DREDGING/DEWATERING Wilde Lake Maintenance Dredging
www.landandwater.com 25 DREDGING/DEWATERING
n the summer of 2012, JND ways and over 3,400 acres of Th omas Company, Inc., a gen- permanent open space including Ieral contractor based in River- three lakes; Lake Elkhorn, Lake dale, CA and Daytona Beach, FL Kittamaquundi and Wilde Lake. was awarded a contract by the Project representatives for the Columbia Association of Colum- Association were Dennis Mattey bia, Maryland for the maintenance - Head of Construction, Diana dredging of Wilde Lake. Th e com- Kelley, CPPB - Contract Admin- prehensive “turn-key” operation istrator and Charles Grey - Proj- included dredging, construction of ect Manager. the dewatering and staging areas, Wilde Lake is a 22-acre dredging methodology, dewatering man-made lake, located in Co- technology and equipment con- lumbia. Prior to its development fi guration, trucking and fi nal off - in 1966, the site was a grassy site disposal of the lake sediments meadow containing a small and the restoration of the site. Th e stream. Th e lake is surrounded Columbia Association funded the by residential and open recre- project for approximately $1.7 ational space and fed by an un- million. named tributary from the north and a fi fteen-foot high concrete Background dam exists at the outfall channel. Th e Columbia Association is Th e outfl ow of Wilde Lake pass- a community-controlled, private, es through Lake Kittamaqundi non-profi t service corporation cre- (another Columbia man-made ated to provide services, amenities lake) and eventually fi nds its and facilities for the benefi t of Co- way to the Little Patuxent River. lumbia, Maryland. It builds, op- Th e lake accepts drainage from erates and maintains community approximately 1,200 acres con- facilities, neighborhood centers, Unloading of Moray dredge at Wilde Lake. sisting primarily from residential sports clubs, pools, parks, path- properties. Over time, Wilde aquablok.com
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26 November/December 2012 DREDGING/DEWATERING
Lake had accumulated too much sediment, which diminished its overall holding capac- ity causing a rapid decline in water quality and excessive vegetative growth in undesir- able locations.
Engineering and Permitting Th e design, plans, specifi cations, cost estimating, engineering, permitting and construction oversight for the dredging project were performed by Anchor QEA of Columbia with local on-site supervision by Walter Dinicola, P.E. Regulatory oversight and permitting were secured through the Maryland Department of the Environmen- tal Dam Safety Division and the Howard County Department of Inspections, Li- censes and Permits.
Challenges and Mobilization Meeting the “turn-key” requirements of the project coupled with the complexi- ties of working within a highly populated Dredge removing accumulated sediment at inlet of Wilde Lake. residential area posed many challenges. First and foremost was the challenge of mobilization and deployment of dredging ing the addition of under drains prior to are trucked onsite without requiring any and dewatering equipment. Th e dewater- site preparation to meet compaction and “special” height or width permits. Th e de- ing site selected for the Wilde Lake Dredg- grading specifi cations. JND Th omas Com- watering plant has a relatively small foot- ing Project that off ered minimal disruption pany’s dredge and dewatering plant con- print and once assembled, takes less than to the residents had an active spring requir- sists of mobile, portable equipment that one half acre. In this case, a grassy knoll
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www.landandwater.com 27 DREDGING/DEWATERING
within an open space of Wilde Lake Park was selected. Th e construction of access THE CLEAR CHOICE FOR SEDIMENT CONTROL roads was minimal, all erosion control and silt fencing including safety postings were implemented and a turbidity curtain was installed 150’ in front of the outfall dam, all as required by the contract. Two cranes, 70 and 150 ton, were used for lowering the dredge and positioning the components of
Meeting the “turn-key” re- NATURAL SEDIMENT FLOCCULANT quirements of the project coupled with the complexi- ties of working within a highly populated residen- tial area posed many chal- lenges.
the plant. Th e mobilization took approxi- To inquire about Biostar-CH products and availability mately seven days from start to pumping, in the U.S. and International markets, contact us directly at 1-715-426-5131 allowing for coordination of traffi c, pipe- or visit us at www.biostar-ch.com line fusing and testing. Key JND partici- pants were David Driver - Off site Mgr, Email: [email protected] Keith Ayers - Project Mgr and Patrick HILD&ASSOCIATES,INC. Dunnigan - Dewatering Superintendent in ©2010 Hild & Associates, Inc. Biostar-CH is a trademark of Hild & Associates, Inc. addition to a team of six employees sharing dredging, dewatering, staging and loading responsibilities.
