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Pacific Southwest, Region 9: Superfund

Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations

San Gabriel Valley (area 1) El Monte, South El Monte, Whittier Narrows

Superfund Site

Record of Decision

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Date Title / pdf File
11/01/99 Whittier Narrows Operable Unit, Interim Record of Decision Amendment, Tables

Table 1: Summary of Chemicals of Concern and Exposure Point Concentrations in Groundwater

Groundwater Area
Chemical of Concern
Frequency of Detection
Minimum Concentration
(ppb)
Maximum Concentration
(ppb)
Exposure Point Concentration
(ppb)
Statistical Measure
Shallow Zone - MostChloroform
3/10
ND
0.35
0.35
Max
Contaminated1,1-DCE
9/10
ND
1.0
0.68
95% UCL
1,2-DCA
2/10
ND
0.3
0.26
95% UCL
1,4-Dioxane
2/2
1.0
6.5
6.5
Max
PCE
10/10
38.5
245
149
95% UCL
TCE
10/10
2.5
6.5
5.73
95% UCL
Shallow Zone1,1-DCE
8/22
ND
0.4
0.40
Max
PCE
22/22
3.0
51
23.4
95% UCL
TCE
20/22
ND
4
2.45
95% UCL
Intermediate ZoneChloroform
12/39
ND
2.0
0.59
95% UCL
1,1-DCE
26/39
ND
0.9
0.60
95% UCL
1,2-DCA
3/39
ND
0.2
0.20
Max
PCE
39/39
0.3
170
41.4
95% UCL
TCE
37/39
ND
17
5.70
95% UCL
Notes:
ND = non-detect
ppb = parts per billion or ug/L (micrograms per liter)
95% UCL = 95 percent upper confidence limit on the arithmetic mean groundwater concentration
Max = Maximum concentration detected in a specific groundwater area. Used as a default in place of the 95% UCL.

Table 2: Criteria Used to Evaluate Potential Groundwater Risks
Chemical of Concern
MCL
Risk-Based PRG = 1x10-6
Risk-Based Concentration = 1x10-5
Risk-Based Concentration = 1x10-4
Noncancer PRG HQ=1
EPA Region IX Tap Water PRG [1x10-6 or HQ=1]
Chloroform
100
0.165
1.65
16.5
60.8
0.165
1,1-DCE
6
0.0456
0.456
4.56
54.8
0.0456
1,2-DCA
0.5
0.123
1.23
12.3
17.4
0.123
1,4-Dioxane
3*
6.11
61.1
611
NA
6.11
PCE
5
1.08
10.8
108
254
1.08
TCE
5
1.64
16.4
164
36.5
1.64
Notes:
*California action level
All concentrations are in part per billion (ppb) or ug/L.
MCL = maximum contaminant level.
PRG = preliminary remediation goal.
NA = not available


Table 3: Exceedances of MCLs, Carcinogenic PRGs, and Risk-Based Concentrations
Groundwater Area
Concen-
tration Exceeds MCL
Concentration Exceeds 1x10-6
Concentration Exceeds 1x10-5
Concentration Exceeds 1x10-4
Combined Risk - All COCs
Shallow Zone - Most
PCE
Chloroform = 2.1 x 10-6
1,1-DCE = 1.5 x 10-5
PCE = 1.4 x 10-4
1.6 x 10-4
Contaminated
TCE
1,2-DCA = 2.1 x 10-6
1,4-Dioxane = 1.1 x 10-6
TCE = 3.5 x 10-6
Shallow Zone
PCE
1,1-DCE = 8.8 x 10-6
PCE = 2.2 x 10-5
3.2 x 10-5
TCE = 1.5 x 10-6
Intermediate Zone
PCE
Chloroform = 3.6 x 10-6
1,1-DCE = 1.3 x 10-5
6.0 x 10-5
TCE
1,2-DCA = 1.6 x 10-6
PCE = 3.8 x 10-5
TCE = 3.5 x 10-6

T Table 4: Special Status Species that Occur or Could Occur at
Whittier Narrows Flood Control Basin (USACE, 1998)
Species
Status
    Invertebrates
    Greenest Tiger Beetle (Cicindela tranquebarica viridissima)
Category 1
    Fish
    Arroyo Chub (Gila orcutti)
    Santa Ana Speckled Dace (Rhynichthys osculus)
    Santa Ana Sucker (Catostomus santaanae)

