DIG, WE MUST
Malibu Creek Ecosystem Restoration Project by the Numbers
Peering over the abyss of the 100-foot Rindge Dam. From The Acorn.
In order to help the citizens of Malibu, concerned Serra Retreat and Malibu Colony homeowners, hopeful steelhead fishermen, worried surfers and birders, potentially displaced homeless people and cannabis growers and the general public understand the effort to remove Rindge Dam, displace all the sediment trapped behind it and restore the Malibu Creek ecosystem, the following numbers are an attempt to condense the 47-page California Coastal Commission Consistency Determination No.: CD-0006-17 for a report filed by the U.S. Army Corps of Engineers.
This is the Project Description pulled from the title page of the report:
Removal of the Rindge Dam arch and spillway on Malibu Creek; excavation and removal of an estimated 780,000 cubic yards of sediment impounded behind the dam; transportation by truck of an estimated 278,000 cubic yards of clean sandy sediments to Ventura Harbor and then transport by barge for disposal in nearshore waters downcoast of Malibu Pier; transportation by truck of remaining excavated sediments to the Calabasas Landfill; and modification or removal of aquatic habitat barriers on Cold Creek and Las Virgenes Creek upstream of the dam.
Everything in italics is directly quoted from the CD-0006-17 report.
Everything in red is pulled from an email response by Susan M. Ming of the Army Corps of Engineers by way of Larry Simon of the California Coastal Commission on March 5, 2018
Everything in blue are quotes from named sources.
??? = Some costs, cubic yards and other numbers still missing.
TIMELINE: CHUMASH TO NOW
9000 - 13000 years Before Present: Archeological data indicate that prehistoric occupation of the California south central coast dates to at least 9,500 yrs before present (BP) (Erlandson and Colten 1991), with even earlier evidence from the Channel Islands, including a date from Santa Rosa Island of 13,000 BP (Ritsh 1999).
1891/1892: Frederick Rindge buys the 13,300 acre Malibu Rancho to satisfy his need for: “A farm near the ocean, under the lee of the mountains, with a trout brook, wild trees, a lake, good soil, and excellent climate, one not too hot in summer.”
Malibu Creek is that trout brook? Malibu Lagoon is that lake?
1916 x 32”: A May 17, 1916 story in The Los Angeles Times illuminates Malibu Creek as a healthy steelhead habitat, a hundred years ago: In The Best Story Never Told, William S. Saltor won a prize for landing (poaching) a 32-inch steelhead (!!??) in Malibu Creek, but then got in deep kimchee for fishing without a license. Saltor’s court date was announced but his court fate went unreported
The end of the news article describes Malibu Creek as a steelhead Valhalla:
Deputy Harry Pritchard took his limit before 8
o’clock opening day all on the old reliable worm…
Fish and Game Commissioner Connell stuck to the
fly, and had good sport. In the 200 yards Pritchard
fished in getting his limit, was a fine, long pool
very deep, and most of his fish came out of that one
In another spot were three great steelheads, and
while trying to get them up to a fly, the salmon-egg
fraternity appeared… So it always goes. Good fishermen
get trout, but as a rule they do not use salmonroe;
when bait is the necessary thing, it is a couple of
red worms; and that failing, a spinner or with clear
water and fish feeding high, the artificial fly.
Will the removal of Rindge Dam and all that sediment expose those “fine, long pools very deep,” and fill them with steelhead? Hope so.
1926: Year Rindge Dam was constructed: “The 100-foot-high concrete arch Rindge Dam was constructed in a steep narrow canyon gorge on Malibu Creek in 1926. To provide erosion control a spillway was cut into canyon wall bedrock adjacent to the dam and faced with concrete slabs.”
100 feet: Height of Rindge Dam. “The 100-foot-high concrete arch Rindge Dam was constructed in a steep narrow canyon gorge on Malibu Creek in 1926.”
326,000 gallons: Amount of water in an acre-foot: The number of gallons to cover one acre in a foot of water.
15 acre feet: Amount of water Rindge Dam was engineered to store.
4,887,771 gallons: Amount of water Rindge Dam stored at full capacity (15 acre feet x 326,000 gallons).
