Collxlxs 8 2 Raxnr'all Sros on control Rain.taZ� erosoa control atethods ;shall he used, durizi t.ArY1 tough October when precipitation is most 12ke1y `pa accctz , `�ontral aE sedslrtent due to rainfall erosio2 Shall .be . .aecgmplished by ',:use of structural ; and/a2` vegetatzsre methods. JANUARY 1992 8-3 DESIGN CRITERIA 8 l 2 1': structural Measures Structural methods which have; proven to be successful include the foilowinga, * Sediment traps Gra. el filter` xntets *: straw bale barriers '* miter fence` * Surface roughening * TerraCeS * Diversions * San2 aq barriers Sediment traps shall be designed 'to the following crxterfa: 1. . volume sha12 be 2lJc? �+d here or contributing watexshed. 2. Beginning basin depth sha1.T be no more Chair S feet from spillway flow xno to �attam of pond. ; . 3 Excavation for sediment storage shalZ,be calculated by: SedT 0.74 x LR y x,A� 1 z ficln 8 2 Where SedT total eubi Bards or 8e6w ernt anticipated during a ItT year stt�rm evemt fear baregropnd : ZoadZzzg ratzo taz baz° ' Appenground conditions See W dra...... .axea nacres} 4 Embankments and spa2Zways sha11 lie pzoperly designed; andk • cnnstruck�d including compaaQn control ConstiuctMori and ivaintenance informat an r-b structural 'imeasuxes is.< , pzovded in the construction details. 'Additional backgrounc information can be founid in :the Reference Manual . JANUARY 1991 8-4 DESIGN CRITERIA 8 al .2 .2 ': Vegetative Measures Permanent erosion; control is: Ach1eved.'.,..,q.bV. establishment of grasses'<and is preferred to structural eresion control methods." Vegetative methods include the following ' ................ ......... * Dry and grass '! * ' Mulches * Temporary grass * '. Cover crops * Erosion control: blankets * Sod Design information is provided in Section 11 Landscaping. Additional: background information: can be found in he Reference Manual . 8;i1 2.3 Performance Standards Performance Standards shalt be 'detersrtined far. each .'major basin : used in drainage reports submitted to the ''City- of.-Fort Collins far approval. "During Construction" and "After Construction" Performance Standards are calculated separately. Table 8-A identifies Performance Standards fpr the City of Fort Collins to be used for "t?uring;Construction" activities. "After Construction" Performance Standards are calculated by dividincr the values :used ifrom Table 8-A bbr 0.85. Table 8 A is' based: the< following er�ua a PS = (1 - Q .OS x LR�,�LRbj X 85 Egn 8-2 Where : PS: = Performance Standard ( !}, loading ratio for historic conditions LRb loading ratio for. bare grou c conditions Ps7in4 ;=parameters from the drainage analyses;' the following, steps; will determine: formance Standards far each major drainage basin whxle using,-:Standard, Form A (SF-A) . JANUARY 1991 8-5 DESIGN CRITERIA i 1 • 1 I O I V C' Ln LP Ln 1 ' I Ln 'I ggqqq 1 I O I m C+ C) m C O O O C O 1 I I 1 I O I CCCCtD lli to Ui lCf l.C) I 1 C l g q q q q q q q q q I ' I C 1 q Q1 L, C101 Q101 C101 Ct 01 .C1000 1 1 1 1 1 M l g q q q q q q q q q q q q q q 1 I I O I I� qq gQ)O� CL 01 Ot OL OI Ol Ci Q101 Ott 01 C� O1 1 1 I 1 I N l g q q q q q q q q q q q q q q q q q q q 1 I I 1 I O I O M c Ln LD tD Ic Lo h h h h h h h h h I� n h g q q q q q � . I I 1 0 1 e T C co c C C c' oo C CO e t V c• C c' W Q M V C C M M 1 I '•1 I 0003 q q q q q q q q qM q q q q q WW q q q q q q q 1 i O I g N M � t0 lii Lff•l0 tD lD l0 lD l0 h h t� h h 1� h h h h g q q 1 O I 1 1 G I 1 g q q q q q q q q q q q q q q q q q q q q q q q q q 1 C I O I C I LDO NMR ID LD tD IC <D LD to <D LD LDhhhh O I g V I 1 g q q q q q q q q q q q q q q q q q q q q q q q q q 1 o I O I Cm .--1 N MMc' CCQU•1 Ln Ln UC lt'f LA Ln 11') LD LD LD LD to ID LJh 1 to I 1 1 Z I f� 1 MMQCCt d' V' C c' cr C' � C' C cf etCC � � <tCc' C � V 1 .-• I 1 g q q q q q q q q q q q q q q q q q q q q q q q q q 1 J 1 1 1 J 1 O 1 O 1 O g C .-•• .-• N N M M M M -�r C' C• Q C' t n t n l t') U'f 'l� to 1 O 1 1 1 I 1 g q q q q q q q q q q q q q q q q q q q q q q q q q 1 C I �C 1 Ln " Lo hq CLOO .--1 .•+ .•'1N NNNNMMMMM V CC V d' 1 O 128 `n LL I LLD I NM MMMMCCc' V cCR V � V vvc V �C V Cc V 1 00 C I W O 1 O_ LP I .•-1q U1 tD lc LDhhh q co qq q q Ct C1 CS C C 000 1 -2 W I O 1 • I a 1 Jl I N N M M M YM co M M M M M P9 co co fM fM co cc co M Q c' C cc C 1 q N I N I g q q q q q q q q q q q q q q q q q q q q q q q q q i F C I C t LD LDq C .+ NM LD LD LD Ic to q q co m 01 i C 1 1 I C 1 V 1 .-•�N N M M M M M M M M M M M M M M 4 ,4 M M M M M M M 1 Z I i g q q q q q q q q q q q q q q q q q q q q q q q q q l Q I I I NF LD Ln h. q O N N. LM M. M c d"V LA L9 LD LD LD h. . W I I g q q q q q q q q q q q q q q q q q q q q q q q q q l U 1 1 1 Z I a) 1 MNIOq QIO r•1NNMMM V d' Lil to L!') tD LD IO LD LD 1 G I 1 � I M I 0 .--1 .-1 .--1 •--1 N N N N N N N N N N N N N N N N N N N N N 1 C 1 I g q q q q q q q q q q q q q q q q q q q q q q q q q l O 1 I LL I Ln 1 LD 611 Ol N Md. LD LO h hh qqq Q1 D1 Cl mCL CL000000 1 C 1 1 1 W 1 N 1 01 C O N N N L1 I 1 h g q q q q q q q q q q q q q q q q q q q q q q q q l 1 O UC> O M t A L O g q M,0 0 0 N M M M M M M 1 I N I q Qt O O O O O O O '-1 .r ti '•1 '-1 .--1 �-•1 .+ .+ ti ti .-1 r-1 .ti '-1 .••� .-+ 1 1 1 h h g q q q q q q q q q q q q q q q q q q q q q q CO I I 1 1 LC1 I g N q •--I c' L1') Ct C1 O O M M M M M 1 q q Q1 T01 Q1 O; OI C10000000000000 00 1 I g q q q q q q q q q q q q q q 1 1 I 1 I O i t0M O C hLT O tiNMM c' QLn L2'f Ln Ln b LD LD to LD bt0 1 I 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . g q q q q p q q q q q q q q q q q q q O� 1 1 I 1 1 LD 1 c1 c• LD I, q q l, �I� ILD LD LD LA M M N N CQ C\ LD ll G1- LD 1 1 1 I O I ON N N NN NN NN NNN 00 1 1 I hhhh 1� hl� h hh hl� hhhh hhhhhhhht�h 1 S 1 1 CD L C.o � t C O C 0 0 0 00 0 0 0 C CD 0 0 CD 0 0 CD 0 0 0 0 0 0 1 1 C - H I C C C C O C O CD CD O CD CD O C O O O C C O O C G C O I I JZLi 1 .-•+ NM Ct.O 1p hq ClO r+ N MCtt') U hgC"LC aT OL7 C LfO I I lL W�..� 1 .-• .n •--� .r .r .-� .-+ .--i 'r r-i N N M M C C In 1 1 J I 1 JANUARY 1991 8-6 DESIGN CRITERIA 1. Evaluate final grade contours and calculate an average'. weighted flow path length.,us the following.equatlon.j X,b = E (L56 x ASb}1 ZAse where Lb =, Average,.,. flow path length:;i {feet) Lsb = Sub-basin flow path length (feet) Ash = Sub-basics area (acres} 2 . Evaluate final grade :::contours:.:- and calculate an a:vezageweighted slope using the follbVing equation. Sb = S{Ss� x Asy}/E�s� gn . 