( T H E INLAND CONTRACTING REPORT)

Prepared for

INLAND CONTRACTIMG LTD. 716 Qkhnaqan Avanlln

PENTTCTON, R.C, Y 2 A 3K6

Prepared by

PACIFIC HYDROLOGY CQMSULTANTS LTD. PITEAU ASSOCIATES ENGJNEERTNG LTD. 204 - 7929 West Broadway AND VANCOUVER. B.C. V6J 123 NORTH VANCOUVER, V7M 367

215 - 260 West Esplanade

With a Contr ibut ion by

HBT AGRA LIMITED 2227 Douglas Street

BURNABY, B . C . v5c 5 ~ a

March 10. 1993

C DPY R IG HTE D

ALL RIGHTS RESERVED. NO PART OF THIS REPORT MAY BE REPRODUCED OR TRANSMITTED I N AMY FORM OR BY ANY MEANS, ELECTROMIC OR MECHANICAL, INCLUDING PHOTOCOPY, RECORDING OR ANY INFORMATION STORAGE AND RETRIEVAL SYSTEM WITHOUT

PERMISSION I N WRITING FROM INLAND CONTRACTING LTD.

MRR-10-1993 11 : 44 P. 02

DRAFT EYALUATIOM OF THE GROUNDUATER REGIME IN THE AREA OF

#Ax LAKE ROAD AND FORSYTHE DRIVE ON THE WEST BCNCH AT PENTICTON, B.C.

TARI-E OF CONTENTS

Section Su bj.ec t

LETTER OF TRANSMITTAL

1 .O SUMMARY AND CDNCLLISIONS

3.n RECOMMENDATIONS

3.0 T NTROOLJCT JnN

3.1 Purpose and Scope 3.2 Rackgroiind

4.0 INVESTIGATION PROGRAM

4.1 4.2 4 * 3

4.4

4.5

General Hydrogeol ogi c Reconnai ssance T e s t Drilling, Well Canstructfon and PleZOmeter Installation Pump Testing 4.4.1 General 4.4 .2 T e s t Ne11 TW 4-92 4 . 4 . 3 T e s t We17 TW 2-92 4.4.4 John Thomas Well Groundwater Quality

5.0 HYDROGEOLOGIC ENVIRONMENT 5.1 General 5 2 Topography 5.3 Geology

5.3.1 Bedrock Geology 5 -3.2 Surf i ci a1 Geology

5.4 Climate

6.0 GROUNDWATER REGIME 6.1 Groundwater Hydrology 6.2 6.3 Hydraulic Conductivi ty

Groundwater Gradient and D i r e c t i o n of F low

i

1

4

8

0 e

9 14 14 14 15 16 16

10

18

19 19 20 21

ia

22

22 27 28

MRR-10-1993 ‘II: 45 6El473361370 P. 04

Section

7 .o

0.0

APPENDIX A

APPENDIX B

APPENDIX C

APPENDIX 0

APPENDIX E

APPENDIX F

APPENDIX G APPENDIX H

Number llllllr

TABLE OF CONTENTS fcont' d 1

Su bJ ec t --

Ilar. LW 1993 ll:53RM PI35

U

WATER BALANCE

7 . 1 Fst.lmatSng Grnundwater Recharge 7 - 1 - 1 7.1.2 %@page Flow Method

Hydrograph Method

7 - 2 Patcnti a1 Impact From Propased Development

lM?LICATIONS Or GROUNDWATCR REGIME WITH RESPECT TO POSSIBLE IMPACTS r R O M INLAND'S PROPOSED WCST BENCH ESTATES DEVELDPMENT

APPENDICES

Page

29

29 29 30 30

31

32

ILLUSTRAT 1OtUS

1992 TEST HOLE AND TEST WELL LTTHOLOGS, TEST WELL AND PIEZOMETER CONSTRUCTION

PUMPING TEST DATA AMD PLOTS, HYDROGRAPHS OF B.C. HIGHWAYS TEST WELLS AND DATA FROM PENTICTON CLIMATE STATIONS GROUNDWATER QUALITY

PACIFIC HYDROLOGY LETTER DF JUNE 25, 1992, "GROUNDWATER REGIME IN THE WEST BENCH AREA AT PENTICTON"

E.G. LEBRETON REPORT OF DECEMBER 13, 1976, "GROUNDWATER STUDY - HESTBENCH/SAGE MESA AREA, PENTICTON, B. C. "

WEST BENCH SILT - A MEMORANDUM B Y H HAWSON - HBT AGRA LTD. CURRICULUM VITAE OF COMMITTEE MEMBERS

ILLUSTRATIONS

T i t l e - Page

Figure 1 West Bench Groundwater Investigation - Plan (pocket 1

Figure 2 West Bench Groundwater Investigation - Sect ion A - A ' A - 2

MRR-16-1993 11 : 49 F. 05

TABLE OF CONTENTS (cont I d )

ILLUSTMTIONS (cont'd)

T l t l e - Number - Figure 3 West Bench Groundwater I n v e s t i g a t j o n - Section 6-B'

Figure 4 West Bench Groundwater Investigation - Scction C-C'

F i g u r e 5 West Bench Groundwatcr Investigation - Sect ion D - 0 '

Figure 6 West Bench Groundwatcr I n v e s t i g a t i o n - Section E - E '

Figurc 7 West Bcnch Groundwater Invcstigat4an - Scction F - F '

Flgure 8 West Bench Groundwater Investigation - Sec t ion G - G '

Figure 9 West Bench TI41 -92 Construct ion DetaS i s

Fjgure 10 West Bench TW2-92 Constructlon Oetall s

Figure 11

Figure 12

Figure 13

West Bench TH3-92 Construct! on Retai 1 s

West Bench TW4-92 Construction Details

West Bench TH5-92 Construction D e t a i l s

* A - 3

A - 4

A - 5

n - 6

(pocket 1

(pocket 1

B - 7

B - 8

B - 9

5 - 10

6 - 11

Figure 14 Semi-logarithmic Plot of Drawdown i n West Bench TH 4-92 and Wash P l a n t Observation Well C - 15

Figure 15 Seml-logarithmic Plot o f Recovery of Water Level j n C - 16 West Bench TW 4-92

Figure 16 Semi-logarithmic Plot of Recovery o f Water Lwel i n Wash Plan t Observation Well on West Bench C - 16

Figure 17 Semi-logarithmic Plot o f Change i n Water Level i n John Thomas We1 1 During Pump Test ing o f West Bench Tw 4-92 C - 17

F'igure 18 Semi-logarithmic P l o t of Orawdawn i n West Bench TW 2-92 C - 18

MRR-10-1993 11:49

- i v -

6047386070 P. 06

Number

DRAFT TABLE OF CONTENTS ( c o n t ' d )

FIGURES I cont ' d 1

- T l t l e Paae

Figure 19 Semi- logari thmic P l o t o f Recovery o f Water Level i n West Bench TW 2-92 c - 18

Figure 20 Seml-logarithmic Plot of Drawdown i n John Thomas Well on West Bench c - I9

Figure 21 Semi - logar i thmic P l o t o f Recovery o f Water Level in John Thomas Well on West Bench c - 19

Figurc 22 Changcs i n Water Level Elevations i n Piczomctcrs of WcSt

Bench TH 3-92 Between January 11 and February 23, 7993 C - 20

Figure 23 Changes i n Water Level Elevations i n Piezometers of c - 20 TW 5-92 During February 1993

c - 21 Figure 24 Hydrographs o f B.C. Highways Test Wells

Number

Tab le 1

-

Table 2

Table 3

Table 4

T a b l e 5

Detai 1

TABLES

Ti t l e

-

About T e s t Uells and T e s t Hol Drilled and Constructed i n Inland's West Bench Groundwater I n v e s t i g a t i o n

Chemical Quality o f Groundwater f r o m T e s t Wells on Inland's West Bench Property

Details o f Piezometers a t Tnland TH 3-92

Oetails uf Piemmeters a t Inland TH 5-92

Sumnary o f Normalized Data for Two Penticton Cl imate Stations f o r Period: 1951 t o 1981

13

17

.24

25

c - 22

- v -

MRR-18-1993 11 : 50 6047386070 P. 07

3.0 S W Y AND CONCLUSJOMS

The most important findings t h a t have reslilted f r om the i n v e s t i g a t i o n c a r r i e d out b y the C o m l t t e e , which was assembled by Inland Cont rac t ing Ltd. tu f u r t h e r investigate the groundwatcr flow regime f n the area of Max Lake Road m u Forsythe Drive on the West Bench a t P e n t i c t o n , and whlch consisted of Ed L i v i n g s t o i l , P. Cng., Chairman, (Pacific Hydrology Consultants L t d . ) , PI. A l l a n Dakin, P . Lng. ( P i t e n u AssocSatcs Engfneering L t d . ) , and H e r b e r t Iidwson, P . Eng. (IN37 AGRA Limited), arc the following:

1.

2.

3.

4 .

5.

The topography o f the bur ied bedrock surface under ' the sand and gravel area west o f West Bench i s an 'important f a c t o r fn determining the groundwater hydrology o f the area . Ixportant features include a buried rock v a l l e y extend ing southward from the mouth o f Max Lake V a l l e y , w i t h a buried rock ridge s e p a r a t i n g t h i s buried valley from the t h i c k S i l t under l y i n g West Uench.

Except for a small raised delta, located s o u t h o f the mouth of t he Valley o f Max Lake and mostly east of TH 1-92, the sand and grave? underlying West Bench conri sts o f permeable tones wi th in heterogeneous sediments best called ice contact depos i ts ; the permeable zones arc probably a l l hydraulfcally connected but, on ly indirectly.

The bedrock ridge separating Max Lake Valley from the th ick s i i t undcrlyi ng West Bench prevents easterly movement o f groundwater S n t O the S I It.

dater l eve l elevations i n piezometers a t TH 3-92, which i$ lncated in t h e Pctcr's Brvs grave l p i t near. t h e south boundary o f t h e Inland Property, illustrate t h a t there 7 s s l o w upwnrd movement o f grmndnater from t h e bedrock into the i ce contact deposits. Water level elevatjons measured i n va r ious T e s t Wells and Test Holes f rom t h e present study, and i n several existing Wells I n the gravel p i t area, confirm t h a t groundwater moves i n a south/southeast direction th rough t he i ce contact. sediments . TH 5-92, which was drilled i n the south branch o f the south gully i n the West Bench area, shows t h a t the s i l t underlying the Bench i s very th ick - Over 100 m - with only a t h i n t i l l between i t and the underlying bedrock. The response of t h e water level in t h e piezometer I n bedrock i s evidence tha t t h e permeability o f the bedrock is very low.

