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RC 20260213000701
Instrument Number: 20260213000701 Document:COV Rec: 5341.50 Page-1 of 39 Record Date:2/13/2026 3:24 PM Electronically Recorded King County, WA City Clerk's Office City of Renton 1055 S Grady Way Renton, WA 98057 FOR INSPECTION AND MAINTENANCE OF DRAINAGE FACILITIES AND ON -SITE BMPS Grantor: Renton School District.No. 403 Grantee: on M_qj�iki �Icor rati_�Oqn Renton hin t Legal Description, LTS A & B, LLA No. LUA-1 1-016-LLA, Rec. 20110616900016,,. and PT N SW 08-23-05. See Exhibit C -for full Le2L Assessor's Tax Parcel ID#: 7224000676, 7224000675, 7564600105 Residential Building Permit E] Commercial Building Permit Clearing and Grading Permit J� Civil Construction or Utility Permit Or MT staTT and obligations set forth and described in Paragraphs 1 through 9 below with regard to the Property, and hereby grants (grant) an easement as described in Paragraphs 2 and 3. Grantor(s) hereby grants (grant), covenants (covenant), and agrees (agree) as follows: �1=1111 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-2 of 39 Record Date:2/13/2026 3:24 PM King County, WA treat stormwater on the Property, On -site BMPs include dispersion and infiltration devices, bioretention, permeable pavements, rainwater harvesting systems, tree retention credit, reduced impervious surface footprint, vegetated roofs and other measures designed to mimic pre -developed hydrology and minimize stormwater runoff on the Property, 2. City of Renton shall have the right to ingress and egress over those portions of the Property necessary to perform inspections of the stormwater facilities and BMPS and conduct maintenance activities specified in this Declaration of Covenant and in accordance with the Renton Municipal Code, City of Renton shall provide at least thirty (30) days' written notice to the Owners that entry on the Property is planned for the inspection of drainage facilities. After the thirty (30) days, the Owners shall allow the City of Renton to enter for the sole purpose of inspecting drainage facilities. In lieu of inspection by the City, the Owners may elect to engage a licensed civil engineer registered in the state of Washington who has expertise in drainage to inspect the drainage facilities and provide a written report describing their condition. If the engineer option is chosen, the Owners shall provide written notice to the City of Renton within fifteen (15) days of receiving the City's notice of inspection. Within thirty (30) days of giving this notice, the Owners, or engineer on behalf of the Owners, shall provide the engineer's report to the City of Renton. If the report is not provided in a timely manner as specified above, the City of Renton may inspect the drainage facilities without further notice, If City of Renton determines from its inspection, or from an engineer's report provided in accordance with Para,,,,,,,,, that maintenance r iair, rest o ratio n_andAD=ffi',1 ation wo6, is required to be done to any of the drainage facilities, City of Renton shall notify the Owners of the specific maintenance, repair, restoration, and/or mitigation work ("Work") required pursuant to the Renton Municipal Code, The City shall also set a reasonable deadline for the Owners to complete the Work, or to provide an engineer's report that verifies completion of the Work. After the deadline has passed, the Owners shall allow the City access to re -inspect the drainage facilities unless an engineer's report has been provided verifying completion of the Work. If the Work is not completed within the time frame set by the City, the City may initiate an enforcement action and/or perform the Work and hereby is given access to the Property for such purposes. Written notice will be sent to the Owners stating the City's intention such notice is mailed, If, within the sole discretion of the City, there exists an imminent or present danger, the seven (7) day notice period will be waived and Work will begin immediately, -7717neasures L I y the City to address conditions as described in Paragraph 3. Such responsibility shall include reiAik,urstnTei,it to tke City within thirty (30) di�iys of the receipt of the invoice for any such Work performed. Overdue payments will require payment of interest at the maximum legal rate allowed by RCW 19,52.020 (c entLv_tweJ-,,tp-per-r-P-QL4u2z4LV �, _C!Lt� 2 enforce this agreement, the prevailing party in such action is entitled to recover reasonable litigation costs and attorney's fees. 5. The Owners are required to obtain written approval from City of Renton prior to filling, piping, cutting, or removing vegetation (except in routine landscape maintenance) in open vegetated stormwater faces (such as swales, channels, ditches, ponds, etc.), or performing any alterations or modifications to the drainage facilities referenced in this Declaration of Covenant. Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-3 of 39 Record Date:2/13/2026 3:24 PM King County, WA 6. Any notice or consent required to be given or otherwise provided for by the provisions of this Agreement requested.Mail, return receipt parties,7. With regard to the matters addressed herein, this agreement constitutes the entire agreement between the and supersedes all prior discussions, negotiations, whatsoever whether oral or written. 8, This Declaration of efficient and effeproperty ctive management of surface water drainage of the realdescribed d Rentonabove, and shall inure to the benefit of all the citizens of the City of and assigns, This Declaration of Covenant shall run with the land and be binding !Y Grantor(s), and Grantor's(s') successors in interest, and assigns. terminated 9. This Declaration of Covenant may be recordedOwners and the City that is IN WITNESS WHEREOF, this Declaration of Covenant for the Inspection and Maintenance of µ n School District No, 403 STATE OF WASHINGTON ) COUNTY OF KING )ss. On this day personally appeared before me —09�Vjj�a�' to me known to be the individual(s) iescribed in an,4 who . td the within *4: 2cknowliedg&-4—�at they Given under my hand and official seal this day of !��.. �...A 20 ,_, , Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-4 of 39 Record Date:2/13/2026 3:24 PM King County, WA Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-5 of 39 Record Date:2/13/2026 3:24 PM King County, WA EXHIBIT B - OPERATIONS AND AINTENANCE MAIWENANCE IN&FRACT IONS FOR SOIL AMENDMENT Your property contains an on -site BMP (best management practice) called "soil amendment," which was installed to mitigate the storrnwater quantity and quality impacts of some or all of the pervious surfaces on your property. Soil amendment is a method of regaining greater stormwater functions in the post development landscape by increasing treatment of pollutants and sediments, and minimizing the need for some landscaping chemicals. To be successful, the soil condition must be able to soak water into the ground for a reasonable number of years. This on -site. BMP shall be maintained per Appendix A of the City of Renton's Surface Water Design Manual. MAINTENANCE RESTRICTIONS The size, placement, and composition of these devices as depicted by the site plan and design details must be maintained and may riot be changed without written approval from the City of Renton or through a future development permit from the City of Renton, INSPECTION FREQUENCY AND MAINTENANCE GUIDELINES To be successful, the sail must be able to soak water into the ground for a reasonable number of years. • Return leaf fall and shredded woody materials from the landscape to the site when possible in order to replenish soil nutrients and stricture. • On turf areas, "grasscycle" (mulch -mow or leave the clippings) to build turf health. • Maintain 2 to 3 inches of match over bare areas in landscape beds, • Re -seed bare turf areas until the vegetation fully covers the ground surface. • Avoid using pesticides (bug and weed killers) which damage the soil. • Where fertilization is needed (mainly turf and annual flower beds), a moderate fertilization program should be used which reties on compost, natural fertilizers, or slog -release synthetic balanced fertilizers. RECORDING REQUIREMENT 'I"hese on -site BMP maintenance and operation instructions must be recorded as an attachment to the required declaration of covenant and grant of easement per Requirement 3 of Section C. 1.3 A of the City of Renton Sur le ce Water Design Manual. The intent of these instructions is to explain to future property owners, the purpose of the BMP and how it must be maintained and operated. These instructions are intended to be a minimum; the City of Renton may require additional instructions based on site -specific conditions. See the City of Renton's Surface Water Design Manual website for additional information and updates. za�� Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-6 of 39 Record Date:2/13/2026 3:24 PM King County, WA mil//m %o ENGINEERED SOLUTIONS FilterraO Maintenance Steps MAINTI NANCE INSI'RUCTIO CS EPtt t..