8-4 where ; Sb, = Averageslope if$} L = Sub-basin slope (�} Asb = Sub—basin area (acres) 3 . Find Performance Standard by using Table A. �# . Determine the eradibi3ity zones} from the maps at the end of this document. Effectiveness The city of Fort *Collins requires that all submittals demonstrate that methods proposer far erosion contF01 shall be effective sn reducing sed%srcent:: For rainfall ezosianA effectiveness shall be calculated using the following equation and Standard Fars B {SF B} .< FiFF (1 X.P] X 1aQ Eqn 8-5 Where EFF ='.E€fectiveness (a} C = :C-Factor P = P-Factor Cover: €actor (C Factarj ualuesrepresent tf�e ratio-of, sil loss.' from Iand:. under..*.. ."; reated conditions 'j (e 4., vegetation, mulch} to corzespandirtg losses ;lfrom ; bare ! .gzduna conditions.'; C-Factor Values arex.assocaated with vegetation,,: scaulches, sealanfis: and pavement aspillustrated in Table B and Figure A JANUARY 1991 8-7 DESIGN CRITERIA Table 8-8 C-Factors and P-Factors for Evaluating EFF Values . Treatment C-Factor P-Factor BARE SOIL Packed and smooth . . . . . . . . . . . . 1 . 00 1 .00 Freshly disked . . . . . . . . . . . . 1 . 00 0 . 90 Rough irregular surface . . . . . . . . . 1 . 00 0 .90 SEDIMENT BASIN/TRAP . . . . . . . . . . . . . . 1 . 00 0 . 50( 1 ) STRAW BALE BARRIER , GRAVEL FILTER , SAND BAG. . 1 . 00 0 .80 SILT FENCE BARRIER . . . . . . . . . . . . . . 1 . 00 0 . 50 ASPHALT/CONCRETE PAVEMENT . . . . . . . . . . . 0 . 01 1 . 00 ESTABLISHED DRY LAND ( NATIVE) GRASS . . . See Figure 1 . 00 SOD GRASS . . . . . . . . . . . . . . . . . . . 0 . 01 1 . 00 TEMPORARY VEGETATION/COVER CROPS . . . . . . . 0 . 45 (2) 1 . 00 HYDRAULIC MULCH @ 2 TONS/ACRE. . . . . . . . . 0 . 10 (3) 1 .00 SOIL SEALANT . . . . . . . . . . . . . . . 0 . 01-0 . 60(4) 1 . 00 EROSION CONTROL MATS/BLANKETS . . . . . . . . . 0 . 10 1 . 00 HAY OR STRAW DRY MULCH A t Ilantin rass seed , apply mulch at a rge % tons acre minimum) and adequately anchor , tack or crimp material into the soil . Maximum Slope Length ( o) ( feet) 1 to 4 . . . . . . . . . 0 . 06 1 .00 6 to 10 200 . . . . . . . . . 0 . 06 1 .00 11 to 15 150 . . . . . . . . . 0 . 07 1 .00 16 to 20 100 . . . . . . . . . 0 . 11 1 . 00 21 to 25 75 . . . . . . . . . 0 . 14 1 . 00 25 to 33 50 . . . . . . . . . 0 . 17 1 . 00 > 33 35 0 . 20 1 . 00 NOTE: Use of other C-Factor or P-Factor values reported in this table must be substantiated by documentation . ( 1 ) . Must be constructed as the first step in overlot grading . ( 2) Assumes planting by dates identified in Table 11-4 , thus dry or hydraulic mulches are not required . ( 3 ) Hydraulic mulches shall be used only between March 15 and May 15 unless irrigated . ( 4) Value used must be substantiated by documentation . JANUARY 1991 8-8 DESIGN CRITERIA Table 8-B C-Factors and P-Factors for Evaluating EFF Values ( continued from previous page ) . Treatment C-Factor P-Factor CONTOUR FURROWED SURFACE Must be maintained throughout the construction period , otherwise P-Factor = 1 . 00 . Maximum length refers to the down slope length . Basin Maximum Slope Length ( o) ( feet) 1 to 400 . . . . . . . . . 1 . 00 0 . 60 3 to 5 300 . . . . . . . . . 1 . 00 0 . 50 6 to 8 200 . . . . . . . . . 1 . 00 0 . 50 9 to 12 120 . . . . . . . . . 1 . 00 0 . 60 13 to 16 80 . . . . . . . . . 1 . 00 0 . 70 17 to 20 60 . . . . . . . . . 1 . 00 0 . 80 > 20 50 . . . . . . . . . 1 . 00 0 . 90 TERRACING Must contain 10-year runoff volumes , without overflowing , as determined by applicable hydrologic methods , otherwise P- Factor = 1 . 00 . Basin Slope (o ) to 2 . . . . . . . . . . . . . . . . . 1 . 00 0 . 12 3 to 8 . . . . . . . . . . . . . . . . 1 . 00 0 . 10 9 to 12 . . . . . . . . . . . . . . . . 1 . 00 0 . 12 13 to 16 . . . . . . . . . . . . . . . . 1 . 00 0 . 14 17 to 20 . . . . . . . . . . . . . . . . 1 . 00 0 . 16 > 20 1 . 00 0 . 18 NOTE : Use of other C-factor or P-factor values reported in this table must be substantiated by documentation . JANUARY 1991 8-9 DESIGN CRITERIA ESTABLISHED GRASS AND C-FACTORS FORT COUBS, COLORADO 0.40 ............. ............. .............. ......... .............. ......... ..:.............'.............I.............. 0.35 i ............ .......... .............. .... ..................... ............. ............. ............. ............ .............. ...... ............. 0.1 ............ ............. .......................... ......... ....... ..... ....... ...... ..... . 0.25 ..... .......... C) ... .......... .......................... ....I...... ............. T----------- 0.20 ............. ... ......... ........... ........ L 0.15 ............. ............ .......... ..... ......... 0.10 ... ..... ....... ......... ............ ............. ... ........... .. ...................... ............. fss;�� 1............. .......................... ............. . .... .......*­.. ...... ------------ ............ 0.05 ............. .............I................. ........................ . 0,00 0 10 20 30 40 50 60 70 80 90 100 ESTABLM GRASS MOUND COVER (7o) FIGURE 8-A JANUARY 1991 8-10 DESIGN CRITERIA Practice factor (P;-Factor) values represent the ratio oflsoil loss with a general surface condition (e g., straw bales, sediment basins): to soil loss from disturbed: bare : ground conditions. ; P-Factor values are associated with 'structural erosion control methods as illustrated in Table 8-B: The falloving equation shall '' be used. to; calculate net effectiveness for each major; drainage basin. EFFnes = E(EFF % A �EAsb Eqn 8-6 THE 'NET EFF=1VENESS OF: SI BB M1WS SHALL BE EQOAL To OR GRERTE& THAN THE PERFORMANCE STANDARD. 8.1 .3 Installation Sequence Once an erosion control plan has'. been 'developed, an installation sequence shall.lse completed using Standard r[Far C '? (SF-C) . The erosioix control installation schedule shall!: be coordinated with the; construction schedul er.: 8.1.4 Elements: of an Eresi€in Control Plan An erosion-Control. plan shall address how movement. of sediment' due fta both. grind and::: rainfall citl :be mitigated. Fortunately, controlling rainfall erosion often results. in controlllhq wind erosion ' Consequently, :an erosion' control;; plan ; for rainfall' erosion 2. usually completed first'.:: Control of rainfall erosion is aecpmplished by implementing structural acid/or vegetative methods_:; Structural methads . .stapcovtng sediments hereaa vegetative methods1�1 prevent ;initial sediment movement.. When possible ; vegetative methods ,are preferred since they, are usually permanent. Development of an erosion :control plan, 3nclurles the fa114wing steps:,:. 1 . Determine the rainfaZI Performance Standard for each major drainage basin. 