MFIR-10-1993 11:50 6047386070 P. 08

7 . A l o r 1 9 - d u r a t i o n pi1mp4ng trp7t o f a properly const ructed screened p r o d u c t i o r , w l l (lW 4 - 9 2 ) , l o c a t e d a t the n o r t h e d g e of t h e I n l a n d C u r i l r ,11,1Irq Pr opvft,y i n t he b u r i e d valley o f blax Lakc, Slluitrate' tha t :

0 .

rev and f o l

1 .

2.

3 .

a . i n l ' l o w f r o m Max L a k e V a l l e y i s relatively stua11;

h. pumping at, n . r a t e i n t h e r a n g e o f 7 t o 78 1 . 1 5 ~ ~ (90 t o . 1 0 0 I g p n ) r r i I I y d d l l d l 1y de;qo ter p e r t , , a n d probably m o s t , O f t h e i C C c o n t a c t sand and gravc.1 u n d e r l y i n g t h e I n l a n d Property.

Gt-nunrlwater m o v i n g t h r o u g h t h e sed imen ts filling thc Valley nf Max l a k e , LIS s lrnw~ Ijy a wate i - a i i a l y s 4 s ot g r o u n d w a t e r collected f r o m TW 4-92, i s quit.(: h igh ly niincral i r e d .

I-rom the present investigation, from previous work, avd f r o m 3 cw of r e l e v e l i t pub1 i shed and unpub l ished dwuments, concerning geology grotiri i lwatw i n t h a \Jest Dench a r e a a t Pentjcton, we conclude t h e

owi nq :

'I he e!+. 1 s t i n g yroi indwater t-eginie on t he Inland Proper ty is q u 4 t e Separate frurn t h d t UII the rivrtlierrr y d r - t of West Bench. Contrary to t h e Klohn l e o n o f f Report, I n f o r i n a t l o n collected d u r i n g t h e present i n v e s t i g a t i o n I n d i c a t e s t h a t qroundwater f r o m the I n l a n d Property does riot f l o w t d s t w L i t d under tilt i w r t t i e r i i p a r t crt the Bench. Calculations show t h a t t h e e f f e c t s o f i r i d i v i d u d l domestic wastewater disposal facilities on the eastern edge of t h e I n l a n d Property ( 0 1 1 t h e eastern slope o f t h e bedrock r idge) w i l l be negligible.

S o w groundwater fvom the I n l a n d Propel - ty i i iay f low eastward under t h e southern pat- t of \.lest: Bench, south o f Bar-tlett; Road. Groundwjter f l o w i n g under I d e s t Bench flows t h r o u g h very thick saturated s i l t , and ~ 8 1 1 d . y s i l t Loward 0 k d i i a y a n L d k e . Because of t h e s m a l l q u a n t i t y o f water f l o w i n g t h r o u g h t h e great t h i c k n e s s of s i l t , t h e groundwater gradient arid velocity u f groundwdter f l o w at-e b o t h very low and are incapable o f causing s t ruc tu ra l changes j n the s i l t .

Groundwater condi t ions a t t h e In1 and Property can be control led by w e l l known convPnt inna1 methods involving pimping o f one or more wells, a?ong w i t h careru? i uon i to r iny of water leve ls i n a network of a h c i p r v a t i o n w p l l i , . ! ,u f f ic ient : work h a s been done t o show t h a t th is 1 s fcas i l i l e arid the cost; w i l l n o t be p r o h i b i t i v e .

- 2 -

P. 02

4.

5 .

6 .

7 .

a.

Water which i s produced i n a program of groundwater control i s likely t o be rnincralfrcd h u t I+. can be put to b e n e f i c i a l use; zuch u5e may includc, f o r cxample , i r r i g a t i o n o f t h e park lands.

Thcrc i s I ~ Q evidence t o indicate t h a t groundwater contro l measures on t h e proposed I n l a n d Development w i l l have any e f f e c t on the wetlands i n Max Lake Valley and, i n prlrticiilsr, on Max Lake. I n f a c t . water pumped in groundwatcr control operations could bc conveyed to Max Lakc to s u p p l m c n t i t s prcscnt inflow. Thc groundwater moving through t h e sediments filling the buried valley o f Max Lake. as represented by a sample collected fram Well TW 4-92 after about s i x days of pumping, i s quite highly mineralized. Although there i s no indication t h a t t h e quality of t h e groundwater In the burted valley sed'lments i S

incompatible w i t h the quality o f Max Lake water . compatibility of the groundwater and water from Max Lake i s best examined at: the end of suntmer and not in spring when the Lake water may be diluted w i t h surface runoff . The e f f e c t on the northern part o f the Indian Reserve Lands of groundwater control a t the proposed Inland Oevelopnient would be m i n i m a l . Water for the gravel mining uperation ad jo in tng the I n l a n d Property i s obtained from a deep well completed i n rock and th is well would not be affcctcd by pumping from the sand and gravel a t t h e Inland Property.

Under the prevail i n g hydrogeologic conditions . as conf i riiied by the present study; d i s p o s a l o f storm water f rom pavement, building roofs and other Smpermeable surfaces i n the proposed Development 1 s considered to be a r o u t i n e matter; i t i s assuined, however, t h a t such disposal w i l l be according t o htgh standards o f design, construction and maintenance. Storm water f rom thet small p o r t i o n o f the s i t e which I s located on t h e eastern slope of the rock ridge can be conveyed t o the sand and gravel area f o r ground disposal.

The proposed Inland Contracting Development c a l l s f o r the use of individua.1 conventional domestit wastewater disposal systems consisting of a septic tank and t i l e drain f i e l d , Such facilities w i l l have only a mintma1 effect on groundwater qual 4 ty; effluent discharged i n t o the d r a i n f i e l d s w i l l contain a small amount of n i t r a t e but t h i s w i l l have no signif icant impact an e x i s t i n g groundwater quality and i s unlikely to be detected once i t has entered and become p a r t o f the natural groundwater.

- 3 -

MUR-10-1993 14 : 58 6047386070 P . 0 3

1 . t k t e i - I \-IC dnnicst i c - ilnrl irrigation natcr systems i n the Development SO

t o c.nc,tire thbt I ( , n k s a n d / o r ej;ces.;ivc water use can be detected before increac ,es to groundwater rccharge are slgnificant.

2. R c ; t r - l c t the u s c o f swimming stid,/ot- ornsmcntal p o o l s on t h a t part of t h e r n l a n d Property whicl, i s l o c a t c d on t h e e'ast slupe o f t h e buried bedrock r i d g p .

3 . I l fot i i tot- t h e response o f water l eve ls i n t h e piezometers o f TH 3-92 reg i r ln i - ly , s t a r t l n g before any Development a c t i v i t y , as a basis fo r d e c i d j t i g whether p m p i n g o f TW 4-92, and/or a n o t h e r well canstructed for t h a t p u r p n w , s h c u l d hc stdrtcd t u cuiitrol gruurdwater under t h e si te .

4 . Urge t l l a t U . C . E n v i r o n m e n t add TH 3-92, TH 5-92 and the o ld John Thomas We1 I tti t h e P rov I nc ia l Observation He1 1 Network operated by Groundwater Spc t i cm o f R.C. Firv i roninent.

The above ineasut-es a re considered t o be rout lne proccduras t o bc irnpletnentect i n a Development of t h e type proposed and, i n f a c t , had been discussed a t the ore l imiridry stdge o f investigatlon and were assumed t o be i nip7 emea t.ed a t t h a t t 1 nle ,

FIRE-11-1993 1El: 1-1 F. 03

3.0 INTROOUCTIOM

The purposes o f t he investlgation described i n t h i s Report, 3s

s t a t e d S n a letter datcd Novcmbcir 30, 1992 from Pacif ic Hydrology Cnnsiill.an1.s L t A . (on b e h a l f of the West Bench CommitLee) t o Inland Contracting L td . , were t o r

1. Resolve some of the questions a b o u t groundwater conddtions a t t h e b a s e n f the s l l + , iunricr Wcst 5cncht

2. Show whether possible neyat?vc impacts from Inland's proposed West Bench Estates Development can bo prevented by proceeding on a c e r t a i n defined course o f act ion .

3, Assess the feasibility of developing a s u p p l y o f gnod qualfty groundwater on the I n l a n d Property.

Because the surficial geologic u n i t s underlying West Bench - particularly the sand and gravel and t h e l a c u s t r f n e s i l t - extend across land boundaries, and because the relationship between these u n i t s I s relevant., the area of t h e study logically extends beyond Inland's Property.

3.2 Backqraund

The surf ic ia ' l geology o f the subject area has been o f i n t e r e s t for a long t r m e because o f the lacustrine s j l t which i s very widespread in the Okanagan and Thompson Kiver Valleys and i n the Shuswap area. As irrigation becamc more widespread in the dry Interior of E.C. and i r r i g a t e d orchards were established on s i l t , problems w i t h stability o f steep slopcs I n t h e s i l t became apparent. In the ear ly 1970's, P r o v i n c l a l and local governments becamc concerned about development o f semi-rural r e s j d e n t i a l s u b d i v i s i o n s a t West Bench and Sage Mesa, so a study o f stabilfty problems was carried O u t

MRR-10-1993 11 : 58

- 5 -

6047386070 P. 01

li; r c s i d c i i t i a l development t o o k p l a c e at1 West Bench an# on the h i l l north o f t h e [ n l a n d Proper ty , t.he sond and gravel was being mined i n extens ive p i t s e x t e n d i n g from the mouth o f Max take Valley southward Onto thc Pcnt i r ton I n d i An Rcscrvc. T h t . g r a v e l minlng operat ion, which star ted ou t on the hillside i s now occtjpied b y t he West: Bench Estates Subdivlslon.