` ERRA VAULT f . Inspection of Filterro and surrounding area 5. Clean area around Filrerra 2. Removal of tree grate and erasion control stones 4, Mulch replacement b. C:ornplete paperwork and record plant height and width C.ontech has crr ated a network of Certified Maintenance providers dCCivil" s) to provide maintenance on Filterra systems. 10 find a CCM' in your area please visit www,conteches„corn/maintenaance 2015 Conlach Enginecrrd Sohatlons LLC. Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-7 of 39 Record Date:2/13/2026 3:24 PM King County, WA �ol)� i ENGIINEERED SOLUTIONS This Owner's Manual Applies to gall precast Rterra Configurations, including Filterra Bioscape fault and Filterra HC. Pa, 7 . , 39 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-8 of 39 Record Date:2/13/2026 3:24 PM King County, WA Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-9 of 39 Record Date:2/13/2026 3:24 PM King County, WA Table of Contents Iniroduction ........... .................... -- ...... ............. -4 Activation Overview . .................................... Filierra Plant Selection Overview...,..„ ................... . .................. Warranty Overview ,, ..... ... — -- .. ......... . ... .. . .................. 6 Routine Maintenance GuHelines— ... - ........... - ....... ......... 6 Maintenance Visit Procedure.. ..... 9 Plant Care .... ........... ...... I Appendix t - Activation Package., - � ...... ...... 12 Appendix 2 - Filterra Tree Grate Opening Expons;on Pfocedure — 1 9 C-1,,doNTECH' ENGINEERED SOLUTIONS www.Contec,hES.com/fOterra 1 1300-338 1122 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-10 of 39 Record Date:2/13/2026 3:24 PM King County, WA TMTT�� Thank you for your purchase of the Filterra" Bioretention System. Fillerra is a specially engineered stormwater treatment systern incorporating high performance biofiltrafion media to remove pollutants from stormwater runoff, The systern's biota (vegetation and soil microorganisms) then farther breakdown and absorb captured poNutants, At; COMPC)nenk of the system work together to provide a sustainable long-term solution for treating slormwater runoff. the Filters systern has been delivered to you with protection in place to resist intrusion of construction related sediment which can coniarrinale the biofiltration Fnedia arid result in inadequate systern performance. These protection devices are intended as a best practice and cannot fully prevent conlrsip4irsfion, If is the purchaser's responsibility to provide adequate measures to prevent construction related runoff from entering the Filterra systern. Included with your purchase is Activation of the Filters systern by the manufacturer as well as a I -year warranty from delivery of the system and a final site assessment of unit condition (mulch replacement, debris removal, and pruning of vegetation) scheduled between 6 and 12 months offer activation, Upon request, Design and Installation Each project presents different scopes for the use of Filrwro systerns information and help may be provided to the design engineer during the F.&inning process. Correct Filterra box sizing (by rainfall region) is essential to predict pollutant removal roles for a given area The engineer shall submit calculations for approval by the local juvisdiaon. Tire contractor is responsible for the correct installation of Filterra units as shown in approved plans, A comprehensive installation manual is available at wwwContechES,corn, Activation Overview Activation of the Fifterra system is a procedure completed by the manufacturer to piece the system into working condition. This involves the following rfernsr, Removal Of COnStFU01011 runoff protection devices, Planting of the systern's vegetation (provided by the purchaser). • Placement of pretreatment mulch layer using mulch acceptable for use in Filterra systems. Activation MUSI be provided by the manufacturer to ensure proper site conditions are met for Activation, proper installation of the vegetation, and use of pretreatment mulch acceptable for use in Nterva syderns, More information is available in the Filters Activation Package, `1 www.ContechES.com/filterra 1 800-338-1122 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-11 of 39 Record Date:2/13/2026 3:24 PM King County, WA Minimum uire eats The ininirnurn requirements for Filterra Adivation are as follows 1. The purchaser must have procured vegetation meeting the requirements outlined in the Fiiterra Activation Package. 2. The site landscaping must be fully stabilized, i.e, full landscaping installed and sorne grass cover (not just straw and seed) is required to reduce sediment transport. Construction debris and materials should be removed from surrounding area,. 3. Final paving must be completed, Final paving ensures that paving materials will not enter and contaminate the Filters system during the paving process, and that the plant will receive runoff from the drainage area, assisting with plant survival for the Filters systern, 4. Filterra throat opening should be at least 4`° in order to ensure adequate capacity for Inflow and debris, THROAT OPENING' A CAST -IN -PLACE GUTTER AND TFIROA f THROAT PROTECTION DEVICE OPENING 3ENC (BY CC1rfi"SAC Tt)R EEf �.".,.. ti0t NOTREMOVE tCiVE -LEAVE lid PLACE LOCALSTANDARDS) DS) UNTIL. SITE iS STABILIZED AND FILTE RA IS ACTIVATED The Filterra Activation Package is available on the Contech website (www,Co;atechES.com/filterra) and ensures that the proper conditions are rnet fear Contech to perform the Activation service, Vegetation meeting C'ontech's requirements must be provided at time of Activation. If the site does not meet the conditions required for Activation, or acceptable vegetation is not provided by the purchaser at time of Activation, o change of $1,500 will be, invoiced to the purchaser. www.ContecliES.com/fi)terra 1 800-338-1122 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-12 of 39 Record Date:2/13/2026 3:24 PM King County, WA Fliterra Plant Selection Overview A Plant List is available on fide Confech website highlighting recommended plants for Filterra systerns in your area. Keep in mind that plants are subject to availability due to seasonality and required mininnuun size for the Filterra system, Plants installed in the Filterra system are container plants (max 15 gallon) frorn nursery stock and will be hurnature in height and spread at Activation, It is the responsibility of the owner to provide adequate irrigation when necessary to the plant of the Filtena system. More information is available in the Filterra Activation Package, Warranty Overview Refer to the Contech Engineered Solutions 11-C Storunwater Ireartmeni Sysrern LIMITED WARRANTY far further information. The following conditions rnay void the Filterro system's warranty and warve the manufacturer provided Activation and Final Site Assessment services: Unauthorized ictivalion or