Technical Memorandum

Golder Associates Inc.

18300 NE Union Hill Road, Suite 200 Redmond, Washington 98052 Telephone: (425) 883 0777 Fax: (425) 882 5498

TECHNICAL MEMORANDUM

TO: Joe Simmler and Larry Grimm., OTAK, Inc. DATE: December 5, 2008 FR: Michael Klisch, L.Hg. and Carl Einberger, L.Hg. OUR REF: 083-93430.001 HYDROGEOLOGIC CONDITIONS, GREATER HALL LAKE, HALL CREEK, RE: CHASE LAKE, ECHO LAKE, LAKE BALLINGER AND MCALEER CREEK WATERSHED

This technical memorandum (TM) has been prepared by Golder Associates Inc. (Golder) to present an overview and interpretation of the geology and hydrogeology in the vicinity of Lake Ballinger, including Hall Lake, Hall Creek, Chase Lake, Echo Lake, and the McAleer Creek areas (‘the watershed’). Groundwater interaction with surface water and the potential for stormwater infiltration into local hydrogeologic units are also discussed. This information was summarized from existing information, including:

• Booth, D.B., B.F. Cox, K.G. Troost, and S.A. Shimel, 2004, Draft Composite Geologic Map of the Sno-King Area, 1:24,000, http://geomapnw.ess.washington.edu/index.php?toc=maintoc&body=services/publications/m ap/SnoKingDisc.htm. • King County, 2003, Final Environmental Impact Statement, Brightwater Regional Wastewater Treatment System, Appendix 6-B, Geology and Groundwater. • Smith, M., 1975, Preliminary Surficial Geologic Map of the Edmonds East and Edmonds West Quadrangles, Snohomish and King Counties, Washington, Washington Department of Natural Resources, Division of Geology and Earth Resources Geologic Map GM-14. • Thomas, B.E., J.M. Wilkinson, and S.S. Embry, 1997, The Ground-Water System and Ground-Water Quality in Western Snohomish County, Washington, U.S. Geological Survey Water-Resources Investigations Report 96-4312. • Washington State Department of Ecology, 1973, Lakes of Washington, Volume I, Water Supply Bulletin 14.

The existing information is supplemented by water surface elevations from Lake Ballinger collected by the City of Mountlake Terrace and geological and groundwater level data collected by the Olympic View Water District from a well on SW 228th Street, in the upland west of Lake Ballinger. In addition, Golder recently installed and collected groundwater level data from a new monitoring well drilled on the east side of Lake Ballinger.

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1.0 GEOLOGIC UNITS

The geologic units in the Lake Ballinger area consist of unconsolidated glacial and alluvial deposits. A geologic map of the Lake Ballinger area based on the Sno-King geologic map is shown on Figure 1, and geologic cross sections are shown on Figures 2 through 4. The following geologic units are present in the area:

Vashon Recessional Outwash and Alluvial deposits (Qyal, Qoal, Qf, Qvr) – deposits formed by retreating ice sheet and streams, includes both coarse-grained fluvial and fine-grained lacustrine deposits. Generally less than 40 feet thick. Occurs as isolated deposits in upland areas and along walls and bottoms of drainages. Exposed northwest and east of Lake Ballinger, near Echo Lake, and southeast of Lake Ballinger near McAleer Creek. Generally less than 40 feet thick. Alluvial materials are present around Lake Ballinger and in the channels of McAleer and Lyon Creeks.

Vashon Till (Qvt) - deposits of variable grain size, from clay to boulders, poorly sorted to unsorted. Mostly consolidated lodgment till. Exposed in upland areas surrounding Lake Ballinger, including around Hall Lake, Echo Lake, and Chase Lake. The till is generally 30 to 40 feet thick.

Vashon Advance Outwash (Qva) – glaciofluvial materials deposited by advancing glaciers, generally fine to medium sand with some gravel. The advance outwash is about 50 feet thick near Lake Ballinger, where till is absent and the outwash is exposed, but may be up to 200 feet thick in the upland areas west and northeast of Lake Ballinger.

Lawton Clay (Qvlc) – fine-grained glaciolacustrine deposits with dropstones, 20 to over 100 feet thick (not exposed in the surface in this area).

Pre-Vashon Units (Qpf, Qpff) – older glacial and non-glacial deposits underlying Vashon sequence. Not exposed at ground surface except in valleys and in cliffs along Puget Sound. Some fine-grained pre-Vashon materials are exposed in the McAleer Creek valley.