Dredging Th e dredging specs of the project called for removing accumulated sediment to the previous 1993 dredged grades (6”+ tolerance) in the northwest third of the lake. Neither the original lake bottom nor the current existing elevations are a smooth surface of uniform depth, but rather, an Filter Sock irregular bottom with varying depths that “Bringing You Compliance have evolved into sediment islands over- Without Complications” grown with undesirable vegetation. An 8” DSC Moray swinging ladder dredge with GPS positioning capability was deployed. Th e Moray can operate at a minimum wa- ter depth of 48” (ideal for Wilde Lake’s shal- low condition) and has the ability to work in tight areas by utilizing travel and posi- tioning spuds instead of cables for move- Attention: Blower Truck Dealers and Installers, Landscapers, ment. Capable of dredging depths up to Homebuilders, Wattle and Netting 18’, the Wilde Lake project depths around Manufacturers, Pipeline Contractors 6’ were easily accomplished producing and Erosion Product Distributors nominal fl ow rates up to 2,000 gpm @ 185 TDH (Total Delivered Horsepower). Th e Call Today For: cutterhead is a sealed planetary drive; 24” 6SHFLÀFDWLRQV3ULFLQJDQG7HFKQLFDO6XSSRUW inside diameter 5-blade basket cutter with 1.888.623.8823 nominal production capacity around 90 in-situ yards per hour. Th e Moray was con-
28 November/December 2012 DREDGING/DEWATERING
SPILLDAM ENVIRONMENTAL, INC. SILTDAM™ Turbidity Control Curtains: designed, engineered and manufac- tured to meet the demanding site requirements of our customers.
Dewatered silts, clays & organic sediment after being processed through JND’s Marine Construction plant. Demolition Dredging nected to a maximum of 3,200 feet of 8” in suspension and pumped to four - 14” Remediation HDPE fl oating and submerged discharge Hydro-cyclones. Any material larger than Erosion Control pipe (placed as specifi ed in the plans mini- 225 mesh drops onto two Linear Motion Shoreline Revetment mizing hiker/biker path interruptions and/ King Cobra Shakers where it is dried and or closures with all crossings being bur- removed. All remaining material less than ied). An additional DSC fl oating booster 225 mesh and water is collected below into Options include: pump was incorporated after beginning a second mix tank where it again is kept s IN MM IN MM AND the project to assist with the pumping of in suspension and pumped to the Clarifi er. IN MM &LOTATION sand and gravel. Hydro Data of Chester, Various types and amounts of specifi cally s 0ERMEABLE OR IMPERMEABLE VARIETIES Connecticut verifi ed all dredging progress formulated polymers are injected at various s 3KIRT DEPTHS FROM FT M TO FT with bathymetric surveys after the comple- points between the fi rst and last tanks to M tion of each section. Dredging began in the maximize the fl occulating process (separa- SMU1 and SMU2 prioritized areas located tion of solids from water). When applied at the northwest third of the lake. at the correct mix points and correct ratios, the polymers enhance the separation and Dewatering and Material Handling settling of ultra fi nes (organics, clays and JND’s dewatering plant uses mechani- silts presented as cloudy, discolored water) cal operations and clarifi cation tanks in and suspended solids (presented as fi ne free combination with the addition of poly- fl oating particles). Th e Amber Group of mers to dewater dredge spoils. Th e second- Irvine, CA provided the technical exper- ary benefi t is the enhanced clarifi cation of tise and product selection recommenda- lake water, which is returned back to the tions for the Wilde Lake project. Th ick- lake after exiting the plant. Th e process ened slurry is consolidated at the clarifi er begins with lake sediment and water be- and equally distributed to three 1.7-meter ing pumped from the dredge to the de- Charter Machine Company Belt presses watering plant at 10 – 15 percent solids. where the thickened fi nes are pressed to Th e slurry is fi rst directed over two sets of remove all Capillary (Intercellular) water. Dual Tandem Trash Shakers, exposing the Capillary Intercellular water can only be DBA "ROCKTON %QUIPMENT3PILLDAM )NC fl ow to 20 square feet of surface area for separated from solids by overcoming adhe- 0/ "OX removing any debris larger than 1/8th inch sive or capillary forces in pressure sections, "ROCKTON -! 53! in size. Th e pass thru slurry is collected be- like a belt press or centrifuge. By combin- &AX WWWSPILLDAMCOM low in the fi rst mix tank where it was kept ing all three processes in a continuous,