performance of any of the items listed in the activation overview Any tampering, modifications or clarnage to the Fikerra systern or runoff protection devices Removal of any Filterra systern components • FailLue to prevent construction related runoff from entering the Filterra system Failure to properly store and protect any Filterra components (including media and underchck stone) that may be shipped separately from the vault Final Site Assessment Wifli proper routine maintenance, the biol'tiration mcchn within the Filterra system should lost as long as traditional hioretention rnedia, A final site assessment is included by the manufacturer, upon request, an all Filterra systerns between 6 and 12 months offer, activation, This includes a final assessrrient of unit condition, debris removal, Mulch replacerneni, and Pruning, of vegetation. More information is provided in the Operations and Maintenance Guidelines, Some Filterra systems also contain pretreatment or outlet boys. Depending on site pollutant loading, these boys rnoy require periodic removal of debris, however this is not included in the final site assessment, and would likely not be required within the first year of operation,. these services, as well as routine r-nairflenance outside of the included first year, can be provided by certified maintenance providers listed or) the Contech website, Training can also be provided to other srouTiwater maintenance or landscape providers. 6 www,ContechES.cojm/filterra 1 800-338-1122 P.,�, 12 of 39 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-13 of 39 Record Date:2/13/2026 3:24 PM King County, WA Why Maintain? All storaiwoler treatment systems require maintenance for effective operation, This necessity is often incovporaied in your property's permitting process as a legally binding BW maintenance agreement, Other reasons to maintain are: Avoiding legal challenges from Your jU6scliclion's maintenance enforcement program, Prolonging the expected lifespan of your Filtenra rnedia, Avoiding more costly media replacement, Helping reduce pollutant loads leaving your property. Simple maintenance of the Filterra is required to continue effective pollutant removal train stonmvater runoff before discharge into downstream waters. ]-his procedure will also extend the longevity of the living biofilter systern. The and will recycle and accumulate pollutants within the biomass, but is also subjected to other materials entering the inlet, Nis may include Trash, silt and leaves etc. which will be contained above the mulch layer. Too much silt may mkinit the Filterra's flow role, which is the reason foi site stabilization before activation Regular replacement of the mulch stops accumulation of such sediment. When to Mointoln? Maintenance visits are scheduled seasonally; the spring visit aims to clean alp after winter loads including salts and sands while the fall visit helps the system by removing excessive leaf litter. It has been found that in regions which receive between 30-50 inches of annual rainfall, (2) two visits are generally required; in regions with less rainfall often only (1) one visit per unnum is sufficient, Varying land uses can affect maintenance frequency. Contributing drainage areas which are subject to new development wherein the recommended erosion and sediment control measures have neat been implemented may require additional maintenance visits. Some sites rnay be subjected to extrerne sediment or trash loads, requiring more frequent maintenance visits. This is the reason for detailed neater of maintenance actions per unit, helping the Supplier and Owner predict future maintenance frequencies, reflecting individual site, conditions, Owners must promptly notty, the maintenance provider of any dernage to the plant(s), which constitutes) an integral part of the bioretention technology. www,ContechES.com/filterra 1 800-338-1122 7 P.s3,: 13 of 39 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-14 of 39 Record Date:2/13/2026 3:24 PM King County, WA Exclusion of Services Clean up due to major contamination such as oils, chernkals, toxic: spills, etc. will result in additional costs and are not included as part of the final site assessment, Should a major corriamination event occur the Owner must block off the outlet pipe of the Filterfa (where the cleaned runoff drains to, such as drop inlet) and black off the threat of the Filterm, Fhe Supplier should be informed irnmedialely, Maintenance Visit Summary Each maintenance visit consists of the following simple tasks (detailed instructions below). I . Inspection of Filters and surrounding area 2. Removal of tree grate and erosion control stones 3. Removal of debris, trash and mulch 4, Mulch replacement 5. Plant health evaluation and pruning or replacement as necessary 6, Clean area around Fdtwna 7, Complete paperwork Maintenance Tools, Safety Equipment and Supplies ldea6 tools include: camera, bucket, shovel, broom, pruners, hoe/rake, and lope measure, Appropriate Personal Protective Equipment (PPE) should be used in accordance with local or company procedures, This may include impervious gloves where the type of trash is unknown, high visibility clothing and barricades when working in close proximity to traffic and also safety hats and shoes. A I-Bor or crowbar should be used far moving the tree grates (up to 170 lbs ea.). Most visits require minor trash removal and a full replacement of mulch. See below for actual number of bagged mulch that is required in each media bay size, Mulch should he a double shredded, hardwood variety. Some visits may require additional Filterro engineered soil media available from the Supplier. Other sizes not listed - I bag per 8 ft" of media, www,ContechES.cmn/filterra 1 800-338-1122 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-15 of 39 Record Date:2/13/2026 3:24 PM King County, WA Maintenance i it Procedure Keep sufficient documenictcm of rnai,tenmrce u;tlons to p(edict locotion spccric �naint.r�anee frr ,r.n�ios ono i reeds. An example Mainienunce Repoia is indu ied in this manual. 1. Inspection of Fllterrca and surrounding area Ra,cord individual unit before n'iainter a ce wiih photograph, (numbered), ' ,-co,d on Molnte.nance Repoi4 (see-.xumple in this do(a,ment) the follo,r:it q, . Removal of tree grate and erosion control stones Rernco us' mp grates for c)rr ass Into !-ilterra box, Jig ou s,11 (if anand mulch and rem oi: rmsh , Fmeigr darrs 3. Removal of debris, trash and mulch After rE ,voi of MUkhi and .Erns; rr-.a_ur dr zr r t sr/O , he -oo c^ dr' -iiteiro iCzGIU s. I `ta she on p` the t u slnn . i-no re +,ne n,e,os,„rod 6s!cnLe c, The ai 'arch sh rr ° . on the pcver 1, �ontr(3ct nmgs the system. Ada . 1terra s d,a root top soil or ather) 1.� �,�rng mcU ra un as )E ,:red Tc to;cured on dmw rgs. All l:66Rp�r9'Pfsf4ilcire c C r`ata�r %s; Tc s a Tc�p S%1 b (ndl'Q lnc"�es rif Ahecirs`%dcde;x� www.ContechES,comffilterra 1 800-338-1122 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-16 of 39 Record Date:2/13/2026 3:24 PM King County, WA 4. Mulch replacement • Add double, Ji cdded mulch evenly ocr rss the entire unit to a depshh rot d", • Refer �n rdterra Mulch Spy cification., for infarmation on acceptable sources. Ensure correct reposition: ray of erosion control stones by the: Fi(terra inlet to adder for entry of lrash during sk"w'. event. • Replra c Filterrn of ctes corructly using appropriate Ping or msvin!J roofs, taking care not to dumaye, the planr S. Planet health evaluation and pruning or replacement as necessary • Fxc nine the pkM's hoolt, and replace if necessory prune '] accessary to eni nosy,, groMh in tar;, area dire cons 6. Clean area around Fdterra ru:denn area Ground unrf and remove o11 rrfusr f) as dlsp sed of onproprintey. 7. Complete paperwork • Juhv.ef VPmrii ena')Ce Repori, Jam .iadicti.r.=. Ploy require. sAmission of maintenonrc eporis in w cc dance with approvals h is the responsih lity of the Uwner to a)mrdy wire loca8 re, {uleticns www.ContechES.coin/f!1terra 1 800-338-1122. Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-17 of 39 Record Date:2/13/2026 3:24 PM King County, WA Plant Care for FilterraO Systems After Activation, the Contractor is responsible for proper care of the vegetation unfil the site is handed over to the Owner. After that, it is the Site Owner's responsibility to care for the vegetation. Contech recommends the following core for the plants: I . To prevent transplant shock (especially if planting takes is face, in the hot season), it may be necessary to prune, some of the foliage to compensate for reduced root uptake capacily, this is accomplished by pruning away some of the smaller secondary branches or a main scaffold branch if there are too many, foe, much foliage relative to the root bail can dehydrate and damage the plant, 2, Plant sinking may be required, 1 W6 all trees/shrubs, rernove dead, diseased, crossed/ rubbing, sharply crotched branches or branches growing excessively long or in wrong direction comp ared to majority of branches. 4. Contech recommends irrigation of the Filferra' Vegetation. The following guidance will help to ensure the vegetation is properly irrigated, Irrigation Recommendations: Each hiterra" system must receive adequate irrigation to ensure survival of the living system during periods of drier weather. irrigation sources include rainfall runoff from downspouts and/or gutter flow, applied water through the free grate or in sore cases from an irrigation system with emitters installed during construction. At Activation: Apply about one (cool climates) to two (warm climates) gallons of water per inch of trunk diameter over the root ball. During Establishment: In common "with oil plants, each Filters"'' plant will require more frequent watering during the establishment period. One inch of applied water per week for the first three months is recommended for cooler climates (2 to 3 inches for warmer clitnates). If the system is receiving rainfall runoff frorn the drainage area, then irrigation may not be needed. Inspection of the sail moisture content con be evolualed by gently brushing aside the mulch layer and feeling the soil. Be sure to replace the rnulch when the assessment is complete. Irrigate as needed**, Established lslants: Established plants have fully developed root systems and can access the entire water column in the media, Therefore Irrigation is less frequent but requires more applied water when performed, For a rnaftme system assume 3.5 inches of available water - within the rnedin gnabix. Irrigation demand can be estimated os I" of irrigation demand per week,. 7herefore if dry periods exceed 3 weeks, irrigation may be required, " Five gallons per square yard approxiamtes I inch of water, Therefore for a 6'x 6 foot Fifterro' approxtmately 20-60 golions of apphed water is needed. To ensure even afishibution of water it needs to be evenly sprinkited over the entire surface of the filter bed, with special attention to make sure the root ball is completely welted. NOTE: if needed, rneasure the fwnp it takes to fill a five gallon bucket to estimate, the applied water flow rate. I hen coiculate the time needed to irrigate the Filterra' , For example is the flow rate of the sprinkler is 5 gaflonsfininule then it would fake 12 minutes to irrigate a 6x6' 0, c Plant Replacement: In some cases, plants will require replacement. Please follow the procedures below to ensure a properly functioning Filters' system. I . Remove the existing plant, and leave as much of the Filterra" rriedirs in place as possible. 2. Select a replacement per the Filterro0h) Activation Package, 3. Prior to removing the plant from the container, ensure the soil moisture is sufficient to maintain the integrity of the root ball. If needed, pre -wet the container plant, C Cut away any roots which are growing out of the container drain holes. 5. Plant(s) should be carefully removed from the pot by gently pounding on the sides of the container with the fist to loosen root bail. Then carefully slide out. Do not lift plants) by trunk as this can break roots and cause soil to fail off. Extract the root ball in a horizontal position and support it to prevent it from breaking apart. Alternatively, the pot can be cut away io minirnize root ball disturbance. 6. Excavate a hole with a diameter 4" greater than the root ball, gently place the plant(s), 7. Plant the tree/shrub/grass with the top of the root &iH I above surrounding media to allow for settling, 8. All plants should have the main stern centered in the tree grate (where applicable) upon completion of insiaHation, 9. Reinstall or add match to a depth of 3" per Contech's mulch specifications for Fiherro@q) systems, www.ContechES.com/filterra 1 800-338-1,122 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-18 of 39 Record Date:2/13/2026 3:24 PM King County, WA Maintenance Checklist Excessive Accumulated sediments or Inlet should be free of obstructions allowing free Sediments and/or trash Inlet sediment or trash trash Impair free flow of distributed flow of water should be removed. accumulation. water into Fifterra. into Filters. Trash and debris should be Trade and Excessive trash arid/or Minimal trash or other removed and mulch cover Mulch Cover floatable debris debris accumulation. debris on mulch cover. raked level. Ensure bark accumulation, nugget mulch is not used. "Pending" in uniFo—ouFdT—e r.-n of clogging due to Stormwater should drain Recommend contact Mulch Cover "Poncr ng" of water [indicative excessive fine sediment freely and evenly manufacturer and replace mulch cover. accumulation or spill of through mulch cover. mulch as a minimum. prtroleum OH& Plants not growing Soil/mulch too wet, evidence Vegetation or in poor of spill. Incorrect plant Plants should be healthy Contact manufacturer for condition. selection. Pest infestation. and pest free. advice. Va'nd��IiT tad Plants should be Thrn/prune plants in Vegetation Plant growth appropriate to the species accordance with typical excessive. IZg I g.U� f F I I r I landscaping and safety needs. Cracks wider than 1/2 inch or Structure Structure has evidence of soil particles Vault should be repaired. 'ble cracks. Viol entering the structure through the cracks. Filterra Inspection & Maintenance Log Filterra System Size/Model: __Location r0uld' 6 Depili of Height of fion ssli'q "'Jill I )cite, Ued)w IM u C il NW I,- h W q'� Ic � i 0' 1 conmnis B I a 1 cl Abufc-. e C' i S ys I e 1) 1 Roinov'��l Ad, e� I G a I e -Removed blockage in downstream structu 12 www,ContechES.com/filterra 800-338-1122 Purge 18 of 39 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-19 of 39 Record Date:2/13/2026 3:24 PM King County, WA Appendix I - Filterra"Vault Activation Package The Filterra system will be (or has been) delivered to you with protection in place to resist intrusion of construction related sediment which can contaminate the biafiltration rnedia and result in inadequate system performance. These protection devices are intended as a best practice and cannot fully prevent contamination. It is the purchaser's responsibility to provide adequate measures to prevent construction related runoff from entering the Filterra system, Included with your purchase is Activation of the Filterra system by the manufacturer as well as a 1-year warranty frorn delivery of the system and a Final Site Assessment (assessment of unit condition, mulch replacement, debris rernoval, and pruning of vegetation) scheduled between 6 months and I year after Activation, upon request. Activation of the Filterra system is a procedure completed by the manufacturer to place the system into working condition. This involves the following items: Removal of construction runoff protection devices Planting of thesystern's vegetation (provided by the purchaser) Placement of pretreatment mulch layer using mulch acceptable for use in Filters systems, Activation MUST be provided by the manufacturer to ensure proper site conditions are rnet for Activation, proper installation of the vegetation, and use of pretreatment mulch acceptable for use in Filterra systems. The purchaser should request Activation from Contech after the site is stabilized, but prior to turning over the site to the owner. Please allow 1-2 weeks to schedule Activation. The purchaser must ensure that the site is acceptable for Filterra Activation. A checklist (included as page 3 of this document must be completed and submitted to the Contech Activation Coordinator. The minimum 4 requirements for Filterra Activation are as follows: 1. The purchaser must have sourced vegetation meeting the requirements outlined in "Plant Selection for Filterra Systems" starting on page 4 of this document. * UNPREPARED SITE FEE NOTE: A charge of $1500.00 writ be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation ANDIOR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perforrr? Activation of Filterra systems; unauthorized activations wiII void the system warranty and waive manufacturer supplied activaVon and final inspection, www.ContechES.com/filterra 1 800-338-1122 ffiterra: fdl,w. A,6—N- po,k,,ge I rng,, a P.,. 