2.0 HYDROGEOLOGY

2.1 Hydrogeologic Units

The hydrogeologic units in the area are consistent with the geologic units discussed above, and are summarized as follows:

Recessional Outwash/Alluvial Aquifer – The recessional outwash and alluvial materials form an unconfined aquifer where they are saturated. The recessional outwash and alluvium are saturated in the low-lying area around Lake Ballinger, between Lake Ballinger and Hall Creek, and along McAleer Creek. The recessional outwash and alluvium form an unconfined aquifer that is in continuity with surface water.

Till – The till forms an aquitard because of the low permeability associated with silt and clay-rich materials. The till caps much of the upland area around Lake Ballinger, and limits recharge to deeper aquifers in these areas.

Advance Outwash – The advance outwash forms an extensive, typically unconfined aquifer at elevations above about 100 to 200 feet. In most of the area, advance outwash is generally overlain by the till, with the exception of low-lying areas such as the between Lake Ballinger and Hall Lake, and

120508_Hydrogeologic Conditions Technical Memo.docx Golder Associates December 5, 2008 -3- 083-93430.001 in stream valleys. As shown on the geologic cross sections (Figures 2 through 4, respectively), the advance outwash is partially saturated in the areas west and northeast of Lake Ballinger.

Lawton Clay – The Lawton Clay forms an aquitard, separating the advance outwash from the older, pre-Vashon aquifers and aquitards.

Pre-Vashon Deposits – The pre-Vashon deposits form a series of productive confined aquifers and aquitards below the Advance Outwash.

2.1.1 New Monitoring Well

Golder supervised the drilling and construction of one monitoring well (LB MW-1) drilled in Ballinger Park on the east side of Lake Ballinger (Figure 1). This well was installed to evaluate the hydrostratigraphy and provide a location to monitor groundwater level response to precipitation and changes in lake level.

The well was drilled on November 7, 2008 by Cascade Drilling Inc. using hollow-stem auger methods. The borehole was advanced to a depth of 80 feet below ground surface. The geologic units encountered in the borehole are:

• 0 to 2 feet: Grey sand (Fill) • 2 to 5 feet: Brown peat • 5 to 20 feet: Grey saturated sand with trace silt (Outwash or Alluvium) • 20 to 80 feet: Greenish gray silty clay (Glaciolacustrine deposits – Lawton Clay)

No significant higher permeability materials were identified below 20 feet of depth. Based on this information, the monitoring well was installed at the base of the shallow sand deposits. The well screen extended from 15 to 25 feet below ground, and the borehole was backfilled with bentonite chips from 25 to 80 feet below ground. A dedicated pressure transducer and datalogger were installed following well completion to monitor groundwater levels. The well is housed in a flush vault monument. The City of Mountlake Terrace surveyed the top of casing elevation at 289.91 feet msl. The well log is included in Attachment A.

The new well indicated the thickness of the glacial outwash sediments on the east side of the lake at this location are thinner than expected based on well information from the Nile Temple County Club about 1,500 feet south of the new well, where about 30 feet of sand was present.

A groundwater elevation hydrograph is shown on Figure 5. The depth to water following well completion was about 4.5 feet below ground. About 10 days later, the water level had risen to about 3.8 feet below ground (Figure 5) in response to precipitation recharge. The groundwater elevation at LB MW-1 is about 7 to 9 feet higher than the elevation of Lake Ballinger (Figure 5), indicating that at the time of measurement, groundwater was discharging to the lake in this area.

2.2 Aquifer Hydraulic Properties

The USGS compiled information on the hydraulic conductivity of the principal aquifers in Snohomish County based on well test information presented on well logs. Hydraulic conductivity data are summarized in Table 1.

120508_Hydrogeologic Conditions Technical Memo.docx Golder Associates December 5, 2008 -4- 083-93430.001

The alluvium and recessional outwash aquifers have the highest hydraulic conductivity, while the hydraulic conductivity of the advance outwash is lower, as expected, because it has been overridden and compacted by glacial ice following deposition.

2.3 Groundwater Recharge and Discharge

Groundwater is recharged by infiltration of precipitation. Recharge to the advance outwash aquifer is limited because it is capped by low-permeability till in many parts of the watershed. The USGS estimated groundwater recharge in the Lake Ballinger area using a regression equation for infiltration to till and outwash soils, and the distribution of precipitation. The regression equations were modified for urbanized areas to account for the increase in impervious surfaces. Based on this analysis, the USGS estimated groundwater recharge to range from about 20 to 24 inches in the areas were outwash or alluvium are exposed at the ground surface with little urban development, to less than 10 inches in the till-capped areas that are heavily urbanized.

