Post on 24-Jun-2018
TowerLakesOurmostimportantAsset
� 68AcresincludingNorthLake� 4milesofshoreline� 2majorinletstoMainLake� 3existingsilttraps� Vastmajorityofwaterenters
fromstormwaterrun-off� Acrosslawns� Stormwaterdrainpipes
LakeCommi*eeGoals&Impacts
Rain=Watershed&RoadRun-off
Sun
Fishery&NaturePreserve
Boating
Nutrients,Phosphates&Trash
Swimming&WaterSports
InvasiveWEEDS ALGAES
WATERQUALITY
DEPTHSILTUSE
IMPA
CT
LakeManagementChallengesEutrophica:on
Eutrophication:Theprocessbywhichabodyofwaterbecomesenrichedwithdissolvednutrients(suchasphosphates)thatstimulatethegrowthofaquaticplantlifeusuallyresultinginthedepletionofdissolvedoxygen.Lakesthatcannotcontrolthisprocesswillendupas“dead”lakes,andeventuallybogsorswamps.
LakeManagementChallenges
Nutrients• FOODforplants• PhosphatesandNitrogen
naturallyoraddedviarunoff• ExistingSiltfromlakecreation• Siltenteringthelakefrominlets
andstormwaterrunoff• Siltcreatedbyorganic
decomposition• Leaves• Sticks• Deadaquaticplants
AquaticPlants• GOODforfish
• ProvideOxygen• Createhabitat
• Fedbynutrients• Difficultforswimmingand
boating• Weexecuteaplantomanage
speciesandcoverage• EliminateorMitigateNuisance
Weeds
SiltRemovalProject2012-2016WhyRemoveTheSilt?
• LargebuildupofNutrient-RichSedimentoverseveraldecades.
• EngagedinRegularCycleof:• (1)ObservePlantorAlgaeGrowth• (2)ChemicallyKilltheGrowth• (3)ObserveRe-GrowthofPlants&Algae
• WantedtoBreaktheCycle.
SiltRemovalProject2012-2016Op:onsConsidered
• TraditionalDredging(Scoop&Haul)
• Expensive• DraintheLaketodoproperly• Limited(ifany)useoftheLakeduringtheTraditionalDredgingprocess
• HydraulicDredging(SlurryVacuumOperation)
• Lessexpensive• LeastdisruptiveorvisibletoHomeowners• Considered“Barge”vs.“Diver”(UsedBoth)
SiltRemovalProject2012-2016HopedForResult
• Removelargevolumesofmuck• Significantlyreducenutrientsourcethatfuelsundesirableplantandalgaegrowth
• CreateimprovedLakeconditions• Appearance• Biosystem(Health)• EnhancedRecreationalUse
• Boating• Fishing• Swimming
• Donewithout“chemicalizing”theLake.
SiltRemovalProject2012-2016
• TLIAmembersapprovedin2011• $250/yearassessmentfor5years• Siltremovalandrestorationonly• Projectedthreeareas• Originalsilttraplocations
• Davlin’sandChannel• RobertsRoad• SoutheastMainLake
• 78%MembershipApproval
SiltRemovalProject2012-2016NecessaryPre-Work(#1)
• SiltChemicalAnalysis(ConfirmnotHazardousMaterial)
• SiltGrowthTests(ConfirmGrassorPlantGrowthPossible)
• HomeownersAssociationMarketing&Buy-In• DevelopmentofaComprehensive5-YearPlan• IndependentSiltSurveys(ConfirmAmountandLocationofSilt)
• ResearchSiltCollectionBagLocations(Pros/Cons)• ContractingwithEnvironmentalConsultant
SiltRemovalProject2012-2016NecessaryPre-Work(#2)
• DevelopmentofHydraulicDredgingContractorOptions• SomeContractors“toobig”;Some“toosmall”;• Onlyafewwere“justright”
• DevelopmentofRequestforProposals• ReviewofContractorBids• ContractorSelection• Permits!(USArmyCorpofEngineers;ILEPA;LCSWM)
SiltProjectPhaseI(2013)–SUMMARY
• Removed9,000CubicYardsofwetsilt
• 900CubicYardsofdriedsilt
• Deepenedsomeareas2feetto4feetdeeper
• Re-established#1SiltTrap
SiltProjectPhaseIIRobert’sRoadSouth(2014-15)
• Fallof2014andSummer2015
• Removed3,500CubicYardsofwetsuspendedsilt
• 350CubicYardsofdriedsilt• UtilizedcapacityatNorthLakeEntrance