2 . Eval'iate each subbasin to determine where structural'.. and/or vegetative erosion Icontrol methods are to be used. JANUARY 1991 8-11 DESIGN CRITERIA ....... . ..... . .................... 3 . For each major. drainage basin, determine he net effectiveness of erosion control methods proposer within each subbasin. The neteffectiveness shall be equal :. :to or; greater than., the,:, Performance Standard:: 4 . For >each +aubbasir., evaluate proposed rainfall erosion control methods to determine <whether criteria for controlling wind erosion are being met`:' If wind erosion control 'crrlteria are not beiing meth implement one armore of the methods de-Scribed..s Section 8 . .2: 5. Develop an installation schedule which 2 coordinated with the construction schedule. 81.5 Example An erosion control % plan shall include methods to control!: both wind erosion and' rainfall erosion': Since wind erosion ' cantral often occurs as a result c providing rainfall erosaon.cantrz:I, evaluation of thg latter is completed first The fallowing i11us€rates. how to !demonstrate comp anrre with. the; City of Fork Collins' erosion caitrol criteria. Calculations.ara illustrated on Standard Forms A and 8 (SF-A and .... ..... ......... A 23 .5 acre parcel of rangeland (so. cover of grass is to be developed nta single family, ihousing called oxt Collins Meado�rs Before averlot ;gradlzg oecztrrer, the" maximum overland flow. distance was' 4S5 feet and the average slope was 2 .5 The sail credibility zones are moderate ;sfor both wind and rainfall , Upon development„ -the site shall consist. of three subbasihs having the fallowing drainage::parameters .; Subbasin Ai: Area - 7.7 acres ?ierage Sl ape;; _ .1.2 Flow path - 175tT feet. subbasin A2 :. Area 9.9 Acres Average slope;:: z Flow path = 1tl45 feat Subbasi'h A3: Area - `S.9 acres Average slope:' 2'.6 Flow path = 2410 feet JANUARY 1991 8-12 DESIGN CRITERIA Determine the Performance Standard,., develop an erosion control plan and calculate the net EFF Value .` Development of an erosion control .plan is exemplified by following the steps outlined in Section 8 .i'.4.< STEP 1: '' Determine the Rainfall Performance Standard By using, Standard Form A (see completed form at end of this section) and the above information; it has I been determined PS 80 .2%. Therefore, an erosion control; plan shall be developed 'to, contain 80 .2$ of the rainfall' sediment that would normally fllow off a are gsaund site daring a'.; 10-year, or `;less, precipitation event. STEP 2 Evaluate Each Subbasin 1 : During overlat grading, a 1 .46 acre-feet (23.5 acres x 100 cubic yards/acre) sediment trap shall be constructed) which will eventually be a detention pond. Use of equation 8-1 indicates that about Z3$ cubic yards. of soil can be anticipated from the bare ground Isite:> if a 10-year rainfall event occurs. 2 For the first year, cranstruc€ion of homes shall': occur in Subbasin Al only. Twenty nine .percent :of the land shall be in paved roads and/or cement walks with ,gravel filters to be installed at inlets.; 3'z Subbasin A2 shall have 'S% of the land in curb and gutters a temporary cover crop planted ar_d straw bale barriers placed in the. rozgh cut roads . ... .. . ........................... 4 Thirty five percent of Subbasin A3 (shall ' not be graded and .,all disturbed land': will be planted ids perennial grass using hay mulch . S2EP 3: ' Determine the Net Effectiveness Using 5F-S (see completed €arm at end af:.this section} and informaticn found in the erosion control..Bolan, i has been determined the net EFF is 82.6's. Since net ,E'F'F is greater than the required Performance Standard, the proposed erosion control plan is in compliance with .... ....... the criteria .. ....... .. ..... ........ .............. . ................................................... STEP 41. RevleW lor 'wind Erosion:. 'Control, Once the rainfall =-erosion control plan has been demor_strated to be in compliance,; the entire ;plands evaluated to determine if proposed methods shall .. JANUARY 1991 8-13 DESIGN CRITERIA control,;' wind ; erosion. Thls ._ ,s accomplished b analpzing eack subbasin. Subbasiu Al: The Zand sha1Z remain' bare anti: construction of Names ;Therefore, to controliwind erasion; the ground shall .he roughened to farm south to east ridges an<t a perimeter barrxerjinstaZZ.ed along the entire "south to east houndary. . Additional barriers shalZ..be installed aZanga south to east. direction where unsheltere distances exceeci.2oct feetx Subbasi A2Y A perimeter barrier shall be iris taxied along the entire northeast to southwest boundary. Additional barriers shall be installed along,a northeast to southwest direction where unsheltered distances between: barriers elfCeed 2E3.Q feet::. once vegetation becomes: established, the Barriers shall be resrtaved after approval from the Czty of Fort;Collins xs oFtaxned 5ubbasxn 113 tFo further action 'is needed, since live vegetation and two :;tonsjacre hazy mule shall lc usedover the. entire area.; 1?eveap an 3nstal3atxanSequencs An installation schedule ishaiZ be completed using Standazd Farm;! C (SF=cJ whichs coordi,� ated sixth the constrrct :on. schedule. JANUARY 1991 8-14 DESIGN CRITERIA RAINFALL PERFORMANCE STANDARD EVALUATION ---------------------------------------------------------------------� 1PROJECT: Fort Collins Meadows STANDARD FORM A COMPLETED BY: JSF DATE: 6/15/91 1 ---------------------------------------------------------------------I IDEVELOPEDIERODIBILITY1 Asb I Lsb I Ssb I Lb I Sb PS ISUBBASIN I ZONE I (ac) I (ft) I (q) ( (feet) I (Y) (a) --------- ----------- ------- ------- ------- ------- ------- ------- Al MODERATE 7.7 1750 1.2 A2 MODERATE 9.9 1045 2.0 A3 MODERATE 5.9 2010 1.6 23.5 1518 1.6 80.2 --------------------------------------------- I I EXAMPLE OF CALCULATIONS Lb = sum (Lsb x Asb)/ sum Asb (1750 x 7.7 + 1045 x 9.9 + 2010 x 5.9)/23.5 = 1518 feet <===== Sb = sum (Ssb x Asb)/ sum Asb = (1.2 x 7.7 + 2.0 x 9.9 + 1.6 x 5.9)/23.5 = 1.60 <===== Using Table 8-A, PS = 80.2% <_____ (By Interpolation) ---------------------------------------------------------------------� HDI/SF-A:1989 JANUARY 1991 8-15 DESIGN CRITERIA EFFECTIVENESS CALCULATIONS ------------------------------------------------------------------� (PROJECT: Fort Collins Meadows STANDARD FORM B (COMPLETED BY: JSF DATE: 6/15/91 Erosion Control C-Factor P-Factor Method Value Value Comment ------------------------------------------------- Bare Soil 1.00 1.00 Sediment Trap 1.00 0.50 For all subbasins Roads/Walks 0.01 1 .00 Gravel Filters 