The Olympic View Water District has been monitoring the groundwater elevation in a well completed in the advance outwash aquifer since 2004. This well is shown on the geologic cross-section on Figure 4, which illustrates that the advance outwash is capped by about 40 feet of till at the well location. Groundwater elevation hydrographs for water years 2004 through 2008, inclusive are included in Attachment B. The groundwater elevation in the well shows short-term (on the order of one to several days) fluctuations of up to about one foot. These fluctuations are likely barometric pressure fluctuations caused by the cap of low-permeability till over the advance outwash. There are also longer-term (on the order of months), relatively low magnitude fluctuations of about one foot. Groundwater elevations are at the lowest point in the winter, and highest in summer. The long-term groundwater elevation fluctuations represent seasonal groundwater recharge and discharge, and illustrate a lag in recharge to the aquifer system, given that highest groundwater elevations are associated with the drier portion the year.

Groundwater divides in the watershed are not well defined because of the limited groundwater elevation data available for accurate delineation. Based on available data, it appears that the groundwater divides are similar to the surface water divides. There may, however, be some areas where the divides do not coincide because of local hydrogeologic conditions.

Groundwater flow in the recessional outwash and alluvial materials (where present) is towards Lake Ballinger, Hall Lake, and the streams in the area. Groundwater flow in the advance outwash aquifer is shown on Figure 6. Groundwater flow in the advance outwash north and west of Lake Ballinger is towards Puget Sound, where it discharges to springs and seeps along bluffs where the advance outwash is exposed. East of Lake Ballinger, the advance outwash discharges to streams such as McAleer Creek and Lyon Creek. Groundwater in the advance outwash is also expected to discharge to Lake Ballinger where the advance outwash is in continuity with the recessional outwash and alluvial deposits around the lake. There is also a downward component of hydraulic gradient between the advance outwash and the underlying pre-Vashon aquitards and aquifer, as illustrated by water levels in wells depicted on the geologic cross sections (Figures 2 through 4, inclusive). The pre- Vashon aquifers discharge to Puget Sound.

2.4 Groundwater -Surface Water Interaction

2.4.1 Lake Ballinger

Lake Ballinger has a mean depth of about 15 feet and a maximum depth of about 35 feet, with a lake level elevation of about 278 feet msl. The lake level varies with precipitation, with significant

120508_Hydrogeologic Conditions Technical Memo.docx Golder Associates December 5, 2008 -5- 083-93430.001 changes possible during storm events. Figure 7 shows the relationship of lake level and precipitation in October and November 2008, and illustrates that the lake responds rapidly to precipitation. Between October 31 and November 9, 2008, about 3.9 inches of rain fell at the Brugger’s Bog rain gage located about 1.4 miles southeast of Lake Ballinger. The lake level increased from an elevation of 276.7 feet on October 31 to 278.25 feet on November 8, an increase of 1.55 feet.

Groundwater elevations in the 228th Street well and LB MW-1 and the lake elevation are shown on Figure 8. The groundwater elevation at LB MW-1 is about 7 to 9 feet higher than the lake elevation, indicating that groundwater discharge is occurring from the outwash sediments on the east side of the lake to Lake Ballinger. Similarly, the groundwater elevation in the 228th Street well completed in advance outwash is about 280 to 282 feet msl, or about 2 to 4 feet higher than the lake elevation. This suggests that groundwater in the advance outwash is discharging to Lake Ballinger in this area from the advance outwash through the alluvium and recessional outwash sediments near the lake.

2.4.2 Hall Creek

Hall Creek flows north to south, connecting Hall Lake to Lake Ballinger. As shown on the geologic map (Figure 1) and geologic cross-section (Figure 2), Hall Creek flows on recessional outwash and alluvial deposits, and is underlain by advance outwash. The till is absent in the area of the Hall Creek channel and the recessional outwash and alluvium are in continuity with the advance outwash. It is likely that Hall Creek is in continuity with the recessional outwash and alluvial aquifer as well as the underlying advance outwash aquifer, and is a gaining stream along its reach. This is supported by the water level map (Figure 6) and cross section A-A’ (Figure 2 from the Brightwater EIS, which suggest that Hall Creek is an expression of the water table.