Sensitive
Sensitive
Sensitive
    Amphibians

    Red-legged frog (Rana aurora draytoni)
    Southwestern Arroyo Toad (Bufo microscaphus californicus)
    Western Spadefoot Toad (Scphiopus hammondii)

Category 1
Endangered
Category 1

    Reptiles
    Southwestern pond turtle (Clemmys marmorata pallida)
    San Diego horned lizard (Phrynosma coronatum blainvillei)
    Coastal western whiptail (Cnemidorphorus tigris multiscutatus)
    San Bernardino ringneck snake (Diadophis punctatus modestus)
    Two-striped garter snake (Thamnophis hammondii)
    Coastal rosy boa (Lichanura trivirgata rosafusca)
    Coast patch-nosed snake (Salvadora hexalepis)

Category 1
Sensitive
Sensitive
Sensitive
Sensitive
Sensitive
Sensitive
    Birds
    Least Bell=s vireo (Vireo bellii pusillus)
    Peregrine falcon (Falco peregrinus)
    California horned lark (Eromophila alpestris actia)
    California gnatcatcher (Polioptila californica)
    San Diego cactus wren (Campylorhynchus bruneicappilus couesi)
    Tricolored blackbird (Agelaius tricolor)
    Southern California Rufous crowned sparrow (Aimophila ruficeps)
    White-faced ibis (Plegadis chihi)
    Southwestern willow flycatcher (Empidonax trailii extimus)
    Horned grebe (Podiceps auritus)
    Least bittern (Ixobrychus exilis)
    American bittern (Botaurus lentiginosus)
    Canvasback (Aythya valisineria)
    Cooper=s hawk (Accipiter cooperii)
    Red-shouldered hawk (Buteo lineatus)
    Sharp-shinned hawk (Accipter striatus)
    Northern harrier (Circus cyaneus)
    Ferruginous hawk (Buteo regalis)
    Osprey (Pandion haliaetus)
    Common barn owl (Tyto alba)
    Burrowing owl (Athene cunicularia)
    Bewick=s wren (Thryomanes bewickii)
    Yellow warbler (Dendrocia petechia)
    Yellow-breasted chat (Icteria virens)

Endangered
Endangered
Sensitive
Threatened
Sensitive
Sensitive
Sensitive
Sensitive
Endangered
Audubon blue list
Audubon blue list
Audubon blue list
Audubon blue list
CDFG Sensitive
Audubon blue list
Audubon blue list
Audubon blue list
Sensitive
CDFG Sensitive
Audubon blue list
CDFG Species of Special Concern
Audubon blue list
CDFG Species of Special Concern
CDFG Species of Special Concern
    Mammals
    San Diego black-tailed jackrabbit (Lepus californicus bennettii)
    California leaf-nosed bat (Macrotis californicus)
    Greater western mastiff bat (Eumops perotis californicus)
    Spotted bat (Euderma maculatum)
    Los Angeles little pocket mouse (Perognathus longimembris brevinasus)
    San Diego desert woodrat (Neotoma lepida intermedia)
    Northwestern San Diego pocket mouse(Perognathus[Chaetodipus]fallax fallax)
    Southern grasshopper mouse (Onychomys torridus ramona)
Sensitive
Sensitive
Sensitive
Sensitive
Sensitive
Sensitive
Sensitive
Sensitive
    1 Status
    Endangered: Listed as a federally endangered species
    Threatened: Listed as a federally threatened species
    Category one: Taxa for which FWS has sufficient biological information to list as endangered or threatened.
    Sensitive: Taxa for which existing information indicated that listing may be warranted, but for which substantial biological information to support a proposed rule is lacking
    Audubon blue list: The Audubon Society’s watch list of species considered to be declining or threatened. (Tate 1986)
    CDFG Endangered: Listed as endangered by the State of California
    CDFG Sensitive: Listed as sensitive by the State of California
    CDFG Species of Special concern: Taxa with populations declining seriously or otherwise highly vulnerable to human developments.
Table 5: Chemical-Specific ARARs for Chemicals of Concern
Compound
ARAR ug/l
Source
1,1-Dichloroethane
5
California MCL
1,1-Dichloroethene
6
California MCL
1,1,1-Trichloroethane
200
Federal MCL
1,2-Dichloroethane
0.5
California MCL
Chloroform1
100
Federal MCL
cis-1,2-Dichloroethene
6
California MCL
1,4-Dioxane
3
California action level
Ethylbenzene
700
Federal MCL
Styrene
100
Federal MCL
Tetrachloroethene
5
Federal MCL
Trichloroethene
5
Federal MCL
Toluene
150
California MCL
Xylenes, total
1,750
California MCL

