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HomeMy WebLinkAbout3.0 Army Corps of Engineers Reportwestern Coiciadc ileeulatcry Ciiic,-' DEi ? 2 iEg? MOORE /ENGLUND PROJECT REF. # PN199775319 December L9, L997 Ms. Susan Bachini NallEnvironmental EngineerWestern Colorado Regulatory OfficeU.S. Arny Corps of Engineers 4O2 Rood Avenue, Room 142Grand Junction, Colorado 91501-2563 REFERENCE: pN199775319/Moore and Englund SUBJECT: App_Iicants' Response to Corps Letter Dated November 21,L997 1. we were -d.isappointed in the brevity of your response tcour discussion of the Cattair-dominated wetrands within the'ilil=;;Pond and thoug_ht some of the imf"iii"t points we were trying tomake hlere overlooked. rt is trui the ac6umulation of seaiirenl isa normal condition which increases slowly over a period of ti...Unusual activities or events, such a= ,"16 experien'ced in the late1980's with the construction of the Blue crlek subdivision, -;;; (""9- did) s-ignificantly accelerate the amount of sediment depositedi1-the.ponds. As expelt,ed, the area of the pond with the heaviestsirtation is where the i.nfrow or diversion from Brue creek entersthe pond. The emergent wetl.ang vegetation or ncattailstr which giverise _to your crassifying this aiea as a wetrand, deverop iErvquickly and only at tnL ena of the siltation cycle iwrren tne aeptirof the water is reduced to the point where erner-gent vegetation wifithrive). Thus, w€ do not beliLve the combination of sediment andcattails should be considered a rrnormalr! condition which exists inthis man made pond. We believe our removal of the accumulatedsediment is a normal, necessary and legitimate rnaintenance act,ivityrequired to keep our man hade siructures (the fish p""a=jfunctioning in a normaL manner and to keep or-,. uairrdicated waterstorage rights in force. we also beiieve tnit signifi;;tprecedent exists for this view with regard to ongoing naintenanceactivities of. the state, county, and, r6cal goveriments as werr as]gcar irrigation and water suppry entities. your crassificaiion oithe 0.L25 acres of cattails in-ttie Johnson pond as a jurisdictionaLwetland requiring mitigation at a ratio of 2 to 1, d-oes not appearto be a fair and reasonable interpretation of your definition of awetland or the intent of the -c1ean Water Act and suUsequen[regulations. we respectfulry ask that you reconsider thisdeternination rn the event that you stirl insist that this area is ajurisdictional.wettand req:uiring 2 to 1 rnitigaiior,,-;; wirl need tomodify our sediment removll pta-ns with regard to the Johnson pondto incrude onry the renovalbf 1,ooo to 2,ooo cubic yards at thewest end of the pond, leaving in place the sediment at tne east endof the pond supporting the Cattair vegetation. This action wourdbe nece-s_sary g! 9yr part because of the rimited on site areasreasonably available for mitigation. 2. Evaluation of ALternatives. a. The alternatives to the proposed site have evaluated under two specifj-c groups, on-site and off-site. general considerations common to both groups are as follows; (1) The purpose of the alternatives analysis is to determine if a practicable alternative, in terms of cost, technical, and logistical factors, exists for the proposed action which will reduce or eliminate the aquatic impacts. The aquatic impacts are represented by the loss of a 0.6 acre man made pond and its associated perimeter wetlands of 0.055 acres. The loss of the pond does not require any rnitigation, however, close scrutiny is given to the }oss of the 0.055 acres of perirneter wetlands createdby the man made pond as they are considered special aquatic resources. Any on-site or off-site practicable alternative should provide some significant or easily identifiable difference in the impact to the aquatic resources, particularly the 0.055 acres of wetlands created by the man made pond. (21 It is assumed that essentially all alternatives other than the proposed plan, will necessitate that the majority of the silt removed from the ponds be hauled to an off-site location for disposal. This action would result in a ninimum increase incost of $so,ooo to the owners for additional hauling. This cost would be hrgher if the disposal sit,e is further than 15 minutes hauling time from the ponds. (3) The technical factors are assumed to be a littte more difficult with regard to construction of suitablebuilding foundations at the proposed site (See paragraph 41. The additj-onal foundation costs per dwelling are estimated at S8,0OO. b. on-Site Alt,ernatives/Location and Descriptions: !