2.4.3 McAleer Creek

McAleer Creek flows southwest from Lake Ballinger to Lake Washington. Below the I-5 crossing, the creek is incised into the advance outwash and older, pre-Vashon sediments. Generalized groundwater flow directions (Figure 6) and information presented in the Brightwater EIS indicates that the lower reaches of McAleer Creek are local groundwater discharge areas, with flowing artesian wells present in the stream valleys of McAleer and Lyon Creeks. McAleer Creek is sustained by baseflow (groundwater discharge) of 3 to 10 cfs in the summer months (Figure 9). Groundwater discharge to McAleer Creek is from the advance outwash and pre-Vashon aquifers.

2.5 Groundwater Use

There are several water supply or irrigation wells near Lake Ballinger are completed in the pre- Vashon materials. Holyrood Cemetery operates two irrigation wells that were drilled in 1950’s. The wells are located about 2,000 to 3,000 feet south of Lake Ballinger, and are completed between 370 and 560 feet deep, with depths to water of about 165 to 175 feet below ground (Figure 3). The Nile Temple Country Club drilled an irrigation well to a depth of 150 feet in 1930. The well appears to be completed in pre-Vashon deposits, and the present status of this well is unknown.

The Olympic View Water and Sewer District has two water supply wells located about 2,000 feet west of Lake Ballinger on SW 228th Street (Figure 4). One of the wells was originally completed in the pre-Vashon materials but was reconstructed in 2003. The lower part of the well in the pre-Vashon deposits was backfilled and the well was perforated in the Advance Outwash. The second well is completed in the pre-Vashon materials.

120508_Hydrogeologic Conditions Technical Memo.docx Golder Associates December 5, 2008 -6- 083-93430.001

Well logs for these wells are included in Attachment C. There are no other known water supply wells near the lake.

3.0 SUMMARY OF CONCEPTUAL HYDROGEOLOGIC MODEL

The conceptual hydrogeologic model for the Lake Ballinger area is summarized on Table 2.

Lake Ballinger is a relatively shallow lake. The lake appears to be underlain by low-permeability Lawton Clay and/or pre-Vashon deposits. The upland areas around the lake are either capped with till or have advance outwash exposed at the ground surface. Alluvial materials and recessional outwash are exposed along the shores of Lake Ballinger and in stream channels. Groundwater discharge to the lake is from alluvial and outwash deposits surrounding the lake. In addition, the lake receives water from Hall Creek, local stormwater discharge, and direct precipitation. Discharge from the lake is to McAleer Creek and by evapotranspiration.

The principal aquifers are the unconfined alluvial and recessional outwash and advance outwash aquifers, and the confined pre-Vashon aquifer system. Groundwater recharge ranges from 20 to 24 inches a year where permeable alluvial or outwash materials are exposed at the ground surface to less than 10 inches a year where low-permeability till is at the ground surface or the area is heavily urbanized. The alluvial deposits and recessional outwash have a high degree of continuity with surface water. Groundwater discharge in the alluvial and recessional outwash materials is to streams and Lake Ballinger. In the advance outwash, there is less continuity with surface water except in areas where recessional outwash or alluvial materials are in direct contact with the advance outwash. Groundwater in the advance outwash discharges to surface water via hydraulic connection with recession outwash or alluvial materials, and also recharges the underlying pre-Vashon aquifers. The groundwater divides are likely consistent with surface water divides, with possibly some localized differences because of hydrogeologic conditions.

4.0 POTENTIAL INFILTRATION SITES

Infiltration sites for local stormwater could potentially be developed in several areas within the watershed in advance outwash. The potential locations should:

• Have a thick unsaturated section of advance outwash to allow storage of relatively large volumes of water; • Ideally be located in an area where the till is thin enough to be removed or is absent to allow surface or near surface infiltration to the advance outwash; • Target areas where the groundwater retention time is significant enough to provided an appropriate lag time to mitigate flooding from storm events; • Target areas where the travel time is sufficient to mitigate any potential water quality problems before discharge to springs, surface water, or wells occurs.