1940: Year Rindge Dam was filled with sediment: “To provide erosion control a spillway was cut into canyon wall bedrock adjacent to the dam and faced with concrete slabs. Rindge Dam interrupted the sediment transport regime in the watershed and interfered with habitat connectivity for aquatic species, including the endangered southern California steelhead, which is currently blocked from former spawning and rearing habitat in Malibu Creek and its tributaries upstream of the dam. The dam was constructed without an outlet structure, and the half-mile-long water supply reservoir behind the dam was essentially filled with sediment by the mid-1940s.”
1947: Year these photos were taken of a Happy Few fishing for Malibu Creek steelhead at the mouth of Malibu Creek and below Rindge Dam - and making it look gooood.
Fishermen on Malibu Creek - at the mouth and below the dam circa 1947.
1967: Year Rindge Dam was decommissioned: “The reservoir was decommissioned by the California Department of Water Resources as a water storage facility in 1967 because it no longer stored more than 15 acre-feet of water. The dam and adjoining property were subsequently purchased by the California Department of Parks and Recreation and added to Malibu Creek State Park.”
3/7/1994: Date the tidewater goby was federally listed as endangered.
1998: Year the Rindge Dam removal and Malibu Creek restoration project was first proposed: “The consistency determination states that the California Department of Parks and Recreation (DPR) and numerous stakeholders have long been interested in pursuing the modification to, and possible removal of, Rindge Dam. In 1998 the Corps and California DPR initiated a joint study of ecosystem restoration possibilities in the Malibu Creek watershed. An initial public workshop was held in January 1998, and the Corps and California DPR signed a Feasibility Cost Sharing Agreement in July 2001, which initiated the feasibility study process.”
2002: Feasibility study put before public. “A public scoping meeting and workshop for the feasibility study was conducted in May 2002, and a Notice of Intent to prepare an environmental impact study for ecosystem restoration was published in June 2002. Meetings coordinated by the Corps and California DPR continued through subsequent years, and included the establishment of a Project Delivery Team and a Technical Advisory Committee, both of which included federal, state, and local agency representatives (including the Coastal Commission), regional and community public interest groups, and local individuals.”
15 years: Amount of time it took to draft the Feasibility Report: “After nearly 15 years of work, the Corps published the Draft Integrated Feasibility Report/EIS/EIR for Malibu Creek ecosystem restoration in January 2017.”
15 more years: Time it will take to complete the project from 2018, if they start in 2025 and finish in 2033.
WHY IT TAKES SO DAMNED LONG TO GET ANYTHING DONE
10: Other State and Federal agencies that need to be consulted, and approval achieved for this proposed project to commence:
U.S. ARMY CORPS OF ENGINEERS, REGULATORY BRANCH
U.S. FISH AND WILDLIFE SERVICE
NATIONAL MARINE FISHERIES SERVICE
U.S. ENVIRONMENTAL PROTECTION AGENCY
CALIFORNIA DEPARTMENT OF PARKS AND RECREATION
CALIFORNIA STATE LANDS COMMISSION
CALIFORNIA DEPARTMENT OF FISH AND WILDLIFE
LOS ANGELES REGIONAL WATER QUALITY CONTROL BOARD
CALIFORNIA STATE HISTORIC PRESERVATION OFFICER
NATIVE AMERICAN TRIBAL CONSULTATION
Four: Alternatives eliminated during the screening process, which were given detailed analysis in the Integrated Feasibility Report (????). Complicated, read the report, page 15.
FROM PAGES 14 AND 15 OF THE A.C.E REPORT
Several alternatives were eliminated during the screening process, including constructing a Vnotch in the dam to allow direct sediment bypass through the dam, restoration of the water supply function of the dam, construction of fishways around the dam, and trapping and hauling fish around the dam. These alternatives were eliminated due to their infeasibility, inability to meet restoration objectives, or potential environmental impacts.
Ultimately, four primary alternatives received detailed analysis in the Integrated Feasibility Report: the no action (Alternative 1) and three action alternatives (Alternatives 2, 3, and 4) each with multiple options (sub-alternatives) addressing methods of sediment transport and deposition, spillway removal, and upstream barrier modifications (Exhibit 10). The four alternatives are summarized as follows:
Alternative 1 (No Action). The dam, spillway, and impounded sediment remain in place and the upstream barriers are not modified or removed.