I n 1991, lnlartd C o n t r a c t i n g Ltd. pi-oposed t o discontinue t h e gravel n i i t i i n g and c ~ l r r y out, dcvP1ootni:rit o f a cornbiried res ident ia l and g o l f course developnient. Water f o r irrigation o f the golf course and for domestic scrpply was proposed t o corle f r o n i Okanagan Lake by way of t h e West Bench Irrigation D i x t r i c t . However, because o f some concern about the p o s s i b l r E f i . P c t < of' adding a s i g n i t i c a n t amount. o t w a t e r to t h e sand and g r a v e l B C - P A , P a c i f i c Hycirolngy Coristrl t .ants L t d . ( P H C ) was engaged by I n l a n d Contracting L t d . t o address t h e s e concei-ns, and t o a t t e n d a p u b l i c n e e t i n g subsequently c e l l e d Lsy t.he Regional Dis t r ic t i n order t o conslder the PHC letter-report, dated June 25, 1991 and.which is included w i t h t h i s R e p o r t 8 s

Appendl'x F .

Decaiise o f concern about c o n t i n u l n g developiiient o f the West Bench - Sage Mesa area and t he s a n d a d g r a v e l area t o the west, the Regional Dis t r ic t o f Okanagan-Sirrri lkanieen arld B . C . M i n i s t r y of Transportat ion and Highways decided t o r e - a s 5 ~ S s the hazards associ ilted w i t h developments i n the area underla in by the l a c u s t r i n e s i l t . Klohn Leonoff L t d . were engaged t.0 car ry out a study o f the area, t h e resul ts o f rrhikh are prewnted i n a Report d a t e d A u g u s t 1992 and t i t l e d "West Bench/Sage Mesa Area Geological Hazards Review", t.hc resu l t o f w h i c h was a moratorium on a l l development i n the West BenchiSage Mesa a r e a , including t h e s u b j e c t Inland Property.

- 6 -

F. 04

rmi : FRCIFIC H'iWOLOGr' iTE4SULTRNTS PHOPE No. : 6M4738GD713 ~

L. Mar. 11 1993 7:37kM PI33

V

Inland Contract ing Ltd. assembled a Committee t o c a r r y out a re-~s~essriient o f t h e hydrogeol ogy of the area, particularly the sand and gravel area where f n l a n d proposes t o carry out their Development; t h e pruject was i n i t i a t e d by a Committee Meeting in Penticton and a tour OC t h e area an October 20, 1992. The elembers of the Committee are the authors of t h S s Report;. A t the o u t s e t , it was the optnjon o f 1;he Cornnittee tha t as much a s possib le o f t h e detailed infarmat ion used in preparatqon of t h e Nyland-Mlller Report should be assembled to a i d i n the C O m m l L t m ' % eva lua t ion and i n preparation o f the Report. T h i s information i n c l u d c s o r i g i n a l d r i l l hale logs , water lcvcl data from piczonieters and o l d aerial photographs. Documents containing t h i s information and which are on f i l e in the Materials and Testing Off ice of B.C. Ministry o f Transportation and Highways i n Kamloops, were made available t o Klohn Leonoff f o r the preparation of t h e K . L . Report; the same courtesy was extended by B.C. Ministry o f Highways t o the Committee, so the Committee Chairnian v i s i t e d t h e Ministry's Kamloops O f f i c e and examined the old files, rnaklng notes and copying documcnts. Subsequently, a copy o f a ld ter -report by C . G . Le Breton (Clackground Document No. 6 ) . which discussed the hydrogeology uf the subject area, was obtained from Groundwater S e c t i o n o f B.C. M i n i s t r y of Environment. lands and Parks. I n h i s report, Le Breton drew attention t o the f 01 1 owing :

1 . The topography o f t h e buried bedrock surface i s l i k e l y t o be an important factor i n the d i r e c t i o n o f groundwater f low.

2. Seismic profiles indicated the possibility o f a buried valley which caul d convey groundwater southward and eastward.

3 . The permeable sands and gravels underlying West Bench are l i k e l y impor tant i n controlltng the directioti o f groundwater f low.

4, Increases i n density o f development would have little e f f e c t ' i n r a i s i n g the water t a b l e .

5 . P r O G l M S of instability i n the s i l t are a result o f activity On t.he s i l t .

The present In land Development c a l l s f o r residential subdivision of the e n t i r e . 57 hectare (140 acre) parcel to 0.2 hectare (0.5 acre) density, except for the main park area of 2.8 hectares ( 7 acres) and some smaller greenbelt areas f o r walking paths. The subject Property C O t I S d S t S Of Lot A of P l a n 19435, t o t 3 o f Plan t5612,and L o t s 1, 2 , 3 and 4 Of Plan 24215, a l l of D.L. 4947, and D . L . 4948, Osoyoos D i s t r i c t .

- 7 -

MRR-11-1993 07: 33 6047386078 P. 03

DRAFT 4.0 INVESTIGATION PROGRAM

4 , l General

In addition to a review of relevant background dbcurnentS, the i n v e s t i g a t i o n of t h e groundwater regime o f t h e West eench area consisted of:

1.

2.

3.

5.

Hydrogcol o g i c f i c l d rtlconnai ssance 3f exposures and of c o d t f b n s +in gullies, g i v i n g particular a t t e n t i o n t o cvidcncc o f surface watcr f l o w .

D I - i 11 i ng o f f i ve cased hol cs o f vary1 ng depths , w l t h cornpletiors eqther as screened pumping wells o r water level moni tor ing piezometer si tes .

Pump t e s t j n g of two screened wells, TW 2-92 and TW 4-92, cunstructed during the i nvest iga t ian ; an old e x i s t i n g water we1 1 (John Thomas We1 1 1 i n the gravel p i t area was a l s o tested.

Sampling fo r groundwater qualjty from TW 4-92 which may eventually be used as a water SOUPCC, and checking t h e t o t a l mineralfzation of groundwater yielded by TW 2-92 and an e x i s t i n g well by measuring conduct iv i ty w i t h a field meter.

4.2 Hydrogoologic Reconnaissance

Ed Livingston of the Commfttee spent three days i n t h e f i e l d a t the start of t h e drilljng i n December. Several d r i l l hole l o c a t j o n s were selected and n a t u r a l and man-made exposures o f s i l t , several sink holes and the t w o main gullies i n the s i l t were examined, g i v i n g part-fcular attention t o any evidence of recent surface r a t e r f l a w i n four culverts under t h e railway grade at the heads o f branches of the north and south gullies. An hand auger hole was dug in t h e bottom o f the north gully t o a depth of 3 i metres, a t whfch depth t h e s i l t was "powder dry". Subsequently, f n March, before f i n a l i r i n g t h e Cornmi ttee Report, a r a p i d reconnaissance was carried out by Ed Liv ingston and Herb Hawson to reconsider ansite the results o f the t e s t dri l l ing/pump testing program, with t h e hydrogeologic sections i n hand.

- 8 -

604'7386070 P. 03

4.3 Test Dri 11 4 ng , Well Construct4 on and P i etmeter Instal 1 atjon

The i n i t i a l drilling was c a r r i e d a u t by Clark Drilling Serv ices of Langley using a BE 22W cable tcol drilling r ig , and welded steel C 8 S i n 9 of 150 and 200 mm ( 6 and 8 " ) diameter. Although the weather was unusually co ld and windy d u r i n g t h e early p a r t o f the dr.illirfg, good progress was made until t h e l a s t h o l e (TH 5-92) i n the s i l t , where the depth t o bedrock turned o u t t o be much deeper than an estCtnate based on e x i s t i n g information. This hole was completed by Mex Schib l i Drilling usfng a small a i r r o t a r y drillCng r'rg and 125 rnm ( 5 " ) diameter casSng.

The o b j e c t i v e s of t h e drilling program were t o :

1. Improve t h e knowledge of geology of the sand and gravel , of the s i l t and of the relationship between t h e two materials.

2. Determine, .if possible, a mre precise assessment o f the groundwater hydrology o f the area, particularly t h e path and q u a n t i t y of groundwater whSch i s moving tram t h e sand and gravel t o Okanagw Lake or i n t o the main unconsolidated f i l l of the Okanagan Val ley.

3. Construct several permanent water level observat ion f a c i l i t i e s , either observation wells or piezometers, t o permit long term monitoring of groundwater levels and, possibly. water qual i t y under present conditions and, i n future, in the event t h a t the proposed In land Development or o t h e r developments proceed.

4 . Better define t h e topography of the surface o f the bedrock under the surf i c i a1 sedi rnents ( sand gravel and s i 1 t 1 ,

5. Determine whether i t may be feasible t o counteract, by pumping o f o ther means, possible effects on t h e groundwater regime from water added t o the sand and gravel by the proposed Development.

6. Determine whether i t i s p o s s i b l e t o develop a supply o f good quality groundwater f o r the proposed Development.

The s i t e for t h e f i r s t hole (TH 1-92) was chosen on the western p a r t of the raised d e l t a a t a s i t e where i t seemed l ike ly t h a t there was an old buried valley connecting the Max Lake Va?ley and Okanagan Lake. TH 1-92

- 9 -

MRR-10-1993 12:01 P. 04

kta5 drilled w i t h 2 0 0 111111 (0") diametcr c a s i n g , E O t h a t in the w e n t It encountered an a q t t l f e r , L ~ I P a q u i f e r - could he cvd lua ted b y pump t e s t i n g . i t turned o u t , the h n l e relic,/& bedrock a t a shallow d e p t h of 7.3 in ( 2 4 f t) , showing t h e presence uf a bedrock r l d g e s e p a r a t i n g t h e birried Mag Lake Valley syb tem f r o m Okdridgar't Lake . The c a s i n g shoe becsnw stuck I n thp i,fip Of the weathered b e d r o ~ k 50 the ho le wdb coniplctcd B S at\ observation well w l l h 50 tm ( 2 " ) i l i m i ~ ~ t e r s l o t t e d PVC c a s i n q s c t i n t h e bedrock..

ltit.: X'LVIIJ I jv Ic ( T I 4 2 - 9 2 ) t i as drillcd at t h e southeast corner o f the I n l a n d Properly; 200 win ( 8 " ) dfbnieter casing was used because of the very bouldery c o n d i t i o n s encviintered 111 TI1 1-32, TW 2-92 was d r i l l e d through i c e c o n t a c t depos i ts t o bi?drock a t a depth of 27.8 in ( 9 1 . 5 f t } , It encountered alr aquifer a n d was completed w i t h a well screen; however. i n i t i a l development i n d i c a t e d poor well performance and pump t e s t l n g has conf i rmed t h a t t h e c a p a c i t y o f TY 2-92 i s low. .Since t h e ice contac t depos i ts a t TW 2-92 conta ined some s l l t , t h e Well may be ?mated on or a t ai l i n k f i n y e r i n g c o n t a c t between the i c e con tac t d e p o s i t s and t he main body of s i l t .