• Re-established#3SiltTrap(1994)
Lathan’sLanding–WetlandRestora:on
• Collaborationw/VOTLandLakeCountyStormwaterMgt
• $12,000LCWMBgrant(Dec2014)
• $21,750VOTLmatch• Remediatedwetland“swamp”• Fixedoldcatchbasin&replaceddrainagepiping
• SiltatNLentrancemovedandseeded
• Depressionfilledandre-landscaped
SiltfillfromPhaseIandII
Lathan’sLanding–WetlandRestoration
Endresultisanawesomeboatlaunch
Largercatchbasin
SiltProjectPhaseIII(July–October2016)
KelseyWoods• JulytoSeptember2016• Removed9,000CubicYardsofwetsilt
• 900CubicYardsofdriedsilt
• Deepenedsomeareas2feetto6feetdeeper
• Re-established#2SiltTrap• Mostefficientprojecttodate
• Kelseysitehascapacityandpermittingforfutureprojects
SiltRemovalSummary� Removedapproximately:
� 25,000WetSuspendedcubicyardsofsilt� 2,500Drycubicyardsofsilt
� DeepenedallthreepreviousSilttraps� Developedextensivelearningviacollaborationwithlocalagenciesand
neighboringlakes� Becamemoreefficientovertime� Provided:
� Exampletoothercommunities� Deliveredmultiple“howto”presentationsasrequested
� Successfullyimplementedfirststepsto“longtermmaintenance”ofourlakes
Consul:ng,$(43,140.64),
-10%
Permieng,$(8,370.00),-2%
Lathan'sLanding,$(29,177.27),-7%
Remedia:on,$(8,083.02),-2%
BAGCost,$(43,847.00),-10%
SiltPumping,$(283,150.00),-65%
SetUp,$(19,941.32),-6%
TotalExpenditures$435,709.25
Financials
Financials• ImportantMetrics:(approximations)
• ActualSiltRemoval(pumping)was~65%ofProjectcost• TotalSiltRemoval(setup,bags,pumping)was~80%ofcost• Therefore,Non-SiltRemovalcostswere~20%ofTotalProjectcosts
• IncludedcostsofConsultant(s),Permits,Remediation• Smallerprojectswillhaveconsiderablyhigher“other”costs• ThescaleofourProject(3Phases)drovedowntheNon-SiltRemovalCosts
from~33%(Phase1only)to~20forPhases1–3• DriedSiltrelocationand/ordisposalcostscouldbesubstantial
• (Thesiltwasusedon-site,hencenodisposalcosts)
• VERY,VERYROUGHESTIMATES:(Useatyourownrisk!)• Totalcostwas~$175perdried,compressedcubicyardofsiltremoved• Totalcostwas~$17perwet,dispersedcubicyardoflakesedimentremoved
SiltRemovalChallenges&LessonsLearned• CosttoHomeowner’sAssociation• StakeholderSupport(Criticaltohave“Buy-In”fromallrelevantparties)Terrificsupporteventhough~75%ofTLIAHomeownersdonotownshorelineproperty.• Permits(timing)arecrucialtoProjectschedule• MusthavegoodrapportwithSiltRemovalContractor
• However,mustdiligentlymonitorContractorandkeepontaskthroughoutProject
• SiltDrydownTime-Longtimetodryout;Unsightly!• SiltDisposal-Unabletosell.UltimatelyusedallthesiltwithinTowerLakes.Thisisa
critical(andpossiblyunder-appreciated)issue.Disposalcostscouldbesubstantial.
• Mustminimize“extraneous”costssofaraspracticalDifficult,butmaximizingSiltRemoval(Pumptime)iscritical.
• Difficulttotell(withcertainty)oftheoverallsuccessoftheprocess-Underwater!Initiallyappearstohave“worked”.
LakeMaintenanceRequest–BestManagementPrac:ces(BMPs)
• WeedHarvesting• AlumTreatments• Aeration• WaterElevators• WaterMovers• FloatingIslands
Needtoresearchandevaluatethese
potentiallakemanagementsolutions
LakeMaintenanceRequest
• Stillneedtoremovesiltincriticalremainingareas
• Fundsfortwomoreremovalprojects
• KelseyRoadsiteisavailableandpermittedformoresilt
• AlsoneedtoresearchandexperimentwithotherlakemanagementBMPs
• AskingfornewLakeSpecialAssessment@$200/HHfor5years