Alternative 2. Options include removal of the Rindge Dam concrete arch and impounded sediment removal using traditional mining methods, and consideration of various shoreline and upland placement options for the impounded sediment. The mostly sands layer of the impounded sediment, an estimated 278,000 cubic yards, would be placed along the Malibu shoreline or nearshore area using trucks (shoreline) or a combination of trucks and barges (nearshore). Other variations for the Alternative 2 options include removal of the dam spillway and the modification or removal of other upstream aquatic barriers on Cold Creek and Las Virgenes Creek tributaries. The overall construction timeframe is estimated to take 7-8 years to complete. Alternative 3. Options include removal of the Rindge Dam concrete arch and impounded sediment over many decades, allowing for storms to erode controlled volumes of the impounded sediment before implementing the next incremental notching of the dam arch, repeating the cycle until the dam arch and sediment is removed. The costs for these alternative options are less than other alternatives and use far less trucks, but there are much greater uncertainties about the time needed to complete construction and potential adverse downstream effects of incremental releases of the impounded sediment, including an increased flood risk to CD-0006-17 (U.S. Army Corps of Engineers) 15 downstream communities.
Other variations for the Alternative 3 options include removal of the dam spillway and the modification or removal of upstream barriers. The overall construction timeframe is estimated to take at least two decades, but more likely multiple decades to a century to complete. The large range for construction completion is based on the uncertainties associated with the frequency of storm events of sufficient magnitude that allow for the next cycle of incremental dam concrete arch notching, followed by the timeframe for storms that mobilize and naturally transport the next layer of exposed impounded sediment.
Alternative 4 = Gradual notching of Rindge Dam for natural sediment transport. Options are similar to the Alternative 2 options, except the Rindge Dam concrete arch would be lowered an additional 5-ft each winter storm season during the 7-8 year construction cycle to allow opportunities for a controlled volume of the impounded sediment to erode downstream during the storm seasons between mining season operations. These alternative options potentially reduce the number of trucks needed to transport the impounded sediment, but increase the risk of detrimental impacts to downstream reaches of Malibu Creek compared to Alternative 2 options. Other variations for the Alternative 4 options include removal of the dam spillway and the modification or removal of upstream barriers. The overall construction timeframe is estimated to take 7-8 years to complete.
IS THE SEDIMENT TOXIC?
2002 - 2013: Years the Southern California Dredged Material Management Team measured and monitored the toxicity of the sediment behind Rindge Dam. “Prior to placement of any dredged or excavated materials into ocean waters, the materials must be determined physically and chemically suitable for such disposal in order to ensure that the materials will not adversely affect the marine environment. The Southern California Dredged Material Management Team (DMMT) is the regulatory body that reviews and approves the placement of dreaded (sic) materials [I suggested they correct “dreaded” to “dredged” 😇] in ocean waters and on shoreline beaches in the southern California bight. The Corps undertook initial physical and chemical testing of core samples of the impounded materials behind Rindge Dam in 2002 and made a preliminary determination that approximately 278,000 cu.yds. of sandy materials were free of contamination and suitable for nearshore placement. The DMMT reviewed the sediment test results in February 2013 and January 2015 and agreed that based on the preliminary test results the materials appear to be suitable for nearshore disposal. However, the Corps will undertake additional sediment grain size and chemical analysis during the future Pre-Construction Engineering and Design phase of the project and bring its sampling and analysis plan, test results, and a preliminary suitability determination to the DMMT for its review and approval. Therefore, the Commission will continue to retain oversight over the future sediment suitability determinations through its role in the DMMT. In addition, the Corps states in the consistency determination that:
WHAT WILL IT COST?
Rindge Dam as seen from the reservoir below. From The Acorn.
$100 million in 2013: From The Malibu Times (2-16-2017): Early descriptions of the project, as presented to city council in 2013, were heavily scrutinized at the time — though much of that scrutiny likely came from poor opinions many in Malibu held regarding the Malibu Lagoon Restoration Project of 2012. Back then, the project was estimated to cost at least $100 million…”
$161.6 million in 2017: From The Malibu Times (2-16-2017): “….with those estimates now reaching $161.6 million for the Army Corps of Engineers’ recommendation (called the “National Ecosystem Restoration” plan), or up to $166.5 million for the California State Parks preferred project (called the “Locally Preferred Plan”).
$100 million in 2018: From The Acorn (2-14-2018) “The removal project is expected to cost more than $100-million.”
