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Home My WebLink About881331.tiff LAIDLAW SOUTH LANDFILL DESIGN AND OPERATIONS PLAN LAIDLAW WASTE SYSTEMS INC. IC Project No. 2-1803 Prepared For: taidlaw Waste Systems Inc. -6015 East 58th Avenue Commerce City, Colorado 80022 Prepared by: Industrial Compliance, Inc. 511 Orchard Street Golden, Colorado 80110 March 28, 1988 88133.( PLO 4-i5 JA Aro ATA -M.TI LAIDLAW WASTESYSTEMS INC. March 28 , 1988 ` p? 41988 Mr. Steve Orzynski, P.E. Public Health Engineer �� :r• cot Colorado Department of Health Hazardous Materials and Waste Management Division 421D East 11th Avenue Denver, Colorado 80220 Subject: Transmittal of review documents to finalize the transfer of the Certificate of Designation from Western Disposal to Laidlaw Waste Systems, Inc. Dear Mr. Orzynski : The enclosed document fulfills the requirements set forth by Weld County and the Colorado Department of -Health for the transfer of the Western Disposal Certificate of Designation (CD) to Laidlaw Waste Systems, Incorporated. The document clarifies the operations at the site for review by CDH and Weld County. It should be noted that Laidlaw is notifying the state at this time, that we would like to accept asbestos wastes, both friable and mon-friable, under a grandfather clause. Laidlaw is proposing to comply with the asbestos waste disposal regulations set forth by the state. Thank you for your time and please let us know if you have any questions or require any further information regarding the facility. Sincerely, Danamarie Schmitt Special Projects Manager Laidlaw Waste Systems, Inc. cc: Weld County Commissioners Weld County Planning Department Weld County Health Department _6015 EAST 58TH AVENUE, COMMERCE CITY, COLORADO 80022-3994 (303) 288-5558 LAIDLAW SOUTH LANDFILL OPERATIONS PLAN TABLE OF CONTENTS 1 . 0 INTRODUCTION Page 1 2 . 0 GENERAL INFORMATION Page 2 2 . 1 Landfill Location Page 2 2 . 2 Landfill History Page 2 2 . 3 Facility Description Page 3 2 . 4 Surrounding Zoning and Land Use Page 5 3 . 0 SITE DESCRIPTION Page 6 3 . 1 Existing Site Topography and Vegetation Page 6 3 . 2 Climatology Page 6 4 . 0 GEOLOGY/HYDROGEOLOGY Page 9 4 . 1 Regional Geology/Hydrogeology Page 9 4 .2 Site Setting Page 11 4 . 2 . 1 Topography and Drainage Page 11 4 . 2 . 2 Site Geology Page 11 4 .3 Near-Surface Hydrology Page 14 4 . 3 . 1 Ground-water Occurrence Page 14 4 . 3 . 2 Material Permeabilities Page 17 4 . 3 . 3 Ground-water Flow Relationships Page 19 5 . 0 FACILITY DESIGN Page 20 5. 1 Waste Characteristics and Volume Assumptions Page 2D 5. 2 Disposal Area Design Page 2D 5. 2 . 1 -General Filling Plan Page 21 5. 2 . 2 Phased Filling Sequence Page 22 5. 2 . 3 Excavation Areas Page 23 5. 2 . 4 Liner and Cover Construction Page 24 5 . 3 Surface Water Control Page 25 5 . 4 Asbestos Waste Placement Page 25 6 . 0 SUPPORT FACILITIES _ Page 28 i 6 . 1 Access Page 28 6 . 2 Site Fencing Page 28 7 .9 CONSTRUCTION AND OPERATION QUALITY CONTROL Page 29 7 . 1 Excavation Inspections Page 29 7-.2 Clay Liner and Final Cover Construction Inspection and Quality Control - Page 29 7 . 3 General Operational Inspections Page 29 7 . 4 Material Balance Inspections Page 30 8 . 0 FACILITY OPERATIONS Page 31 8 . 1 Site Management Page 31 8 . 2 Equipment and Personnel Requirements Page 31 8 . 3 Control and Record Keeping Page 31 8 . 4 Safety Control - Page 32 8 . 5 Water Requirements - Page 32 9 . 0 CONTROL OF NUISANCE SITUATIONS - Page 33 9 . 1 Litter Control Page 33 9 . 2 Vector Control - Page 3-4 9 . 3 Odor Control Page 34 9 . 4 Dust Control _ Page 34 9 . 5 Fire Control Page 35 9 . 6 Methane Gas Control Page 35 9 . 7 Environmental Monitoring - Page 35 9 . 7 . 1 Ground-Water Monitoring Page 35 9 . 7 . 2 Leachate Detection and Monitoring Page 38 9. 7 . 3 Methane Gas Monitoring Page 38 9. 7 . 4 Proposed Action in Case Of Negative Monitoring Results Page 40 10 .0 CLOSURE - - - Page 41 10. 1 Reclamation and Revegetation Page 41 10. 2 Topsoil - - Page 41 10. 3 Fertilizer _ Page 41 10. 4 Seeding - Page 41 10. 5 Mulching _ _ _ Page 42 10 . 6 Conclusions - Page 42 11.9 POST-CLOSURE _ - - Page 43 11. 1 Post-Closure Monitoring Page 43 11. 2 Post-Closure Inspection Page 43 ii 11. 3 Subsidence Monitoring Page 43 11. 3 . 1 Monument Locations And Construction Page 44 11. 3 . 2 Monitoring Program _ Page 44 11. 4 Post-Closure Land Use Page 45 iii 1 . 0 INTRODUCTION Laidlaw Waste Systems, Incorporated (Laidlaw) acquired the Western Landfill on January 1, 1988 . This document outlines the design and operational procedures at the facility, and completes the requirements set forth by the Colorado Department of Health (CDH) letter dated November, 10, 1987 relating to the change of ownership. The CDH letter states, " . . .this Department recommends that the transfer of the Certificate of Designation be approved subject to a condition that a revised Design and Operations Plan be submitted for review by the County and the State. . . " The technical information used to compile this document is taken from data collected during the initial site permitting process, and included in the original Design and Operations Plan, and during subsequent well installation and subsurface investigation programs_. It should be noted that the Pratt Property, immediately to the east of the Laidlaw South landfill, is not owned by Laidlaw but, -because of the proximity of the two sites, will be monitored as a part of the post-closure plan by Laidlaw. Additionally, Laidlaw will revegetate the site in accordance with the approved closure plan. The Pratt closure plan, dated _March 29, 1988, has been completed and submitted to Weld County. 1 2 . 0 GENERAL INFORMATION The Laidlaw South Landfill was originally permitted as the Southwest Weld County Landfill (SWC, also known as the Columbine Landfill) and was subsequently acquired by Western Disposal and then Laidlaw. The general information contained in th-is report includes a brief section noting the location of the landfill, a history of the site, a description of the facility as it is today, and a description of the land surrounding the site, including land use and zoning. 2 . 1 Landfill Location The Laidlaw South Landfill is an area of approximately 160 acres located approximately 1-1/2 miles southeast of Erie, Colorado. It is located in the East 1/2 of Northwest 1/4 , and the West 1/2 of the Northeast 1/4 of Section 29, Township 1 North, Range 68 West of the Sixth Principal Meridian, Weld County, Colorado. Access to the landfill is from Interstate 25, Colorado Highways No. 52 and 7 , and Weld County Road 5. These roadways provide efficient and safe traffic flows to the site. 2 . 2 Landfill History The Laidlaw South Landfill was originally permitted by the Weld County Board of Commissioners under a Special Use Permit (40D-79-22) and a Certificate of Designation (CD) was issued to SWC on December 10, 1979. The permitted site was located adjacent to a 25 acre abandoned and uncontrolled dump that is known as the Pratt Property. The Pratt Property was operated from approximately 1965 to 1970. Industrial Compliance has no records regarding the Pratt Property site during the period from 1970 to 1979. In September 1982 , the owners of SWC applied to the Weld County Commissioners to request a change in the existing Special Use Permit to include filling and covering the Pratt Property. The owners of SWC entered into an agreement with the owner of the Pratt Property to complete the filling, bring the Pratt Property up to a final grade that would promote surface water runoff, and eliminate potential health hazards. It should be noted that the owners of SWC did not take deed to the Pratt Property and ownership has not changed. The Colorado Department of Health (CDH) recommended that the Pratt Property be required to apply for an additional CD prior to filling and completing the Pratt 2 Property. A Design and Operations Plan for the Pratt Property was completed and submitted to Weld County for review. Approval to fill and close the Pratt Property was _given by the Use By Special Review Permit 534- The SWC landfill and the Pratt Property were both operated by Colorado Landfill Inc. until December 1985, when they were acquired by Western Disposal. Western Disposal completed the Pratt Property, brought it to grade and capped it to promote runoff and impede the infiltration of any surface waters. The operators of Lai-dlaw South will monitor and revegetate the Pratt Property but have not taken title to the property. 2 . 3 Facility Description The Laidlaw South Landfill, an area consisting of approximately 160 acres, is located immediately south of the Denver Regional Landfill, formerly Landfill Systems Inc. , also owned by Laidlaw. The location of the -site is shown on Figure 2 . 1 and the site boundaries are shown on Plate 1. The landfill is permitted to accept dry household and commercial refuse and construction demolition debris. The l-andfill is also permitted to accept sewage sludges that have been digested and dewatered and tires and oil wastes, if they are in reasonable quantities that can te incorporated in the fill without interference of the operations at the site. Industrial wastes can be received if special arrangements are made prior to their acceptance. Fly ash and contaminated soil can be taken under certain conditions. Asbestos wastes are accepted if it is properly packaged as outlined in Section 5 .4 of this repo-rt. All asbestos waste materials will be disposed in accordance with the Colorado Department of Health regulations. The landfill will not accept any type of radioactive wastes or _hazardous wastes as defined by the U.S Environmental Protection Agency (EPA) . Refuse filling at the landfill will occur in five phases. Soil will be excavated for use in the operations from three areas. Filling, cover and excavat-ion procedures are detailed in this design and operations plan. Generally, filling will 3 FIGURE 2 . 1 - SITE LOCATION -c e r/ k ,/) P,E0F 1 Ili AA]If2ALI• Jr q �All I J !•a Z¢ • °oas 1 ,; `k /YL , ff n(sr FifL�"'C(ioll��in��+��rss 4ssl I� t =ee / F \ � c PI 5 "0 `L-� �1'j5 •° 1 Eaton Gh C '. Sleemboet Swigs (` \ - 4 , e / .sr �ipm M , •-J11.3.2'5. e n F•P Rea. ,. c 41 L GhH A r e'8 1153 03 a 1 . \ C e . 1 :G Loy land; 11511- — y r ~ ey RJ \,.,,,„„,„.,:i I N:ne.•.r. p [ 5 $h 3 cJ Li G 17 •RFAPAH0 M POfAYM00NIA)—9 ak G amp on dI kP0 tin D Al P H3 NAr Aal M a B on s,M € / I I �-eN CHYL NanONAL PAFR .[ [WWI k ae Be abD1 ]50 `°y� • 4e.p u 1 Sewm G �'H n - t 2 1!3 GI �/ Y rl. l.b G St, N dL k '. Lyoni�H' I Ne le /! II kept 0. ept� ° k .✓e 216 O ,ye. { ®..9_. —A fIii v I / 5 IE N P GRAND l APAHO S.r 9 _sL0A7011-° ede c I° I IJI 3 r - p pp" 56 .„„v A cd if ee / yPECC-AREA eel I ter.62 P e n ��"`N E R ®JS l Lipton . (/,,. K e 3 P.41401 met meby . e. mot 4-7, Q V �A ®, I4 s nw w ) ROOSEVfu E YOn E Ere D / Mils" ils p,„„•••vueY r 22•K em Ins •e sP G runaxnf BpOldaf tale nl �� a 31 c I •Vachon r � FORM i 9C r I E Flint, n I Y ht I"" l y e.4.