The third hole ( T H 3-92) w a s drilled w i t h 150 I M I ~ ( 6 " ) diameter c a s i n g a t a s i t e i n t h e d e e p e s t p a r t o f the a c t i v e gravel p i t and close t o t h e south halrndary o f t h e Inland Proper ty . YH 3-92 was d r i l l e d through lice c o n t a c t deposits t o twdr-uck a t 34.45 m (113 f t ) , i n d i c a t i n g t h a t the bur ied rock val ley ex tcns ion o f Max Lake V a l l e y pro jec t s southward I n t o the Penticton Ind ian Reserve. T l i 3-92 hus been completed wl th three small diameter p l a s t i c , casings t o serve a s a multl-level observation well to ~ b s e r v e water levels and groundwater g r a d i e n t s i n t h e i c e contact deposits. Measurenients t o d a t e show t h a t there i s a sniall upward gradient from the bedrock i t i t o the overlyi r q i c e con tac t sediments.

The f o u r t h tiole (TW 4-92) was drilled a t a site near- the north boundary o f t h e I n l a n d Property and a t t h e mouth o f Max Lake Valley; no t unexpecledly, TW 4-92 encounterPd thick heterogeneous i c e con tac t Sedlments filling FSax t ake Valley. The h o l e reached bedrock a t a depth of 3 4 . 6 m (113 ft l a f t e r drilling through several water-bearing zones; a screen assembly was selected and installed i n t h e coarser and more permeable zone whjch was present j i i s t ahove the bedrock surface. L a t e r , pump tes t ing o f TU 1-92, a t an average rate about 5.68 L/sec. 190 USgpm) f -or 8605 minutes ( e 6 days ) , resi i l txd i n at1 approximately s t a b l e pumping water level; in te r fe rence drawdown o f 3 . 5 3 III ( 1 1 . 5 8 f t ) was observed i n t h e closest well i n which water levels were tnclnitarcd dur ing the pumping - speclflcally, t h e Wash P l a n t Hell i n the Peter's Bras. Gravel P i t , a t a d i s t a n c e about 20 m (65 f t f ; the substantial i n te r fe rence between Tt( 4-92 dnd the Wash P l a n t Gkll confirms d f a i r l y d i r e c t hydraulic connect ion between the two Hells.

- 10 '-

F. 06

The last hole {TH 5-92) i n the drilllng program was s i ted in the bottom o f the south branch of the south gully close to the east s i d e o f t h e o l d railway embankmcnt. T h i s s i t e i r essentially a t the head o f the gu'lly. The o b j e c t i v e s i n drilling at t h i s s i t e were to:

1. Invcstigatc the na tu re o f the tane between the s i l t and underlying bedrock,

2 . Establish a permanent observat ion well ( 5 ) t o monitor t h e groundwater f l o w eastward f rom t h e sand and gravel area t o Okansgan Lake.

Before starting the drilling, the probable depth t o bedrock was estimated t o be in the range 35.1 to 45.7 rn (115 t o 150 f t ) .

Drilling started us ing the cable t o o l method, as f o r the other s i tes . and 150 mm (6") diameter cas ing . T h i s phase o f t h e drilling had t o be te rmina ted a t a depth af 68.6 m (225 f t ) when the cas ing could not be advanced further and when the hole had been drilled open ahead o f the casing t o a depth about 75.9 nt (249 f t ) , The h o l e t o 75.9 m had been entirely i n s i l t w i t h occasional sandy zones, Drilling continued by the a i r rotary method us ing 125 tiiiii ( 5 " ) diameter casing and t h e hole remained trt Silt and sandy S i l t t o 96.3 m (316 f t ) , a t which depth it encountered a sandy stony t i l l overlying bedrock a t 98.8 m 1324 f t ) . Drilling continued in schist bedrock t o a depth of 103.7 m (340 f t) . The d r i l l e r reported a small amount of rusty s t a i n i n g at the contact with the t i l l ; otherwise t h e rock appeared to be fresh and unweathered. Very l i t t l e water came i n t o the bedrock hole d u d ng dri 11 ing

A piezometer was placed i n t h e bedrock hole, wi th the bottom a t a depth about 102.7 m (337 f t ) ; a seal o f granular bentonite extending i n t o the overlying till was i n s t a l l e d . A second piezometer was placed i n the s i l t , w i t h the bottom of the plpe a t 72.3 m 1237 f t ) . Both piezometers are completed wi th 32 mn (14 '0 diameter PVC casings. The deeper piezometer i s takSng a long tjme to reach i t s equilibrium static water level and, ai: t h e time of submission o f t h i s Report, stability i s not ye t certain. The slow response indicates t h a t the fracture permeabillty o f the fresh bedrock I S very low, The water level in the upper piezometer i n the s i l t reached equi l ibr ium q u i t e quickly, as expected. Mater level readings end corresponding water level e levat tons Sn the two piezometers of TH 5-92 .are contained on Page C - 14.

PIRR-113-1993 12:[32 6047386070 F. [36

Ilar. 11 1933 7:38QM P85

Thc signif icance o f t h e deep h o l e (TH 5-92) i n the s i l t includes the following:

1 .

2.

3.

4 .

T h c depth t o rock a t t h e s i t e o f TH 5-92 i s far grcatcr than had bccn anticipated, suggesting t h a t the slope o f the bur ied bedrock surface under N e s t Bench i s qu5te steep. The re lat ive ly shallovi depth t o bedrock i n thc sand and gravel area of the p i t s i s cvidvncc t h a t thcrc i s a rock bench with a buried south-trending bedrock valley along the f o o t o f the mountainside,

The s i l t irndcr West Bcnch i s vcry th ick ; t h i s was not previously unknown, a s there i s a water well a t the cdgc o f Okanagan Lakc which shows very th ick s i l t ; however, the very t h i c k s i l t extends further i n l a n d than had been anticipated f rom previous work. There i s nu i nd i ca t i on i n the deep hole o f an interf ingering contact w i t h the sand and gravel nor i s there evidence o f a gravel aquifer a t the bottoni of the s i l t .

The durat ion o f time required for the deposi t ion o f the s i l t was q u i t e long. The s i l t i s varved - t h a t i s , i t has alternating f i n c and cOJTSC

beds. Even if the average varve thickness i s several centimetres, a long period of deposftim was involved . For example, i f there i s 120 m o f s i l t and t h e average varve thickness i s 10 cm, 1200 years i s indicated. Such a period of deposition i s longer than previous estimates and i s probably much t o o large; for t h e purposes o f the present study, i t i s n o t necessary t o resalve the l e n g t h o f the deposition period.

Each f i ne-coarse p a i r represents one year 's depasi ti on.

In the southern part of West 5ench south o f Bartlett Drive, steep slopes, which hdve the poten t ia l o f being unstable, a r e underlain by very t h i c k s i l t which i s saturated i n the lower part and, as such, would not be affectcd by v a r i a t i o n s i n groiindwater f low f r o m the west. Even if the horizontal hydraulic conductivity of t h e s i l t i s quite low, which i s probably not the case, i t can carry a large groundwater flaw w i t h a very I ow groundwater gradient .

The main details of the f ive t e s t hbles/test wells completed i n t h e present i n v e s t i g a t i o n are summarized i n Table 1 on t h e following page.

MRR-11-1993 07: 34

- 12 -

6047386070 P. 05

x D 7J

I Y - 0

I + u3 u3 W Table 1. Detaiis About Test Yells amd Test tides Drilled and Constructed i n Inlaid's Y e s t Bench 6roomduater l n r e r t i ~ a t i o o

Text well rota; D r i l l e d S t a t i c d a m F i n a l Pua-ing Rate

TH 1-32 19.1 133)

T i l 2-92 28.2 : ? 2 . 5 ) m m P 4

d

w 3-92b 33.6 (!jO)

3-92c 33.6 [ L ! O )

I

'in 4-92 35.5 (116;)

10.1 : 331 dry -

C.32 ( 5 1 :gtpLcted ri:h z 1.7 7 [5.? f t ) l o n g scrcen

sssEIably s e t bttucer 75.3 ard 2 B . O P (66.3

c i c 3L.B Ft).

5-49 le:] Ctuplcted i i i ' r a 6.5 n [Zl: f t ] l o n g e c r e c r a r r e i b l y set h e t r e e r 28.33 and

3s.3 t (95 an4 1Uf Ft).

cr;

AFT 4.4 Punp Testing

4.4.1 General

Thc pump t c s t i n g o f t h e two screened t e s t wells (TW 2-92 and TU 4 -92 ) completed i n t h e prcscnt l n v c s t i g a t l o n , slcrng w i t h an ex is t ing well i n the grave l p i t area, hereinafter referred t o a s t h e John Thomas Well , were car r ied out by Greenacres Pumps 8 Equipment Ltd. , u s i n g standard methods and proccdurcs and undcr the dlrcc t ion c?f P a c f f i c Hydrology Consul t a n t r l t d . D a t a collcctcd dur ing the testing are attached i n Appcndix C , along w i t h d a t a p l o t s based on s tandard s t r a i g h t l i n e methods o f analysis .