NATIONAL ECOSYSTEM RESTORATION VS LOCALLY PREFERRED PLAN
NER plan vs LPP Plan: From the Malibu Times (3/10/2017) The Army analyzed 21 project alternatives that were narrowed down to two — the National Ecosystem Restoration (NER) Plan (favored by the Army), and the Locally Preferred Plan (LPP) (favored by State Parks). Any plan to remove the dam involves removing tons of sediment accumulated behind the dam, which amounts to thousands of truckloads of sand and gravel traveling over Malibu Canyon and/or Las Virgenes Road for a period of years.
The NER plan is cheaper because it doesn’t involve removing the dam’s spillway — just the dam itself; and sediment would be trucked directly into the Malibu Pier area. The LPP plan costs more, but includes spillway removal and a very different route for trucks — they’d take the 101 Freeway to Ventura, then barge it down the coast to Malibu shorelines.
NER PLAN LPP PLAN
Total First Cost
Interest During Construction
Annualized Investment Cost
Total Annual Cost
OMRR&R = Operations, Maintenance, Repair, Rehabilitation, and Replacement
AAHU = Average Annual Habitat Units
WHERE WILL THEY DUMP THE UNIT 2 SEDIMENT?
2016: Year field surveys were conducted to find the ideal placement/disposal site for that 278,000 cubic yards of sediment, south of the Malibu Pier: “Field surveys were conducted in June 2016 to map habitat areas and marine biological resources along a 3.5 mi stretch of Malibu shoreline from Carbon Canyon Road on the east to 1.5 mi west of Malibu Creek and the 20 foot mean-lower-low-water (MLLW) depth contour. A total of 325 acres of seafloor was mapped by employing sidescan sonar, down-looking sonar technology, remote video, and photographs to identify marine habitat types, identify bottom types (e.g., rock, sand), identify aquatic vegetation (e.g., kelp, eelgrass, surf grass, algae), identify any large objects (wrecks, debris, etc.), and anticipated resources that are known from or potentially present within the identified survey area. Biological characteristics of the study area were also compared to available information.
East of Malibu Pier, the shoreline was generally sandy beach with intermittent rocks on the beach and in the surfline at both the west and east ends of the beach. The majority of the subtidal habitat was sand at depths between 0 and -35 ft. Giant kelp beds were mapped on reefs primarily located west of Malibu Pier. A second smaller bed was located offshore of Carbon Canyon. Surfgrass was observed on low relief bedrock reef upcoast of Malibu Point at a depth of -15 ft MLLW and has been reported to occur in several locations (between survey Areas 1-3) based on historical CDFW habitat maps. Its depth distribution is between the lower intertidal zone and approximately -20 ft MLLW. Surfgrass was not observed on the underwater video east of Malibu Point. Eelgrass, another HAPC for FMP species, was not encountered within the study area. It is located in the sandy subtidal habitat at depths between -47 and -33 ft outside of Area 1 upcoast of Malibu Point (Merkel & Associates, 2015).
DUMP ZONE EAST OF MALIBU PIER
11 acres x 23 feet deep: Dimensions of placement/disposal site where barges will dump 278,000 cubic yards of sediment, 1,500 cubic yards at a time, south of the Malibu Pier: “The estimated 11-acre disposal site currently proposed by the Corps is located several hundred feet offshore in water depths less than 23 feet, which would keep the sands within the limits of the depth of closure to ensure that all materials are retained within the littoral zone. The site is an area that would typically receive sand transported down an unimpeded Malibu Creek. Sediments would then be moved generally in a downcast direction and gradually onto the beach by longshore currents.”
THE ARMY CORPS OF ENGINEERS REPORT AND CALIFORNIA COASTAL COMMISSION CONSISTENCY DETERMINATION
10/17/17: Army Corps of Engineers report on Rindge Dam filed. (???)
2/15/2018: California Coastal Commission Staff report Consistency Determination No.: CD-0006-17 filed.
3/9/2018: Public hearing date in Oxnard (be there!)
47 pages: Number of pages of CD-0006-17: https://documents.coastal.ca.gov/reports/2018/2/w11b/w11b-2-2018-report.pdf
8 steelhead: Number of fish reported by Debbie Sharpton and Rosi Dagit of the Stream Team. Not in Malibu Lagoon, but in all ocean-connected creeks and streams from San Luis Obispo to the Mexican border:
To use a Trumpism: “Sad!”