-d Je _I 231 ]] \ r w00421.01�j En 1"8,00 n 83 Y/® ad I .I -.- MCv/ hI ID°n M0 0 d 12 i SP ApAMS E\ / GeenM 1e ° .� Bond 11 C G •ARAPAHO I A F n•e GILP INII 4e a 13 N;PIE RrVffl N Y AI( FOR & +"s q °e C WC 111103 'r��VPi1 ' Sn 0 / NATIONAL \ ] ehkHF t st ] E°°n I .I M J FOREST 0T'N eG 32 U,e,.t Y ry d 0 M ro. M ge P " So u G e s 185 w h" Ben et' Sv_ dxbu p w°I a au 1 aGeo gem n �" a IA e��iir j^ 163 133 a sE F M[ oy_NF i A?°Ik5 3d w AU GLi3 38E ]95 304 JI0 n- els a .1 7, $IeF \ 0S-rede % 1 03 • F le v / II ARAPAHO f�n aC. 291¢15) �.3�� 131 \ Fns y- R n8gewe3+ 3 • � a Ed d p dl 'ii-*1 Dills ,r,"'An 4. ap %. R CPEEK a NI •1EE r Si Arr M iv• }la a s 101 z f M �I1 6a d �e AF I as It' ,on F ec GII A \. S�l IM MIT c.-p..�". AO LG Confer rR ®�� 185 °r+ TF RIVER ReddlX 180 185 a Nynl d x Pv s / s,i I zk o\ E F EP 5Ot�/ h'AL FORES I t F.A Y 8 eck rdge R si Ik \ e I \� �Seae e / M4 tc I -e5 M" a Tr F F. / Y�\183 0. Kenosha Pas GI �'' 6YAPIDe r4 '` h • EL ,LAK 3rN.e.( 4 M ' 5 f JeM " E D k !.B J de A.Rm °1¢82 FR0e4 1 EW�an _ aEn Como \, PIKE �I A5�' . e.sFeadVille V' NATIONAL( De I)0 1 )- • e `i PARK M• Gln.n 5<+IS ABEL % F vE / ^.- r Woodland Pork �. / 1 Forest P w°" p 4- n4FJ9fsr v:, rf. U A -� - Ti• G Mq a YAti �. Cr 1 f1eR. r CI J n s ; feS GL a �/ t5 M I" i."..A"Po'si ,,i,A ; e Falcon P. Ee q FtGA158ANT1 'Hµ1 N J ie A.A IV V� ad 54n "A V f0S5rtFEN' TELLER �n5Ps clIik� • e HAmn wino 9 C Gi `Y std 3 AA II MON 11Je v M N n o. t s PO* Skyway `� ;CO aI-Easse(3d• prings 'psi,.t 1 2 A Vlhpe 5 ry Ot n"1 Y c eel7. l sP > c eHAFfEE ef,_A �'pPleC creek IW� \.)W see .0 e ev un v y.Goof Id e0el- x e Mk P a..�,.b oe �• '.4I IipMn ' n^.^an ` �^' -- r' c EL 4 be accomplished by excavating and lining an area, placing and compacting refuse in controlled lifts, and covering the refuse on a daily basis until a predetermined final grade is reached. Completed portions of the landfill will be covered withthree feet of compacted soils and six inches topsoil for revegetation. Revegetation will be completed to return the site to an environmentally suitable condition. 2 .4 Surrounding Zoning and Land Use The Laidlaw South Landfill is adjacent to the Denver Regional Landfill to the north. The other areas surrounding the facility are agricultural land. 5 3 . 0 SITE DESCRIPTION 3 . 1 Existing Site Topography and Vegetation The Laidlaw South site topography is shown on Figure 3 . 1. The facility is located on a gently sloping property with a west to east trending natural drainage along the northern portion of the site. The site is undermined by the Columbine Mine, a coal mine that is no longer producing. The site slopes an average of 4 percent and has a maximum elevation of 5200 feet and a minimum elevation of 5100 feet. The natural vegetation of the site consists of native grasses and shrubs typical in most areas along the Front Range. 3 . 2 Climatology Climatology information was obtained from the original SWC Design and Operations Plan and includes wind data only. Wind data was compiled at the Jefferson County Airport, approximately eight miles south of the facility. Table 3 . 1 summarizes the wind data collected The majority of the winds are northerly and westerly at speeds ranging from 4 miles per hour to 12 miles per hour. 6 FIGURE 3 . 1 - SITE TOPOGRAPHY • .- -_ *1111 t - `�- t �j /Y L/ - z --'__ 19 , / 1c — I ` V < - . A'i � I — /_ _ _ _ r_ _ c - - --- / .A( - ti - - _ 0 `� " �f .-. . - I \ 'N_,- .A N ib�'.'�iY - ° i F \ i vr'i _ , fl- , /' i 7 TABLE 3 . 1 - WIND SPEED AND DIRECTION WINDS FROM ALL 240O-10O 240O-300O 10O-240O DIRECTIONS WSW to NNE WSW to WNW NNE to WSW UP TO 12 . 1% N/A N/A N/A 4 MPH 4 TO 69 . 9% 33 . 6% 16. 1% 36 . 3% 12 MPH 12 TO 24 MPH 16. 4% 12 . 6% 9 . 0% 3 . 8% OVER 24 MPH 1. 6% 1. 6% 1. 5% 0 . 0% 8 4 . 0 GEOLOGY/HYDROGEOLOGY This report section presents an evaluation of ground-water conditions as they relate to the Laidlaw South Landfill in southwest Weld County. The information in this section includes background information regarding the site and a review of the regional and local geology and ground-water system found at the site. A number of studies have been completed at the facility over the past several years. These studies focused on installation of monitoring wells, collection of field and laboratory geotechnical data, and preparation of two brief operating plans. The information for this is from reviews of these studies. 4 . 1 Regional Geology/Hydregeology The site is on the northwestern flank of the Denver Basin, a large structural basin that contains important bedrock ground-water resources in the upper portion as well as economic oil and gas reserves at depth. A regional stratigraphic column is included as Figure 4 . 1. The Laramie Formation immediately underlies the site. The Laramie Formation is typically divided into upper and lower parts. The upper part is a buff to dark-gray, organic-rich claystone with minor interbedded sands. Numerous coal seams in this interval were _mined through the 1950's to provide heating coal to the cities along the Front Range. The lower part of the Laramie Formation consists of thin to massive beds of fine-grained, _moderate to well-cemented sandstone that is interbedded with buff to dark carbonaceous claystone. This unit has been further broken into the _A and B Sandstones. The Fox Hills Sandstone is under the Laramie Formation. The upper part, the Milliken Sandstone is composed of fine to medium-grained, parallel, thick-bedded sandstone with thin siltstone and shale interbeds-. It ranges in thickness from 40 to 90 feet. 9 FIGURE 4 . 1 - REGIONAL STRATIGRAPHIC COLUMN ‘— ----I Sill(III , ",ec.rr ., Irv• 1. o. ii_sari 0-32 h Gravels, genes, and Sn ts in stream flood plains. terraces, pediments, and slope ID n rn deposit. • !Cretaceous and Paleocene Denver and bpepenoe frutions of n Grime origin tae preserved 15 miles to the southeast of Boulder. Laramie t} Sandstone. light grey end tan, occasional coal. grey shale, and clays tone interbods; nornarine end marginal advise. P..M:IIa Sandstone. fight ten, fine to medium veined. friable; shallow....int. 930 T '— SMle. Carl grey. sae Silty. upper 1000' sandy- xyglene 5s-Mbr is IBW-}3o0' —o wore the bale; marine. n.r. i — '' Shale. dark grey, calcareous, fossiliferous:marine. 11. maeee 00 ide a v a-le ne0N itslimestone, light grey, hard, fossil iferous• thickly bedded;refine. e•aarrver s• t.._.—.—. Sandstone, fine grained, brtnnn. SMly. numerous burrows: shallow marine. 1 YTO thiS.. light grey. calcareous. and thin limestone beds;marine. _ Shale. dark grey, with some thin bentonite beds; Siliceous in a the lonoot part. marine. Sauce Plena Shale dark grey, silty, with platy sandstone (Pelleniew Y.br) at base end prominent Be0 ridge-forning tan sentntone at top (w mot e);earine and marginal oaring a Lune YO n Sandstone and congloerate with occasionally interbedded light-Colored cteyltone. I; rfont prominent hogback; fluvial origin. o uu.:.aat o sea Cleyttone and sus is torten. grey. tin red,with lvbordl se met beds of brown sandstone and grey siliceous limestone; (Sunlit and lecesbine in origin. •.,tee `0 ✓f /t1\\ Sandstone, light grey, fine grained, well sorted. lenge sets of tabular troll-bees: interpreted as esolian. v.a.m Jr e. forms vane pap Shale and 111 t1[D n<. .<d with vent:e meal male beds near the too. y: me r e and margin.' marine origin. -I y} tlnntw,e. Pink and grey crenelated; algal origin in fallow marine. or hypersaline miroment. ,-q li — shales end slltltone, red; Probable marine origin. -Lades Sandstone. tan or pink. siliceous, fine to meditn grained. well sorted. U typ1lty 330 J- o•gased of very large sets of thin and media, very regular cross-strata; o • interpreted to bee dune deposit. m o roe-ea Sandstone. and conglomerate. reddish.brwn and tan, erhoslc. poorly sorted, and 2 — Subordiante beds of red shales and Si ltstonel; abundant trough cross-bedding; rNJ - " occasional toue-centn. tool and scour rare., and mad cracks: individual units ' rdfeteretly discontinuous. the upper ISO' consists of alternating tongues of III — — roanteln-tibe and Lyons-alb llthologtes; interpreted to be a fangloxrete. w netemorphlc rocks Including enphibeli:r.-mica schist,. end euartvlte. bet. Boulder Creehgrenodiorlte. 'Soot IJ billion years old. • futceuBme+a ':} spa, Silver Plume ever:: •on.onite. .bout LA billion years old. Pegmatite% cmrnn. el,e,e '-- Red,0-o' s{ 4;.keys,:d .de..., 10 The Milliken Sandstone and the overlying A and B sands of the Laramie Formation comprise the Laramie-Fox Hills (L-F) aquifer, an important source of water through out the Denver Basin. The I.-F aquifer is the lowest of the principal aquifers found in the Denver Basin_. The overlying aquifers have been eroded away in the vicinity of the site and need not be considered. The Pierre Shale is below the Fox Hills Sandstone. It consists of a 7000 to 8000-foot thick sequence of gray to brown, clayey marine shales. This formation serves as a gasket that effectively seals all underlying formations from surficial impacts; therefore, the underlying formation need not be considered. The site lies in a structurally complex area. The bedrock has been highly distorted through both folding and faulting, with the faults generally aligned in a northeasterly direction. Near the site, the regional bedrock trend is a 1 degree dip to the southeast; however, local structural deformations may cause appreciable variation. 4 . 2 Site Setting 4 . 2 . 1 Topography and Drainage The site is on a west-facing slope. Total topographic relief (including the abandoned landfill) is roughly 155 feet. A flat terraced area is located in the southwest, where no filling has yet occurred. Another flat upland is found beneath the fill in the southern part of the abandoned area. The average slope of the hillsides is about 4 percent. A -gully exists beneath the abandoned and active landfills and is shown in Figure 3 . 1. Its head is located at the northeastern corner of the abandoned landfill. It has a general east-west trend and roughly bisects the active area. It has an average westerly slope of approximately three percent. The original depth increased from about 5 feet at the eastern active landfill margin to about 20 feet at the western landfill boundary. The gully has been filled with refuse to a line 50 feet east of the western perimeter. West of the site, the gully becomes a well-defined channel that intersects perennial Coal Creek about 2900 feet downstream. 4 . 2 . 2 Site Geology A total of 20 borings were augered to depths of up to 100 feet, geologically logged, and sampled for laboratory testing 11 to provide characterization information. The original boring logs are included -in this report as Appendix _A. Geotechnical laboratory data can be found in the original reports. The surficial material is exclusively a gray to brown, damp to moist, very-stiff to hard silty clay with moderate to high plasticity_. The probable Unified Soil Classification is CL- CH. The material forms a thin mantle, with natural thicknesses apparently ranging from 1. 