Table 6—Option A: Detailed Cost Esimates for the Selected Remedy
Table 6--Option A (North of Whittier Narrows Dam)
Detailed Costs Estimates for the Selected Remedy
Whittier Narrows Operable Unit - Interim ROD
Component
Quantity
Unit
Unit Cost
Cost1
Capital Costs (Including Engineering, Administration, and Contingencies)
Capital Costs
Extraction Wells
    Shallow Wells (approx. 100 ft. deep)
3
ea.
$113,000
$ 339,000
    Intermediate Wells (approx. 350 ft deep)
3
ea.
$263,000
$ 789,000
Treatment Facility (Air Stripper w/LGAC Polishing)
    Treatment Plant (Capacity - 9,000 gpm)
1
ea.
$5,737,500
$ 5,737,500
    Building Pad for Treatment Facility
1
ea.
$148,000
$ 148,000
Pipelines





    16-inch Pipelines from Wells
1,900
lf.
$112
$ 213,000
    18-inch Pipelines from Wells
1,200
lf.
$129
$ 155,300
    24-inch Pipelines from Wells
500
lf.
$173
$ 86,300
    27-inch Pipelines from Wells
1,550
lf.
$223
$ 345,400
    27-inch Pipelines to Purveyors
5,400
lf.
$208
$ 1,124,600
    27-inch Pipeline Across San Gabriel River
1,000
lf.
$395
$ 395,300
    Pressure Reducing Valve
1
ea.
$17,000
$ 17,000
Pumps


    Shallow Extraction Well Pumps- 800 gpm
3
ea.
$14,375
$ 43,100
    Intermediate Extraction Well Pumps- 2,200 gpm
3
ea.
$40,250
$ 120,800
    Dishcharge Pump to Purveyors- 4,500 gpm
3
ea.
$41,675
$ 125,000
    Chlorination Unit
1
ea.
$40,400
$ 40,400
Monitoring Program
    First Year Water Level Monitoring
1
ls
$13,000
$ 13,000
    Piezometers (1 shallow and 1 deep)
1
ls
$46,000
$ 46,000
Total Capital Costs
$ 9,739,000
Re-Capitalization (Incl. Engineering, Administration and Contingencies)
Present Worth Costs
Extraction Wells- $34,000/well every 10 years
6
ea.
$34,000/10yrs
$ 101,000
Treatment Facility- $741,000 every 15 Years
1
ea.
$741,000/15 yrs
$ 365,000
Conveyance System Pumps- $231,000 every 15 years
1
ls
$263,000/15 yrs
$ 127,000
Monitoring Program- $6,000 every 10 years
1
ls
$6,000/10 yrs
$ 6,000
Total NPV of Re-Capitalization Costs
$ 599,000
Annual Operation and Maintenance Costs
(Long-Term Average Extraction Rate of 7,500 gpm Assumed)
Unit
Costs
Annual
Costs
Present
Worth Costs
Treatment Facility- incl. power, carbon, labor, and maint.
1
#####
$343,000
$ 5,271,900
Pipeline Maintenance
1
$9,000
$9,000
$ 138,300
Extraction Well Pumps (avg. unit costs)
6
#####
$136,000
$ 2,090,300
Treatment Plant Discharge Pumps/Maint./Chlorine
1
#####
$362,000
$ 5,563,900
Recovered O&M Costs from Purveyors ($40/af)
12,098
$40
($484,000)
$ (7,439,100)
Monitoring Program
1
#####
$166,000
$ 2,551,400

Subtotal Annual O&M Costs
######
Contingency O&M Costs (15%)
$80,000
Total Annual O&M Costs
######
Total Discounted O&M Costs1
$ 9,408,000
Total Capital Costs
$ 9,739,000
Total Present Worth Costs
########
Notes
(1) Based on 30-year project and 5% discount rate.
ls. = lump sum, lf.= linear foot, ea. = each
Capital cost estimates are not discounted because the construction work will be performed in the early stages of the project. O&M costs are reported as present worth estimates given a 5% discount rate for a 30 year duration. Cost estimates are based on extraction rates and influent quality estimates that may be refined during remedial design. Cost estimates are estimated to be within a +30% -50% accuracy range.