18 miles: Additional steelhead and fish-spawning habitat opened up: “Steelhead and Fisheries. Modifications to the hydrologic regime of Malibu Creek from dam removal will enhance aquatic and riparian habitat, with associated benefits to steelhead, tidewater goby and other native fish species. Dam removal will create an additional 18 miles of steelhead spawning and rearing habitat on Malibu, Cold, and Las Virgenes creeks.”
Malibu Creek from Rindge Dam to the tunnel entrance.
8.5 miles: Miles of Malibu Creek that will be exposed and improved by the restoration project. “While construction of the project will result in the loss of riparian and other environmentally sensitive habitat (ESHA) that has developed on the surface of the impounded sediment reservoir, the project is designed to restore natural aquatic and riparian habitat along the lower 8.5 miles of Malibu Creek, including the footprint of the impounded reservoir and stream reaches above and below Rindge Dam.”
OTHER DIRT AND DAMS
15,910,972 cubic meters: Amount of material removed to create the Panama Canal = 208,107,657 cubic yards
2,000,000 cubic yards: Amount of material that will have to be removed from Montecito after the January rains and debris damage.
34,000,000 cubic yards: Amount of sediment trapped behind two dams on the Elwha River in Washington state. This sediment was allowed to flow out to sea and form a giant sediment delta at the mouth of the Elwha.
From UW News: “It turns out there is even more sediment than originally thought – about 34 million cubic yards. That’s more than 3 million truck loads, enough to bury all of Seattle in a layer almost 3 inches thick.
Aerial photos show sediment starting to fan out around the river’s mouth.
“One of the risks of just looking at these beautiful plume pictures is that you really don’t know the extent of where that sediment actually ends up,” said Andrea Ogston, a UW associate professor of oceanography. “Our focus is looking at what’s happening very close to the seabed – how it’s going to move, where it’s going to get to, what’s its ultimate fate.”
MATILIJA DAM PROJECT IN VENTURA = SLURRY PIPELINE
6,000,000 cubic yards: Amount of sediment trapped behind Matilija Dam: silt, sand, gravel, and cobble.
11,000 - 12,000 feet: Length of “slurry pipeline” proposed to move 2 million cubic yards of material from Matilija Dam to Robles Diversion Dam.
THE CARMEL RIVER REROUTE AND SAN CLEMENTE DAM PROJECT
If you want some insight into the costs and other parameters of the 1920s construction of Rindge Dam and then the 21st Century removal of Rindge Dam, take a look at the 1921 construction of the San Clemente Dam on the Carmel River, and the successful project to remove the dam, displace the sediment and reroute the Carmel River around the dam and into San Clemente Creek - allowing for steelhead and wildlife connectivity.
Removing the San Clemente Dam on the Carmel River.
1918 - 1921: Construction years the arch dam - similar to Rindge Dam - was built to supply water to the Monterey Peninsula. The San Clemente Dam was implemented by Samuel Morse - owner of Del Monte Properties - to replace the Old Carmel River Dam built downstream in 1883. The new dam was designed by J.A. Wilcox and constructed by Chadwick & Sykes Inc of San Francisco
$300,000: Cost to build the 106-foot-tall dam in 1921 dollars - the equivalent of $3,913,689.47 in modern dollars.
106’ x 300’: Height and length of the dam. (Rindge Dam is 100’ x @150’)
7,070 cubic yards (5,410 m3): Concrete used in the construction of San Clemente Dam.
1,425 acre⋅feet/464,337,675 gallons: Original storage capacity of the dam.
1930: Dam sold to Chester Loveland, owner of the California Water and Telephone company.
$42 million in 1966: California American Water pays $42 million for the dam in 1966 - the modern equivalent of $327 million.
2,150,000 cubic yards: Sediment trapped behind the dam as of 2008
1991: Year the California Department of Water Resources (CDWR) issued a warning of potential dam failure and sought alternatives.
1992: California Water and Telephone Company required to upgrade the dam for safety which included a US$1 million project which drilled holes in the face of the dam to relieve hydrostatic pressure.
70 acre feet by 2008: Storage capacity of the dam after decades of sediment build up. From an original 1,425 acre feet.