{e have made every effort to evaluate alI potential on-sitealternative locations whether perceived by us or someone who commented on our application. Drawing 1 in Appendix A, shows theIocation of the various on-site alternatives which have been evaluated and are discussed in detail below. (1) Alternative A considers only a single buildingsite for one dweIling, filling in a portion of the River Pond inlieu of utilizing the entire pond for two dwellings as proposed in our original application. This alternative is shown on Drawing 2in Appendix A and is discussed below. The silt being removed fron the Johnson and |tsrr Ponds and usedas fiII will have }ittle or no shear strength once it has beendisturbed. This means it would not be stable and would simply flowout into the pond unless expensive sheetpiling is used to separatethe building site from the remaining pond area. Because of the area necessary for a building site and the 2 been Some -l required setbacks (50 ft. for the fSDS), the remaining pond(approximately O.2 acres) would be too smal1 to provide adequatefish habitat. As long as a portion of the River Pond remains, the existingflow must be maintained. The remaining pond area would require acostly extension of the current 18 inch CMP overflow/drain from therrsrr Pond. This extension would have to run under the proposed newdwelling and would present a potential hazard when maintenance or replacement should be necessary. Wetland impacts are only slightly reduced by filling in aportion of the pond. (2) Alternative B isPond and the rrsrr Pond and is shown onis discussed below.Virtually all of this site is in located between the Johnson Drawing 3 in Appendix A and a designated jurisdictional wetland area.Garfield County requirements of 5O ft. setbacks from the pondsto an ISDS system would result {.n insufficient land area beingavailable for an ISDS installation of adequate size. (3) Alternative C is located on the north side ofthe Johnson Pond and would have to be created by filling in aconsiderable portion of the Johnson Pond. Filling in the Johnson Pond is not recommended as the Johnson Pond is within the main channel of Blue Creek and as such is the initial and most irnportantsilt receptor for aII 5 ponds (The Johnson Pond easily collects more silt per surface acre than any other pond). Reducing itsability to intercept silt by a significant reduction in its storagecapacity would be very detrirnental. For the purposes of this analysisr w€ evaluated the Johnson Pond with a rnodified water surface as shown on Drawing 4 in Appendix A. Again, this partial filling of the pond could only be accomplished through the use of expensive sheet piling. Theresultant water surface would be the absolute minimum necessary toprovide, a reasonably effective silt recept,or, enough water surfacearea to sustain the silted in area exhibiting cattail vegetationdetermined by the Corps to be a jurisdictlonal wetland, andsufficient water flow area surrounding the approaches to the two decreed overflow structures exiting fron the Johnson Pond into the Moe and Island Ponds.The resulting area for a dwetling is compromised by thefollowing factorsr' An existing 5 inch high pressure gas line alongthe north property line requiring a nininun setback of 25 ft. to any construction activity, a 50 ft. setback required by Garfield County from a stream or waterbody to an ISDS installation enforcedfrorn the water's edge of the Johnson and Moe Ponds, the need to maintain the existing naintenance road between the Johnson and Moe Ponds to provide regular maintenance and vehicular access to theremaining ponds, and a 25 ft. setback from the water's edge of the Johnson Pond for safety.After incorporating all the necessary factors above, the remaining area is physically inadequate for the siting of--1 residential structurL.