1.00 0.80 Straw Bale Barrier 1.00 0.80 Temporary Crop 0.45 1.00 Spring Wheat Hay Mulch 0.06 1.00 1.00 ------Established-Grass ---- -----------50%-Ground-Cover --� � -�--- -------- ----- IMAJOR PS � SUB AREA IBASIN (BASIN (Ac) I CALCULATIONS ----------------------------� A 80.2 1 Al I 7.7 JPavement area = 29% x 7.7 acs = 2.2 acs Therefore, bare ground = 7.7 - 2.2 = 5.5 acs i IWtd C-Factor = (0.01 x 2.2 + 1.00 x 5.5)/7.7I = 0.72 <===== IWtd P-Factor = 0.50 x 0.80 = 0.40 <===== JEFF = (1 - 0.72 x 0.40) x 100 = 71.3% <=====I --------------------------------------------------------- A2 1 9.9 JPavement area = 5% x 9.9 acs 0.50 acs I (Therefore, bare ground = 9.9 - 0.5 = 9.4 acsi I , I IWtd C-Factor = (0.01 x 0.5 + 0.45 x 9.4)/9.9I = 0.43 <===== IWtd P-Factor = 0.50 x 0.80 = 0.40 <====_ IEFF = (1 - 0.43 x 0.40) x 100 =I I 82.9%-<=====I------------------------------ --------------- --- ------ - I A3 I 5.9 (Undisturbed land 35% x 5.9 acs = 2.1 acs JDisturbed land = 65% x 5.9 acs = 3.8 acs IWtd C-Factor = (0.08 x 2.1 + 0.06 x 3.8)/5.91 IWtd P-Factor = 0.50 IIEFF = (1 - 0.07 x 0.50) x 100 = 96.7% <=====I. - ITOTALI 23.5 JEFFnet - sum (EFF x Asb)/ sumAsb-----------I = (71.3x7.74 + 82.9x9.9 + 96.7x5.9)/23.5I it = 82.6% <===== (Since 82.6% > 80.2%, proposed plan is OK I I ----------------------------------------------------------------------I HOI/SF-B:1989 JANUARY 1991 8-16 DESIGN CRITERIA CONSTRUCTION SEQUENCE PROJECT: Fort Collins Meadows STANDARD FORM C SCHEDULE FOR 19 91-92ONLY COMPLETED BY: JSF DATE: 6/15/91 Indicate by use of a bar line or symbols when erosion control measures will be installed. Major modifications to an approved schedule may require submitting a new schedule for approval by the City Engineer. YEAR 1991 # 1992 ------MONTH N I D # J I F M A . 1 M J J A S 0 ---------------- - - ----------------------------------------------------------- OVERLOT GRADING ------- WIND EROSION CONTROL # Soil Roughing ------- Perimeter Barrier --------- i Additional Barriers --------- Vegetative Methods # Soil Sealant # Other u TM # RAINFALL EROSION CONTROL # STRUCTURAL: ---- # Sediment Trap/Basin - Inlet Filters # -------------- Straw Barriers # --------- Silt Fence Barriers # I Sand Bags # Bare Soil Preparation # Contour Furrows Terracing # Asphalt/Concrete Paving # -------------- Other # VEGETATIVE: # Permanent Seed Planting) # -------------- Mulching/Sealant # -------------- Temporary Seed Planting # -------------- Sod Installation # Nettings/Mats/Blankets # Other # #-------------------------------------------------� STRUCTURES: INSTALLED BY MAINTAINED BY VEGETATION/MULCHING CONTRACTOR DATE SUBMITTED APPROVED BY CITY OF FORT COLLINS ON HDI/SF-C: 1989 JANUARY 1991 8-17 DESIGN CRITERIA RAINFALL PERFORMANCE STANDARD EVALUATION ------ --------------------------------------------- 1PROJECT: STANDARD FORM A I i (COMPLETED BY: - DATE: I---------------------------------------------------------------------I IDEVELOPEDIERODIBILITYI Asb I Lsb I Ssb I Lb I Sb I PS I SUBBASIN I ZONE I (ac) I (ft) I (%) ( (feet) I (%) I (%) I --------- -----------i-------I-------I-------I-------I------- -------I I I I I I I I I I I II I I I I I I I I I I I I I I I I I I I I I I I I I I I I ! I I I I I i I I I I I I I I i I I I I I I I I I I I I I I I ! I I I I I I I I I I I I I I I I I I I I I I i I I I I I I I I I I I I I I I I I I I I I I ( I I I I I { I ( I I I I I I I HDI/SF-A:1989 TAN77�VV 1001 inOCTrNT ro TTCDT] EFFECTIVENESS CALCULATIONS ----------------------------------------------------------------� ( PROJECT: STANDARD FORM B I I I (COMPLETED BY: DATE: , Erosion Control C-Factor P-Factor I Method Value Value Comment I i ---------------------------------------------------------- I I I ----------------------------------------------------------------- I I I I I (MAJOR, PS I SUB I AREA I I IBASINI M IBASINI (Ac) I CALCULATIONS I -----I ------ i -----,------i--------------------------------------------� I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I i I II I I I --------------------------------------------I HOI/SF-B:1989 CONSTRUCTION SEQUENCE PROJECT: STANDARD FORM C SEQUENCE. FOR 19 ONLY COMPLETED BY: DATE: Indicate by use of a bar line or symbols when erosion control measures will be installed. Major modifications to an approved schedule may require submitting a new schedule for approval by the City Engineer. YEAR MONTH I ---------------------------- -----------------------------------------------------------� OVERLOT GRADING I � I WIND EROSION CONTROL Soil Roughing I Perimeter Barrier I Additional Barriers Vegetative Methods I Soil Sealant Other I � I RAINFALL EROSION CONTROL STRUCTURAL: I Sediment Trap/Basin Inlet Filters I Straw Barriers I Silt Fence Barriers I Sand Bags Bare Soil Preparation Contour Furrows Terracing Asphalt/Concrete Paving) I Other VEGETATIVE: Permanent Seed Planting) Mulching/Sealant Temporary Seed Planting I Sod Installation I Nettings/Mats/Blankets Other ----------------------------I-----------------------------------------------------------� STRUCTURES: INSTALLED BY MAINTAINED BY VEGETATION/MULCHING CONTRACTOR DATE SUBMITTED APPROVED BY CITY OF FORT COLLINS ON HDI/SF-C:1989 JANUARY 1991 8-20 DESIGN CRITERIA TE: Shaded portions are new text. SECTION lo. DEFINITIONS DEF,TY-MIONSIXROSION CONTROL This section defines terms related to erosion control criteria: Crag Residue: dead vegetation, attached or unattached; laying or standing. Effectiveness (EFF) : the numerical measure of an erosion cositro plans ability- to reduce erosions. Computation of EFF is accomplished according', to the raethcd described herein. Erosion Control Cover F'aetors' ?c a (also :known as cro ?pin} factor) the ratio of soil loss from land under treated conditions to the corresponding .toss:; from; for ': exampte, bare ground conditions. (See TableS.2}„ Ground Cover: the., percentage of-ground. 'shaded' when ;the sun xs directly overhead (also krsowt as canopy cover) .