4.4.2 Test Well TY 4 -42

Pumping o f TW 4-92 was carried out, s t a r t i n g on January 22, 1993, for a t o t a l o f 8605 minutes, o r almost s i x days, wi th pumping over the las t 4000 rnSnutes (2.8 days) a t a rate o f 5 .49 L/sec (87 USgpm; 7 2 . 5 igpm), which was the maximum capacity of t h e t e s t pump. As shown on Figure 14 (Page C - 151, pumping of TW 4-92 a t a rate of 5.49 L/sec resulted i n a maximum drawdown of l6.4G m ( 5 4 ft) t h a t remained approxlmdtely constant for t he last 5500 minutes (3.8 days) o f the test. Analysts of t h e drawdown d a t a f o r TW 4-92 ind ica tes t h a t t h e Well is f a l r l y e f f i c i e n t and i s probably obta in ing a s much water as the aquifer w i l t y ie ld t o a well a t t h a t l o c a t i o n . The nearby Wash Plant Well, a t a distance about 20 rn ( 6 5 ftf, wdS used a s an observat ion well during the pumping o f TW 4-92; as expected, the pumping o f TW 4-92 caused s i g n i f i c a n t interference drawdown i n t h e Wash Plant Well, which supplies water to t h e Wash P l a n t a t the Peter's Bros. Gravel Operation and which i s completed i n the upper aquifer a t a depth about 12 rn (40 f t ) . Observations of the water level i n the Wash Plant Well showed t h a t the interference drawdown Increased slowly for about ~ 0 0 0 rnrnutes t o a constant drawdown o f a l i t t l e more than 3.35 m (11 f t) [see Figure 1 4 , Page C - 15). Water levels were also observed i n t h e John Thomas Well, a t a distance about 200 m (650 f t) southeast o f the pumping Well TW 4-92; no drawdown was evident until about 1740 minutes when the discharge water from t h e test o f TW 4-92 began t o pond up around the Well and t h e level began t o rise showing t h a t infiltration had s tar ted .

MRR-18-1993 f 2 : 05

- 1 4 - 6047386070 P. 02

Following the t e r m i n a t i o n o f pumping, the water level of TW 4-92 recovered at a moderately r a p i d ratc , w i t h recovery to the o v i q i n a l pr?-pumping s t a t i c level i n aboilt one day or a t t i t ' o f about 3 , 5 5 shown on Figure 15 (Page C - 16) . The water level contirrued to r i se and 22 d w S h f t c r pumping stopped, t h e w a t e r level was 2 .54 m ( 8 . 3 3 f t ) above the o r i g i n a l prc-pumping S t a t i c level; t h i s behaviaur i s prabebly due to the natural seasonal rise from the onset o f aqui fer recharge. 7hc d a t a and Figure 1s show t h a t t h e Wash P l a n t Well behaved i n B s i m i l a r manner to TU 4-92, wi th a f i n a l water level which, after 22 days o f pumping, was 1 .77 m ( 5 . M f t ) above the o r i q i n s l s tat ic water l e v e l .

Using t h e standard well rating calculation, based on the use of 70% o f t o t a l available drawdown, the capacity o f Tlnl 4-92 i s about 5.7 L/sec (90 USgpm) f o r long-term pumping, Such a r a t e w6uld cause d drawdown of about 3.7 rn {12 f t ) -in the upper aquifer under the conditions prevailing a t the pump t e s t . I D la te wnwner and autumn, because o f lower recharge f rom p r e c i p i t a t i o n , the drawdown i n t h e upper aquifer due t o pumping of TW 4-92 may be greater than t h a t shown by t h e test.

, 4.4.3 Test Well TU 2-92

Well TW 2-92 was pump tested start ing ov January 22 for 298 minutes (abour f i v e hours) a t a canstaht r a t e o f 15.1 L h i n (4.0 USgpm) for the last ' 200 minutes of the test as shown on Figure 18 (Page C - 181. This caused an approximately cons tan t drawdown o f 7.6 m (25 f t ) w h i c h was a l m o s t steady f o r the last 20 minutes o f the t e s t .

The water level recovered a t a moderate rate w i t h complete recovery indicated as shown on Figure 19 (Page C - 18). Although no water level observatjons were taken from three hours after stopping t h o test until about; a week la ter , complete recovery occurred during t h a t t i m e .

gel1 TW 2-92 obviously has a very low capacity. t h e d a t a indicate t h a t t he Wcll i s c f f i c i en t and tha t , like Well TW 4-92, i s probably obta in ing as much r a l e r as the a q u i f e r can supply a t t he location of t he Mell; thus, TW 2-92 i s more va luab le as an observation well than as a product ion o r dewatering we1 1 ,

PlRR-1B-1993 12: 57

- 15 -

6047386070 P. 02

l'lar. 11 1953 10:21kH PD7

w

A punping test was a l s o c a r r i e d n u t on the John Thomas Well w h i c h , as previously mentloncd, i s located abou t 200 rn (650 f t ) southeast o f Well TW 1-92. The reG0rc.l u f t h i s Well has n o t been found i n s p i t e of a search th rough t t ip f i l e s uf Giwutidwtrtet-. S e c t i o n of B . C . Envfronmcnt and the f i l e s uf P x i f i c Water We' t Is L t d . t h e Well was used i n t h e p a s t t o supply water f o r a grave l wash p l a n t and I s reported t o be completed a t depth about 12.2 1 1 1 (40 f t } . It b o 5 on h l n g e d c a p which i s not Secure so the conditlon o f the Well i s uriknov:tr. S t a r t i n g on February 4 , 1993, the Well was pumped fur- 1225 iiiiniites a t a constant r a t e of 3 0 . 3 L/min (0.0 USgpm); t h i s pumping caused d drawdown of 2.32 ni (7 .6 f t ) , which was increasdng very slowly at t h e end o f the test .

A t the end o f . pumping, t h e water level rase very rapidly t o a level higher than the s t a t i c l eve l a t t h e s t a r t o f p m p i n g . One day after. . the end o f pumping, t h e water level was 0.56 m I1.03 f t ) abavt t h e original l e v e l . T h i s high l eve l r v c n t u a l l y declined t o 0.049 n i (0.16 f t ) on February' 23.

The bchaviour o f t h e water level in t h e John Thomas Well during t e s t i n g i n d i c a t e s t h a t t l i e Well i s v e r y Jnefficient and t h a t an e f f i c i e n t well a t t h a t l o c a t i o n would h a v e an h igher capacity. The inefficiency may be due t o o r i g i t i a t well coni t ruc t ion or t o clogging from d e b r i s , or for some other unknuwti reasnn. I t may be p o s s i b l e t o rehabilitbte t h i s w l l b u t , because i t i s riot deep and there is so little i n f o r n i a t i o n about i t , construction of a new wel l a t t h a t s i t e i s probably preferable i f , o f course, there i s a need f o r a well i n that area, e i ther f o r water supply or for dewater ing. In t he mcantimo, the e x i s t i n g well should he preserved a s a w a t e r l evc l abscrvat ion w c l l ,

'

4.5 Groundwater Qual i tz

A watcr sample was collected froni Well TW 4-92 a t t h e end o f the sin-day pumping Lest. dnd subwi t t e d for- a n a l y s i s . The a n a l y s i s , which i s cant-ained i n Appendix 11. shows t h a t the groundwater moving through the 5edJments filling Max Lake V a l l e y i s a hard water w h i c h may be clnSsed as a

MRR-11-1993 18: 17 P. 07

complex calcium i rnagncsiunr + sodium/sulphate i hlcarbonats type water . The t o t a l mineralization. as shown by the total dissolved 5c l ids of 892 mg/L i s q u i t c h i g h . Evcn so, t h e water i s generally s u i t a b l e for domestlc and other purposes except, perhaps, f o r a content o f 0.49 mg/L o f manganese which m i g h t cause s t a i n i n g o f laundry. and plumbing f i x tures . The analysfis indicates t h a t the groundwater I s from a long f l o w system o r i g i n a t i n g i n the mounta ins t o the west.

The conduct ivStks, as measured wi th a por tab le f i e l d mctcr, of groundwatcrs f rom Well TW 2 32 and the John Thomas Well show, as expected, similar water quality i o that f rom Well TW 9-92. As shown in Tgble 2 below. t h e conducttvity o f water i n Max Lake i n early March i s much less mineralized than the groundwater moving through t h e sediments T i 11 ing Max Lake Val l e y . However. the Lake water niay be more mineralized a t t h e end of summer when there is no iofluence f r o m spring runoff. Table 2. Chemical quality o f Groundwater from T a d Wells on Inland's Yest Bench Propcrty

. ---- Source Conductivity Remarks

( u S / c m ) . -I._I--

TU 4-92 1100 L a b o r a t o r y a n a l y s i s s h o w s a corplex groundwater

u i t h t o t a l d i s s o l v e d d o l i d s o f 992 mg/L f e r a

sample collected a t the cad o f six days o f steady

pumping.

TY 2-92 900 Sample collected a f t e r about 20 hours o f pumping.

iohti I'loaas h e l l qon Sample collected a f t e r abvu1 hours o f pumpinq.

#ax L z k e 400 Sa~iiplc Lollected on March 8, 1993.

PIFIR-I 1-1 993 67 : 35

- 17 -

6047386070 F. 06

5.0 HYIIROGEOLOGIC ENVIRONMENT

A s <tai.erl earlier, one o f t h e p r i m a r y o b j c c t i v c s o f t h e investigation Q f t h e groundwater rcgirnc on, arid i n the area o f , Inlal id C o n t r a c t i n g ' s proposed West Bench Estates Developliurlt was t o improve the knowledge crf t h e subject aren's complex hydrogeologic environment. The program of i n v e s t i g a t i o n has been q u i t e successful i n t h i s erdadvuur,

It. i s t h e Cornittee's opinion that a discussion of several fundatiiental coiicrpts concerning unsaturated groundwater f 1 ow, s5turated f 1 Ow

i n m i sotropic conditions character is t ic o f i c e cvntact sediments, and recharge-di scharge relations o f groundwater flaw should be discussed before eval u a t i rig the groundwater f l o w regime and, particularly, before assessing whether Inland Contract ing Ltd. I s proposed West Bench Estates Subdivision i s likely t o result i n negative impacts t o the West Bench east o f the proposed Development. However, before consider1 ng these fundamental issues of the groundwater regime, the framework i n which t o consider t he implications of Inland's proposed West Bench Esta tes Development must also be defined. The components of t h i s framework {hydrogeologic environment 1 are topography, geology and climate.