2008: California Department of Water Resources approves a plan to reroute the Carmel River and demolish the dam.
2010: Agreement reached with CAW to implement the plan.
One half mile: Channel built to re-route the Carmel River around the dam and back into the Carmel River, below the dam.
380,000 cubic yards: Sediment excavated from San Clemente Creek to a permanent holding area upstream, on the Carmel River. Which will allow removal of the dam.
$84 million: Project cost with $49 million coming from CAW, $25 million from the State of California and the remaining $10 million coming from Federal and other sources.
Removal of San Clemente Dam on the Carmel River. Rindge Dam will look something like this as they take it down.
2013: Construction began.
December 2104: Carmel River is diverted.
November 2015: San Clemente Dam removed.
2016: Project completed.
LAYERS AND AMOUNTS OF SEDIMENT BEHIND RINDGE DAM
780,00 cubic yards: Estimate of sediment impounded behind Rindge Dam. “Project Description: Removal of the Rindge Dam arch and spillway on Malibu Creek; excavation and removal of an estimated 780,000 cubic yards of sediment impounded behind the dam;
278,000 cubic yards: Clean, sandy “Unit 2” sediments to be trucked to Ventura Harbor, placed on barges and then deposited south of the Malibu Pier. “Project description (cont.): “...transportation by truck of an estimated 278,000 cubic yards of clean sandy sediments to Ventura Harbor and then transport by barge for disposal in nearshore waters downcoast of Malibu Pier;”
CAPACITY AND COSTS TO HAUL SEDIMENT OUT BY TRUCKS
A 10 cubic yard dump truck towing a 10 cubic yard pup trailer.
20 cubic yards: Capacity of trucks hauling sediment to Calabasas and Ventura Harbor: “Trucks are 10 cy capacity with 10 cy capacity pup trailer. Total is 20 Loose Cubic Yards (LCY) Max Capacity.”
$14/$280 - $23/$460 cost per cubic yard/truckload:
a. To Calabasas Landfill: Approximately $14/cy. Not including disposal fees.
b. To Ventura Harbor: Approximately $23/cy.
c. Cost varies as excavation becomes more confined at the bottom.
$52.32: Per-ton tipping fee for sediment at Calabasas Landfill.
Landfill disposal fees = $52.32/ton.
Assuming 1.55 ton/loose cubic yard =
$81 cubic yard: Tipping fee for Calabasas Landfill.
$40,500,000: Cost to dump the remaining 500,000 cubic yards (787,000 - 287,000) of sediment into the Calabasas Landfill. (500,000 x $81)
AN EIGHT-YEAR PROJECT BEGINNING IN 2025
2025: Year the eight-year Malibu Creek Ecosystem Restoration Project will begin.
200 vertical feet: Height of Sheriff's Honor Camp Site (Sheriff's Overlook) above Rindge Dam which, “...will be used throughout construction as a temporary construction staging area during the entire duration of the project construction, used for oversight and management of the dam and impounded sediment removal activities. This staging area is expected to include trailers, vehicular parking and equipment storage. After construction is completed, the site would be restored and used as one of the turnout areas available to vehicles travelling northbound along Malibu Canyon Road for short term parking and a scenic overlook for viewing of the creek and canyon area. At the conclusion of the staging use, several signs about the site history (Rindge Dam) and the ecosystem restoration project are proposed to be installed at the site. Any construction work taking place at this site shall avoid all historic features related to the honor camp . . . Other temporary staging areas will be used during construction for storage and temporary disposal areas and at the upstream barriers”
40,000 cubic yards: Dirt moved to provide staging and access road from Sheriff's Honor to Rindge Dam. “About 40k cy will be used to construct two access ramps at the upper end of the Rindge Dam impounded sediment area to provide equipment access from Malibu Canyon Road to the work site, allowing for the removal of existing mature vegetation on the surface and temporary diversion and control of Malibu Creek to allow for needed work space for mining and other actions. A temporary cofferdam about five feet in height will be constructed upstream of the southbound ramp and direct water into a series of culverts. Controls and best management practices (BMPs) will be in-place to reduce turbidity level of discharges to background levels immediately downstream of the dam. Dewatering wells will be installed in the impounded sediment. Well water will be CD-0006-17 (U.S. Army Corps of Engineers) 7 conveyed immediately downstream of the dam and released into Malibu Creek after Best Management Practices ensure that turbidity and other constituents are maintained at appropriate levels. Wells will be designed with casings that can withstand winter storm flows. Each well casing will be protected in-place prior to each storm season during construction. Any remnants of the wells will be removed at the end of construction.