19 of 39 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-20 of 39 Record Date:2/13/2026 3:24 PM King County, WA 2. The site landscaping musk be fully stabilized„ i.e. full landscaping installed and some grass cover (not.just straw and sexed) is required to reduce sedimerit transport. Construction debris and materials should be removed from) surrounding area. 3. Final paving must be completed. Final paving ensures that paving materials will not enter and contaminate the Filterra system) during the paving process, and that the plans: will receive runoff from the drainage area, assisting with plant survival for the Filterra system, 4. Where curb inlets are: included as part of the Filterra system, Filterra throat opening should be at least 4" clear in order to ensure adequate capacity for Inflow and debris. THROAT OPENING r CAST -IN -PLACE. GUTTER AND THROAT THROAT PROTECTION DEVICE OPENING (BY CONTRACTOR PER -� " m � DO NOT PEMOVE - LEAVE IN PLACE LOCAL STANDARDS) UNTik. SITE IS STABILIZED AND FILTE RRA IS ACTIVATE( * UNPREPARED SITE FEE NOTE: A charge of $d 500,00 will be invoiced for each activation visit requester) by customer where Contec;h determines that the site cues not meet the conditions required for Activation AND11OR acceptable plants are not provided by the contractor. ONLY Contact) authorized representatives can perform Activation of Filterra systems, unauthorized activations will void the system warranty and waive manufacturer supplied activation and final 14 www.ContechES.com/filterra 1 800-338-1122 Ofillera Fihc+ra A�ivaii«v Pac4.age (Page 2 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-21 of 39 Record Date:2/13/2026 3:24 PM King County, WA Filterral Vault Activation Checklist ENGINEERED SOLUTIONS Project Name: _-Company: Site Contact Name: Site Contact Phone/Ernail: ...... Site Owner/End User Name: Site Owner/End User Ptrone/Ernail: Preferred Activation Date: _ , . . .......... . ....... . ....... . _____(provide 2 weeks minirrium from date this form is submitted) :71 V eg on top Opening I 1 ' final Psvorria4 I 11 '1 , ' '�;"'��' 6�" 1&p on t I Type I r,' I c6m, 0 free Grate D Verified :1 Verified 0 Verified 13 Verified 0 Species on 0 Full Grate (No FT Plant List tree opening) DContainer Grown 0 Bioscape (15 gal niax) Vault (Open 114'TaH Min. (Tree planter) grate units only) mm Qty provided 0 Tree Grate 0 Verified 0 Verified 0 Verified C Verified 4 W y 0 Species on 0 Full Grate (No FT Plant List tree opening) oContainet Grown 0 Bioscape (15 gal rnax) Vault (Open 04'Tall Min. (Free planter) grate units only) Qty provided OTree Grate Cl Verified 0 Verified 0 Verified 0 Verified •0 Species on 0 Full Grate (No FT Plant List tree opening) OContarner Growr 13 Bioscape (15 gal max) Vault (Open 04'Tall Min, (free planter) grate units only) * Tree Grate ID Verified 0 Verified 0 Verified C Verified 0 Species on * Full Grate (No FT Plant List tree opening) oContainer Grown 13 Bloscape (15 gal max) Vault (Open 04'Tall Min. (Tree planter) grate units only) Qty provided Attach additional sheets as necessary. NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by custorner where Contech determines that the site does not meet the conditions required for activation AND/OR acceptable plants are not provided by the contractor, ONLY Contech authorized representatives can perform activation of Filterra systems; unauthorized activations will void the system warranty and waive manufacturer supplied activation and final inspection, Signature Date UNPREPARED SITE` FEE NOTE: A charge of $1500.00 will be invoiced for each activation vifitrequested by customer where Contech determines that the site does not meet the conditions required for Activation ANQ10R acceptable plants are riot provided by the contractor. ONLYCcritech authorized representatives can perform Activation offilterrasystems; unauthorized activations will void the systern warranty and waive manufacturer supplied activation and final inspection. www.CotitechES.com/flterra 1 800-338-1122 21 of 39 1�, A� 1 Pcq�. 3 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-22 of 39 Record Date:2/13/2026 3:24 PM King County, WA Planting Selection i tern c�a It Systems All Filterra systems require vegetation for proper long-term performance. As indicated in the Activation Package, the Contractor is responsible for sourcing the proper vegetation prior to Activation. Contech or a Contech representative will install the vegetation during the Activation process. Contractors should identity the Top Opening style for each Filterra requiring Activation on the Activation Checklist. Contech offers three types, which are detailed on page 5 of this document: Vault with Tree Crate Vault with Full Grate Bioscape,/ Open Planter Contractors must ensure the vegetation meets the following 4 requirements: 1. Select plant(s) as specified in the engineering plans and specifications AND that are listed on Contech's Configuration Specific: Plant Lists**. 2. All plants MUST be container -grown in nursery containers no larger than 15 gallons. Crated and/or Ball/Burlap plants are NOT permitted. 3. For Vaults with Tree Grates, plant height must: be 4' Minimum, from soil surface to top of plant. 4. Provide plant quantities per the following guidance: Vault with Tree Grate - 1 per Tree Grate Vault with Full Grate - 45 Small or Extra Small Grasses per Frill Grate Bioscape - Quantities should be selected based on plant palette options found starting on page 6 of this document. If Contech or Contech's representative shows up for Activation and any of the 4 requirements above are not met, Activation cannot be performed and the Contractor will be billed a $1,500 Unprepared Site fee*. Some additional vegetation recommendations for the best possible Activation and Installation are as follows: Select plant(s) with full root development but not to the point where root bound. g For Filterra systerns with a Tree Grate, select plants with taller trunks. Lower branches can be pruned away provided there are sufficient branches above the grate for tree or shrub development.. • For Filterra systems with a Tree Crate, plant(s) should have a single trunk at installation. b Plant species shall not have a mature height greater than 30 feet. Requested Plant Species: Approved: Cate: * UNPREPARED SITE FEE NOTE: A charge; of $1500.00 wUt be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation ANDI'OR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations wilt void the system warran(y and waive manufacturer supplied activation and final inspection. f www.ContechES.com/fiilterra 1 E00-335.1122 Fir—. Ad-fi- Fack.ge I r,,q£ a (' �. 