< Historic sediment or Erosion• the amount of sediment that moves through and is eroded from a site assuming dryland grass' vegetat1. indgenous to the area':: Land Disturbing '!Activi''ty: inoludes, without limit1.ation, overlot grading, road' and: utiltlr installation and removal of vegetation by mechanical or chemical means.: Overlot Grading:: the changing of the grade of the earths su ace, strpping :of soil and/or vegetation. and filling.: Performance Standards: ; the benchmark against vhioh erosion control.: plan effectiveness is measured. Ferfarmance Standards are derived to meet the goal of either restricting sedimentifrom a disturbed site to historic leveis or •-to a percentage of the ", difference between hzstorie' and. bare ground sediment discharge. Permanent Erosion Control: the final devices installed in order to limit erosion to the historic erosion; rates:: Includes final landscaping, terracing`; or other grading design methods, drainage control structures such as ponds or catch basins etc.: Practice Factor fP-Factort : :the ratio of soil 1oSs to. a gen'eZa surface conditions to soil loss from? a reference surface condition (also:known as erosion, practice .factor, see Table 5.3) JANUARY 1991 10-4 DESIGN CRITERIA Raindrop'Erosion: the initial phase of water erosion from a` sol2 surface. Raindrop energy;,` is dissipated byi dislodging ; soil particles which: are then more eas,:y moved by surfl. ace. resrtoff.' Rill and gully Erosion; erosion' WWI h occurs below sheet Oraslorx on: a slope. As water concentrates into small channals, stream power increaseslas does bother©sio and sediment transprrt. ' Taut increasing distance downslope, sheet erosion leads to rill erosion which leads to gutly. erosion,; saltation: t1?e process of sediment movement by Iwhlch > sai particles: move intermittently along the eradingsurfaee matiyate+3 by either wlnd a water; Securit�r a perfozmance bond. irrevocable Ietter of; credit; oz cash escrow submitted to the"':C,i tav ensure the fulfillment of the Errxsion �ontral ', Plan.? Sheet Erosion: ? the removal of particles. from a soil' surface by shallow, :non-channelized water flow. The energy available far removing soil particles is relatitPOIY less than raindrop eroslon but transport capability is higbJ„ Stream Channel <Erosion: erasion which includes both the dawn- cutting of the ;'channel bottom: and side cutting; of channel banks caused by friction forces of flowing,water over. soil. Sediments fzom either the chan:zel bottom. or,hank ate removed from their original :location by novemen along the 'channel bottom, carTz6a suspendediin flowing water or a combination of Both processes: Structural : Erosion Control PfeasrYrs: structuxzes built for tlxe Purpose of controlling, either wind or water borneisediments. T: may include drainage structures that are temporarily incorporated into an erosion control..p3an such as storm: water detentian faC.illtias, storm water Inlets, etc. Temporary' .Erosion contrbT'. ; davlces installed prior toi; and.: sometimes' during clearing and grading of 11nd, used to controliwiad or,water borne sediments for, shortttme periods only {usually one year of less) .: y'eeretation Erosion Control :the use of t ry ar permanent; couericrops with mulcbt Water. Erodibillty Zone: an ;area defined according to;l; th z$tln of 'the susceptibility of surface sails in Fort; Collins to water erosion.: JANUARY 1991 10-5 DESIGN CRITERIA a€e; L"rcrsivn the process (bp which sediments ;are moved b the hydr+?dynamio farces acting oii sail. ;;part�.cles hTater loosens: anct moves sail particles from the soil ,:surface by x�rtpact ar friction andi pressure. Tie souse of 'water tttay be ;ra�aZl, sncsw, 'streams or ;unmade ' caii�cyaaces. Raindrop sheep, rill and ':gully,,; and ahennel .ezos,�on .;are types of.water erasi�,ri wing# EtriiLfbil.�ty done• !;...........n area cia Red according to the' ratiny or .....susceptibility of .surface sails sn FartaZlins to wind ernsozz win'r� Rrason: Ize .prooess toy which sediments ale mxtived b the aerodynamic fcirees acting oTT sail particles. filie physics of .wind erosion are similar to water erosioh: zn that wtnd, iiiitiates erosion by rapplying lift and' drag forces. ta 'sail ,particles. Particles con �saue < movement b satatinn.;. (which loosens additional:. particlesl , surface creep and suspenszoir. The prevaiTncj wind is Of, primax ccnaern in an erosion pzntrol..plan. JANUARY 1991 10-6 DESIGN CRITERIA AasRa�rrATraxsrEResrr��r cnx�RaE AG ACS G Factor Czppgi '<Facto Cr3tera. Csty Aforttr alins ;storm zaix�aijegsgta Crz a ;and C�nstruC, an. 3t and BFF Effectiueness a Erosion Control Plan SedY' S.01 Mm nt YseI {tans acre , edfi Sedxtnentixeld {cubic=yards; if Faetar dxb Sol. Itiraxlxtr Factcs LR Loading Patio LS-Factor Length and S3ope 2'opographie Factor MUSLE Modified Universal Soil Lass, Et{u* ation PLS Pyre Live Seed P-Factor' Erosion Practise FaCtFZ ROW ; Right of;WAV SC5 Sal Conservation Service U5LE, Uruuersal Saii Loss Ee€tzation JANUARY 1991 10-7 DESIGN CRITERIA "E: Shaded portions are new text. CITY OF FORT COLLINS STORM DRAINAGE CONSTRUCTION STANDARDS SECTION 1. GENERAL PROVISIONS 1. 1 Purpose And Scope The purpose of this manual is to set forth the minimum standards for construction and installation of storm drainage facilities within the City of Fort Collins and its Urban Growth Area. Subdivisions, planned unit developments, or other proposed construction shall include an adequate plan for storm drainage in accordance with the Storm Drainage Design Criteria. Prior to construction, approval of plans shall be made by the City Engineer. As with any construction standards, occasions may arise where the minimum standards are either inappropriate or cannot be justified economically. In these cases a variance to these standards shall be considered. Written requests for variances should be directed to the City Engineer. 1.2 Revisions to the Construction Standards These standards shall be periodically revised and amended. Future revisions and amendments shall be reviewed by a committee representing the private sector with City staff prior to final approval by the Storm Drainage Board and City Council. Revised Construction Standards shall be mailed immediately to users on the current mailing list. All revisions and amendments shall become effective immediately upon publication of notice that such revisions and amendments have been approved. Interested parties are asked to submit to the City of Fort Collins any revisions to the Construction Standards they deem necessary. 