5.2 Topography

The a r e a of i n v e s t i g a t i o n i s located on an east -s lop ing bench along the west s ide o f the Okanagan Valley; t h i s bench extends from S h i n g l e Creek on the south to t h e mouth o f a steep-sided valley i n which Max Lake is located. l h e west boundary o f the area i s the sleep slope o f t h e mountains forming the Okanagan Valley; the east boundary i s Okanagan Lake arid further south, the f l a t valley bottom between Okanagan take nnd Skaha Lake.

Within these l i m i t s there are three main topographic elements:

1. Along t he western edge are several levels o f high gravel twraccsr t h o highest being a t clevat ion about 520 rn (1700 ft).

- 18 -

Mf?R-11-1993 07: 35 6047386070 P. 07

E , An died o i very ~rr-egular zopograpny composed o f i r r e g u l a r ridge% and srndll hill 5 Interspersed w i t h k c t t l c s (enclosed depressions) . The o r i g i n a l topuyraphy has bcrcn m o d i f i e d -In p a r t by extensive gravel p i t s lioth on t he Inlarid Pvoyerty drid on thc a d j o i n i n g Indian Rescrvc land t o the s o u t h .

3 . Eas t o f the irregular topogrsph lc element i s a gently east-sloping urea bounded UH the east by steep b l u f f s facing Okanagan iakc. This area i s p a r t l y dis>ect,ed by several stcop-sjded gullies; i t also contains many siiiall (arid a few l a r g e ) sinkholes, which are not cvcnly distributed b u t t e n d to be located close t o the s t e e p bluffs and the steep s ides of gull i es .

In a d d i t i o n , there are several minor topographic elements o f s ign i f i cance - for instance, a small raised d e l t a eas t o f the mouth o f the valley Of Max Lake and low l aws t r inc terraces a l a q Okanagan Lake.

The o r i g i n o f these features i s o f course related l o the geology o f t.he u n d e r l y f n g s t i r f i c l a l depos i ts which are i n turn related t o the geologic history - in particular, to events at the end o f the last g l a c i a l event I n t h e area ahout 10,000 years ago.

5.3 Geology

5.3.1 Bedrock Geo 1 ogy

P a c i f i c Hydrology's let ter-report o f June 25, 1991 which coatained a preliminary eva lua t i on of the groundwater regime 7'n the West Bench Area described the bedrock geology o f the s j t e as follows; "The West Bench area a t Pent lc ton i s underlain by metamorphic rocks o f the Shuswap Group, cons i s t i ng mostly o f s c h i s t and gneiss o f pre-Cambrian age". F o r the purposes o f t h e present Report, there i s no need t o expand t h i s discussion other than to note t h a t water supply wells 4n t he hedrack -in the s u b j e c t area h a w capacities estimated t o be low t o very low, showing limited fracture pcmoabi 1 i ty.

MFR-18-1993 13: 00

- 19 -

6647386876

5,3.? Sirrficial GC?OJOCJ~

Ttie surficial gcolngy o f t he s u b j e c t area has been descrlbed in several published/unpublished reports, i n c l u d i n g those by Nasmith (1962) and

NylarrJ/Milier (1977) ( s e e Rocumcnts 1 and 2, Scct ion 9.0). Sased on an investigation of water resources i n t h e Fauldcr-Mcadow Valley area West Of

Summerland, PHC concluded that., st t h e e n d of t h e most recent 9lacia.l episode a l l (or at l e a s t most) o f T rou t Creek flawed southward down the valley o f Max Lake l n t a the sand and gravel area west o f West Bcnch. I n f a c t , much o f thc sandy gravelly i c c contact dcpos l ts may have been deposited f rom T r o u t Creek on top of and around stagnant i c e i n t h a t area. The volum o f Trout. Creek flow w a s probably wry targc and it may have deposited a continuous mass 07; gravel south o f the present West Bench; the topographlc map Suqqests this. When i c e c lea red from the southern part Of the F a u l d e r a r ea , T r o u t Creek flowed eastward a l o n g i t s present course; i n f a c t , much o f the deep T r o u t Creek Canyon may have been c u t a t t h a t t i m e . The s h i f t o f Trout Creek t o i ts present course may have occurred q u i t e abruptly; i f sa , the stream sediments j n the bottom of Max-Lake Valley would be expected t.o he q u i t e coarse arid t o carry underflow down t h e Val ley, helping t o explaln I n par t why t.he water in Max Lake and other wetlands along the Valley remains f r esh . Water from T r o u t Creek may have cut. the l a rges t of thc g ir l l i e s th rough the s i l t when the high-level l ake in t h e Okanagan Valley was drained.

The present i nves t i ga t i on , p a r t i c u l a r l y the drflling of f i v e holes, h a s added fu r ther information concerning the r'ollowing:

1, the topography of t h e bedrock surface under the s u r f i c i a l sediments;

2. the character o f the sand and grave l a t several loca t ions ; and

3 . cnnditions a t the base of the 1a.custrine s i l t a t West Bench.

The lithologs o f test holes i n the sand and grave l , along w i t h excellent exposures in t h e existing gravel p i t s , show clearly t h a t the sand and gravel underlylng TW 2-92, TH 3-92 and TW 4-92, whlch were {nstallcd dur ing the present investigation, i s best c l a s s i f i e d as i c e contact depos i ts rather than outwash sand and gravel. The i c e contac t deposits in the subject area c o n s l s t o f a jumbled mixture o f sediments whlch vary i n gra3n sSze from coarse open-work gravel w i t h very little sand t o c l a p s i l t . Thcre i s some averlap i n these terms, as a l l o f the sand and gravel o f e i t h e r c l a s s i f i c a t i o n came from melting i ce ; however, the main difference between

- 20 -

MRR-10-1993 13: 01 6047386070 P. 04

Ilar. 11 1993 7:413HM P88

w

outwash and i c e contact deposits i s the presence o f large collapse structures and contortions in the i c e c o n t a c t deposits a t locations W ' w e t he sand and gravel was deposited on and around m e l t i n g i c e . Sediment classcd a s outwash, on t h e other hand, aften shows bedding and other c h a r a c t e r i s t i c s o f niore regular deposition from flowing water. There i s a small area o f such outwash i n t h e form o f a r a i s e d d e l t a , e a s t of the gravel p i t s , a t c l c v a t i o n about 455 m (1490 et), as shown on the p r o j e c t S i t e P l a n (Figure 1 i n Appendix A ) -

The c u r r e n t i n v e s t i g a t i o n has n o t entirely c l a r i f i e d the physical relationship between the ice contact deptxi ts and the l a c u s t r i n e s i l t . There i s no doubt t h a t the t w o materials are approximately the same age; both were deposited a t t h e end af the I d s t g l a c i a l episode i n the area. In f a c t , i t i s q u i t e l ike ly Chat t h e deposition o f t h e i c e cuntact deposits arid tho lacustrine s i l t was a t least partially simultaneous 50 that i n some Places one or other may bc oldcr while, i n ather places, t h e opposite may appear t o be t h e case. However, as discussed later i n t h i s Report, t h e time required f o r deposi t ion o f t he th ick s J l t m a y have been longer t h a n previous est imates. This suggests tha t the lower p a r t o f the s i l t i s older than the sand and grave l ,

5.4 Climate

Pipes (Eackground Document 31 describes (Page 7) the climate of t h e Okanagan Valley as follows; "The reg ion i s shielded from westerly storm by the Cascade Mountains, and experiences a senii-arid climate t h a t provides only limited amounts of surface runoff". As p a r t o f water b a l a n c e calculations (See Page 281, Environment Canada's Principal Stat ion Data for Penticton were examined and at-e presented on Figure 24 i n Appcndix C (Page c - 211.

MQR-11-1993 El7: 36

- 21 -

6047386070 P. El8

llar. 11 I993 18 : 23411 PQ8

U

6.0 GROUNDWATER REGIME

6.1 Groundwater ..Y, Hydrnlnrjy ~

The cnmplexi t y o f the i cc con tac t d e p o s i t s underlying West Bench ubviously lids an e f f e c t on groundwater hydrology. Thc paths oc groundwater f l o w under such c o n d i t i o n s can be q u i t e complex, w i t h water tendfng to take the pa th uf least rehistonce th rough t h e permeable parts o f t h s ! scdiments. For this rt.a>o(i, t h e water t a b l e m y not be a broad sloping surface. In F i l c h !;ediinr?ritb, cons t r -uc t l on of h i g h C d p a c l t y wells i s Of ten not possdble and a well const ructed In coarse permeable gravel may have limited capacity because t h e gravel m y be surrounded by l e s s permeable sediments. T e s t drllling i n an area o f i c e contact sediments may encounter only very low capacity aquifer w h i l e t h e r e may be much be t te r cond i t ions a short distance away; even s a , i n t he type o f i c e c o n t a c t deposits i n t h e subject areah there i s general hydraulic continuity a l t h o u g h i t may b e rather poor a t some 1 o c a t i ons .