22 of 3 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-23 of 39 Record Date:2/13/2026 3:24 PM King County, WA <r= CLEANOUT (CAST -IN) 4 g P Q „k M FRONT FACE OF CURB P 36" X 36° TREE. � 4'-0` CURES WIDTH GRATE (CAST -IN') Figure 1a. Filterra with Tree Grate Drawing CLEANOUT (CAST -IN) FRONT FA OFCURB 36 FULL GRATE 4-0° CURB WIDTH (CAST -IN) Figure 2a. Filterra with Full Grate Drawing r Figure 2b. Filterra with Full Grate Photo w ,ContechES„corn/filterra 1 800-338-1122 fiII.er ° P 2 f FIk,e Adw.tio Pa k.q7 � Page 5 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-24 of 39 Record Date:2/13/2026 3:24 PM King County, WA IM2�01AM-Upfff KEY: (refer to plant list for species sizing) * UNPREPARED SITE FEE NOTE: A charge of $1500.00 will be invoiced for each activation visit requested by customer where Contech determines that the site does not meet the conditions required for Activation ANDIOR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation of Filterra systems; unauthorized activations will void the systern warranty and waive manufacturer supplied activation and final inspection. www.ContechES,corn/filterra 1 800-338-1122 P:,,. 24 of 39 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-25 of 39 Record Date:2/13/2026 3:24 PM King County, WA 20x8 Media Bay f ._� .... ;.U�R8L7 Sf7F.. F F VfiiE. A ctrarWaf i-F� 6:6 v ill k9e rravorced tdr each a�tivatr`oea vrsr€;;zW; sty d %y cZ; torraF where Contech determines that the site does not meet the conditions required for Activation ANt IOR acceptable plants are not provided by the contractor. ONLY Contech authorized representatives can perform Activation cat ilterra systems; unauthorized activations will void the systerrr warranty and waive manufacturer supplied activation and final www.ContechES.com/filterra 1 600-338-1122 Fag. 25 of 39 . Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-26 of 39 Record Date:2/13/2026 3:24 PM King County, WA Filterral TreeiiProcedure 1"he standard grates used on all Filterra configurations that employ Tree Grates are fabricated with a 6" opening that Is designed with a breakaway section that can he removed, allowing the gran: opening to be expanded to 12" as the tree matures and the trunk widens. 1"he following tools are required to expand the opening: ® Mini sledgehammer (3 lb, or greater) • Safety Glasses / Goggles The following guidelines should be followed to properly expand the free opening from 6" to 12": Remove: the grate from the Filters frame, place it flat on a hard surface, and support the grate by stepping on the edge or using other weighted items such as a few mulch bogs if this is being done during as Fibers maintenance event. Prat on safety glasses/goggles. Align the mini sledgehammer as shown in the figure to the left. The head of the sledgehammer should be aimed just inside the wide cast iron bar between the larger grate section and the breakaway section. 2. Repeatedly hit the grate at this spot with the mini sledgehammer„ 3. After several hits, the breakaway section should snap cleanly off of the larger grate section. Reinstall the grate into the Filters orate frame. Recycle or dispose of the breakaway section per local guidelines, www,ContechES.com/flilterra 1 800-338-1122 efilterra P., e 26 of 39 %'g " ,a" Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-27 of 39 Record Date:2/13/2026 3:24 PM King County, WA w wwr.ContachES.com/fitltarra 1 800-338-1122 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-28 of 39 Record Date:2/13/2026 3:24 PM King County, WA ContechE . m/fiBterra 6 800-33$-1122 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-29 of 39 Record Date:2/13/2026 3:24 PM King County, WA ContechES.com/fiiaterra ! 800-338-1122 P— ,,. 29 of 3 Instrument Number: 20260213000701 Document:COV Rec: S341.50 Page-30 of 39 Record Date:2/13/2026 3:24 PM King County, WA 0woNTECo"nae ENGINEERED SOLUTIONS 9100 Centre Pointe Drive, Suite 400 West Chester, OH 45069 info@conteches.com 1800-338-1122 www.Cc)ntechES.com @ 2023 Contech Engineered Solutions LLC, a QUIKRETE Company NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF� SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, PDF 1/23 EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH, SEE CONTECH'S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECFiES.COM/COS) FOR MORE INFORMATION. P.,. 30 of 39 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-31 of 39 Record Date:2/13/2026 3:24 PM King County, WA Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-32 of 39 Record Date:2/13/2026 3:24 PM King County, WA FEE LJsing patented continuous deflective separation technology, the CDS system screens, separates and traps debris, sediment, and oil and grease from stormwater runoff. The indirect screening capability of the system allows for 100% removal of floatabIcs and neutrally buoyant material without blinding, Flow and screening controls physically separate captured solids, and rninirni7e the re -suspension and release of previously trapped pollutants, Inline units can treat up to 6 cfs, and internally bypass flows in excess of 50 cfs (1416 Us), Available precast or cast -in - place, offline units can treat flows from 1 to 300 cfs (28.3 to 8495 Us). The pollutant removal capacity of the CDS system has been proven in lab and field testing, Operation Overview Stormwater enters bict diversion chamber where the diversicirr weir guides the flow into the unit's separation chamber and pollutants are rernoved from the flow. Ali flows up to the system's treatment design capacity enter the separation chamber and are treated, Swirl concentration and screen deflection force floetables arid .solids to the center of the separation chamber where 100% of floatables and neutrally buoyant debris larger than the screen apertures are trapped. Storrnwater then moves through the separation screen, tinder the oil baffle and exits the system. -1 he separation screen remains clog free due to continuous deflection. During the flow events exceeding the treatment design capacity, the diversion weir bypasses excessive flows around the separation chamber, so captured pollutants are retained in the separation cylinder. P.,,. 32 of 39 Elam There are three primary methods of sizing a CDS system. The Water Quality Flow Rate Method determines which model size provides the desired removal efficiency at a given flow rate for a defined particle size. The Rational Rainfall Method" or the and Probabilistic Method is used when a specific removal efficiency the not annual sediment load is required. Typically in the Unites States, CDS systems are designed to achieve an 8011Xo annual solids load reduction based on lab generated beiformance curves for a gradation with an average particle size 050) of 125 microns (prin). For sorne regulatory environments, CDS systems can also be designed to achieve an 80% annual solids load reduction based on an average particle size (d50) of 75 microns (jnn) or 50 microns (urn). Water Quality Flow Rate Method In some cases, regulations require that a specific treatment rate, often referred to as the water quality design flow (WQQ), be treated. This WQQ represents the peak flow rate from either an event with a specific recurrence Interval, c..g, the six-nionth storm, or a seater quality depth, e.g. 1/2-inch (13 mrn) of rainfall. The CDS is designed to treat all flows up to the WQQ. At influe rates higher than the WQQ, the diversion weir will direct most flow exceeding the WQQ around the separation chamber. 