The area west of Highway 99 is one location where there is potential for stormwater to be infiltrated to the advance outwash aquifer. As shown on Figures 2 through 4, inclusive, the advance outwash is about 120 to over 200 feet thick in this area. The advance outwash is unconfined, with a saturated thickness of about 100 feet, and there is about 20 to over 100 feet of unsaturated advance outwash in this area. The advance outwash is overlain by about 10 to 40 feet of till. Groundwater in the advance outwash in this area likely discharges to Hall Creek and Lake Ballinger. Infiltration in this area could

120508_Hydrogeologic Conditions Technical Memo.docx Golder Associates

TABLES

Golder Associates December 5, 2008 083-93430.001 TABLE 1

Summary of Hydraulic Conductivity Data for Glacial Sediments

Hydraulic Conductivity (ft/d) Aquifer Unit Minimum Median Maximum Alluvium 3.6 88 3,200 Recessional Outwash 0.08 180 1,800 Advance Outwash 0.18 40 2,800 Pre-Vashon Aquifers 0.22 31 1,800

Figures-Tables Golder Associates December 5, 2008 TABLE 2 083-93430.001

Conceptual Hydrogeologic Model

Median Saturated Hydraulic Thickness Groundwater Groundwater Conductivity Geologic Unit Hydrostratigraphic Unit (feet) Recharge (in/yr) Discharge (ft/d) Potential for Infiltration Alluvium Alluvia and Recessional To Streams and Lake Low - Limited unsaturated thickness and 0-40(?) 20-24 180 Recessional Outwash Outwash Aquifer Ballinger good connection to surface water <10 where exposed on Vashon Till Aquitard na na 53 Low - Low Permeability surface

15-20 where exposed Good where exposed at ground surface and Advance Outwash Aquifer 10-100 40 at surface, <10 when To Streams and to sufficent unsaturated thickness exists. Low under till Pre-Vashon Aquifers where present under till unless till removed. Lawton Clay Aquitard na na na 7 Low - Low Permeability Pre-Vashon Aquifers and Aquitards Variable <10 Puget Sound 31 Low - deep, water supply aquifer

Note: Median hydraulic conductivity of Qvt biased because no wells are completed in low-permeability sections - only in sandy lenses of higher permeability

Figures-Tables Golder Associates December 5, 2008 TABLE 3 083-93430.001

Potential Monitoring Wells

Well Name Owner TRS Location Depth Purpose Completion Unit LB MW-1 City of Mountlake Terrace SE-NW Sec 32 T27N/R4E 25 Monitoring1 Alluvium and Recessional Outwash 228th Street Well Olympic View Water District NW-NE Sec 31 T27N/R4E 280 Monitoring2 Advance Outwash Nile Temple3 Nile Temple Country Club NW-SE Sec 32 T27N/R4E 150 Irrigation Pre-Vashon(?) Several wells, Ballinger Golf Course3 City of Mountlake Terrace SE-NW Sec 32 T27N/R4E 15 to 30 Monitoring Alluvium and Recessional Outwash Edmonds Community Several wells, Edmonds Community College NW-NW Sec 28 T27N/R4E Monitoring or test Advance Outwash and Pre-Vashon(?) College3 to 260

Notes: 1. Equipped with pressure transducer and datalogger 2. Conversion of water supply well. Equipped with pressure transducer and datalogger 3. Current Status Unknown

Figures-Tables Golder Associates

FIGURES

Golder Associates Legend Qyal - Younger Alluvium Qoal - Older Alluvium Qf - Fan Deposits Qw - Wetland Deposits Qvr - Recessional Outwash Qvt - Vashon Till Qva - Advance Outwash Qpf - pre-Fraser Deposits A Qpff - pre-Fraser Fine-Grained A' Deposits E' E LB MW-1 Location

B Cross Section Location B' Boundary of mapping sources for map compilation

Source: Booth, D.B., B.F. Cox, K.G. Troost, and S.A. Shimel, 2004, Draft Composite Geologic Map of the Sno-King Area, 1:24,000 (http://geomapnw.ess.washington.edu/index. php?toc=maintoc&body=services/publications /map/SnoKingDisc.htm).

Title Geologic Map Drawn JP Checked MPK Project No. Project Name Lake Ballinger Watershed 083-93430.001 Reviewed CE

Client Name Date FIGURE OTAK,Inc. December 5, 2008 1

V:\PROJECTS\_2008 PROJECTS\083-93430 Lake Balllinger Watershed Study\Report\Figures-Tables Legend Qyal - Younger Alluvium Qoal - Older Alluvium Qf - Fan Deposits Qw - Wetland Deposits Qvr - Recessional Outwash Qvt - Vashon Till Qva - Advance Outwash Pre-Fraser Deposits gf: glalciofluvial gt: glaial till gl: glaciolacustrine gm: galciomarine gd: glacial diamicton

Source: Figure 2-6a, King County, 2003, Final Environmental Impact Statement, Brightwater regional Wastewater Treatment System, Section located approximately along 228th Street SW Appendix 6-B, Geology and Groundwater.