- AIso, the lan& area available for an ISDS installation is grossly inadequate as indicated by the shaded area shown on Drawing 5 in APPendix A- While this -=ite is tttiffy inaaequate in terms of its physical constraints, it would also havE numerous and very serious aesthetic deficiencies. A dwelling sitea in this location would be subject to terrible traffj.c noise from State Highway 82. The immediately adjacent property to the north is being-used as a parking Io! 11dsiiging arei fof a construction excavation company. Though t!t" oorr,61 5f tni= land has elevated the property with I ft. of fiII, it has had no effect in mitigating ani noise from the highway' fh: unsightly parking of ,,.r*"t6.r= co-nstr:uction vehicles, junk cars, lTditaii"tiininate mounds of dirt and debris would have a dramatic n-gative effect on any dwelling located next to it. (4) Alternative D considers two locations north of the Moe Pond as shown on Drawing 6 in Appendix A and which are discussed below.A 10 inch and a 6 inch high Pressure gas line owned by Rocky Mountain Natural Gas extends fnrilugn these two areas which were ia""tifi"a in the comments as poisible sites. The setbacks issociated with these two very large and potentially dangerous gas Iines together with the setbicks iequirea by Garfield Count'y for ihe rsos instarlations as werl as the building setbacks, cornpletely eliminates the possibility of any dwelling construction at these locations. c. our assessment regarding the on-site alternatives is that no pract,icable alternativ6 exisfs to the proposed action of iiffi"g it the River Pond to provide homesites regardless of the nrr*U"r-of sites (1 or 2) eventlualty approved by Garfield County' d. off-Site Alternatives/General Considerations: Some general considerations considered common to all the external alternatives are as follows; (1) The reason or purpose for building a hgne on the existing site is to provide s-netler so the therapeu.tic . Pdrecreational opportunitieJ of the area and in particular this site, can be utilize'a-ana enjoyed by the owners. If it were not for the iviif"Uility of the - uni{ue therapeutic and _r-ecreati:ll};pp;;a"nitil= afforded by the current site, there. would be no need oi^ desire by the owners to build a home to provide shelter' Any evaluation of off-site alternatives must reasonably provide for the continued and frequent use of the existing site in terms of cost and logistics. (21 The owners desire is to create a country living experience in a'Iow density residential setting. In that regard, the existing sites would have a reLative density of one home per 11acres. This density is consistent with current advisory guidelinesdesired by the Garfield County Planning and Zoning Commission to restrict rural housing to one home per 10 acres. While it would be unreasonable to expect the alternate sites being evaluated to allcontain the Roaring Fork River and 4 fishing ponds, it certainly appears appropriate to evaluate only those sites which offer a sinilar living experience with regard to residential density. We have evaluated sites within a 5 mile radius of the existing sitewhich would contain no less than 2 acres for a single fanily dvrelling. e. Off-Site Alternatives/Location and Description: Areal estate multi-Iist service was used for locating propertieswhich are currently avaj.lable and are within the 5 mile radius. These propert'j-es are considered representative of what is availablein the area. The general location of these properties relative tothe owners existing site is shown on Drawing 7 in Appendix A. Theindividual properties are briefly described below. The legaldescription available from the multi-Iist information is shown inparentheses. (1) Site 1, (Lot 3, Ries Exemption), $265r000,consists of 2.56 acres with 400 ft. of frontage on the Roaring ForkRiver, approxirnately 2 rniles by road from the proposed site. (2) Site 2, (TR S35 T7S R11 5PM), $280,000,consists of 8.95 acres approximately 3 miles by road from the proposed site. (3) Site 3, (Lot 4, Pinion Grove), 5425,000,consists,)f L4.4 acres approximately 5 miles by road from the proposed ,site. (4) Site 4, (Lot 29, Mountain Meadow), $450,000,consists of 9.9 acres approximately 5 miles by road from the proposed site. (5) Site 5, (Filing 2, Lot 36, Mountain Meadow), $390,000, consists of LL.77 acres approximately 5 miles from the proposed site. (6) Site 6, (Legal Not Available), $500,000,consists of 3.19 acres with 600 ft. of frontage on the Roari.ng ForkRiver, approxirnately 6 niles by road from the proposed site. f. The off-site area propert,ies owned in whole or inpart by Mr. Moore