1.3 Definitions, Abbreviations and Terms 1.3.1 Definitions Whenever the definitions, abbreviations and terms listed in this section are used in these standards they shall be defined as follows: City - The City of Fort Collins. City Code - The latest officially adopted City Code Regulations of Fort Collins, Colorado. JANUARY 1991 1-1 CONSTRUCTION STANDARDS Consultant - A person, partnership, or corporation duly registered as a professional engineer according to Colorado Statutes who is hired by the land owner or developer and is empowered to act as his agent. Contractor - A person, partnership, or corporation duly licensed and bonded in the City of Fort Collins in accordance with the requirements of the City Code. Days - Intended as calendar days; not normal working days unless stipulated as working days. Design Engineer - The engineer who either designed or is responsible for the design of the structure which is being built. Developer/9"er - The person or persons, puh�ic Q private; legally responsible for construction of improvements within a specific subdivision, panne unit development, cxr?CFty €ended c pstal or main enance project.; Engineer - The City Engineer, City of Fort Collins, Colorado, or his authorized representative acting on behalf of the City. Inspector - The authorized representative of the Engineer assigned to make detailed inspections for contract performances, standards and contract compliance. May - A permissive condition. No requirement for design or application is intended. Plans (Drawings) - Detailed and working drawings including plan, profile, and detail sheets (utility drawings) approved by the Engineer. Right-of-Way - A general term denoting land, property, or interest therein, usually in a strip acquired for or devoted to a street. Shall - A mandatory condition. Where certain requirements in the design or application are described with the "shall" stipulation, it is mandatory that these requirements be met. Should - An advisory condition. where the word "should" is used, it is considered to be advisable usage, recommended but not mandatory. Deviations may be allowed when reasons are given which show intent of the design standards is met. JANUARY 1991 1-2 CONSTRUCTION STANDARDS Street - A general term denoting a public way for purposes of vehicular travel, including the entire area within the right of way (include alleyways) . Storm Drain - Any conduit and appurtenance intended for the reception and transfer of storm water. Utility - Tracks, overhead or underground wires, pipe lines, conduits, ducts, or structures, sewers, or storm drains owned, operated, or maintained in or across a public right of way or private easement. 1.3.2 Abbreviations AASHTO - ' American Association of State Highway and Transportation Officials. ACI - American Concrete Institute AISC - American Institute of Steel Construction ANSI - American National Standards Institute APWA - American Public Works Association ASA - American Standards Association ASTM - American Society for Testing and Materials AWWA - American Water Works Association CDOH - Colorado Department of Highways 1,3.3 Terms Wherever the words "as described, " "as required, " "as permitted, " or words of like meaning are used, it shall be understood that the direction, requirements or permission of the Engineer is intended. Similarly, the words "approved, " "acceptable, " "satisfactory" shall refer to approval by the Engineer. References to standards, methods of testing materials, testing materials codes, practices or other requirements refer to the latest edition, including amendments in effect and published at the time of approval in issuing a permit. JANUARY 1991 1-3 CONSTRUCTION STANDARDS "These Standards" or words of similar connotation shall mean the City of Fort Collins Storm Drainage Construction Standards including all parts, supplements, and revisions pertaining thereto. 1. 4 Authority of the Engineer The Engineer shall have the authority on behalf of the City to ascertain that all design and construction is equal to or exceeds the minimum requirements set forth in these standards. 1. 5 Authority of the Inspector The Inspector shall have authority on behalf of the Engineer to make detailed inspections for contract performances, standards, and contract compliance. 1. 6 Contractors Licensed and Bonded The Contractor shall be licensed and bonded with the City of Fort Collins prior to construction of storm drainage facilities for acceptance by the City. 1.7 Contractor' s Responsibility The Contractor shall be responsible to comply with these standards and other applicable laws and regulations. The Contractor shall furnish conveniences and assistance to the Inspector for inspection of materials used and workmanship involved in construction. 1.8 Notice Before Beginning Work The Contractor shall notify the City Engineer's office a minimum of 24 hours before beginning construction. 1.9 Traffic Control The Contractor shall provide an approved traffic control plan and shall comply with the City of Fort Collins Work Area Traffic Control Handbook. If the Engineer finds the construction area to have inadequate traffic control he has the authority to stop that portion of work until corrective measures are taken. 1. 10 Preservation of Property Existing improvements, adjacent property utilities, trees, and plants that are not to be removed shall be protected from injury or damage resulting from the Contractor's operations. JANUARY 1991 1-4 CONSTRUCTION STANDARDS 1. 11 Replacement of Surface Improvements All improvements removed within the public right of way shall be replaced in accordance with the City of Fort Collins Design Criteria and Standards for Streets. Other improvements shall be replaced as shown on the drawings. 1. 12 Rejected Materials The Contractors shall remove defective or inferior materials from the work area within a reasonable length of time. The Contractor shall separately stockpile rejected materials until they are removed from the work area. 1. 13 Site Maintenance and Cleanup Throughout all phases of construction, including suspension of work, and until final acceptance of the project, the Contractor shall keep the work site clean and free from rubbish and debris. Materials and equipment shall be removed from the site as soon as they are no longer necessary. Upon completion of the work, the Contractor shall clear the work site of equipment, unused materials, and rubbish. 1. 