Table 6—Option B: Detailed Cost Esimates for the Selected Remedy
Table 6--Option B (South of Whittier Narrows Dam)
Detailed Costs Estimates for the Selected Remedy
Whittier Narrows Operable Unit - Interim ROD
Component
Quantity
Unit
Unit Cost
Cost1
Capital Costs (Including Engineering, Administration, and Contingencies)
Capital Costs
Extraction Wells
    Shallow Wells (approx. 100 ft. deep)
3
ea.
$94,000
$ 282,000
    Intermediate Wells (approx. 350 ft deep)
3
ea.
$249,000
$ 747,000
Treatment Facility (Air Stripper w/LGAC Polishing)
    Treatment Plant (Capacity - 9,000 gpm)
1
ea.
$3,339,000
$ 3,339,000
Pipelines


    18-inch Pipelines from Wells
2,150
lf.
$123
$ 263,400
    24-inch Pipelines from Wells
500
lf.
$173
$ 86,500
    27-inch Pipelines from Wells
100
lf.
$194
$ 19,400
    30-inch Pipeline to Rio Hondo
5,260
lf.
$259
$ 1,362,300
Pumps

    Shallow Extraction Well Pumps- 800 gpm
3
ea.
$14,375
$ 43,100
    Intermediate Extraction Well Pumps- 2,200 gpm
3
ea.
$40,250
$ 120,800
    Dishcharge Pump to Purveyors- 4,500 gpm
1
ea.
$24,438
$ 24,400
Monitoring Program
    Two Additional Multiple Port Wells
2
ea.
$148,000
$ 296,000
    First Year Water Level Monitoring
1
ls
$13,000
$ 13,000
    Piezometers (1 shallow and 1 deep)
1
ls
$46,000
$ 46,000
Total Capital Costs
$ 6,643,000
Re-Capitalization (Incl. Engineering, Administration and Contingencies)
Present Worth Costs
Extraction Wells- $34,000/well every 10 years
6
ea.
$34,000/10yrs
$ 101,000
Treatment Facility- $615,000 every 15 Years
1
ea.
$615,000/15 yrs
$ 296,000
Conveyance System Pumps- $151,000 every 15 years
1
ls
$151,000/15 yrs
$ 73,000
Monitoring Program- $6,000 every 10 years
1
ls
$6,000/10 yrs
$ 6,000
Total NPV of Re-Capitalization Costs
$ 476,000
Annual Operation and Maintenance Costs
(Long-Term Average Extraction Rate of 7,500 gpm Assumed)
Unit
Costs
Annual
Costs
Present
Worth Costs
Treatment Facility- incl. power, carbon, labor, and maint.
1
#####
$195,000
$ 2,997,200
Pipeline Maintenance
1
$7,000
$7,000
$ 107,600
Extraction Well Pumps (avg. unit costs)
6
#####
$128,000
$ 1,967,400
Treatment Plant Discharge Pumps/Maint.
1
#####
$32,000
$ 491,800
Monitoring Program
1
#####
$166,000
$ 2,551,400
Subtotal Annual O&M Costs
######
Contingency O&M Costs (15%)
$79,000
Total Annual O&M Costs
######
Total Discounted O&M Costs1
$ 9,331,000
Total Capital Costs
$ 6,643,000
Total Present Worth Costs
########
Notes
ls. = lump sum, lf.= linear foot, ea. = each
(1) Based on 30-year project and 5% discount rate.
Capital cost estimates are not discounted because the construction work will be performed in the early stages of the project. O&M costs are reported as present worth estimates given a 5% discount rate for a 30 year duration. Cost estimates are based on extraction rates and influent quality estimates that may be refined during remedial design. Cost estimates are estimated to be within a +30% -50% accuracy range.

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