5 to 15 feet. Figure 4 . 2 shows the surficial material thicknesses logged in the borings. The materials are colluvial or residual-weathering profiles. Defineable alluvial deposits are not found until near the confluence with Coal Creek. The bedrock is dominantly a silty claystone. This material is described as relatively massive with some jointing present. Thin and discontinuous clayey siltstones and sandstones up to 2-feet thick are interbedded within the claystone. -A limited number of coal stringers (lignite) are also present. One report indicated that the coal was highly fractured, and slicken -sides were noted on the coals. The existing data does not indicate the degree and complexity of any localized folding that may be present. An outcrop exposed in the soil borrow area contained a dry, plately silty clay overlying claystone bedrock. Stringers up to 1-foot thick of friable buff silty sandstone are embedded in the claystone. These stringers are elongated in a north- south manner and are continuous up to distances between 100 to 50O feet. The sand stringers are rippable and unsaturated. Existing mine maps indicate that a commercial coal seam is located beneath the site. This seam was mined until 1951. The mine lies between 200 and 350 feet below the original land surface. A mined-out seam was noted from 245 to 253 feet in a well drilled at the site. The seam had a thickness that varied between 5 and 15 feet. The L-F aquifer is tapped by two wells within 1 mile of the site. Their approximate elevations are 5360 and 5170 feet. 12 FIGURE 4 .2 - SURFICIAL MATERIAL THICKNESSES JINr Co ilwtR Scrio.- L4,Tea m.y(rp IN, Rt--".' I EGEno Gv-Z ® w-1 O (I orctcr;Th 4lells (lo) (so) ■ ¶e≤t Holds (-7)T h:ckr,e65 04 F.11 or Topsoil over aee.rccK 1\ G1J-S (a2/ !SISII -5 (5) kNNLNN:z:___ I 7 IA-5 , * (4.5) r I �L, R r,'1. II ■ ?5) it Th,-1 i ■ 81 Tr-r5 ix-9 6 ■ (\S) ■ \ ■ (45) (45 Tr, ) -it; II ■ (15) I Tr:7 ral Gw-3 TIii;,-3 ■ ) 01) (>i • (I) ,_ lilt-8s'1 NOR-CH G (co (6) 13 The top of the aquifer -is 480 and 400 feet below land surface in these wells. Depths to water are 300 and 200 feet respectively and indicate that the wate-r is in a confined state. Neither log showed water-bearing sandstones above the L-F Aquifer. Coal seams of commercial thickness (>5 feet) are found at 367-374 and 245-253 feet respectively in the two holes. 4 . 3 _Near-Surface Hydrology 4 .3 . 1 Ground-Water Occurrence Ten test holes (TH-1 to TH-10, Figure 4 .-2) were drilled in 1979 to collect subsurface information. Nine wells (GW-1 to GW-9, Figure 4 . 2) were installed in 1983 in the abandoned and active landfill areas. Summary information on the wells and test holes is in Table 4 . 1. Schematic -well-completion diagrams for the wellsare included -in Figure 4 . 4 . Geologic logs for the well and test holes are in Appendix A. None of the ten test -holes produced free water. Only one well, GW-1, produced water during drilling and installation. Three of the eight wells, GW-1, GW-6 and GW-8 contained water. Well GW-6 was broken and has been abandoned. These wells are completed into the gully-. Three test pits were excavated in 1984 to collect additional shallow-water information. One was excavated in the small collection pond in the gully bottom at the -western property boundary. One pit was also excavated in each of the two runoff retention ponds_. These ponds are located immediately to the northeast and southeast of the collection pond. -all three ponds are completed in soil-fill or natural materials. The leachate collection pond trench was excavated to a depth of 15 feet. The upper 3 to 4 feet were saturated and seeping. The materials got drier with depth. The trench filled up with water almost immediately. The trench in the southern retention pond was excavated to 13 feet. The soil was moist in the upper 5 feet and got drier to a 15-foot depth. The soil was reported as having a consistent moisture throughout the profile. The trench in the northern retention pond was excavated to a 15-foot depth. The soil wasreported as having a consistent moisture throughout the profile. The trench slowly filled with waterovernight to a depth 1-foot above the bottom of the excavation. 14 FIGURE 4 . 4 - SCHEMATIC OF WELL COMPLETIONS HPLP6 Nn 2.15 F'na. c ni: ‘PCP ‘001.0 t .. 5� rtv i_ ° _ doyY l.y�7o 11 � I_� 'rl 7,/ r- �f MKTLIR {rFCQr-;ATRr i i *.„/CV t.dn. 4 fart nr2TdbTF, ! _ 9 5/..ND _ Sw.;n � of LAlF�_ ------N- / 5f -Ev--- — - II>54.1 lent 1/ U-- f21-4.11, 2.•P PVC Z..4,per . ;I-- — I:: .1---- r- I i-- Lc,Grn P0aro3nz m n . r ri t.:eon..a.•.p..(..._..:....e 15 TABLE 4 . 1 - WELL AND TEST HOLE INFORMATION Hole or Total Depth Interval Tapped App. Depth to Well (feet) (feet) Water (feet) Comments TH- 1 12 NA Dry Hole TH-2 5 NA Dry Hole TH-3 3 NA Dry Hole TH-4 4.5 NA Dry Hole TH-5 5 NA Dry Hole TH-6 6 NA Dry Hole TH-7 25 NA Dry Hole TH-8 19.5 NA Dry Hole TH-9 19.5 NA Dry Hole TH-10 30 NA Dry Hole OW-1 100 52-100 93-95 Water at 91 feet during drilling 0VJ-2 Well Destroyed OW-3 95 5-95 Dry Dry Hole OW-4 122O) 5-122 Dry Dry Hole OW-5 50 5-50 Dry Dry Hole OW-6 93.4(?) 5-93.4 28 No water during drilling OW-7 26 18-26 Dry Dry Hole -GW-8 30 22-30 21-25 No water during drilling GW-9 100 52-100 Dry Dry Hole Notes: 1) Holes TH-1 to TH-10 were never completed as wells 2) There are discrepencies between the measured and reported well depths for wells GW-4 and OW-6. 16 Moisture content data was collected during the field studies. Plots of moisturecontent verses depth are included for a hole at or near the center of the drainage (GW-6) and for a hole that has never had ground water (GW-4) . Neither of the holes had samples with moisture contents that would imply saturation (typically 35 to 40 percent) . The materials beneath the drainage had higher overall moisture contents than the drier hillslope areas. The materials from both holes had moisture contents that decreased with depth, although the trends were fairly defined. The average moisture contents for both materials, 13% for GW-4 and 16 . 8% for GW-6, are below optimum and would probably require additional water if the silty clays were to be compacted to maximum density for use as liner material . 4 . 3 . 2 Material Permeabilities A total of eight samples were subjected to falling-head permeability testing_. The results for this testing are summarized in Table 4 .2 . One sample, a lignite from well GW-1, had a permeability of 2 . 3x10- cm/sec. The remaining samples had extremely low permeabilities that ranged from 9. 7x10-7cmLsec. The geometric mean for these samples was 5x10- cm/sec. Laboratory permeabilities are often a factor of ten lower than in-situ permeabilities, so the estimated in-place permeability of the natural materials should be around 5x10- 7cm/sec, an extremely low value. No field permeability testing has been completed to verify the in-place permeabilities. No testing to evaluate materials storativities has been completed. Any ground-water flow in low-permeabilities will probably occur through fractures. The dominant-claystone bedrock is described in the reports as massive with relatively small amounts of fracturing, s9 the effective storativity is probably quite low. 17 TABLE 4 . 2 - PERMEABILITY TESTING RESULTS 1 HOLE DEPTH PERMEABILITY LITHOLOGY 6W-1 100 2.3x 10-6 cm/sec Coal sample GW-3 53.5 9.7x10-9 Claystone GW-4 78.5 9.7x10-9 Claystone OW-5 50 1.9x10-8 Claystone OW-10 12 6.8x10-8 Claystone fill 0.5 8.7x 10-8 Surface sample 0.5 2.4x10-7 Surface sample TH-1 4 ¶.5x10-7 TH-2 1.5 1.9x 10-8 Recompacted to maximum density 1 18 4 . 3 . 3 Ground-Water Flow Relationships The results from the design studies and the existing well network indicate that all shallow ground water is apparently associated with the colluvial materials in the gully. In a typical system, the ground water would move down the drainage, with a velocity related to the gradient, permeability and storativity of the materials. At the site, this would mean that any ground-water flow would be westerly beneath the drainage bottom from the eastern part of the abandoned landfill to the western site boundary. The natural system has apparently been altered at the site by the embankment that was built across the drainage at the boundary between the abandoned Pratt Property and the operating landfill during operation of the original Pratt landfill. This embankment may restrict ground-water flow and result in ground-water mounding in the refuse in the abandoned landfill area. If this were the case, the water- table elevation would rise and, if there is a continuum of saturated material in the drainage, the gradient could eventually be reversed. Subsequent ground-water flow in this area would then be from the west to the east. Also, if sufficient recharge is available, the mound could continue to rise until it could flow westward over the buried embankment. This scenario is unlikely because of the clay cap over the Pratt Property impeding the flow of surface water into the site. Another interpretation is that the ground water is in discontinuous pockets of saturated materials. The water in GW-1 comes from a coal seam at the 100-foot depth. There is a distinct possibility that this water may not be connected to the shallow saturated materials associated with the gully. If this is the true system, the ground water flow would then be highly restricted. 19 5. 0 FACILITY DESIGN 5. 1 Waste Characteristics and Volume Assumptions The facility is permitted to handle the following wastes: * Non-hazardous, non-radioactive garbage and refuse from industrial, commercial and residential activities. Industrial waste includes Fly Ash from the Public Service Company power plants and other ash which have been approved for disposal by the CDH. Other special waste will be disposed of after appropriate analytical work has been done and after approval by CDH. * Contaminated soil which has been subjected to analytical analysis by the generator and been approved for disposal by CDH. * Tires and waste oils in reasonable quantities that can be incorporated without interference of compaction and cover operations. * Industrial liquid wastes, if special arrangements have been made and the amount to be received can be handled withoutundue interference with the solid waste disposal operation. * Sewage sludges that have been digested and dewatered * Friable and non-friable asbestos wastes, if properly packaged prior to delivery to the site. Disposal will be completed according to the regulations set forth by the Colorado Department of Health. The site operator has the right to determine whether to accept or deny acceptance of the wastes listed above. The operator also can add further restrictions if he feels that incorporating any of the wastes listed above into the landfill may cause potential problems. No hazardous wastes will be knowingly accepted from any sources including small quantity generators. 