Download presentation
Presentation is loading. Please wait.
Published byPierce Hopkins Modified over 8 years ago
1
The Orange County Water District Riverbed Filtration Pilot Project Jason Keller 1, Michael Milczarek 1, Greg Woodside 2, Adam Hutchinson 2, Adam MP Canfield 2, Robert Rice 1 1 GeoSystems Analysis, Inc 2 Orange County Water District
2
Orange County Water District Recharges groundwater basin using Santa Ana River (SAR) water and other sources of water Over 1,000 acres of surface spreading basins Average recharge of 230,000 acre-ft/yr SAR flow comprised of tertiary-treated effluent and stormwater SAR water quality: Total Suspended Solids (TSS) varies from 5 to 400 mg/l Total Organic Carbon (TOC) typically 5 to 10 mg/l Spreading basin performance declines in exponential fashion due to clogging Want to improve performance and recharge volumes
3
Riverbed Filtration System Pilot Project Objectives Evaluate riverbed filtration technology to treat SAR water Design pilot scale riverbed filtration system Want a shallow collection system to induce recharge Want low tech, low cost Construct pilot project in SAR off-river channel Evaluate potential long-term performance Monitor: –Clogging rates –Influence on groundwater system –Shallow water level response –Increased recharge rates with filtered water
4
Santa Ana River Channel Off-River Channel
5
Design for 10 cfs (4,500 gpm) Guided by two-dimensional model (HYDRUS-2D) –Variable depth and spacing of lateral drains –Foulant layer incorporated to evaluate formation of surface clogging Pipe flow capacities calculated using Manning’s equation Pilot System Design
6
Deeper lateral placement depth increases system capacity Lateral drain length needed are similar at 80 and 160 ft spacing Desaturation increases as lateral spacing decreases Model Results
8
6 inch diameter drains carry substantially less flow Reduced footprint with 80 ft spacing vs 160 ft spacing Gain in efficiency with depth reduced due to added cost for deeper excavation and installation Pilot system built using 8 inch diameter lateral drains at 80 ft spacing and 5 ft bgs Pilot System Design
12
Monitoring system to evaluate riverbed filtration system performance 13 Monitoring Wells and piezometers Temperature at 1, 6 and 10 ft bgs in selected wells Stream flow gaging →Flow in – Flow out = GW recharge and drain capture (transmission loss) Bi-weekly samples of raw source water and riverbed filtration system effluent collected and analyzed for water quality Percolation testing using raw water and riverbed filtration effluent to evaluate percolation decay Pilot Project Monitoring
13
Pilot Study Results
14
Water Quality Riverbed filtration significantly improved water quality Reduced TSS and turbidity by >99% and 96% Decreased TOC, TKN, iron, and manganese by 50% or greater Riverbed filtered water quality significantly better than other treatment technologies evaluated –Cloth filter, flocculation-sedimentation, dissolved air flotation, ballasted sedimentation
15
Percolation Decay Percolation rates 50% of initial percolation within: Raw water ~ 7 hours Riverbed filtered water ~ 58 hours Air entrapment during early period of riverbed filtration column.
16
Inlet Surface Flow and Pumping Rates
17
Phreatic Surface Depth
18
West East
19
South North
20
Pumping and Phreatic Surface Summary Under no-pumping conditions, unsaturated zone exists East side of drain system less productive than west side Water from west supplying east laterals Strong hydraulic gradient to north Phreatic surface depths deeper after pumping than prior to pumping Pumping capacity responsive to surface water flows Maximum Pumping Capacity Test Period 1 (w/out L-berms) = 1,350 gpm Test Period 2 (w/ L-berms) = 2,000 gpm 30% - 40% of target collection rate (4,500 gpm)
21
Transmission Loss and Groundwater Recharge
22
Conclusions Riverbed filtration significantly improves water quality and percolation performance System performance dependent on surface water flow rates and depth Maximum pumping capacity of: –1,350 to 2,000 gpm –30% - 40% of target collection rate Lower than expected groundwater elevations Strong south-to-north gradient reduced system efficiency Drainfield east of the collection vault was less productive than west of the collection vault Drain system induces infiltration during pumping and most of water collected from induced infiltration
23
Future Studies Surface clogging may have contributed to a reduction in induced recharge Longer term study required to evaluate surface clogging influences Treatment options Effective surface water and groundwater depths System optimization System expansion planned What can you say to others that may want to try this? What did we learn?
24
THANK YOU!
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.