or Mr. Englund and/or their spouses are; (1) The lL acre tract owned by Englund and Moore, 5 adjoining theapplication. adjoining theapplication.and businessdwellings. propose{ site on the east as shown on our original (2) The 1.32 acres owned by Luther and Diana Moore, proposed site on the north as shown on our originalThis property contains the owners combination home(bed and breakfast) as well as 2 other rental (3) A 1,800 sq. ft., 3 bedroom, 2 bath, house ownedby Mr. Englund at 0253 Surrey St. on the Ranch at Roaring Fork.This is investment property and is currently occupied by a renter. (4) A 1,000 sq. ft., 2 bedroom,house at 405 Park Avenue, Unit A-1, Basalt, Co. Moore own a 50t interest in this property which isand listed fbr saLe. 2 L/2 bath, town Luther and Diana current,ly rented g. our assessment regarding the pract5-cability of theoff-site alternatives is as follows; The 11 acre tract on the east, (paragraph 2.t,. (1)), currentlyprovides no site which is not either in a wetland or the floodwayof the Roaring Fork River.The L.32 acres on the north, (paragraph 2.f .(2)1, owned byLuther and Diana Moore provides a significant portion of theirincome and could not be used without adversely affecting theirwelfare. This was a successful business when they bought it in November L994, and it should remain so until they decide to retireor otherwise dispose of it. The other dwellings (paragraphs f. (3) and f. (4) ), are incomeproperties unsuitable for the needs and desires of the owners astheir private residences. The other off-site properties discussed in paragraph 2.e.,appear to provide an adequate rocation for the siting of anacceptable single fanily dwelling for the sole purpose of shelter.AII of these sites (particularly the ones with river frontage)would need to be exanined by a wetlands specialist t,o ensure thata residence and associated driveways, could be sited such thatwetland impacts would be significantly below the 0.055 acresincurred on the existing site. Since this is a very small wetlandimpactr w€ believe this would be very difficult to achieve unlessthere are no wetlands at aII on these alternative sites. Theaverage distance from the existing site to these off-sitearternatives is more that 8 uriles round trip. Logistically, thiswill at the very least, cost the owners several dollars per trip tovisit their existing property and return, be a seriousinconvenience, and subject them to the conmon hazards of asignificant amount of unnecessary travel. The average cost ofthese off-site alternatives is $aes,Ooo. Considering the haulingand offsetting technical costs, this would result -in increasedcosts to the o$rners of approxinately $800rOOO for two single farnily homesites. This would only be reduced to approximately $4301000for one single family homesite. These costs do not reflect theadditional costs which the owners would incur for annual property taxes and naintenance. Based on the above cost, technical, and logistical factors, itis the clear view of the owners that no practicable off-sitealternative exists for the proposed River Pond honesites regardlessof their number. two the 3. Drawing 8 in Appendix A shows the overall layout for the homesites in the River Pond area including the footprint for ISDS and wetland nitigation requirements.. We have submitted a Sketch Plan and application to theGarfield County Planning and Zoning Commission to subdivide ourproperty. The commission net in regular session on December 17, and there was no opposition from the public to our subdivision plan. The consensus of the commission was they would not proceed withpreliminary plan approval until we have successfully conpLeted the 4O4 permit action with the Corps of Engineers.If the county hlere to deny our application for subdividing ourproperty, our plans would be reduced to the construction of only one residence at the River Pond site. At this point, w€ would also be forced to find some means for consolidating the ownership under one individual or fanily. Our property has an existing residential zoning designation sothe construction of one single family residence (a use by right)requires no special approval by the commission. The residence and associated utilities must only meet the applicable building codes which is a rather routine affair. 