1 his allows removal efficiency to remain relatively constant in the separation chamber and eliminates the risk of washout during bypass flows regardless of influent flow rates. Treatment flow rates are defined as the rate at which the CDS will remove a specific gradation of sediment at a specific remov efficiency. Therefore the treatment flow rate is variable, based on the gradation and removal efficiency specified by the design engineer. Rational Rainfall Method" Differences in local climate, topography and scale make every site hydraulically unique. It is important to take these factors int consideration when estimating the long-term performance of any stormwater treatment systern, The Rational Rainfall Method combines site -specific information with laboratory generated performance data, and local historical precipitation records to e,ztimare removal efficiencies as accurately as possible. Short duration rain gauge records from across the united States and Canada were analyzed to determine the percent of the total annual rainfall that fell at a range of intensities. IJS stations' depths were totaled every 15 minutes, or hourly, and recorded in 0.01 -inch increments. Depths were recorded hourly with 1 -Mril resolution at Canadian stations. One trend was consistent at all sites; the vast majority of precipitation fell at low intensities and high intensity stomr, contributed relatively little to the total annual depth. These intensities, along with the total drainage area and runoff coefficient for each specific site, are translated into flow rates using the Rational Rainfall Method. Since most sites are rdativiely small and highly impervious, the Rational Rainfall Method is appropriate. Based or) the runoff flow rates calculated for each intensity, operating rates within a proposed CIDS systern are Instrument Number: 20260213000701 Document:COV Rec: S341.50 Page-33 of 39 Record Date:2/13/2026 3:24 PM King County, WA terrtuned, Performance efficiency curve deterrnrned from full ole laboratory tests on defined sediment PSDs is applied to culate solids removal efficiency. The relative removal efficiency each operating rate is added to produce a net annual pollutant naval efficiency estimate. 11'robabilistic RafiorW Method The Probabilistic Rational Method is a sizing program Contech developed to estimate a net annual sediment load reduction for a particular CDS model based on site size, site runoff coefficient, regional rainfall intensity distribution, and anticipated pollutant characteristics, The Probabilistic Method is an extension of the Rational Method used to estimate peak discharge rates generated by storm events of varying statistical return frequencies (e.g. 2-year ,term event). Under the Rational Method, an adjustment factor is used to ladk.ast the runoff coefficient estimated for the 10-year event, corrdating a known hydrologic parameter with the target storm everit. The rainfall intensities vary depending on the return frequency of the storm event under consideration. In general, these two frequency dependent pararTieters (rainfall intensity and runoff coefficient) increase as the return frequency increases while the drainage area remains constant, These intensities, along with the total drainage area and runoff coefficient for each specific site, are translated into flow rates using the Rational Method, Since most sites are relatively small and highly impervious, the Rational Method is appropriate. Based on the runoff flow rates calculated for each intensity, operating rates within a proposed CDS are determined. Performance efficiency curve on defined sediment PSDs is applied to calculate solids removal efficiency. The relative removal efficiency at each operating rate is added to produce a net annual pollutant removal efficiency estimate. The inlet threat area is Sr7c:d to ensure that the WQQ passes through the separation chamber at a water surface elevation equal to the crest of the diversion weir. The diversion weir bypasses excessive flows around the separation chamber, thus preventing re -suspension or re -entrainment of previously 1captured particles. Hydraulic Capacity The hydraulic capacity of a CDS system is determined by the length and height of the diversion weir and by the maximum ,allowable head in the system, lypcal configurations allow hydraulic capacities of up to ten times the treatment, flow rate. The crest of the diversion weir rnay be lowered and the inlet throat may be widened to increase the., capacity of the system at a given water surface elevation. The unit is designed to meet project specific hydraulic requirement,.;, Performance Full -Scale Laboratory Test Results A full-scale CDS system (Model CDS2020 5B) was tested at the facility of University of Florida, Gainewdle, FL, ibis CDS unit was evaluated under controlled laboratory conditions of influent flow rate and addition of.sedirnent. P.,,; 33 of 39 & OK-1 10) were used in the CDS perfoinnance evaluation. The particle size distributions (PSDs,) of the test rnaterials were analyzed using standard method "Gradation ASTM D-422 "Standard Test Method for Particle -Size Analysis of Soils" by a certified laboratory. OF Sediment is a mixture of three different products produced by the U.S. Silica Company: "Sit-Co-Sil 106", '41 DRY" and "20140 Oil Frac". Particle size distribution analysis shows that the OF Sediment has a very fine gradation (d50 = 20 to 30 ium) covering a wide size range (Coefficient of Uniformity, C averaged at 10.6), In comparison with the hypothetical TSS gradation specified in the N3DEP (New Jersey Department of Environmental Protection) and NJCA1 (New Jersey Corporation for Advanced Technology) protocol for lab testing, the UP Sediment cover, a similar range of particle size but with a finer d50 (d5O for NJDEP is approximately 50 prn) (N.IDEP, 2003). The OK-1 10 silicasand is a commercial product of U.S. Silica Sand. I -he particle size distribution analysis of this material, also included in Figure 1, shows that 99.9% of the OK-1 10 sand is finer than 250 microns, with a mean particle size (d50) of 106 microns. The PSDs for the test material are shown in Figure 1. 100,0 1 1 I'll 11 I'll 11 1 1 I'll, 11 1 T". a 90,0 UP Sediment (Avg) 80,0 OK. 110(Avg) 700 NJCAT 60,0 500 Cy 40.0 30,0 200 100 10 t gC4 1000 9MEMEMEM Figure 1. Particle size distributions Tests were conducted to quantify the performance of a specific CDS unit (1.1 cf, (31.3-L/s) design capacity) at various flow rates, ranging from 'I % up to 125% of the treatment design capacity as the unit, using the 2400 micron screen. Ali tests were conducted with controlled influent concentrations of approximately 200 ryxj/L. Effluent sarnples were taken at equal time intervals across the entire duration of each test run. These samples were then processed with a Dekaport Cone sarnple splitter to obtain representative sub -samples for Suspended Sediment Concentration (SSQ testing using ASTM D3977-97 "'Standard Test Methods for Determining Sediment Concentration in Water Samples", and particle size distribution analysis. Results and Modeling Based on the data from the University of Florida, a performance model was developed for the CDS system. A regression analysis was used to develop a fitting curve representative of the scattered data points at various design flow rates. This model, which demonstrated good agreement with the laboratory data, can then be used to predict CDS systern performance with fa"5pe Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-34 of 39 Record Date:2/13/2026 3:24 PM King County, WA to SSC rernoval for any particle size gradation, assuming the particles are inorganic sandy -silt. Figure 2 shows CDS predictive performance for two typical particle size gradations (MCAT gradation and OK-1 10 sand) as a function of operating rate. 10000 40,00 2000 . . . ...... .. I-- OK 1101 0,00 0% 20% 40% 60% 80% 100% 120% 140% % Design Flow Rate Figure 2. CDS stornwater treatment predictive performance for various particle gradations as a function of operating rate. Many regulatory juiris&ctions set to performance standard for hydrodynamic devices by stating that One devices shall be capable of achieving an 80% removal efficiency for particles having a mean particle size (d50) of 125 microns (e.g. Washington State Department of Ecology -- WASDOE - 2008). The model can be used to calculate the expected performance of such a PSD (shown in Figure 3). The mode) indicates (Figure 4) that the CDS systern with 2400 micron screen achieves approximately 80% rernoval at the design (1(70%) flow rate, for this particle size distribution (d50 -= 125 jim). i0o 90 ao 70 60 53 40 It zo 10 0 I 100 so 50 40 2.0 0 In Raffido Dtsipbubon to im 10a) particle Size (inicrofl) Figure 3. WASDOE PSD CD3 (hit Pedurmance fox EcokW PSD d�,=125 lifn 7 y 145x 1W, 92 UM T111 20% 40% 6VA ST% I 001A 120% W% % Design Flcw Rae P.,. 