14 Safety Requirements The Contractor shall comply with Federal, State, and local safety requirements. I. :Xs:- Enforcement::.,- Arosiati control Changes to .the erosion control plan or .time sequence ':must be submitted in :writing to the City Por apprcual prior to implementing• changes. Dev3at£oas from the gi"aa or cr£giaal time aequence, without Citg appsoYal may result sn.: a. € stoppage of all ar paxt'of tha work,; b. holding of bnzlding pesstis < c. holding oficertificatea of occupancy.. Or commere al industry sitesr an for calling .. ffiecurity!n; Approval or di sapprQval 'of' plaxs_or sequence chances will made in five working days. JANUARY 1991 1-5 CONSTRUCTION STANDARDS is warranty Eres£cm,,et�ntroI The owner sha3 warrant :that the Peasures "shawts an the approved eLa3k�TP egntra7 `plan ',are pr©gerl Constructed;:: nstailedF aria ark : free `franc defectsae �naterfas ;"atsd�e warkmaishkg wtT� said warxant�r�tia cantknrse�crs the terms set be�.aw.. .,a. ....,. .. .... The Dwrxex sha7 warrant and taaintan axX stxuctura nEeasures far one; year after knstaltittrs. Ttie E3wner s13a1 warrant and maintain a vage# at#ve measures Ear yeazs ' aftez instaTlatian ; 'Any< ceptanee of 3nsta1led meaatites sriaTl nat be cQnstruec ; a re3 ere khe, t3wrse a E' tkti .dutya w arz ant and malntan as afQresaxd« JANUARY 1991 1-6 CONSTRUCTION STANDARDS TE: Shaded portions are new text. SECTION 11. LANDSCAPING 11 .1 General Landscaping shall be based on acceptable horticultural practices concerning soil, weather and topographic conditions. Materials and procedures for fertilizing, seeding, mulching, sodding, and planting in drainage areas shall meet the requirements of this section. In addition, they shall meet requirements found in the City of Fort Collins Landscape Guide and the City of Fort Collins Landscape Standards for Streetscapes, Medians and Detention Ponds. The latter documents are available at the Development Center or the Parks and Recreation Department. 11 .2 Materials 11 .2 .1 Fertilizer Fertilizer shall be uniform in composition, dry, free flowing and have the manufacturer's guaranteed analysis provided. Fertilizer which becomes caked or otherwise damaged, making it unsuitable for use, shall not be accepted. Soils should be tested to determine ° fertilizer. requirements. ` 1 Sites wilx be .fertilized according' t4 laboratory soil' analysis and recommendation.; 2 In absence of soil analysis'; and approved by the City t7f FCzrt Collins, j a minimum of 4Q pounds of available nitrogen and 4,Q pounds of available phosphorus r U1 be 'a : lied per acre.;: 11 .2 .2 Grass Seed ph.e city of "Fo t Gn1 ins .prefers ;the t�se of native dryland ; grassspecies where permanent : vegetative Oros ion 'contrc�Z I, :: Use u ed..species. may :be used for Sand that"will euentually; be 3eveloped In or adjacent ta'. environmentally sensitiue areas; ttrore detailed criteria magi apply_. Seed labeling; ; quality and testing shall xr irk accordance with Colorado Department of ure Agricult Seed Laws; Chapter It Article 21= 1'he seed.:sha1 be no more than siYr manttss a1d, catait2 np more;: than A1� weed seeds and be free from noxious weeds . Seed tags shall be attached to seed bags at the time o� JANUARY 1991 Z1-1 CONSTRUCTION STANDARDS v vv v v vvv v v a) v ar m vM; o a) V U V V U U V U U C J J J J J J 7 J J Y q N > O > O > > v L C 4! > > > aj (V0 > > v v v > aJ 0 >a a) N L c > > > > > > O O O > O > > > O > > O O O > > O > ro Y d r i L L •r i •r r i •r L L L•r •r L •r U � q q g q q ro C C G ro c ro ro ro C g q C G C ro ro C ro ro Q1 o f- zzzzzz .^ .» .- z .•• zzz .-• zz .» .. .- zz .- z oY U i q C Q) Y L L Q1 O W L L �••� L L L L L L L L .- N uu u = a u 'uc'� c) v r- u N L L v c 0 0 c c v c c v v c = 0 0 c c c c c v c 0 c •o 0 O C O 0 0 J 7 0 0 J J O O J J O O J J J J O O J O J N O W W N p V) N p p N N p p V) N p p N V) p p p n V) N n V) C Gr a1 U L a C a) O V1 aJ Y •r r• lL C L L a N N J O 1 C C t C i C C C N 0 C N N N O t L') N C < N :.� •r•r Q •--i M C N M N N QJ ro ro a v M O N L L > Q Y C7 O q Y •C Y V- L Y C Q v G ro M \ C v r J v v q o 0 0 0 0 L L 0 0 0 0 0 o i 0 c N — (u L N ro ro ro ro ro q 0 V) C O o o g q ro O ro 0 O O O O m 0 0 0 .- C ro 333333 U _JU V U f..1333 L) 3U U U V U 3v a) L a " v N O L q N L a) v C ••-• � � O Y N d a) O (J CD - .- q L 0 L J roc i O p Q O G aJ M. G CO Cn 10 0 C•O p Y N tiY C:J Q C) C t0 r� C .•+ L N to .-� •--� �•+ v r C \ CTC to nQM •-•� Cn •--� O; C NN v r N a CIS •--� V a; —M a) J 4J> N V- r J N r-� �--� N J �--� ••-i N rr •--i •r .r N .+ e•-i e-+ > G C .- r C C C N v Q) N a) L a) O C N C Y c N W N L L O o r + C U C N L O r a) 3 Y O C v O Ql U Li U V .•� L N G rL c Y cE c c c mroNa) a Y ro 4! f O Y •r ro •r C •r 4! ro r 3 Y C Y J J U Y J L N U 0 Y O i C LT L > a) 0 Y Y O o 7 J ro i i \ a/ q L > Y C wr Y O p a) C CO L C d O O '+ L p C O q N L a) 0_ _ 3 o T 0 0 q O aJ L J N N L' ro Y Q �..� L q ro 0 w Y i L O Y a) Q Y U • C C L C1 J C ro C C1•r q i E N C q 01 g C a 'M aJ w Y L> N C q L > Q! J C U ro a L c > t 7 J q •a a:L C ro Q) v r r `0 0) C L Y •r ro v •r ro Ct•r C V Y O w-• Y L N >r V O a O Y r• r 0 L a) C i r J N N > C i L C J > a) C N v O r 7 L 'O r r q q N ro L C ro 1 J 4 J E O L J ro O i ro ro 0 N' EE L. E o ro 0 J •r C) co J \W BO LL 2Q J > J7 $ J U CLL QG J J N L N— C N V) •"� O Y C 6) J C L L Y N •U N >. U a) 0 3 � C) Q) J Q Yvti NAY O- J T N O 4) •• a) G C N O U O N a) C Y a ✓� 2 ro ^V) ro i i v N T N Q i 0 C S. O q aJ N C N V) O a) (1) O V- G v G q Z N N N (cs N N Y N r > Y c 0 O i Q N N N S. N C N N g N N U•r v N P C Q) v J C M V) (o g q 01 N O q q a) ro N al J a) tor EL T ro a) aE) ro cm m m (aq wL T 01 01 3 M L N a) N v 0 0 C E E L Y O =• Y Y Y al E Y m C Y Y Y Ct L ro a) •r U r Z a/ q C N L Q g q q L q a) N a) J q q aJ q a) w Y J w O , 3 a) O C Y L N G a) 3 O a) w a) 3 L N E a), U a) a) Y Qf E , N 1 O L a C U to N m N ro J ro J t L L 01 ro N O J v L L rot q O 'm O a q N a roN .- E +•+ 333Y Eroir a) T33 •r3EL a) E n m F- c) .- OJNi aroc H cNro Lana) F- v rona) a, N Z r Y M W L w J C L V) Y .•� O '- a) C a rot a) O U q a) L U g M L L () a) E L M L C J ro •• a) ro r' r C U i, N V) 3 Y a) 0 C U Y .- C N 3 Y L (v Y aL C •-� SM. N •U Y v a) V) N G J cc L'` +) •r Y a) a) L N Y a) O O Y O Y O L N Q! Y Q1 O a) 41 Q/ C C :. q Y J a w r a) N a •C J O Y al w r a) Y N J O Q) ro 3 L •r g q L G N J • 3 l -j C:J L T q ) C O r E L a N C N . C L.� U 3 n N N J C 4. U (.7 Ld ro N O J N M C Te1.YIIARY 1991 11-2 CONSTRUCTION STANDARDS delivery to.:a Site and submitted to the City Engineer for verification and documentation :: The establishment of perennial drylanc grass wx! h no — irrigation 'shall require at least:; two ;;species identified in Table I1-I and' be protected bg a mFiZch.< Special attention shall. ie paid: to the soil. typ zs which seed is introduced : The establishment of temporary vegetation ar€a ccivr crop 'without Jrrgation shall requ:xre Only ' one species. identified in. 2'able 12 2 Protection of temporary vegetation or a cover cropjhy a mulch is not required. Table> II-2 i Recommended species and AppYication Rates of `Seeds "for �s.tablisliment: of Temporary Vegetation : andfar Cover Craps.: Drilled Pounds Saecies Season ': :! of Seedlkc e Annual'..,",... ei s*s Cool 2a' cats. Cool 7lX Cerea . Rye . ! Cool 4Q wheat :- Winter': Cool 41!' Wheat ;: spring `:Cool 6g Harle Cool 6U Millet Warm all Hybzid Sudan: Warm 15 sorghum _ is�'arm IQ: CarzZ season grasses make 'their "':mayor �ro�*th: .