An obvious q u e s t i o n t h a t r ises when toinparing the experience a t West Ocnch w i t h o t h e r areas i n the South Okanagan 1s: Why h a s there been so little t r o u b l e frwn waCer in the West Bench area which has been developed for agriculture (o rchards) and .housfng over t h e pas t forty years? We know, of course, about problems caused by water m a i n breaks and a ft?w- Ot.hL'r specific inc tdents . I t seems l ike ly t h a t there have been other accidents and many iniproper and excessive uses o f water over t h e years; examples would perhaps i ncl ude acci dent a1 over - i rr i g a t i on, coiit i nuously 1 eaki ng w a t e r majns. leaking swianing and ornamental pools and leaks o f domestic p l p i n g , e l t l i c r dlrcct ly onto the ground or by way o f domestic plumbing into effluent disposal f i e l d s , I n c i d e n t s o f t h i s k i n d , which a r e o f l i t t l e consequence under most c o n d i t i o n s , might be expected t o cause serious end obvious problems a t s i t e s u n d e r l a i n by dry s i l t . Far example, the Nyland-Miller Report (Background Document 2 ) and reports from other areas, show t h a t large ernounts of water, particularly f r o m the now obsolete dl tch i r r i g a t i o n , are assoclated with serious problans, particularly l ands1 ides. Long-time residents report t h a t d l t c h i r r i ga t ion was not practised on West Bench b u t , even s o , other excessive uses o f water have apparently not resulted i n i n s t a b i 1 i ty arid assvoi a t e d problems a s in other areas.

b1AR-11-1553 18 P. p18

A possible exp lanat ion f o r t h e lack o f severe or cvcn small problems i n t h e Wcst Bench area ljes i n an understanding of the rrature of uncaturated f law (or l a c k c i flow) f r om sources on the surface of the t h i c k s i l t . Varved silty lake beds are composed o f pairs of beds; a t h l n fine- grafned w i n t e r layer and a th icker coarser summer layer. The beds were dcpositcd a t the cnd af t h e last, g l g c i a l episode 4n the Okanagan when the Volley was occupied by a hugc l a k e w i t h a water surface about 150 m (500 f t) above t h e present lake, with thc coarser beds deposited i n the summer months when t h e r e was a large inflow o f sediment-laden meltwater f rom i c e in the uplands and t h e f lner beds deposited in winter when q u i e t water conditions prevailed, probably under ice. The varved p a i r s a t t he bottom o f the s i l t are very t h i c k , up t o one metre per pair, and t h e thickness o f the pairs decreases upward so t h a t those a t the t o p ai-e less than one centimetre th ick e t some l o c a t i o n s . The g r a i n s ize , and therefore permeability, o f the lake beds decreases w t h varve thickness.

Under the condit ions described above, i n which a thick p i l e Of sediments have lower permeability a t t h e t o p than a t t h e bottom, a source of water on or close t o surface percolates slowly by saturated f low through the slowly permeable fine Iwlnter) beds a t the top o f the varved sediments wi th the flaw becoming unsaturated f l o w as i t reaches more permeable beds. Such behaviour tends t o prevent s i g n i f i c a n t mounding or l a t e r a l flow through the coarser {summer) layers. If t h l s hypothesls 1 5 correct, i t may p a r t i a l l y account f o r the lack o f settlement i n t h e varved s i l t s below sources of water on the ground surface.

The present j n v e s t i g a t i o n has added much t o knowledge o f groundwater f low through the sedlments underlying the West Bench a t Penticton, and i t has confirmed t h e conc lus ions reached by Le Breton's Groundwpter Study OT 1976 (Background Document 61, which was carried out during the i n v e s t i g a t l o n by B.C . Min ist ry of Highways and Publ ic Works t h a t resulted in the Nyl and-Mi 1 ler Report (Background Document 2 ) . The impor tan t polnls are:

1. There i s a deep (34.5 m; 113 ft) rock valley filled wi th glacial sediments trending south from t h e Max Lake Valley under t h e Mash Plant I n the e x i s t i n g gravel p i t . At the Wash Plant , t h i s Valley contains two aquifers, a shallow one which supplSes the Wash Plant Well and a deep one above bedrock. TW 4-92, constructed as a screened production well during t h i s invest igat lon, i s completed in t h e lower aquifer.

MRR-ID-1993 13: 13

- 23 -

6047366078 P. E32

2 . TH 1-92 confirms t h a t side o f the Max Lake

there i s a bur jed rfdge o f bedrock along the e a s t Val 1 ey; t h i s ridge prevents f l o w of groundwater

eastward from t h e north end of t h e bur ied valley mentioncd prev ious ly .

3. The drilling of TH 3-92 i n the lowest part o f the e x i s t j n g gravel p i t near the south boundary o f the Inland Proper ty has shown that t h e deep buried valley extends southward under t h e P c n t i c t a n IndCan Reserve. Evidence for t h i s conclusion i s the driller's lithologs of t w o recently drilled hole5 a t t h e Band's grovel p i t ; however, the product ive grave l and sand aquifer i n TW 4-92' does not extend t o TH 3-92. Bedrock i s a t a depth of 39.6 m (130 f t l bctm t h c bottom o f the gravel p i t .

TH 3-92 ( a t elevation 467.8 m ) 5 s completed w i t h t h r e e small diameter piezometers a s shown on Figure 11 {Page E! - 11) and as summarized i n Table 3 which follows.

T a b l e 3. Details of Piezometers i n In land TH 3-92

D e p t h t o R i d d l e E l e v a t i o n D i s t a n c e Y a t e r Tahlo Date o f

P i c r o m r t c r o f P i e z o m e t e r o f Bottom t o W a t e r Elevation ObsPrvat i on

( T t ) ( m l (ml ( n ) - ~~ - -

a-92a [6haiiow) 25.5 (83.5) 408.5 8.13 461.7 Jan. 15/93

3-92b ( m i d d l e ) 33.8 ( I l l ) 434.0 5'53 4 8 2 . 3 Jan, 35/93

3 4 2 c [deep) 39.6 (130) u a . 7 5.94 481.9 Jan. 15/93

The three piezometers were installed a t t h e selected depths i n order t o show the groundwater gradient; i n other words, whether groundwater i s moving upward from t h e bedrock i n t o the aquifer or donn from land surface i n t o bedrock. The observations of January 15, 1993 show that the water t ab l e i n bedrock 4 s higher than i n t h e tniddle piezoewter; these water levels are evidence t h a t water movement i s upward from the bedrock i n t o the valley f i l l . T h i s I s not unexpected, a s TH 3-92 i s located a t the discharge end o f a very long grwndwater flow system i n which water i s moving through fractured rock f r o m the mountains eastnard t o the Okanagan Yalley. Accordfrrg t o Table 3 , the water t a b l e in the shallow piezometer on January 15, 1993 was a lso higher than t h a t In the middle pfezometer. This may be due t o winter recharge o f water f rom p r e c i p i t a t i o n in t h e p i t area, as by January 26, 1993 (see Figure 22, Page C - 23), the levels showed an upward gradient f o r a11 piezometers, followed by a reversal again by February 23, 1992, a t which time, the elevation of the water table i n the shallow piezometer was again higher than t h a t i n the middle piezometer.

- 24 *

MRR-18-1993 .13:14 6047386070 P. 03

tlar. 11 I993 7:421iM P1B

W

4 .

5 .

TW 2-92, a screened well located near t h e southeast corner o f the In land Property, was drtlled through icc contact sediments t o bedrock a t a deptti o f 29.7 rn is13 ft). The ice con tac t sediments conta in patches ~f s i l t , M i t h t h e largest patch extcndfng from 23.5 to 26.2 m (77 to 8t f t ) , cithor i r id icdl iny t.l-rat thcrc is an interflngering contact betueen the i c e contact deposits and the s i l t , o r t h a t thc si l t i s part of t h e i c e contact deposits w i t h no connection t o t h e sJlt under West Benc t i .

TH 5-92, which, a s illustrated on Figure 7 contained i n the pocket of Appendix A , and which I s located in the bottom o f t h e south branch of the south gully, has s h a m very t h i c k section o f saturated sllt under West Bench. TH 5-92 ( a t e levat ion 379.3 rn; 1244 f t ] i s completed w i t h two snrall dlarrreter piezometer-s (see Figure 12, Page B - 121, as summarized Sn Table 4 which follows.

Table 4. DcLailr of' Piezometers in I n l a n d TH 5-92 ~~ ~~~ ~.

fispth t o Middle f l e v a t i a n D i s t a n c e d a t e r l a b l e Date n f Picrometcr o r P i e z o m e t e r a f gottom t n W a t e r FIevetion D b r c r v a t i o n

mi ( f t ) ( e ) ( m ) ( m ) .. _ _ . .. . ,..

5-9i'a ( s l i a l l o u ) 73.2 (240) .mj.i 3b.06 344.30 Felt. 1(1/93

5-92a ( d ~ c p ) 103.7 (340) 275.6 75.05 30fb.25 rob. 16/93

34.9) 3 4 4 . 3 3 MaF. Ob/93

36.43 342.87 Mar. 08/93

A s shown above i n Table 4 , the water level i n the shallovi piezometer i n the s i l t reached equilibrium almtrost immediately but the lcvcl in the deep piezometer completed in t h e bedrock may ( a s o f March 8, 1993) n o t ye t have rgached equilibrium indicating t h a t recharge t o the s i l t from the bedrock i s n o t substant ia l .

Same o f t h e questions concernjng groundwater hydrology which have been substantially confirmed by the present. i n v e s t i g a t i o n include:

f - The hydrology o f the valley o f Max Ldke ($oiriethws c a l l e d Madel ine Lake 1 .

Nasmi th 's Report (Background Document ? 1, and more rcccnt work near Faulder west o f Sumeriand, show that Max Valley vas a meltwater channel a t the end nf the last glacial episode, when Trout Creek flowed down Max

- 25 -

PIRR-11-1993 E37 : 37 6047386070 P. 10

Lake Valley. An examination of t h e Valley indicates t h a t t h a r c has not. bccn any surface f low i n the Yallcy since t h a t t i rnc, Max Lakc and scvcral o the r sloughs i n the Valley result from t h c t rapping of 5UrfaCC water by small f a n s which were deposited i n post-glacial time. There 4 s virtually no surface f l o w but the question remains as t o the amount of onderf ' low down t h e Max Lake Valley. The results o f drilling and t e s t i n g TW 4-92 rcsolvc Ll i is uucstion. The rwck vslley a t TW 4 . 9 2 i s twltcr*+kdlrly deep (34.5 nl; 713 ft.) and dri119ng c n c b u n t c r e d two o q u i f c r zones! ant? nlfar surfacc and t h c other j u s t above bedrock. The lower aquifer obviously carrips t h e undprflow through t h e Valley and the pump testing Of a properly screencd wclll i n the lower aquifer shows qui te convi nci ngty that:

a.

b . pumping o f t h e well a t d moderate r a t e cai), a t least partially,

down-valley flow through the aquifer i s quite s m a l l ;

dewater the sand and gravel area.

2. Eastward f l o w o f water frQm t h e sand and gravel undcr the s i l t has been considered t o h e a factor i n the stability o f the s i l t . There are several questions:

a . HOW much groundwater i s flowing from the sand arid gravel a t the

h. Does i t f l o w i n the bottbrn of the silt just above the bedrock?

c . What i s t h e p a t h of f low of the water i n the sand and gravel as i t travel 5 toward Okanagan Lake?

d . What might be the effects of addit ional water i n the sand and gravel area?

present ti me?