Title Geologic Cross Section A-A' Drawn JP Checked MPK Project No. Project Name Lake Ballinger Watershed 083-93430.001 Reviewed CE

Client Name Date FIGURE OTAK,Inc. December 5, 2008 2

Source: Figure 2-7a, King County, 2003, Final Environmental Impact Statement, Brightwater regional Wastewater Treatment System, Appendix 6-B, Geology and Section located approximately along NW 205th Street Groundwater. Title Geologic Cross Section B-B' Drawn JP Checked MPK Project No. Project Name Lake Ballinger Watershed 083-93430.001 Reviewed CE

Client Name Date FIGURE OTAK,Inc. December 5, 2008 3

Source: Figure 3-3, King County, 2003, Final Environmental Impact Statement, Brightwater regional Wastewater Treatment System, Section located approximately along SE 228th Street Appendix 6-B, Geology and Groundwater.

Title Geologic Cross Section E-E' Drawn JP Checked MPK Project No. Project Name Lake Ballinger Watershed 083-93430.001 Reviewed CE

Client Name Date FIGURE OTAK,Inc. December 5, 2008 4

V:\PROJECTS\_2008 PROJECTS\083-93430 Lake Balllinger Watershed Study\Report\Figures-Tables 288 Precipitation from Bruggers Bog Rain Gage 1.2 (http://green.kingcounty.gov/WLR/Waterres/hydrology/DataDownload.aspx?G_ID=122)

286 1.0

284 Manual Readings 0.8 Transducer Measurements Lake Ballinger Elevation 282 Daily Precipiation 0.6

280 Precipitation (inches) Precipitation 0.4 278 Groundwater and Lake Elevation (feet msl)(feet Elevation Lake and Groundwater

0.2 276

274 0.0 11/1/08 11/6/08 11/11/08 11/16/08 11/21/08 11/26/08 12/1/08 12/6/08 Date

Title LB-MW-1 Hydrograph Drawn JP Checked MPK Project No. Project Name Lake Ballinger Watershed 083-93430.001 Reviewed CE

Client Name Date FIGURE OTAK,Inc. December 8, 2008 5

V:\PROJECTS\_2008 PROJECTS\083-93430 Lake Balllinger Watershed Study\Report\Figures-Tables Source: Figure 2-9, King County, 2003, Final Environmental Impact Statement, Brightwater regional Wastewater Treatment System, Appendix 6-B, Geology and Groundwater.

Title Groundwater Flow Map Drawn JP Checked MPK Project No. Project Name Lake Ballinger Watershed 083-93430.001 Reviewed CE

Client Name Date FIGURE OTAK,Inc. December 5, 2008 6

V:\PROJECTS\_2008 PROJECTS\083-93430 Lake Balllinger Watershed Study\Report\Figures-Tables 279.0 Precipitation from Bruggers Bog Rain Gage 1.2 (http://green.kingcounty.gov/WLR/Waterres/hydrology/DataDownload.aspx?G_ID=122)

Lake Ballinger Elevation 278.5 1.0 Daily Precipiation

278.0 0.8

277.5 0.6 Precipitation (inches) Precipitation

Lake Elevation (feet msl)(feet Elevation Lake 277.0 0.4

276.5 0.2

276.0 0.0 9/1/08 9/16/08 10/1/08 10/16/08 10/31/08 11/16/08 12/1/08 12/16/08 Date

Title Lake Levels and Precipitation Drawn JP Checked MPK Project No. Project Name Lake Ballinger Watershed 083-93430.001 Reviewed CE

Client Name Date FIGURE OTAK,Inc. December 5, 2008 7

V:\PROJECTS\_2008 PROJECTS\083-93430 Lake Balllinger Watershed Study\Report\Figures-Tables Groundwater level measurements provided by Olympic View Water District. 288 Precipitation from Bruggers Bog Rain Gage 3.0 (http://green.kingcounty.gov/WLR/Waterres/hydrology/DataDownload.aspx?G_ID=122)

286 2.5

284 2.0

282 1.5

280 1.0 bPrecipitationDaily (inches) Groundwater and LakeandGroundwater Elevation (feet msl)