�T1 the spring Waztp season grasses make their ma}cir'> graw�tf in late' spring and summer. Tatle 31.';-4 identfe planting dates for perennial and temporaryfeausr crap grasses. ".. Detrelopment .,of 'a seed mix she1Z 8e :; competed as illustrated in the follos✓ ng example ; ' ... �fiite"d Pounds' aP , $erCent ql° Soecie"s PLSlAcre of mzx PDSfre Pubescent Wheatgrass'. 21 .8 41 Smooth,: Srome, 26.1 ! 35 5. Sideoats Grama 10.9 20 ve TOTAL 100 'i Z7 6 JANUARY 1991 11-3 CONSTRUCTION STANDARDS Seed: mixtures for sites with distinctive soll. problems (e.g., a2kalinity, .salinIty: .or high water table) shald be cievelaped by. a trained specialist.; 11 .2 .3 Mulch Mulchzng"S;b4I be :!used to assist in-es.fiabZishment ofi vegetation:. One <or more .of the foZlowingmulehes shall be used with a perenna dryland grass seed mikturE.�: .. .. ............... ... ........ ...................................................... AcceptabI Mulch [rates cif Ilse _ A�pZicaticn 22ata Straw or Hay Jan Q3: Dec:! 3Z tonsjacxe Hydrau3ic Mar 151 Mayi1S 2 tons/icra (woad or paper) Erosion Control San 01 Dec 31 Not apZscable �1ats° or Baanlcets Hay or straw mulch shall be tree o€, noxious' weeds and .at"least 5C7 of the fiber,shall. be IQ inches ,[r more::; in length. I4hen seeding. wzth 'zzatve l grasses hay tram ai native grass ss , a suggested u[ulchic material, if available.; 1f izrigatan isr used, : Ytydzaulic mulches; may be applied from Marr 15 thravgh .September 3Q 11 .2 .4 Sod T$e. pity of Fort Col2xns ;encourages the use ctf natave grass sod:: All sod shall be free from weeds, pests and annual Bluegrass. It shall be at least one year old with a healthy, thick and even stand of grass with a root system sufficient to insure survival of healthy grass. Sod shall be fertilized two to four weeks before cutting and shall not be cut more than 24 hours prior to laying. 11 .2 .5 Plants All plant material shall meet the specifications of the American Association of Nurserymen (AAN) for No. 1 grade. Plants shall be sized according to Table 11-3 . JANUARY 1991 11-4 CONSTRUCTION STANDARDS Table 11-3 . Plant Sizes. Type size Standard Deciduous Trees 1-31411 to 211 in caliper Small Ornamental & Flowering Trees 1-11211 to 1-31411 in caliper Evergreen Trees 51 to 61 in height Shrubs Adequate size to be consistent with design intent. 11 .3 Construction Requirements 11 .3 .1 Seeding Seasons Unless... 6fhexw-**ds* e specxf2ed, seeding sn"areas that U re, not.•=rl gated: shall 11 a, 00. 44 to tie seasarrs - . defined in Table 1144-,�, ........... Table 11-4 . Recommended Planting Dates for Perennial and Temporary/Cover Crop Grasses . PERENNIAL TEMPORARY/COVER GRASSES CROP GRASSES DATE Warm cool Warm Cool Jan 01 - Feb 28 Yes Yes No No Mar 01 - May 15 Yes Yes No Yes May 16 - May 31 Yes No Yes No Jun 01 - Jul 31 No No Yes No Aug 01 - Aug 31 No Yes No Yes Sep 01 - Sep 30 No No NO Yes Oct 01 - Dec 31 Yes Yes NO No * , -P ti Areas where seeding is required shall be graded to lines and grades shown on the plans. fihe 'seed bed ....... ... at pAper depth ;: restrct.xue ; layers and then harrowed: or rvlled�te firma tl7a seed bed The prepared surface shall be relatively free from weeds, clods, stones, roots, sticks, rivulets and gullies. Before apply n topsoil, , the disturbed and cciju�sacted< land oust •b JANUARY 1991 11-5 CONSTRUCTION STANDARDS seed shall not be sown, drilled`;ar otfterwise, glanted when ' the soil is frozen or crusted 'lor when it 5 very windy.; 11 .3 .3 Fertilizing If fertaliaer. is : xequIred, ' .it shall be ;jappl 'ed uniformly at a rate specmfsed ` Equipment shall be operated in a manner to ensure complete coverage of the area to be seeded. 11 .3 .4 Seeding Depending upon the soil, `::grass seed shall be drilled to depths Identified ini Zrable 11 1. !> Kcw 'spacing shall' not exceed 8 inches fvr the. grass drill . If. broadcast methods are used, the soil shall be raked to cover the seed: Drillls fvr 'establishing temporary vegetatlon shall: have 'a cuxt:ipacker or other method of firming 'the soil over the. seed'and haire row;spacing o1. 20 anches or less.. Cover crops shall xxat;be pZarted on slopes greater than 15�. Row spa t exceed 2;Q inches and racy be harvested i stubble �s left. 40 less than 6 inches; high.; 11 .3 .5 Mulching All seeded areas shall be mulched within 24 hours after seeding. Hay—or. straw mulch shall be anchored to the svil: hy use of a 'crsmper, netting (properly staked} 'or tackifzex rf crimped;. the fiber shall be crimped€our inches ar more into the svili. ' 11 .3 .6 Laying Sod Sod shall be laid on topsoiled areas with closely matching joints. When sod is placed on slopes, it shall be laid approximately parallel to the slope contours. After the sod has been laid, it shall be thoroughly soaked. After soaking, the sod shall be rolled in at least two directions to secure a tight bond of the sod to the subgrade and between strips. 11 .3 . 7 Protection of Seeded Areas Appropriate warning signs and barriers shall be erected where necessary to help protect seeded areas from damage by vehicle or pedestrian traffic. JANUARY 1991 11-6 CONSTRUCTION STANDARDS Traffic damage and vandalism that may occur during the first two growing season shall be repaired. I1 .3 .8 Maintenance Seeding success depends upon control: ca!f weed camped Hors dursnq the first two ,gxow%ng seasons 2 There€ors, the owner sha'ZZ be ,responsible far the control of weeds by mowing ar applying herbicide � proper times for aiperiod of two years. This shaZ be accomplished to order.; to meet the s,*eeds,; t�rush = aTi d rubbish ordinance (Reference' Chapter 2V Articl III,: FTeeds Brush, and 'Ruhbish in the City Code} 11 .3 .9 Planting All plants shall be artificially irrigated, as needed, to become established. All tree shall be balled and burlapped or equivalent . 11! 3 1 d Acceptance Seeded areas shall be evaluated after one growing season to determine whether additional maintenance and/or weed control is required. Acceptance of seeded areas aftez = the secoxra growing;; season shal depend upon whether a satisfactory stand. ofrass. ie ev..del�t and: weeds have .been cattzalled A satisfactory'; stand': of 'grass is where 9n$ of the seeded area lias an evenly`dsstri3auted grass surface;; JANUARY 1991 11-7 CONSTRUCTION STANDARDS