UNIT 1 = 10 FEET OF VEGETATION, COBBLES, GRAVEL, BOULDERS
10 feet: Top layer of Unit 1 vegetation and sediment removed: “Sediment mining will begin to remove the top layer of mostly gravels and boulders (approximately 10 foot depth), with some of the material used for completion of the ramps, hauling the remaining Unit 1 layer to the Calabasas Landfill along with the surface vegetation.
??? feet: First segmentation of Rindge Dam: “The first lift, the horizontal cut in the dam arch, will be removed in order to leave the concrete arch at the level of the remaining impounded sediment by October of the first year, repeating this action each year of construction. The site will be cleared of crews and equipment for the winter season, with the second year of construction beginning the next spring after the winter storm season.
7.4: Miles from Rindge Dam to Calabasas Landfill.
???? cubic yards: Estimated gravel, boulders and rocks in that top Unit 1 10-foot layer of sediment.
??? truck trips: Number of Unit 1 truck trips at 20 cubic yards per load from Rindge Dam to Calabasas Landfill.
$280 per truck load to Calabasas Landfill: Approximately $14/cy x 20 lcy per truckload. Not including disposal fees.
$1620 per truckload: Tipping fee at Calabasas Landfill for a truckload of 20 cubic yards at $81 per cubic yard.
$????: Total cost for ???? truckloads of Unit 1 sediment to Calabasas Landfill at $??? Per truckload.
???? miles: Total miles for ???? truckloads doing the 15-mile round trip from Rindge Dam to Calabasas Landfill.
UNIT 2 SEDIMENT =278,000 CUBIC YARDS TO VENTURA HARBOR
2026 - 2028: The three years it will take to mine, transport and redistribute the second layer of “Unit 2” 278,000 cubic yards of clean, sandy sediment: “The second to fourth year of construction will primarily be associated with removal of the Unit 2 sands with direct transport of sediment mined from the Rindge Dam impounded sediment area up Malibu Canyon and Las Virgenes Road, to Lost Hills Road, U.S. Highway 101 and the Ventura Harbor about 41 mi away from the dam.”
41 miles: Distance from Rindge Dam to Ventura Harbor by way of Malibu Canyon and Las Virgenes Road, to Lost Hills Road, U.S. Highway 101. At Ventura Harbor, the sediment will be loaded onto barges (dump scows) which will then bring the sediment back to Malibu, and dump it south of the Malibu Pier.
82 miles: Roundtrip from Rindge Dam to Ventura Harbor and back.
13,900: Estimated number of truck trips to haul 278,000 cubic yards of Unit 2 sediment at 20 cubic yards per truckload from Rindge Dam to Ventura Harbor.
$460 per truck load: Cost per truck load for 20 cubic yards of sediment at $23 per cubic yard.
$6,394,000: Total cost to transport 278,000 cubic yards of Unit 2 sediment from Rindge Sam to Ventura Harbor.: 13,900 truck loads x $460 per truck load.
DUMP SCOWS FROM VENTURA HARBOR TO MALIBU AND BACK
185 feet long by 48 feet wide by 64 Gross Register Tonnage: Dimensions of a split-hulled, bottom-dump dump scow. Loaded draft is 10 feet. Unloaded draft is two feet.
1,243 cubic yards: Capacity of barges (dump scows) which will be used to transport sediment from Ventura Harbor, back to Malibu to be dumped east of the Malibu Pier: “Assume each scow loads = 621.5 cy/day x 2 days = 1,243 cy/trip.”
“The second to fourth year of construction will primarily be associated with removal of the Unit 2 sands with direct transport of sediment mined from the Rindge Dam impounded sediment area up Malibu Canyon and Las Virgenes Road, to Lost Hills Road, U.S. Highway 101 and the Ventura Harbor about 41 mi away from the dam.. Material would be offloaded from the trucks and placed on barges to be transported to the Malibu shoreline, to the east of the pier. The 1,500 cy capacity barges (dump scows) would transport the material via tugboat downcoast and place the sands in the nearshore area near, but to the east of Malibu Pier in a location that does not adversely affect submerged aquatic vegetation. Both trucks and barges would be making approximate 82-mile round-trips for each load: trucks from the Rindge Dam impounded sediment site to Ventura Harbor and back; and the dump scows from the harbor to the Malibu nearshore site and back. This cycle of activities will be repeated for these three years.”