5. 2 Disposal Area Design The disposal area filling and operations plan has been adjusted to ensure there is an adequate amount of soils to 20 complete the landfill and close it in an environmentally suitable manner. The majority of the information in this section is included on Plates 1, 2 and 3 and also in the original Design and Operations Plan. 5.2 . 1 General Filling Plan The facility will be filled according to the diagrams in Plate 1. There are five phases associated with the filling plan totaling approximately 13, 814, 000 cubic yards of airspace. Each phase and its associated airspace is included in Table 5. 1. It should be noted that Phase 1 is the completed Pratt Property fill and is not discussed in this filling plan as it is not a part of the Laidlaw South Landfill . TABLE 5. 1 - AIRSPACE FOR EACH PHASE PHASE NUMBER AIRSPACE VOLUME (CY) PHASE 2A 538 , 592 PHASE 2B 1, 424, 080 PHASE 3 4 , 345, 064 PHASE 4 4, 605, 460 PHASE 5 2,901, 053 TOTAL 13 , 814, 249 The phase locations, lift development sequence, vertical and horizontal dimensions, and operation directions were selected to ensure that: 1) No wastes are placed in or near any ground water. 2) Surface -water .runon to both the site and the working faces is minimized. 3) Soil use and movement is balanced and optimized. 4) Completed fill slopes can be covered and reclaimed while other active areas are still being filled. 21 The landfill will be filled using a combination area fill method and trench fill method. The filling volumes and excavation volumes have been approximated assuming a refuse to soil ratio of 4 to 1. This ratio will allow Laidlaw an adequate amount of soil to operate and close the landfill in a safe, effective manner. 5. 2 . 2 Phased Filling Sequence Plates 1, 2, and 3 all include information regarding the filling sequences at the Laidlaw South Landfill. Plate 1 includes the filling phases, Plate 2 shows the areas and average excavation depths at the site, and Plate 3 shows lifts, stages and fill advancement details. Phase 2A is a trenched area located in the central portion of the site. Refuse will be trench filled in this area using cover soils that will be taken from the cut portion of the Phase 3 filling area. The Phase 3 filling area is located in the northwestern portion of the site and includes an area with average cuts of 20 feet for use as cover material. The Phase 3 area should be excavated to ready it for use when filling is completed in Phase 2A. Following completion of filling in Phase 2A, filling can begin in Phase 2B. Soils for use as cover material will be taken from the 20 foot cut area in the northern portion of the Phase 3 filling area and then from the southern portion of the Phase 3 filling area in the 15 foot cut area. Temporary Diversion Berm 1 should be constructed prior to filling to route surface water to the perimeter drainage. The northern portion of the Phase 3 filling area can be filled following completion of the excavation in this area. Soils used for cover material should be taken from the southern 15 foot cut section of the phase. This will ready the southern portion of Phase 3 for filling. Soils for cover in the southern portion of Phase 3 should be taken from the 15 foot cut area in the western portion of Phase 4 to start and then moving eastward through the 15 foot and 25 foot cut areas to open the excavation and ready Phase 4 for filling. Temporary Diversion Berm 2 can be constructed prior to filling in Phase 3 . In addition, a temporary berm may be required on top of the filled Phase 2 area to divert surface waters from the working face in Phase 3 . Phase 4 will be filled using soils remaining in the eastern portion of the phase and from the 25 foot cut areas in the Phase 5 filling area. During filling in Phase 4 , temporary 22 diversion berm 3 should be constructed followed by berm 4 as soon as filling advances to that point and excavation in that area is completed. When Phase 4 filling has been completed, it may be necessary to begin stockpiling soil to use for daily cover and the cap on the Phase 5 filling area. This will open an adequate amount of airspace to fill the final portions of the landfill. Temporary diversion berm 5 should be constructed prior to filling in the Phase 5 area. During phased filling of the landfill, yearly material balance calculations should be completed to ensure there are adequate amounts of soils for use in constructing the cover and cap. Caps will be constructed on the phases as they are filled to the correct elevations. 5. 2 . 3 Excavation Areas The Laidlaw South Landfill will require approximately 2 , 763 , 000 cubic yards of soil to operate the site assuming a 4 to 1 refuse to soil ratio. There are three areas designated in Plate 2 that should be excavated for soils to use for cover and capping requirements. The average 15-foot cut area includes the southern portion of the Phase 3 filling area and the northwestern three-quarters of the Phase 4 filling area. It is expected to yield approximately 1, 048, 000 cubic yards of soil for operational uses. The average 20-foot cut area is located in the northern portion of the Phase 3 filling area and is expected to yield approximately 316, 000 cubic yards of soil. The average 25-foot cut area is located in the southeastern quarter of the Phase 4 filling area and nearly the entire Phase 5 filling area. It is expected to yield approximately 1, 645, 000 cubic yards of soil. The total soils for the three areas is 3, 009, 000 cubic yards. The remaining 246, 000 cubic yards of material will be used as unspecified soils during revegetation, construction materials for diversion berms, materials for road construction, and material for maintaining the final elevations on the site. If ground water is encountered during the excavation of soils, the soil will be replaced and recompacted to a minimum depth of 10 feet above the water. Refuse will not be placed in water at the Laidlaw South Landfill. 23 Typically, refuse will be placed at the top of the working face in loose layers approximately two feet thick, and pushed downslope and compacted. A minimum of three passes at an overall slope angle of 6 to 1 using a trash compactor or bull dozer should result in approximate refuse densities of at least 1000 pounds per cubic yard. The actual thickness of each lift will be left to the discretion of operator but approximate thicknesses should range from 10 to 15 feet. Each lift will advance downslope to the approximate end of the filling phase. Many times during operations at the landfill, the refuse will be placed at the base of the working face and pushed uphill . The choice of working uphill or downhill will be the responsibility of the landfill supervisor and will be dependent on the filling location and conditions encountered at the site. 5 . 2 . 4 Liner and Cover Construction Liners at the Laidlaw South Landfill will consist of 6-inches of scarrified and recompacted clayey material. The original operations plan requires that area over high subsidence hazard area be lined with 1 foot of scarrified and recompacted soils and all other areas to have an unspecified thickness of scarrified and recompacted liners placed. Laidlaw will follow these criteria unless it can be proven to CDH and Weld County that subsidence potential in the area is low. If this can be shown, a liner of 6 inches will be scarrified and recompacted over the entire site. Appropriate geotechnical testing will be conducted to verify the suitability of the liner material. A Proctor and a remolded permeability test will be conducted on a sample collected at the site to verify soil properties. The hydraulic conductivity of the installed liner will be 10-6 cm/sec or less. The landfill cap is placed to minimize the possibility of surface water infiltration into the refuse at the site. The cap on the top and sides of the landfill will be -a minimum of 3 feet in thickness. Side slopes on the finished landfill will not exceed slopes of 4 to 1 and the top slopes of the landfill will be crowned with slopes of approximately 2 percent. The placement of the cap and liner will be tested and certified by a qualified engineer during placement. Construction quality control procedures for placement of both the liner and the cap are included in Section 7 . 2 . 24 In addition to the landfill cap, a cap will be placed over the mine adit and air shaft on the site. This cap construction is an original commitment of Colorado Landfill Inc. and will be adhered to at the site by Laidlaw. Laidlaw contracted ATEC Associates to complete a study of the adit and air shaft and prepare a procedure to close them. This report is included as Appendix B. Laidlaw will also build a 10 foot berm around the adit and air shaft using clay materials on site. The berm will route runoff around openings as stated in the original conditions for filling in this portion of the site. 5 . 3 Surface Water Control Surface water will be controlled to ensure that runon is not allowed to enter the active disposal area and that any surface water which falls on the working face is not allowed to leave the site. Intermittent historic flows from the site should not change because of construction of the landfill . No significant changes in the amount or quality of water flowing from the site are expected. To control the surface water, two types of diversions will be constructed on the site. The temporary drainage will be constructed to divert natural flows away from the active filling areas. As landfilling progresses, and the lifts and phases are completed, the temporary diversions will be abandoned and new diversions will be constructed at higher elevations on natural slopes, continually routing runoff from undisturbed natural areas around the landfill. The approximate locations of the temporary diversions are shown on Plate 2 . Permanent diversion channels will prevent surface water runon to the completed landfill and safely route runoff away from the completed slopes. These diversions will be constructed along the north and south landfill boundaries and the temporary diversions will discharge into them. Permanent diversion locations are also shown on Plate 2 . Design information showing the size and construction of the diversions are included on Plate 3 . A surface pond exists on the western border of the landfill boundary. This pond will be removed and regraded to promote positive runoff. 5 . 