www.landandwater.com 29 DREDGING/DEWATERING
calibrated fashion, the plant was capable tons or 13-14 cubic yards per load were the same sub contractor who performed of producing dewatered sediment “cake” at used to transport the dewatered sediment. the initial site preparation. Minimal resto- 40 – 45% moisture (55 – 60% dry), eas- On average, 17 truckloads per day were ration was required due to the overall small ily capable of stacking for staging. Cleaned transported off site to an approved disposal footprint of the dewatering plant and con- water from the plant was returned to the site. Th e trucking was sub contracted to Ag sisting primarily of removing base gravel lake and sampled for turbidity as required Tran of Jessup, Maryland. by federal, state and local regulations with a DR-850 turbidity meter averaging 48 Demobilization and Site Restoration Minimal restoration was NTU (Nephelometric Turbidity Units) Th e project was completed in late July required due to the overall for the duration of the project. During the with demobilization occurring after neces- small footprint of the de- staging process, a 4 cubic yard wheel loader sary scheduled maintenance thereafter. Th e watering plant and consist- collected and mixed dewatered sediments equipment was disassembled and relocated ing primarily of removing from all three screening/dewatering points to Elkhorn Lake for additional work. Site base gravel and rock, silt and consolidated it for loading into trucks. restoration was sub contracted to RF Wat- perimeter fences and the Tri-axle trucks capable of hauling 20-22 son Contracting of Upper Falls, Maryland, replanting of grass.
and rock, silt perimeter fences and the re- planting of grass. Th e Wilde Lake dredging project re- sulted in the removal of approximately 15,000 cubic yards of accumulated sedi- ment that settled in the northwest inlet of the lake. Work began in May and was completed in July 2012. Th e crews worked Monday through Saturday from 7:00am – 8:00pm and occasionally on Sundays. Th e project showcased the successful coupling of three distinct operations, dredging, mechanical dewatering and staging/load- ing, representing that all three can be per- formed simultaneously and effi ciently as an alternative to conventional practices when an immediate basin is unavailable. JND Th omas Company, Inc. wishes to acknowledge and thank the Client, Consultants, Sub Contractors and Vendors that participated in the Wilde Lake Project all working together to insure the project Specializing in plants & custom seed mixes for: Ecological restoration services: was successful. L&W > Wetland mitigation > Planning, design & installation > Habitat & ecosystem restoration > Ecological monitoring by Th omas B. Amaro, VP of > Stream & lake shoreline & slope > Ecological assessments & Sales & Mktg, JND Th omas stabilization permitting Company, Inc. > Wetlands, uplands, riparian & woodlands > Erosion & sediment control > Natural stormwater BMPs & rain gardens > Exotic & invasive species control For more information contact JND > DOT & roadside corridor projects > Prescribed burning Th omas Company, Inc., Tim Azevedo, Busi- > Pollinator habitat & CRP plantings > High-level safety ratings & training ness Development Manager at tima@jndtho- > Bonded & insured for large-scale > Specification assistance projects mas.com, or call offi ce: (559) 867-3813, cell: > Contract growing (559) 250-8718. > Quality-tested pure live seed > Mycorrhizal innoculation for seed & plugs > All plant sizes: liners, plugs, quarts, gallons > Vegetated coconut logs & mats 574 586 2412 > Live stakes, fascines & wattles [email protected] www.cardnojfnew.com/nursery online catalog - www.cardnojfnew.com/catalog
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