278 0.5

276 0.0

Date 228th Street Well Title Groundwater and Lake Elevations Drawn JV Checked MPK LB MW-1 Project No. Project Name Lake Ballinger 083-93430.100 Reviewed CE Lake Ballinger Client Name Date FIGURE Precipitation Otak, Inc. December 8, 2008 8

V:\PROJECTS\_2008 PROJECTS\083-93430 Lake Balllinger Watershed Study\Report\Attachment B and Figure 8 Streamflow Measurements from McAleer Creek Gage at Mouth 100 (http://green.kingcounty.gov/WLR/Waterres/hydrology/DataDownload.aspx?G_ID=120)

10 Streamflow (cfs) Streamflow

1 10/1/97 10/1/98 10/1/99 9/30/00 10/1/01 10/1/02 10/1/03 9/30/04 10/1/05 10/1/06 10/1/07 9/30/08 Date

Title McAleer Creek at Mouth Discharge Drawn JV Checked MPK Project No. Project Name Lake Ballinger 083-93430.100 Reviewed CE

Client Name Date FIGURE Otak, Inc. December 5, 2008 9

V:\PROJECTS\_2008 PROJECTS\083-93430 Lake Balllinger Watershed Study\Report\Attachment B and Figure 8

ATTACHMENT A

LB MW-1 WELL LOG

Golder Associates FLUSH MONUMENT Ground Surface Grey SAND (fill) [0 ft to 2 ft] CONCRETE PLUG [0 ft to 2 feet] Brown PEAT BENTONITE CHIP SEAL [2 ft to 5 ft] (2 ft to 13 ft] Compact, medium to dark grey WELL CASING - BLANK PVC (N4) f-m SAND, trace SILT (2- inch DIAMETER) (OUTWASH or ALLUVIUM) SILICA SAND GRAVEL PACK (5 to 20 feet) [13 ft to 28.5 ft] WELL SCREEN - 0.020-inch SLOTTED PVC (2- inch DIAMETER) 25 ft [15 ft to 25 ft]

Dense, dark greenish gray (5GY 4/1) SILTY CLAY, trace gravel dropstones BENTONITE CHIP BACKFILL (GLACIOLACUSTRINE) [28.5 ft to 80 ft] [20 ft to 80 ft] 50 ft

BOREHOLE (10-inch DIAMETER) (0 ft to 80 ft]

75 ft

Note: TOC Elevation: 281.91 feet msl 15 psi pressure transducer and datalogger installed Depth to water = 4.42 feet TOC 11/7/08 Depth to water = 3.80 feet TOC 11/19/10 Depth to water = 4.23 feet TOC 12/3/09 100 ft

LB MW-1 As-Built Well Construction and Lithologic Log Lake Ballinger Watershed Study Logged: MPK Figure A-1 Reviewed: CE

ATTACHMENT B

HYDROGRAPHS FOR OLYMPIC WATER DISTRICT 228TH STREET WELL

Golder Associates Groundwater level measurements provided by Olympic View Water District. 282.5 Precipitation from Bruggers Bog Rain Gage 3.0 (http://green.kingcounty.gov/WLR/Waterres/hydrology/DataDownload.aspx?G_ID=122) 282.0

2.5 281.5

281.0 2.0

280.5

280.0 1.5

279.5

1.0 bPrecipitationDaily (inches)

Groundwater Elevation Elevation Groundwater(feet msl) 279.0

278.5 0.5

278.0

277.5 0.0 10/1/03 10/31/03 11/30/03 12/31/03 1/30/04 3/1/04 3/31/04 5/1/04 5/31/04 6/30/04 7/31/04 8/30/04 9/30/04 Date

Title Groundwater Elevation and Precipitation Water Year 2004 - 228th St. Well Drawn JV Groundwater Checked MPK Elevation Project No. Project Name Lake Ballinger 083-93430.100 Reviewed CE Precipitation Client Name Date FIGURE Otak, Inc. December 5, 2008 B-1

V:\PROJECTS\_2008 PROJECTS\083-93430 Lake Balllinger Watershed Study\Report\Attachment B and Figure 8 Groundwater level measurements provided by Olympic View Water District. 282.5 3.0 Precipitation from Bruggers Bog Rain Gage (http://green.kingcounty.gov/WLR/Waterres/hydrology/DataDownload.aspx?G_ID=122) 282.0