4. The dredged material removed from the Johnson Pond and trSr! Pond used to fill the River Pond is an acceptable source of fillfor the two proposed dwelling sites. This fiII was never intendedto be used as a compacted structural fill for a conventional slab on grade and spread footing design. This fill would be removed from the 2 ponds during winter months to minimize the effect of the BIue Creek flows and facilitate the draining of the ponds. The fill will be transferred to the drained River Pond where theroaterial would be allowed to dry and consolidate for a minimum of6 months prior to the start, of any foundation construction. The appropriate structural design for fill conditions or fill and expansive soil conditions would be a voided grade beam and drilledpier combination. An 8 inch wide x 4 feet maximum depth grade beam would be recommended with 10 inch diameter drilled piers to bedrock(approximately 15 to 20 ft. deep) at a horizontal spacing of approximately L2 ft. The drilled piers wiII be doweled into the bottom of the grade beam. The concrete shall be a water resistanttype 2 cement. A high water table nay necessitate the requirementto line the drilled piers. This assessment will be nade by alicensed geotechnical engineer who will be on site as required by the building code during the drilling and pouring of the piers. The main floor of the dwellings would bear on the grade beams andbe over a ventilated crawl space. Drawing 9 in Appendix Aillustrates the above explanation. 5. t{e retained the services of a wetland specialist to assistus in the development of our uritigation plan. The details of our compensatory mitigation proposal for the loss of 0.055 acres ofperimeter wetlands are presented in Appendix B. 6. The individual sehrage disposal systems (ISDS) cannot bespecifically designed by us and permitted by Garfield County until complete and detailed plans for the residences have been developed and approved. Our engineer, Mr. Yancy Nichol P.E. of Sopris Engineering LLc, has provided a detailed discussion (Appendix C) of what will be required at this site to construct an fSDS which will comply with Garfield County and the State of Colorado 7. We are confused as to your statement that the trpossibility exists that the applioation will be withdrawn and another public notice will be processed to include additional project detailsrr. We don't believe that there is anything really rrnelrrrr in this response and would hope that any particular details on specific features, such as the mitigation proposal, could be easily coordinated with the relevant commenting agencies or individuals. We are very hopeful that you will find the above responses adequate and that we can bring this permit process to a close soon. o".,,"?il* fa"'tPY'o U tuther E. Moore Enclosures; AppendiX A, Appendix B, AppendiX C, DrawingsMitigation Plan ISDS Detail.s I NI'MBER 1 2 3 4 5 6 7 I 9 APPENDIX A DRAWINGS TITLE On-Site Alternatives/Key MaP Alternative A Alternative BAlternative C/Pond FiII PIan Alternative C/ISDS Available Area Alterna*:ve D Off-Site Alternatives/Location Map Plan/Proposed River Pond Sites Foundation Details rinA,"'it rt-7 N$ N\ $ \ N z+ I I lrr $l,t S/ t J \t\ Nt ,( ! I /i lca R IE l:\ N r- 2n- -,: uoE*rQND *LLtV = 6Jl?.6' *: I -.',.-#I --4 .,*.F' i \=_- ISLAND POI,IDELiv : 6;514.B''t f/o1f,!0ffi#ff.V,ouo -tF'.-r 7/\ \\ , { fr ,t X .6 N 6vek-pci(o ,lgld, I _ __{ 4, I ! i '' C/\/4tA',?-{&0*. iN LoT,s'qa ISLAND I I '*- iK5,54J s(1. le x ./// ./ ----x /s"628 ,s 7ff5?.'47" E' ,! 60T. '-/ 631 ?.e'Jiil hi S';ti F: Cri.lD, ,.raa.. 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LOU MOORE 16613 HWY 82 CARBpNDALE, COLORADO 81623 December 17 r 1997 E-1 WETLAND MITIGATION PLAN For MOORE/ENGLUND PN T9977 5319 Garfi eld County, Colorado Site Description The Moore/Englund parcel is located approximately seven miles east of the town of Carbondale, Colorado. The lot I was asked to prepare a mitigation report for is approximately 22.6 acres in size and contains both ponds used as a commercial fishery and a significant amount of emergent jurisdictional wetland of varying quality. As indicated in the supporting documents, the project associated with this parcel will result in the disnrbance of approximately Q.055-"acres of willow dominated wetlands found along the fringe of the "River Pond". The prn',osed wetland disnrbance