4 Asbestos Waste Placement 25 Friable and non-friable asbestos wastes will be accepted for disposal at the Laidlaw South facility as per CDH regulations. The waste is accepted for disposal in a portion of the landfill located in a permanently segregated area away from the non-hazardous solidified waste disposal area. Non-friable asbestos -waste will be accepted in either a contained or uncontained state. If it is contained in plastic _6-mil bags (or similar bags) or in rigid containers, the non-friable asbestos can be stored prior to being placed at the landfill, covered with non-asbestos containing soil and compacted. Any uncontained non-friable asbestos accepted at the facility will immediately be placed in the designated asbestos disposal area and covered with a minimum 6-inches of soil. The handling of the non-friable asbestos will be done in a way to minimize any increase of friability of the waste. Non-friable wastes can be disposed of at the landfill's working face. Friable asbestos will be accepted only if the waste is packaged in sealed, structurally rigid containers and disposed of in a segregated area. The containers are to be labeled with the following words: CAUTION Contains Asbestos Avoid Opening Or Breaking Container Breathing Asbestos Is Hazardous To Your Health The containers may also be labeled as specified by Occupational Safety and Health Standards of the Department of Labor, Occupational Safety and Health Administration (OSHA) , 29 CFR 1910. 100 (g) (2) (ii) . The waste will be accepted only in rigid containers and placed in the asbestos disposal area. The containers will be covered with a minimum of 6-inches of soil within 3 days of placement. The containers may be stored for 20 days prior to placement. All asbestos waste will be accepted on a pre-arranged schedule only. The waste will be unloaded from the transport vehicle at the storage area. The storage area will be a designated area segregated from the main working face of the landfill and fenced for security. The fencing will include signage as per the Colorado final asbestos disposal regulations. If the asbestos is non-friable and uncontained, it will be taken immediately into the cell and covered with a minimum of 26 6-inches of soil. If non-friable waste is packaged for disposal, it can be stored in the storage area for up to 20 days before being placed in the disposal area. If the waste is friable, it will be prepackaged in rigid containers and can be unloaded in the asbestos storage area for placement in the cell within 20 days. All Laidlaw employees handling the waste in the fenced boundaries of the asbestos area will be required to wear the appropriate respiratory protection gear. The containerized waste will be placed in the cell only by Laidlaw employees. The asbestos disposal location will be fenced for security. The entire area will be surveyed to document the disposal location on the site. The surveying will be completed by a surveyor licensed in the state of Colorado. 27 6 . 0 SUPPORT FACILITIES 6. 1 Access Access to the landfill is from Interstate 25, Colorado Highways No. 52 and 7, and Weld County Road 5. These roadways provide efficient and safe traffic flows to the site. The facility entrance is to the west of the completed Pratt Property. A gatehouse is located at the entrance as is an employee lunchroom in an adjacent building to the gatehouse. The landfill has a machine shop that is used to maintain vehicles and also houses offices for on-site personnel . Also on-site are the Laidlaw regional offices for landfill management. Access roads within the landfill are already in-place. Temporary road directional devices, such as signs, barricades and pylons will be used as necessary to control landfill traffic within and around the facility. Separate roads for ingress and egress to the active face are used at the facility. It is possible that additional roads will be required as filling into subsequent phases progresses. These roads should not exceed 6 percent in grade. 6 . 2 Site Fencing The entire site perimeter is fenced with an 8-foot tall mesh fence. Portable fencing is used at the working face of the site to control blowing debris during high wind events. Other fencing at the site will include fences around the Columbine Coal Mine entry shaft and air shaft to limit access to the area. This fencing will be moved as filling at the site advances. Fencing at the asbestos disposal area is addressed in Section 5. 4 . 28 7 . 0 CONSTRUCTION AND OPERATION QUALITY CONTROL Construction quality control is extremely important to ensure that facility designs are implemented and landfilling progresses in accordance with the approved landfill plan. There are four key quality control areas that will be monitored during the continued development of the landfill. These are: * Excavation * Clay liner and final cover construction * Operational inspections * Annual material balances 7. 1 Excavation Inspections Inspections should be made in each new excavated area to ensure that excavations in the landfilling area are constructed in accordance with the design, and that the conditions are consistent with those described in this plan. Inspections should be made by an independent consultant who will document the results in written reports. The reports will include maps showing the areas excavated and observations made by the inspector. 7 .2 Clay Liner and Final Cover Construction Inspection and Quality Control To ensure that the liners and covers are constructed in accordance with the specifications outlined in this report, an independent soils and materials testing firm will be retained to observe materials placed for both clay liners and final clay covers. Areas of the landfill that have been lined will be covered with the initial refuse lift as soon as possible after lining recompaction and certification. This will ensure the integrity of the liners is not damaged due to weathering. If the liner has remained uncovered for a period greater than 2 months, the materials will be reinspected. If the operator knows the liner will remain uncovered for a period greater than two months, a 1-foot layer of unspecified soils should be placed on it for protection. 7 . 3 General Operational Inspections Operational inspections of the activities at the landfill will be completed on a quarterly basis for the life of the landfill operation. The inspections will be made by an 29 independent contractor experienced with the landfill operations at this facility. They will be done to ensure that the landfill operation is progressing according to the landfill plan. 7 .4 Material Balance Inspections The area topography will be mapped on an annual basis to determine actual airspace and the amount of soil used during the previous years operations. A report indicating the results of the material balance inspection and recommendations, if any, for the following years soil use will be prepared and used to make adjustments at the site. 30 8 . 0 FACILITY OPERATION 8 . 1 Site Management The Laidlaw South Landfill operates during the daylight hours. Generally, these hours are 5: 00 a.m. to 9 : 00 p.m. The landfill is open 7 days per week. The facility is closed on major legal holidays. 8 . 2 Equipment and Personnel Requirements The following personnel and equipment are utilized at the site: Personnel : 1 supervisor 1 gate and record keeper 5 heavy equipment operators 1 labor/spotter (as needed) 2 mechanics Equipment: 1 trash compactor 1 scraper 1 bulldozer 1 motor grader 1 2 , 000 gal. water truck Facilities: 1 gatehouse 1 employee building 1 maintenance shop 1 office building 8 . 3 Control and Record Keeping Incoming waste verification and record keeping are performed by gate attendants. These attendants are familiar with the types of wastes allowed at the facility and have the authority to deny vehicles carrying hazardous and/or other unacceptable waste admission to the facility. Accurate records are kept of gate receipt volumes. In addition, results of all of the monitoring activities discussed above are retained. Copies will be maintained on- site by the operator and will be made available for inspection by authorized public agencies. The site operator will keep the following records on site and 31 available for county and state review: 1) Reports of construction quality control 2) Litter policing reports 3) Volume and types of incoming refuse 4) Results of gas and water quality monitoring 5) Any special waste accepted 8 . 4 Safety Control Safety control at the facility is the responsibility of the site supervisor. Normal safety precautions are observed while people are near or are operating the landfill equipment. At least two employees at the site will be trained in first aid techniques. A well stocked first aid kit will be kept in the landfill office at all times. Emergency telephone numbers will be prominently posted in the landfill office. Posted telephone numbers will include local police and fire departments, the nearest hospital facility, Weld County Health Department and the Colorado State Department of Health. 8 . 5 Water Requirements Both potable and non-potable water is required during site operation. Potable water is available from an on-site well and is available at all times. Leachate which may be produced will be used for operations only after analytical testing and approval by the CDH. Water may be required for compaction of clay liners and covers and occasionally for dust control. This quantity of water will vary depending upon the type of activity being conducted at the site. This water will be taken from the well or purchased off-site, transported to the facility, and stored and utilized on an as-needed basis. 32 9 . 0 CONTROL OF NUISANCE SITUATIONS 9. 1 Litter Control The topography of the site and surrounding areas with respect to the prevalent wind direction help to reduce problems associated with blowing refuse. However, windy days will occur and additional measures are implemented as necessary to control litter. The following operational measures are employed to control blowing litter at the site: 1) Application of soil cover during refuse placement and at the end of each day 2) Limiting the size of the working face during windy periods 3) Permanent and moveable site fencing 4) Ceasing operations during periods when high winds are present 5) Litter pickup activities Application of soil cover during refuse placement and controlling the size of the working face are the most effective means of controlling blowing litter. Generally a working face size of 100 to 150 feet will be maintained. On windy days the size of the working face will be reduced. In addition to soil cover control, fencing will be used to control blowing litter. Permanent site fencing for the facility is described in Section 6. 