34 of 39I performance for VVASDOE PSD, "XIEVROM= The CDS systems should be inspected at regular intervals and maintained when necessary to ensure optimum performance. The rate at which the system collects pollutants will depend nn, heavily on site activities than the size of the unit, 1-or example, unstable soils or heavy winter sanding will cause the grit chain to fill more quickly but regular sweeping of paved surfaces will slow accumulation. M= Inspection is the key to effective maintenance and is easily perforrned. Pollutant transport and deposition may vary from year to year and regular inspections will help ensure that the system is cleaned out at the appropriate time. At a r-ninimurn, inspections should be performed twice per year (e.g. spring and fall) however more frequent inspections may be necessary in dirnates where winter sanding operations may lead to rapid accumulations, or in equipment washidown areas, installations should also be inspected rnore frequently where excessive amounts of trash are expected. The visual inspection should ascertain that the system components are in working order and that there are no blockages or obstructions in the inlet and separation screen. The inspection should also quantify the accumulation of hydrocarbons, bash, and sediment in the system, Measuring pollutant accumulation can be done with a calibrated dipstick, tape measure or other measuring instrument, if absorbent n-ratcrial is used for enhanced removal of hydrocarbons, the level of discoloration of the sorbent material should also be identified Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-35 of 39 Record Date:2/13/2026 3:24 PM King County, WA during inspection. It is useful and often required as part of an operating permit to keep a record of each insped;on. A simple form for doing so is provided. Access to the CD5 unit is typically achieved through two manhole access covers, One opening allows for inspector and deanout of the separation charmser (cylinder and screen) and isolated sump. The other allows for inspection and cleanout of sediment captured and retained outside the screen. For deep units, a single manhole access point would allows both sump cleancirjt. and access outside the screen. I he CDS system should be cleaned when the level of sediment has reached 75% of capacity in the isolated sump or when an appreciable level of hydrocarbons and trash has accurnulate.d. If absorbent material is used, it should be replaced when significant discoloration has occurred. Performance will not be impacted until 100% of the SUMP capacity is exceeded however it is recommended that the system be cleaned prior to that for easier rernoval of sediment, The level of sediment is easily determined by measuring from finished grade down to., the top of the sedirnpnt pile, to avoid underestimating the level of sediment in the chamber, the measuring device must be lowered to the top of the sediment pile carefully. Particles at idne top of the pile typically offer less resistance to the arid of the rod than consolidated particles toward the bottom of the Aide. Once this measurement is recorded, it should be compared to the as -built drawing for the unit to determine weather the height of the sediment pile off the bottom of the sump floor exceeds 751Y0 of the total height of isolated sunup. EM Cleaning of a CDS systems should be done during dry weather conditions when no flow is entering the system, -1 he use of a vacuum truck is generally the most effective and convenient method of removing pollutants from the system. Simply remove the manhole covers and insert the vacuum hose into the sunup. The system should be completely drained down and the sump fully evacuated of sediment, the area outside the screen should also be cleaned out if pollutant build -Up exists in this area. In installations where the risk of petroleum spills is small, liquid contaminants may not accumulate as quickly as sediment. However, the system should be cleaned out immediately in the event of an oil or gasoline split. Motor oil and other hydrocarbons that accumulate on a more routine basis should be removed when an appreciable layer has been captured. To remove these pollutants, it may be preferable to use absorbent pads since they are usually less expensive to dispose than the oil/water emulsion that may be created by vacuuming the oily layer. Trash and debris can be netted out to separate it from the other pollutants. The screen should be cleaned to ensure it is free of trash and debris. Manhole covers should be securely seated fallowing cleaning activities to prevent leakage of runoff into the system from above and also to ensure that proper safety precautions have been followed, Confined space entry procedures need to be followed if physical access is required. Disposal of all material removed front the CDS system should be. done in accord a rice Mth local regulations. In many jurisdictions, disposal of the sediments rnay be handled in the same mariner as the disposal of sediments removed from catch basins or deep sump manholes. Check your local regulations forspecific requirements on disposal. Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-36 of 39 Record Date:2/13/2026 3:24 PM King County, WA P..s,. 36 of 3 Instrument Number: 20260213000701 Document:COV Rec: $341.50 Page-37 of 39 Record Date:2/13/2026 3:24 PM King County, WA CDS Model: Location, Water Heatable n f�e Date depth to Layer Maintenance Maintenance Comments sediment' Thickness' Performed Personnel j- i he water depth to sedimenT is determined by taKmg two measurements with a stadia rod: one measurement horn the manhole opening to the top of the sediment pile and the other from the manhole opening to the water surface. If the differerwe between these measurements is less than the values listed rn table I the system should be cleaned out. Note: to avoid underestimating the volume of sediment in the chamber, the measuring device must be carefully lowered to the top of the sediment pile, 2. For optimum performance, the system should be cleaned out when the floating hydrocarbon layer accumulates to an appreciable thickness. In the event of an oil spill, the system should be cleaned immediately. P,�g. 37 of 39 Instrument Number: 20260213000701 Document:COV Rec: 5341.50 Page-38 of 39 Record Date:2/13/2026 3:24 PM King County, WA SUPPORT � s • Drawings and specifications are available at www.ContechES.com. oto "�' ENGINEERED SOLUTIONS • Site -specific design support is available from our engineers. 800-338-1122 www.ContechES.com @2017 Coritech Engineered solutions LLU9 a OUIKRETE Company Contech Engineered Solutions provides site solutions for the civil engineeting Industry. Contech's portfolio includes bridges, drainage, sanitafy SeWarearth st8blittzOljon and stormwater treatment products. For information on other Contech division offerings, visit www-ContechES,Com Or call 800.338,1122 NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY, APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES MATERIALS,WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH'S CONDITIONS OF SALEAND ALL IMPLIED WARRANTIES OF FITNESS (AVAILABLE R.. INFORMATION. Instrument Numbem20260213000701 Ooume trOV R eS3 130#ae3 «3 Record Oke2/13/22 3:2 #M Vin County, WA w■ *» «�< *r 2 » ?;< � w < :#<2 y; ■»»?»§« y<�»»»#.«<,°<<»«»<y» z.. v.� . . � :» <2#2» m 2 » y 24°2»<�»f�}■:? LOTS 1-9 BLOCK - RENTON FARM PLAT :ORDm » O THEPLA THEREOF RECORDED IN VOLUME 10 OF PLATS, PAGE9 IN KING COUNTY,2 SHI GTON EXCEPT THOSE PORTIONS OF LOTS I THROUGH 5 ».CONDEMNED 2: «m» COUNTY SUPERIOR COURTASENO ., »\»-1FORSTREET PURPOSES. ... TOGETHER WITH,a, «, THROUGH a»y.»BLOCK 2 :,*»«?w.,c ACCORDING OTHE PLAT THEREOF< RECORDED IN VOLUME '�� OF PAGE 7, INKING«�CO COUNTY, SHIN G EXCEPT ©E WEST 20FE HEREO