will be replaced at aL:l ratio through the t ,don of approximately Q-12 acreg o! hlgh_quality emergent wetland habitar This in turn will result in the replacement of the "functions and values associated with the disturbance and a net increase in total emergent wetland habitat on the parcel. The mitigation site will be completed on what is currently a dike between the Island Pond and the River Pond see @xhibit one) Project construction and wetland mitigation will be occur concurently and be accomplished during the same year. The starting date for project and mitigation are dependent on approvals that are being sought both at the local and fedeial levels. Constnrction documents for the mitigation site include plans complete with cross section plan see (Exhibit four) views and specific in formation concerning : l. Wetland plant species, numbers of individuals, planting densities and interseeding rates. 2. ,Site preparation requirements including grading, top soil, and soil . amendments 3. .Identification of a dependable water source which will insure the .successful establishment of the mitigation site. p,a 4. 5. &z The presence of a wetland specialist on site during all phases of . constnrction and monitoring The specialist will also generate reports for all phases of the .mitigation project until it is deemed established by ACOE. Veeetatign Mature wetland plants that can be salvaged will be stored and irrigated on site. In addition, native nursery stock will be used to supplement salvaged shrubs. The species that will be used in the creation of the wefland include coyote willow (Salix exigua), Drummond's willow (s. drummondiana), and thin leaf alder (Alnus tenuifolia). Nuusery stock (shrubs) will be an equal mixture of one to five gallon planting and will be planted during midsummer after a proper bed has been constructed. h addition four inch plugs of beaked sedge (Carex utriculata) water sedge (C. aquatilis), andh*dste* bulnrsh (Scirpus acutus) will be planted on five foot centers. See Exhibit Two for configuration and layout of planting scheme. lnterseeding using the native seed mix in Exhibit Three will be applied atarate of 25 lbs/acre. The salil/scrub shrub community qrye at completion will be dominated by an overstoryof coyote willow (Saltx exieua) with an understory of beaked sedge (Carex rcistata), water sedge (C. aquatilis) and Horsetail (Equisetum arvense). The transitional areas will be are dominated by hardstem bulnrsh (Scirpus acutus) and baltic rush (Juncug balticus). Hvdrolosv The created wetlands on the parcel will be maintained hydrologically by the island pond. site grading with an expected pesiametric fringelz to tg inches subsurface will insure that adequate moisture will exist for the establishment of the wetland. Since diversity in an emergent wetland is largely controlled by the amount of water at iooting depth, the use of island pond is an excellent water source. Although speciis such as cattail and reed canary grass (Tpha latifolia and Philaris anurdinacea) function as water filters increasing water quality they also have the ability to form monocultures which decreases biotic diversity and the ability for other important wetland plants to thrive. If water levels appear to be limiting the distribution and density of desired plant species, water levels will be manipulated so that the desired species wilt be maintained. By manipulating t. ,.:iit*t LJ the amount of horizontal and vertical diversity through the manipulation of water levels the owners of the parcel will also have the ability to provide excellent habitat for a variety of wildlife species. Soils Dredged materials removed during the disturbance of exiting wetlands will also be stock piled. Stock piling of dredged material will occur in upland areas and not result in degradation of existing wetland on the parcel. This soil will then be used during the replacement and creation phase of the project. Soils in the mitigation site will consist of dredged material from the Johnson and S-pond and should be an excellent growth medium for wetland plants. In addition the soil will contain native wetland plant seed which are adapted for the site and will help in the establishment of an emergent wetland on the site. It appears that the total amount of dredged material exceeds that needed for the