621.5 cubic yards per day: Amount of Unit 2 sediment delivered to Ventura Harbor per day: “Delivered to Ventura at 113 lcy/hr. x 5.5 hrs./day on average = 621.5 cy/day)”
Four/eight hours: One way/roundtrip for dump scow from Ventura Harbor to Malibu: “Transit time = 4 hours one way ‐> 40 miles / 10 mph. Return time = 4 hours one way ‐ > 40 miles / 10 mph”
12 hours day: Time to load and transport one dump scow: “1,500 CY split Hull Dump Scow @ 1 trip every other day = 6 hr. loading day 1 + 6 hrs. Loading day 2 + 8 hr. traveling = 20 hrs. of work time in a 2 day timeframe. Results in 10
hr./day. Allow 12 hrs./day effective for lost time, unloading, maneuver, etc…
218 scow trips: Estimated number of barge trips from Ventura to south of the Malibu pier: “For indicated volume of 278,000 cy divided by 1,243 cy/trip = 218 scows.”
$34 per loose cubic yard: Cost to transport one cubic yard of sediment from Ventura to Malibu on a dump scow: “Ventura Harbor barged to/from Malibu nearshore = Approximately $34 per loose cubic yard.”
$42, 262: Cost for one barge trip: $34 lcy x 1243 lcy.
$9,213,116: Total cost for 218 dump scow trips at $42,262 each.
WHY NOT A SLURRY PIPELINE?
2.2 to 5 miles: Distance from Rindge Dam to the dump site east of the Malibu Pier. The 2.2 miles is overland. The 5 miles is down Malibu Canyon and east along the beach.
4+ miles down Malibu Canyon. 2.3 miles overland in a straight line
UNIT 3 SEDIMENT - THE BOTTOM LAYER
2029 - 2034: Years that Unit 3 silts and clays will be trucked to Calabasas Landfill: “The fourth through seventh years of construction include the removal of the Unit 3 silts and clays with delivery to the Calabasas Landfill.
???: Estimated quantity of Unit 3 silts and clays.
???: Cost to load, remove and transport that sediment to ???
10,000 cubic yards: Sediment which will remain behind Rindge Dam. “impounded sediment is estimated to remain in the impounded sediment area after construction around the pre-dam bedrock outcrops and boulders exposed by mining to the former (pre-dam) creek bed elevation. This material is expected to be naturally flushed to downstream reaches and the ocean with much greater volumes of sediment generated from the watershed during early postconstruction storm runoff events.”
EIGHT YEARS AFTER: THE AFTERMATH FROM 2035 ON
2035: A year of project clean up. The final year will complete site clean-up, the revegetation of creek slopes exposed during the mining, and removal of one ramp and partial removal of the remaining ramp to limit future access to the site to monitoring and adaptive management activities. The TSP [tentatively selected plan] includes removal of the Rindge Dam spillway.”
2035 - 2040: Post-project monitoring by Army Corps of Engineers. “USACE would be involved in monitoring and adaptive management activities for revegetated areas principally in the former impoundment area, access ramps, and upstream barrier sites for approximately 5 years following completion of construction.”
4.5 miles: Distance of Tapia Water Reclamation Facility from Malibu Lagoon. “The TWRF [Tapia Water Reclamation Facility] is located adjacent to Malibu Creek approximately 4.5 mi upstream from Malibu Lagoon. The facility is jointly owned by the Las Virgenes Municipal Water District and Triunfo Sanitation District. This facility treats municipal wastewater primarily from the cities and unincorporated areas of the upper watershed. The combined service area is approximately 100,000 ac with 90,000 residents in the Santa Monica Mountains.
16 Million Gallons Per Day: Peak operating capacity of Tapia Wastewater Treatment Facility. “Tapia has a processing capacity of 16 MGD (about 25 cfs), but currently operates at approximately 9 MGS (about 14 cfs). The facility is currently exploring ways to increase recycling and to reduce reclaimed water discharge into the watershed.”