2 . Temporary fencing will be placed on each stage, so that the fencing increases in elevation as the fill elevation increases. In this manner, the fence will remain above the height of the working face or the fill to reduce the possibility of blowing trash reaching the permanent site fencing. Temporary removable fencing will also be used in the working face area as necessary to further control litter during windy periods. The use and placement of refuse working face fencing will be left to the judgement of the site supervisor who can best adjust the fencing for local topography and temporal variations and wind directions. Wind velocity measuring equipment will be maintained at the proposed facility. The landfill supervisor will place his daily cover and cease landfill operations during periods when 33 high wind warnings are verified. High wind warnings are defined as sustained winds of 40 miles per hour or greater, or gusts of 55 miles per hour or greater that are expected to persist for one hour or longer. In the event that litter escapes from the working face for any reason, it will be manually picked up and returned to the working face by site personnel and, if required, additional temporary labor. The operator will make every reasonable attempt to satisfy the concerns of the surrounding private property owners with respect to cleanup and removal of blown litter. If needed, this will include scheduling pickup from those properties. Blowing refuse often times comes from vehicles transporting materials to the facility for disposal. To minimize this type of littering, the operator will maintain a fee schedule that will penalize all uncovered loads which come to the site. The penalty for bringing an uncovered load to the landfill will be a fee which is twice the normal disposal fee. 9 . 2 Vector Control Disease and nuisance vectors are controlled by expeditious application of refuse cover to minimize food and harborage. If additional vector control is required, the services of a professional exterminator will be obtained by the site supervisor. 9. 3 Odor Control Odors at sanitary landfills result from a variety of sources, usually contained in the incoming refuse. The odors generally dissipate within a few hundred feet of the working face. Application of soil cover as described in this plan, is the only effective procedure for controlling these odors. 9 . 4 Dust Control Dust and particulate matter originating from winds, vehicular traffic and operational equipment are controlled by the site supervisor. During dry periods the operator will have the option of using either calcium chloride or water to minimize the amount of dust generated at the facility. Applications of these materials will be made whenever deemed necessary by the landfill supervisor. 34 9 . 5 Fire Control No burning of waste will be permitted at the landfill site. If a fire occurs in the refuse, it will be extinguished by excavating and removing the burning refuse and covering it with soil . In addition, all equipment operators will keep fire extinguishers on their machines to control small fires that do not require excavation and covering. 9 . 6 Methane Gas Control Methane gas is a by-product of decomposition of organic refuse. Methane gas generation rates increase as the moisture content of the refuse increases. Refuse moisture content will be minimized through a ban on both saturated wastes and the placement of refuse below the water table. These practices in themselves will not eliminate methane gas generation within the landfill, so migration of methane gas below the natural ground surface will be prevented by the landfill liners and the low permeability natural geologic materials. Methane gas will migrate and escape from elevated portions of the landfill through the covered surfaces. If migration needs to be controlled, an active or passive gas system will be installed. Methane gas monitoring procedures are discussed in Section 9 . 7 . 3 . 9 . 7 Environmental Monitoring Environmental monitoring at the site will be conducted to ensure that the facility design and construction is performing as planned. Components include ground water quality monitoring, leachate detection monitoring, and methane gas monitoring. 9.7 . 1 Ground-Water Monitoring The ground-water monitoring at the site will be done in conjunction with the post-closure monitoring at the Pratt Property. The ground water will be monitored at key points on a quarterly basis as a back up to the leachate detection monitoring system. Well locations are included in Figure 9 . 1 and sampling intervals are selected in a fashion that will : 1) Provide representative background data on the natural waters 2) Intercept the ground water along flow paths directly in-line and down gradient from the the landfill 35 3) Monitor the waters nearest to the surface that would be the first impacted if a release were to occur. The wells containing water will be sampled in accordance with EPA sampling and chain-of-custody procedures. Sampling will be conducted on a quarterly basis, and results of the water quality analyses will be submitted to both Weld County and the Colorado State Department of Health. All water samples will be analyzed for the following parameters on a quarterly basis: FIELD MEASUREMENTS Temperature pH Conductivity Water Level or Flow Rate LABORATORY ANALYSES Indicators Total Dissolved Solids Total Organic Halogen Total Organic Carbon Total Suspended Solids Major Ions Calcium Magnesium Sodium Potassium Chloride Sulfate Nitrogen Species Nitrate Nitrite Total Kjeldahl Nitrogen Trace Metals Iron Copper Manganese Strontium Zinc The operator will make justifiable changes as needed if the Weld County Health Department or the Colorado State Department of Health would like to amend the ground water 36 I'' FIGURE 9. 1 - MONITOR WELL LOCATIONS J. nC o ..eR SIGTiDN 9. wNWIP 1N, Ab8W _ G�• Uw- 1 LEGEnD �� • mnn;tor;„9 Wells • Test Holes y 11 , \ P.pf(OI;MGIQ totecho,. or tk< oriy;NcJ Gully A6ondoned ' t-0••••:0bour,do.rie5 Landfill 46 GW't ) 1 T VA-5 ilTH•8 k N.N.,..3V.\=.- i THAIIIITHE TH'y 'fH-9 T H 6 MI■ INr ■ ct;'e t�.aF,ll TH-lo D�.1 ■ H 7 GW-3 T;3\A ill F�tvre La rdc;ll ----__________________ \ G\J-9s9 W-5 • / r\r_____---ga G f6101-11 37 sampling parameter list at some later date. 9 . 7 . 2 Leachate Detection and Monitoring Construction details for the system are presented on Figure 9 . 2 . Angled wells will be installed reaching from the base of the fill approximately to the top of the filled area on an angle. The system will be constructed at the locations shown on Plate 1 and will be in the natural drainage pathways. The wells will be constructed of 12-inch steel piping and will be installed and advanced as filling progresses. The base of the well will be a sump area with three feet of compacted liner material underlying it and the well will be completed into a minimum of two feet of pea gravel. The bottom two feet of the steel piping will be slotted to allow the potential leachate to be detected and removed. The leachate detection system should never contain water, however; each well will be checked quarterly during every monitoring period. If leachate is encountered, it will be removed and disposed of in a proper manner. 9. 7 . 3 Methane Gas Monitoring Methane gas monitoring will be performed simultaneously with the ground-water sampling episodes. Methane monitoring wells will be constructed, or existing wells utilized, around the perimeter of the final landfill boundary to depths equal to the depth of excavation adjacent to the well. New wells will be placed 500 foot on center on all final landfill boundaries. Wells will be constructed using 2-inch diameter glue-joint PVC casing placed in 4-inch diameter borings. The PVC will be slotted and gravel packed to within 10 feet of the ground surface. The annular space above the gravel pack will be backfilled with dry bentonite. Proposed monitoring locations include the existing wells and additional wells shown on Plate 1. 38 FIGURE 9 . 2 - LEACHATE COLLECTION SYSTEM REVEGETATED 3 FOOT — � SIDE SLOPE CAP r --' r- --- `� - REFUSE LIFTS _%-- \ EXCAVATION SLOPE / " �- s-- / 3 FOOT LINER ---L.„/ /____. NATURAL MATERIAL SEE DETAIL A DRAWING NOT TO SCALE DETAIL A r WELL CAP �` , —_ -1 t -- ----- 12 -- '3 FOOT CAP INCH STEEL PIPE WELL \ • ^ J! �\ .----1\� REFUSE \_\ r J r ` ' J WELL SLOTS .. _ � \ is /~' c' `�. . . •\ • "PEA.GRA'JEL'-'ORSANGFLANKET." r' . /" c—�.- / >--- -, 3 FOOT LINER _ .-/--;- r-, - , / / / / / / - , " - - - URAWING NOT TO SCALE 39 9 . 7 . 4 Proposed Action In Case Of Significant Monitoring Results If at any time significant monitoring results are obtained, the state and county will be notified of the results within five working days. The operator will request a meeting with Weld County and the Colorado State Department of Health to discuss the monitoring results. If necessary, confirmation sampling and testing will be conducted. If an environmental problem is confirmed, the operator will have an additional 30 days to evaluate the data and present a plan of action to both the county and the state. The plan will include specific actions and a time schedule required to correct the situation. On approval, the plan will be implemented. 40 10. 0 CLOSURE AND POST CLOSURE 10 . 1 Reclamation and Revegetation Reclamation and revegetation will be completed at the Laidlaw South Landfill as filling progresses and previously filled areas reach final grades. In this way, Laidlaw can close the site using a phased approach. The following are recommendations for the revegetation program at the Laidlaw South Landfill . The Soil Conservation Services (SCS) of Longmont was contacted for recommendations for restoring the area to a condition that is as close as possible to its original vegetative cover. A copy of Standards and Specifications, Critical Area Planting, and Mulching provided by the SCS is attached. The program calls for laying down a topsoil layer, fertilizing according to the soil analysis, seeding with native grasses, and mulching with a high grade hay. Some of the recommendations concerning the amount fertilizer used may change depending on the results of the soil test. 10. 2 Topsoil The topsoil scheduled to be used in the area will be taken from a stockpile collected during excavation activities. The topsoil is currently supporting vegetation and will sustain the grasses to be used in the revegetation plan. Topsoil building will not be necessary due to a sufficient amount of organic material already present. Approximately 8 to 12 inches of topsoil will be scraped from a soil borrow areas and stored in stock piles until revegetation activities begin. The final layer of topsoil will be a minimum of 6 inches thick. Compaction and settling insures the seed will have a firm bed and will minimize wind erosion. This can be accommodated by rolling or harrowing the topsoil prior to seed planting. 10. 