creation. However, if a shortfall in soil material is realized, topsoil of an appropriate source will be imported and amended as needed to help insure the successful establishment of the wetland. Noxious Weeds When significant ground is disnrbed and available for establishment by invasive plants a threat to native plant establishment exists. This project will result in these conditions and it is imperative that commiunent to conrolling of weed species is acknowledged. Plants of concern in this area are canada thistle (Circ ium arvense), houndstongue (Cynoglossum officionale), and Scotch thistle (????). These species have ttre ability to out compete native plants for space and resources. A careful watch for establishment of these species will occur as will vigilant treafinent using a variery of techniques including pulling, cutting and aquatic approved formulations of 2,4 D. Wetland, Monitorinq Wetland Monitoring will occur during the height of the growing seenon between the periods of July I and August 15 in an average year. Monitoring will start the first year after mitigation work is completed and continue on a year to year basis for three consecutive growing seasons, or until ilre site is acceptedby the ACOE. Monitoring reports will be completed and submitted to the ACOE at the end of the growing season and periodic site visits from &3 '' | 'ff *. .(:8-+ the ACOE will be requested by the owner to ensure full compliance with the mitigation plan is occurring. NIon itorins Techniq ues The created wetlands will be visited by a wetland specialist during the height of the grqwing season for three consecutive yeffs to insure that wetland vegetation, soil conditions, and hydrology have been established. Shnrb belt transects or line intercept method will be used to sample the shrub canopy. In addition daubenmire frame plots will by used to tu-pl. cover-frequency parameters for the grass and forb layer. Permanent photographich plots witl be established so that a visual record of establishment of the created wetland site can be used if ACOE personnel can not visit the site due to time constraint or funding levels. Photos will be incorporated in the yearly monitoring reports in high quality color photo copies and actual original photographs will be available upon request by the ACOE. Mitisation Success Standards The mitigation of the roaring fork bed and breakfast site will be considered a success if survival rates for herbaceousi and shrub vegetation exceeds 75%. In addition close observation of soil conditions including oxidized root channel formation and positive alph4 alpha dipyradil test shows establishment of reducing soil conditions. Plant diversity will be closely monitored and water levels in the island pond will be adjuted to maintain plant diversity. Noxious weeds will be confiolled to the greatest extent possible. Mitisation Maintenance Proqram As in all reclamation work some level of mortality is expected. Replanting of shrubs will occur when mortality exceeds 10% of planted individuals. An attempt will be made to determine what the cause of death is the direct cause of mortality will be dealt with in order to ensure successful establishment of the replacement plant. Supplemental planting and or interseeding may be needed and will be completed though out the life of the project on a case by case basis. tr')t'B-g Summat. This mitigation plan details the conditions that will be created on the Moore/Englund Parcel which will allow the establishment of a high quality emergent wetland. The wetland will be constructed by excavating, grading, and preparing a growing area which will utilize native plants collected on site and supplemented with nursery stoclg soil cierived in hydric conditions which contain aviable seed bank and complete nutrient levels, and a flexible hydrologic regime from a water source which retains a flexibility that allows the managers of the property to manipulate the levels so that adequate plant diversity can be maintained. In addition, there is also a plan in place to deal with invasive species and a monitoring plan complete with triggers which indicatewhenadditionalmanagementmaybeneeded.Inshort,this mitigation plan has sought to provide all three requirements for the area to meet the requirements for j urisdictional determination and successful establishment of high qualrty emergent wetland habitat. 