2.5 281.5

281.0 2.0

280.5 Transducer Shift? 280.0 1.5

279.5

1.0 bPrecipitationDaily (inches)

Groundwater Elevation Elevation Groundwater(feet msl) 279.0

278.5 0.5

278.0

277.5 0.0 10/1/04 10/31/04 11/30/04 12/31/04 1/30/05 3/2/05 4/1/05 5/2/05 6/1/05 7/1/05 8/1/05 8/31/05 10/1/05 Date

Title Groundwater Elevation and Precipitation Water Year 2005 - 228th St. Well Drawn JV Groundwater Checked MPK Elevation Project No. Project Name Lake Ballinger 083-93430.100 Reviewed CE Precipitation Client Name Date FIGURE Otak, Inc. December 5, 2008 B-2

V:\PROJECTS\_2008 PROJECTS\083-93430 Lake Balllinger Watershed Study\Report\Attachment B and Figure 8 Groundwater level measurements provided by Olympic View Water District. 282.5 Precipitation from Bruggers Bog Rain Gage 3.0 (http://green.kingcounty.gov/WLR/Waterres/hydrology/DataDownload.aspx?G_ID=122) 282.0

2.5 281.5

281.0 2.0

280.5

280.0 1.5

279.5

1.0 bPrecipitationDaily (inches)

Groundwater Elevation Elevation Groundwater(feet msl) 279.0

278.5 0.5

278.0

277.5 0.0 10/1/05 10/31/05 11/30/05 12/31/05 1/30/06 3/2/06 4/1/06 5/2/06 6/1/06 7/1/06 8/1/06 8/31/06 10/1/06 Date

Title Groundwater Elevation and Precipitation Water Year 2006 - 228th St. Well Drawn JV Groundwater Checked MPK Elevation Project No. Project Name Lake Ballinger 083-93430.100 Reviewed CE Precipitation Client Name Date FIGURE Otak, Inc. December 5, 2008 B-3

V:\PROJECTS\_2008 PROJECTS\083-93430 Lake Balllinger Watershed Study\Report\Attachment B and Figure 8 Groundwater level measurements provided by Olympic View Water District. 282.5 Precipitation from Bruggers Bog Rain Gage 3.0 (http://green.kingcounty.gov/WLR/Waterres/hydrology/DataDownload.aspx?G_ID=122) 282.0

2.5 281.5

281.0 2.0

280.5

280.0 1.5

279.5

1.0 bPrecipitationDaily (inches)

Groundwater Elevation Elevation Groundwater(feet msl) 279.0

278.5 0.5

278.0

277.5 0.0 10/1/06 10/31/06 11/30/06 12/31/06 1/30/07 3/2/07 4/1/07 5/2/07 6/1/07 7/1/07 8/1/07 8/31/07 10/1/07 Date

Title Groundwater Elevation and Precipitation Water Year 2007 - 228th St. Well Drawn JV Groundwater Checked MPK Elevation Project No. Project Name Lake Ballinger 083-93430.100 Reviewed CE Precipitation Client Name Date FIGURE Otak, Inc. December 5, 2008 B-4

V:\PROJECTS\_2008 PROJECTS\083-93430 Lake Balllinger Watershed Study\Report\Attachment B and Figure 8 Groundwater level measurements provided by Olympic View Water District. 282.5 Precipitation from Bruggers Bog Rain Gage 4.0 (http://green.kingcounty.gov/WLR/Waterres/hydrology/DataDownload.aspx?G_ID=122) 282.0 3.5

281.5 3.0 281.0

2.5 280.5

280.0 2.0

279.5

1.5 Daily bPrecipitationDaily (inches)

Groundwater Elevation Elevation Groundwater(feet msl) 279.0 1.0 278.5

0.5 278.0

277.5 0.0 10/1/07 10/31/07 12/1/07 12/31/07 1/31/08 3/1/08 4/1/08 5/1/08 6/1/08 7/1/08 8/1/08 8/31/08 10/1/08 Date

Title Groundwater Elevation and Precipitation Water Year 2008 - 228th St. Well Drawn JV Groundwater Checked MPK Elevation Project No. Project Name Lake Ballinger 083-93430.100 Reviewed CE Precipitation Client Name Date FIGURE Otak, Inc. December 5, 2008 B-5

V:\PROJECTS\_2008 PROJECTS\083-93430 Lake Balllinger Watershed Study\Report\Attachment B and Figure 8

ATTACHMENT C

WELL LOGS

Golder Associates