3 Fertilizer The SCS suggested a minimum 40 pounds of available nitrogen and 40 pounds of phosphorous (as phosphate) be applied per acre. A soil sample taken of the topsoil from the borrow area was submitted for a soil analysis. This will better determine the application rate of fertilizer for the site specific topsoil . Fertilizing will be done immediately prior to seeding to reduce the possibility of dispersion by wind and rain. 41 10. 4 Seeding The types of native grasses chosen for revegetation in this area are Luna Pubescent Wheat and Arriba Western Wheatgrass. The blend of 80 and 20 percent respectively is recommended. Luna Pubescent Wheat establishes itself quicker to stabilize the soil . Arriba Western Wheatgrass takes longer to establish but is a hardier variety that is more tolerant of adverse conditions such as drought. Seed placement will be accommodated by drill seeding to a depth of 1/4 - 3/4 of an inch. This method uses less seed than broadcast seeding and insures the seed will be at a proper depth for germination. Approximately 7. 2 pounds of Luna Pubescent Wheat and 1. 6 pounds of Arriba Western Wheatgrass seed will be used per acre. Pure live seed (PLS) should be used to insure the no weeds or inert material such as seed hulls or weeds are included in the seed blend. 10. 5 Mulching Using mulch provides protection for the seed by conserving moisture, reducing runoff, and protection from foraging birds and insects. The mulch should be crimped or bent to keep it in place. A high quality hay should be used as mulch. This will provide a good seed later and lower the possibility of introducing weeds that may gain an advantage in the seeded area. An application rate of 4000 pounds per acre is recommended. 10. 6 Conclusions Following the above recommendations will restore the facility to a range land compatible with the natural surrounding vegetation. Erosion by wind and precipitation will be reduced thereby preserving the landfill cap. 42 11. 0 POST CLOSURE 11. 1 Post Closure Monitoring The nine groundwater monitoring wells will be sampled or checked quarterly during the post closure period of five years. Analyses willbe identical to those conducted during the life of the facility. If monitoring results for a given sampling vary significantly from previous samplings, additional samples will be collected and analyzed. If the additional results confirm a significant and adverse change in conditions, the state and county will be notified of the results within five working days. The operator will request a meeting with Weld County and the Colorado State Department of Health to discuss the monitoring results. If necessary, confirmation sampling anti testing will be conducted. If an environmental problem is confirmed, the operator will have an additional 30 days to evaluate the data and present a plan of action to both the county and the state. The plan will include specific actions and a time schedule required to correct the situation. On approval, the plan will be implemented. 11. 2 Post Closure Inspections Inspections of the Pratt Property will be conducted throughout the 5 year post closure period. The inspections will include documentation of surface cracking, erosion, slope angles, drainage, and condition of vegetation. Subsidence monitoring will also be conducted during the 5 year post closure period. 11. 3 Subsidence Monitoring The Laidlaw South Landfill is undermined by the Columbine Mine, one of the largest mines in the Boulder/Weld coal field. The shafts of the Columbine Mine are approximately 300 to 400 feet beneath the surface, creating the potential for subsidence over much of the landfill. In addition to the mines underlying the site, there is the possibility of consolidation of the refuse causing settling of the landfill . Settlement of refuse and subsidence at a landfill may result in depressions in the final cover that will pond water. This ponded water has the potential to infiltrate and create leachate. Any settlement should be filled to promote positive runoff. 43 11. 3 . 1 Monument Locations and Construction Monuments used for monitoring subsidence and consolidation will be constructed at locations on the filled portions of the landfill that will be determined at the time of the facility closing. The monument locations will be selected by the operator and will be approved by Weld County and CDH. The monuments will be set in the ground approximately 18 inches and will be constructed of steel reinforced concrete. Each monument will be permanently numbered. 11. 3 .2 Monitoring Program The monuments will be constructed and the initial elevations and locations will be surveyed and documented by a registered Professional Land Surveyor (PLS) . The elevations of the monuments will subsequently be surveyed on a semi-yearly basis for a period of 5 years. The surveying will be completed and certified by a registered PLS. The results of each monitoring effort will be recorded, interpreted, and forwarded to Laidlaw in letter form incorporating any necessary recommendations. The monitoring results will also be forwarded to Weld County and to the CDH either by Laidlaw or their independent contractor. The results will be interpreted to conclude whether there is a possibility for waterponding on the landfill surface. If there is, actions -will be taken to place soil in these areas and bring the landfill back to final grades to ensure runoff to the perimeter drainages. The refilled areas will then be reclaimed according to the revegetation plan. The monument will be covered over and will therefore, need to be replaced. The replacement monument will be located atop the newly filled area adjacent to the previous monument. It will be constructed in the same manner as the initial monuments and will be surveyed in by a registered PLS and continue to be monitored on a semi-yearly basis. 44 11. 4 Post Closure Land Use Future land use and development will probably be determined by the land owner. No specific plans are included in this document beyond revegetation of the site. Existence of a closed landfill does not prohibit future land use, but such use will necessarily take into account location and size of the property, actual and potential settlement, landfill gas generation, land slope, zoning, and the needs of the landowner. Respectfully Submitted: Reviewed By: INDUSTRIAL COMPLIANCE INC. Curtis J. Ahrendsen Michael H. Stewart, P.E. Environmental Engineer Senior Engineer a`\aoDOREm1 E, ►a' zecn1. � o_ Le 23 9: O04 ••.•I E . soPQ- 3; •.'44,4 to%Volatt%amnuu y'fL H.Sfl' 45 APPENDIX A - BORING LOGS it X111.: , . , ! 111 111 I. � - ! I .. ,.. U KJ C•4 ��1��11�1M11111111IIlllllllf!lII11111!!fllllllllfll�f 11111!1111lll�l��illllg111111illlilllliillll1111 cD cNi o 0 a 1 Lip in In N N N N Cm CO "N. O O 0 N. N. N `O I Ni ... I' II r Il i : ..' 1 ! : ( : I11'1I Q1_. I r J1111� .. I „ ,! in !iii)iY))Y)i,:c.c ijYi)iiii))Y'•;i«i'l.. !w1 `I --{7{ f 44 Nt. ro 7 II�JUJ)))) in o [>, 1I I , '1�: ' ,II • . { ., I . 1". IIIIIIIIlIfhIIIIIIIIiIIII.I<IIII:'I I , ,-1::::II ' I .1 I . I o o aCD o I I' ' I . '. .. -:II I. I . .1I .I.:. 1 . " 1... I Z cv cv oo N N [f) 0 1111 1111 , 1 [ 11 in Ili 1111 1111 1111 1111 m a o 1111 1 [ 11 in to r- co crl c' o 0 0 0 0 0 0 0 0 ( aa j) Hld3Q CN r� o O `IL. in I r-� co L 1C CD a) Q L 4 E c r C » 4n a> a) c o c c c 4) L -8 d) (n Q O 0 ---r a 03 '.-- L cepp �_ a i ca U C1 53 L? L..._L'ijc EJ [::1 :I ri::::A Ell! E:). <`.,' ;',,..-1 1::::::::::::•:..i] l>.1 .., 53 LO i 0 T!r!.„I II!J!JI!JI!J./.7.7 J r!; . Tjy}� 'J),))..1'J'iii?)?`,_}?;:ii;..}iij)! 111 j`,YY]�Y''.''.'Y�i�Y]�lal`al i1 Y�'.�''•'''•i�i] ..'� CJ Ca! O.4 Q O lf) in i g4 O O ` N LO Ln In N C> Ij;i))Y}1?YrJ)11;);)))4))4);..4".,,))))),)))).),)4?).. • ' .)\.;.).;')V):)..).)).).'....":-;')').)..)c'.';')..).).).' .).Stititir •: iiri .i : :.)..)‘)<):)..).>)‘...-).)"..\i;7))i)}i:“ YlI);i;i;.))21 .: N N O CP OD O 00 CCN N) LID Lin a 'y`i Sa,Y (' a1]aY,.i i�i ;%1 tii]ti_y �,L Y. 'Y '.] 1 N C11 _N r fy aLIP up r I III. .. Ii.. .I N) I N CV 4 CO Ln OD hr] 1O I tri Ln 0 0 'Y`;i`;`i';a;;;);;)'r'�,}ii';`;`Y;i;`Y;';)`;';`'r'?'};;?i):;:S;}:; i�:Y.}:,.l.}., •::',;Y;,.1,,.i {,;' , i Y i,Y i,'iY Yl l]_iY,i1,1,1,:'e 1 i:i1 i:Y`r,,i:].]ai:l:ii:]l:Y:'e,i,,,,:e,,'..]a'. [ L N iD ,0 t'7 re) LID {t7 up I Ntn - I l 1[. 1 , U' C� CJ . I. [ ! • _� f� Lt) o NI V 0 0 c L 11II 1111 1111 MI 1111 Jill, MI 1111 1111 1111 0 0 min to r-- o 0 0 o 0 0 0 0 .— c o (1aa3) H1d34 �) a) d) m — co 0J a t Pa) C1. E C Ol c co C QY = -8 Q) W C C C to o �a•1 .J Cl i n C) [) co Cfj C 3 Ls- C. o X ( [ Ji . \ in L APPENDIX B - ATEC SUBSIDENCE REPORT ATEC Associates, Inc. Nyr 1121 Delaware,Unit 4 Corporates. IN : Longmont,Colorado 80501 Indianapolis. N 303-776-9757 (Metro)444-3291 tl A i Atlanotta: a.GA Baltimore, MD Birmingham, AL Chicago. IL Cincinnati,OH Dallas,TX Dayton. OH Denver, CO July 1, 1987 Ft.Wayne. IN Gaithersburg. MD Gary, IN Harrisburg, PA Huntsville.AL Lexington,Industrial Compliance Incorporated oKYLongmont, COC c 511 Orchard Street Louisville, KY Golden, Colorado 80401 Montgomery,AL Nashville.TN Raleigh, NC Salisbury. MD Attention: Mr. Mike Stewart Savannah.GA Toledo.OH Subject: Columbine Mine Shaft Location Washington, DC Columbine Landfill Affiliates: Weld County, Colorado Alexandria, v" Chantilly,VA AMC Project No. 41-74018 Newport News. VA Norfolk, VA Dear Mr. Stewart: At your request, we have compiled the production data and shaft locations for the Columbine Mine. The location of the "main" and "air" shafts are shown on the attached plate entitled "Plate 1 Final Contours/Filling Phase Boundaries and Permanent Drainage Design", ICI Project No. 1-1586. These locations should be considered accurate to within plus or minus 50 feet. Additionally, AEU. Associates, Inc. (Ara.) has located in the field the inferred position of the shafts. Records on file with the Colorado Division of Mines show that the Columbine Mine operated from 1920 to 1946. During this 26 year period over 7.2 million tons of subbitumenous grade coal was produced, making the Columbine one of the largest mines. within the Boulder/weld coal field. Mining of the reported 6 to 12 foot thick seam was accomplished using a modified room and board method. This mining method could produce extraction rates of 75 to 80%. Consulting Geotecrnical.Environmental& Materials Engineers Industrial Compliance Inc . July 1, 1987 Page 2 The Division of Mines records indicate the depth to the mined seam beneath the landfill site is approximately 300 feet. However, due to a major north-south trending fault that parallels the eastern boundary of Section 29, two levels of mining are present. The upper level east of the fault was approximately 150 feet above the lower seam. A 3,600 foot long "rock tunnel" connected the lower and upper intervals. Additionally, a 625 foot long "slope" connected the two mining horizons. Both of these entries were within the mine and did not intersect the surface. A third shaft, to serve the upper interval, occurs approximately 3,200 feet east of the main production shaft well off the landfill site. Due to the presence of the "main" and "air" shafts within Phase 4 of the landfill operational plan, AEL would recommend that a structural and hydrological cap be constructed over each shaft. Additionally, it is recommended that landfill operations not be conducted near the uncapped shafts due to the possibility of uncontrolled collapse. Listed below is an acceptable procedure to be followed in capping the shafts. 