8-6 Extia;r #l-ruroNgL):zr!- /-- -./ .1\,,, T-) o!rrfi -za a- ,,!ffs ;6*'; c4 r3 129- @- gr t-o-l -I--A a N) C)nrrla =c+ (o'I c+ o-f t,e+) Il- T.J o1lo LN r0 a- o rrlt- rTI<U; il -CIo)ouz ;l o co- oU!t- z -t 3 Tl ooO = -{ t-o-l .-J J aA onfq r-sal o an @t-tJnhZ rrNtJl -;b, ru aTl tdrtJ Fr 6r Z0 \CS n rTIn o rrln-t.| ,-o, =C) - zz. N\E Ha EJa (, OOO (A rl /lt ,/ i, (,/) IJ V' (, cloO ? ] &1Exuis;r {z H U 6 L 1lo )L {Fi'' o+oco{acA-?3L -r:ai 'o J' }Jf$!- i- ] CA TI e) \ tA tt\ F- P la 9 ! .T-f,8-g MOORE ENGLAND_PN1997753 1 9 MITIGATION PLAIY Revegetation of 5,817 square feet of wetland approximately 0.12 acres of newly constnrcted wetland will be completed by completion of the subdivision of the Roaring Fork Bed and Breakfast Parcel. Approximatel 240 adult wetland plants will be planted along with the distribution of the 25 lbs of wetland r..i -i* p., u.* ADULT PLANTS NU]VIBER SCIENTIFIC NAME Beaked Sedge 50 Carer rcstrats Water Sedse 50 Carer aquetilis Nebraska Sedse 50 Cerer nebreskensis Baltic Rush 20 Juncus belticus Eard Stem Bulrush 20 Scimus acutus Drummond's Willow 20 Salir dnrmmondiana Coyote Willow 30 Salir erieue Adult plants shall be four inch clump or greater and shall be planted at five feet centers. lnterseeding will be completed using seed mix. Substitutions shall be allowed with the sign off from Army corps of Engineers representative. SEED MIX LBS/AC SCIENTIFIC NAME Beaked Sedse 2.5 Carer rostrets Water Sedse 2 Carer aouatilis Nebraska Sedge 2 Carer nebraskcnsis Baltic Rush .75 Juncus balticus llardstem bulrush 1.5 Scirous rcutus Csttail .25 Typha latifolia American sloughgrass 5 Beckmania swigachne Tufted hairgrass .75 Deschamosia caespitosa DO{IBIT 3 ' F,'"fr APPENDIX C ISDS DETAILS C-7- december 12,1997 Lou Moore 16613 Highway 82 Carbondale, CO 81623 RE:Individual Sewage Desposal System (ISDS) for Two Single-Family Residences per Sketch Plan Prepared by Land Design Partnership Dated lll5l97 Dear Lou: The following is a preliminary engineering evaluation of tlte above-mentioned site plan with regard to the feasibiliry of corrsrructilg an ISDS for two single-thmily lots. I havc reviewed the proposed site plan and visited the site. Since the area for the proposed ISDS is in a fill area, no site specific percolation test can be done at this time. The on-site native materials are of a grave I narure and would have a rapid percolation rate. However, it is my understanding the ISDS will be placed in an area filler1 with material from two existing fish ponds. The fill material will be silt accumulated from Blue Creek and most likely will have a slow percolation rate. ISDS Design Several possible design solutions exist that would meet the site conditions. Because of the potential high groundwater and the ISDS being placed in flrll material, a sand filter of the mounded type would be the recommended system. I have assumed a percolation rate of 60 min./inch for the silt material to estimate the bed size, which most likely will be conservative. The design is also based upon the following assumptions: l) 4 bedrooms 2) 2 people/be&oom 3) 75 gallon/person 4) 150% of average for design flow: Q = 4x2x75x1.5 :900 gallors/day design flow Long Term Acceptance Rates (LTAR): A = Absorption bed in square feet 4=Q/LTAR A=900/0.30=3000S.F. Septic Tank - 1250 gallon A 3000 S.F. absorption Ld would be required based upon the above assumptions. Site Setbacks The absorption bed will need the following minimum separations: Island Pond 50' S Pond 50' Property Lines l0' Wells 100' Waterlines - unless pipes are encased 25' River Overflow Channel 50' Top of Fill Bank 24' House 20' Septic Tank 6' Based upon the site plan, these separations can be met and still have adequate area for a 3000 S.F. absorption bed. 502 main street . suite A3 . carbondale, C0 81623 ' (970) 704-0311 ' fax (970) 704-0313 $oPmts EttGltNErRIt{G 11G civil consultants l L-z Lou Moore ISDS December 12. 1997 Page 2 Summarv It is my opinion that an on-site wastewater disposal system can be designed and constructed on the two residential lots that wrll meet the Garfield County and Colorado State Board of Health regulations for ISDS. If you have any questions or need any additional information, please do not hesitate to call. Sincerely, SOPRIS ENGINEERING, LLC Yancy'Nichol, P.E.