1. Excavate and remove all debris within the shafts to a minimum depth of 15 feet. 2. Extend the excavation to provide a minimum of 5 feet of penetration into claystone bedrock. 3. The bottom of the excavation should be at least twice the size of the shaft (example: 10' X 20' shaft should have 20' X 40' excavation) . *Note: Do not have personnel in bottom of excavation without safety lines. Industrial Compliance Inc. July 1 , 1987 Page 3 4. Prepare the bottom of the excavation by scarifying 6 inches and recompacting the CLAYSTCNE to 98% of standard Proctor density (ASTM D 698) within plus or minus 2% of optimum moisture. 5. If the shaft is open at this depth 6 inch channel steel or suitable material should be positioned to allow for concrete placement. 6. The concrete cap should be 18 inches thick and cover a minimum of twice the shaft dimension (i.e. 10' X 20' shaft 20' X 40' cap) . 7. It should be constructed of 2 lattices of #5 reinforcing steel on 1 foot centers. The steel should be free of corrosion and trinait] so that the ends are not exposed after concrete placement. 8. It is recommended that sulfate resistant concrete with a minimum strength of 4,000 psi in 28 days be used. Placement should occur at a 2 to 3 inch slump and be consolidated with a vibrator. 9. The excavation can be backfilled after the concrete reaches 75% of strength. 10. Backfilling should be accomplished using CLAY or CLAYSTO E (CL-CH) material compacted in maximum of 6 inch lifts to 98% of standard Proctor density (ASIM D 698) within plus or minus 2% of optimum moisture. Should you have any questions or require clarification of the procedures, please feel free to contact me. Sincerely, AILL ASSOCIATES, I Greg D. Sherman Longmont Branc an ger GDS/tlj APPENDIX C - SOIL CONSERVATION SERVICE RECOMMENDATIONS UNITED STATES DEPARTMENT OF AGRICULTURE Soil Conservation Service Colorado Technical Guide Section IV All Field Offices July 1985 STANDARD AND SPECIFICATION PASTURE AND HAYLAND PLANTING (Acre) 512 STANDARD Definition Establishing and re—establishing long—term stands of adapted species of perennial, biennial, or reseeding forage plants. (Includes Pastures and Hayland Renovation. Does 'not include Grassed Waterway or Outlet on cropland.) Purpose To reduce erosion, to produce high quality forage, and to adjust land use. Conditions Where Practice Applies On existing pasture and hayland or on land that is converted from other uses. SPECIFICATIONS 1. Seedbed Preparation Irrigated Sites A. Seedbed should be smooth and firm. It should be relatively free of weeds and other plants that may interfere with stand establishment and crop production. B. Seeding may be on bare ground, weed—free stubble, or chemically treated sod. Seeding into stubble or chemically treated sod is an ideal seedbed and is especially well adapted for slopes where erosion from irrigation may be a problem. C. Companion crops may be recommended if needed to control erosion until pasture and hayland planting is established. (However, discretion must be exercised in recommending a companion crop. Seeding rates are often too high and crop management favors harvest of the companion crop, rather than stand establishment of the pasture and hayland planting.) TG Notice #94 (Rev. 2) (Page 1 of 17) Colorado, SCS, July 1985 Non-Irrigated Sites A. Wind and water erosion is not a hazard. 1. A firm seedbed free of clods or weeds will be prepared . B. Wind and water erosion is a hazard. Seedbeds in major land resource areas 67 (Central High Plains), 69a, 69b (Upper Arkansas Valley Rolling Plains) , 70 (Pecos—Canadian Plains and Valleys) , 72 (Central High Plains) , and 77 (Southern High Plains) are required to have satisfactory protection from wind erosion by means of one of the following methods or condition in paragraphs 1-5, as selected and approved by the local conservationist. Field or areas that are too gullied, hummocky, or in need of mechanical conservation measures should be shaped as necessary to plant and grow a locally adapted small grain cover crop. 1. Prepared stubble cover of sorghum, cane, sudan or broom corn if left • standing to give maximum protection from blowing. a. On sandy lands drill forage sorghum at the rate of 10 to 15 pounds per acre or hybrid sudangrass at the rate of 15 to 25 pounds per acre in rows not to exceed 20 inches, between June 1 and July 15. If more growth is produced than desirable, or if sorghum will produce mature seed, the cover will be clipped to • not less than approximately 8 to 12 inch stubble height and should be removed from the field. If establishment of a cover crop has removed excessive soil moisture, one additional year of chemical fallow should be considered to improve soil moisture conditions. b. On medium and heavy textured soils, grain sorghum or forage sorghum may be planted at the rate of 4 to 8 pounds per acre in rows up to 42 inches wide , cultivated, and harvested if stubble is left approximately 18 inches high. (Note: This is the recommended procedure. The closer the row spacing the lower the stubble height down to 8 inches as a minimum on 12 inch spacing. ) 2. Existing stubble cover in lieu of preparing a cover crop. a. In LRA's 69a, 69b, 67, 70, 72, and 77, harvested sorghum with a stubble height of 8 inches for grain or feed may be used, providing there is adequate cover to protect the grass seedlings and the soil from wind and water erosion. b. Millet with a stubble height of 8 inches may be used if adequate cover exists to protect the land from wind and water -erosion. c. Small grain stubble other than cereal rye, wheat and barley where volunteer growth will not be a problem may be used. TG Notice #94 (Rev. 2) (Page 2 of 17) Colorado, SCS, July 1985 d. Annual weed cover is the least desirable method of preparation. Seedbeds having an annual weed cover are satisfactory if the seedbed is firm and if the stand of weeds -is not dominated by tumbling Russian thistle, sandbur, cockelbur, fetid marigold, Canada horse— weed, kochia or by other seriously competitive weed species. Steps must be taken to control weeds to protect the new sending should weeds make rank growth following the seeding. Where competitive weeds exist the labeled application of a non—selective goad spectrum contact herbicide , (e.g. Roundup) 1/, could be used in lieu of plowing to prepare a satisfactory seedbed. 2. Seeding Seeding should be done with equipment capable of proper seed placement and accurately metered for the proper rate for the selected species. 3. fertilizer Application Host plantings should be -fertilized at time of seeding and on an annual basis as needed. Recommendations should be based on results of soil test. If these are not available, s minimum of 10011 of a 20-10-4 or similar fertilizer should be applied. - 4. Selection of Species A. Select adapted species for the given -Land Resource Area based on adaptation to site, intended use of planting and on adequacy for erosion control. Species and varieties may be added with approval of the State Agronomist_. B. Irrigated — If a species is designated as being adapted to irrigated sites in a given Land Resource Area, the species is usually adapted to the entire area where irrigation is used. C. Non—Irrigated - Item 4B above is usually not applicable when species are recommended for non=irrigated sites in a given Land Resource Area. Species adaptation on non=irrigated sites is much more critical. -See Standard and Specifications for "Critical _Area Plantings," Range Seeding, or other references if specific information is _needed for species on non—irrigated sites. Table 2 lists additional legumes and forbs for non=irrigated pasture and haylands. D. Pure stands of grass(es) or legume(s) or mixtures of grass(es) and legume(s) qualify for pasture and hayland plantings. (See item 4E below. ) 1/ Use of trade name is for clarity only and does not imply endorsement of any one product over other-s labeled for the same treatment. TG Notice #94 (Rev. 2) (Page 3 of 17) Colorado, SCS, July 1985 E. If the purpose of pasture and hayland planting constitutes -a change in land use from cultivated crops to permanent vegetative cover, the seeding mixture must _contain not less than twenty—five (25) percent, by pure live seed rates of perennial grasses. 5. Rate of Seeding See Agronomy Technical Note 1/61 for "Seeding Rates-- 6. Time of Seeding Date of seeding will be at the discretion of the Field Office personnel . Non-irrigated plantings should generally be made immediately prior to anticipated periods of precipitation, during late fall or early winter, so that -germination will occur in the spring. Recommended seeding dates for non-irrigated plantings. Grasses, legumes, and other seeded species shall be planted within the seeding periods specified -in Table 3, with the provision that up to 1D days tolerance from the -specified periods may be allowed for the purpose of adapting to local soil moisture conditions. Table 3. See-ding Dates for _Pasture and Hayland Plantings Cool Season Plants Warm Season Plant-s MLRA* Dormant-Spring Summer Dormant-Spring Summer D-34A,B,C Oct 15-Apr 30 Jul 15-Aug 31 Oct 15-Apr 30 Jun 15-Jul 15 D-33,D-37, D-39 E-48A,- -48B, Oct 1-Apr 30 Jun 15-Jul 15 1/ Oct 1-Apr 30 Jun 15-Jul 15 E-47 Jul 1-Aug-12 2/ Jul 1-Aug 1 2/ E-49-A, E-49B Oct 15-May 15 Oct 15-May 31 E-31 Oct 15-Apr 15 Jun 15-Jul 15 Oct 15-Apr 15 Jun 15-Jul 15 G-67 So. Colt Nov 1-Apr 30 Nov _1-May 31 G-70, H-77 G-67 No. Colo Oct 15-May 15 Nov 1-May 31 H-72 G-69A, G-698 Nov 1-Apr 30 Nov 1-May 31 * Major Land Resource Area. 1/ Applicable to MLRA E-48A and E-48B on eastern slope of Rocky Mountains. 2/ Applicable to MLRA L-48A and E-48B on western slope of Rocky Mountains. 1G Notice 494 (Rev. 2) (Page 4 of 17) Colorado, SCS, July 1985 7. Management (Tor -establishment) A. Harvest or grazing during initial establishment -season will be limited to the same requirements found in the Standards and Speci— fications for Pasture and Hayland Management (Code 510). B. Control -weeds and seed production from volunteer small grain and cover crops. Mowing at a height of 6 to 8 inches at the appropriate time is usually a very effective -control. Herbicides are recommended for weed control in grass seedings. (See Colorado Weed Control Handbook for information on herbicides.) TG Notice 094 (Rev. 2) (Page 5 of 17) Colorado, SCS, July 1985 Hello