The present. i rlvestigation provides convincing evidenctr t h a t the amOllnt o f yroufidwator entering t h e sand and gravel f r o m the vat ley Of Max Lake 1s smal I . The amount o f water from precipitation on the sand and gravel area has been shown by the report on the C a n s Landing Watershed by P i P C S (background Document 3) to be very sinal 1 , w i t h 15 ttl e p rec ip i ta t ion reaching the water table .

From the drilling of TH 5-92, i t i s clear t h a t the elevation of the bedrock surface i s much lower under t h e s i l t than had been estimated p r e V i O U S l y , w i t h a very t h i c k section o f saturated s i l t undcr West Bench. l h c thick zone o f saturated s i l t i s capable of carrying laore than the

MRR-11-1993 07:36 6047366B70 P. 11

Mar. 11 1993 7:43kM PL2

U

present sa.stward groundwater flow, a t a low velncity and low grad ient f a r

below what would be required to bring about changes i n t h e s i l t 1 . l ~

mobi 1 i z l ng c l a y or by nther processes.

6.2 Groundwater Gradient and Direction of Flow

Whcrc the in format ion i s suffcclent t o do so, the groundwater f l o w

directions have been i ndicoted on the hydrogcotogic section.; prcscntcd On Figures 2 to 8 (Appendix A ) , An examination o f these sect ions shows t h e f 01 1 owi ng :

1 . A s indicated earlier. t h e more pernlcable r o n m i n thc scdimcnts are located predominantly i n the western port ion of the study area. The permeable zone5 w e generalty o f limited areal cxtcnt, and are often poorly interconnected

2. There i s no evidence f o r a continuous aquifer extending from the West towards Okanagan Lake.

3. Piezometric heads i n TH 3-92 and TH 5-92 suggest t h a t there i s a downward vertical component of groundwater flow i n much o f the study area. Evfdence for t h i s i s given by the behaviour o f t h e water level i n t h e upper piezometcr of TH 3-92 in response t o recharge events, as evidenced during the present invest igat ion and as summarized by the data on Page C - 13. Evidence o f an upward gradient i s given by:

a. The relationship o f the water levels i n t h e three piezometers I n TH

b. The water wel l t.hat supplies Redwing Resorts (Well 2-2 an Figure 7

3-92, as measured on January 26, 1993,

i n the pocket o f RppendAx A ) and which has a s l ight artesian head.

4 . Both t h e seismic survey and our interpretation o f the confirmed elevations of the bedrock surface, ind ica te that there i s a low-lying bedrock valley which extends from Max Lake f n a south-easterly di rec t ion towards Penticton. A low-lying buried bedrock ridge appears t o f o r m the eastern boundary o f t h i s val ley . As previously mentioned, the' presence of t h i s r i d g e has the effect of promti r ig groundwater f l o w i n a predominantly south-cast d i r e c t i o n from Inlands' proposed subdivision.

MW-11-1993 07:39

- 27 -

6047386070 P. 12

6.3 Hydraul i c Conductivity

A n ana lys i s o f the results 04 the aquifer pumping test conducted i n fkl 4-92 suggests t h a t the hydraulic conduct iv i ty of sediments I n t h c gravel p i t ; area i s i n the order of 4 x 10‘5 m/s. Simi lar ly the sedinients i n t h e v i c i n i t y of TW 2-92 ape! dn the order o f 1 x m/s. As TW 4-92 5 5 i n B chsnnel ( s e e i-igure 6, Page A - 61, most o f t h e groundwater w i 11 f l o w i n a south-easterly direction { i . e . au t o f the plane o f the sectSon) i n the more permeable and thicker silty j c e contact sediments o f the extensfan o f Max Lake Valley, rather than eastwards ( i n t h e p l a n e o f t h i s sect<on), and over the subsurf ace bedrock ridge.

- 28 -

6047386070 P. 07

Ilar. 18 1993 ::ZIPM PO8

‘CJ

7.0 UATER BALANCE

7.1 Est imating Groundwater Recharge

Recharge to the groundwatcr flow systems i n a sem5-arid area, Such as Penticton, w i l l only occur when ra in fa l l or snow rnctt exceeds the water- hirldqng capacity u f the surface sediments. I n the eastern portion of the In land Pruperty, wtiar.c? f iirr-yr a i i i d soi 1 s p r t d a d n a t c , thc water hold4ng capacity is likely in the order o f 200 mm and, on thc western side, t h e capacity may be BS little as 100 mm.

As s general “rule-of-thumb”, groundwater recharge in BrCtZsh Columbia can be est imated as anywhere between 5 and 30% o f t h e average annual t o t a l p r e c i p i t a t i o n , the Iwer percentage being appl iceble to the drier areas, such as Pentictcn. The average annual total prec ipi tat ion f o r the Pent ic ton A i r p o r t S t a t i o n i s 282.9 nm; on t h i s b a s i s , for t h e development a rea where gravels are exposed near surface, 10% of the prec ip i ta t ion , or 28 mm, would be judged a reasonable estimate f o r the average annual recharge. Other, more rational methods arc: analysis of hydrographs and back analyses o f seepage flaw.

7,1+ 1 Hydrqraph Method

Hydrographs o f water levels monitored durlng 1977 and 1978 j n 6.C. Ministry o f Fighways Test Hole No’s . 2 , 3, 6, 7 and 8 are presented i n Figure 24, dlong w i t h relevent precipitation and temperature i tiformation. These hydragraphs clearly show t h a t the only time groundwater recharge takes place I s I n the spring, when accumulated snaw on the ground Surface m e l t s and some o f the water seeps down t o the water table. The niagnitude o f the water t a b l e r i s e varies from virtually zero in TH-2 t o two metres i n TH-7, This r ise i s only an Sndicatjon of recharge and cannot be directly correlated t o the magnitude of the recharge event.

A s the water f i l l s the pores between the sediment grains, a Water level r i se n f say one metre is indicative of a t most 300 m o f infiltratlon; however, i n areas around the gravel p i t where TH-7 i s located, there 5 s l ike ly to be some pooling in t h e subsurface reservoir, which w i l l result i n a greater rise i n the water table.

~ I R R - I B - I ~ ~ ~ 13: 17

- 29 -

6047386070 P. 08

F;-clm : PFICIFIC H"3RCCOGI CCNSULTHtJTS PHOt-IE No. : 03473336078

tly

A s indicated on F4gure 24 (Page C - 211, i n January o f 1940, there was about 6.5 cm (75 m} o f snow on t h e ground surface; assuming a water content of 10%. t h i s translates to an cqujvalent depth of 6.5 uiin uf water. If a l l o f this water seeped i n t o ;he ground, assuming d s o i l pvrusity of 0.35, then the calculatcd net r i s e 4n the water t a b l e , assuming no p u o l i a y effect, i s 6.5/0.35 or 18.5 mm or 0.018 111,

The average annual prec ip i ta t ion falling as mow i s 76 mm (see Table 5, Pagc C - 22) and hence, after allowing for evaporation losses, the 65 mm snow accumulation in January 1980 should be consfdered above average. Raced on a l l o f t h e above considerations, We judge t h a t the average local recharge ta the water t a b l e i s likely t o be in the order of 30 mm-

7.1.2 Seepage Flow Met hod

The hydraulic gradient (i 1 between Th 3-92 and TW 2-92 i s about 33 m per km; i f t h e average hydraulic conductivity (K) i s assumed t o be 1 x lo-5 rn/s over a channel 300 m wide and 10 rn thick, then the f l o w through a cross-sectional area o f 3,000 mu can be calculated using the Darcy equation: Q = K1A = 9.9 x 10-4 m*/s

The local catchment area feeding t h i s channel i s probably less than one km; hence, the recharge f l u x i s 9.9 x 10-6 tn'/s/106 o r 9.9 X

10-10 d s . T h i s converts to an equivalent recharge o f 31 inin per year, which i s sjmilar t o the value determined from the hydrograph method.

7.2 Potential Impact From Proposed Dwelopaent

It i s understood t h a t the probable maximuin area being considered fur res ident ia l l o t s i s I n the order or 52.6 tlECLdr.eS (130 acres) . As the proposal i s t a develop 0.2 hectare (half-acre) density, t h i s suggests t h a t the maximum number o f lo ts wSll be 260, Assuming t h a t each house discharges the normal average o f 1.35 rn'iday (300 igpd) t o a sept lc tank, and based On experience elsewhere, we can assume only half o f t h i s discharge w i l l f lnd i t s way down to the water tab le . T h i s increased recharge w i l l not cause the water tab le t o rise more than a few centimetres, further evidence t h a t Signi f icant diversion o f groundwater towards t h e east w i 11 not occur.

- 30 -

~ I ~ R - I I -I 993 07 : 39 6047386070 P. 13

8.0 IMPLICATIONS UF GROUNDWATLR REGIME WITH RESPECT TO POSSlnLE IMPACTS FROM INLAND'S PROI'OCJCD NEST BEHCll ESTATES

Thf! n o ~ l tinportant q u c s t i o n to bc addressed by t h l r Report Wllat, i s likely t o happen F f t h e prol,osed I n l a n d CurltraCting D@veJOprnPrli.

Two scenarios under which Develapmerlt ntight proceed nccd t 5 be

l h e Uevelopdant proceeds as proposed wi th no prov l s ion f o r control of t h u yr.aut?dwat.er or surface w l r l c r hydrology, except 'as nccessary t o S W V B the hr?vr?.lopnient.

[he Development proceeds but i t i n c l u d e s f a c i l J t Z c s to carefully monltor and cvntrol the hydrolbgy of the area i r i such a way 4 s t o ensure that- there are no adverse impacts on e x i s t i n g c o n d i t i o n s a t West Bench. The log ica l agency t o carry out i non l to r l ng i s Groundwater Section o f R.C.. Environment who o p e r a t e a Provincf a1 Network of water level observation wells.

i s ; proceeds? cons i &red :

a .

b.

There i s now enough subsurface infoimatlon on hand t o sliow t h a t i t . i s (lossSble to proceed on either b a s i s and, further, tha t the best est imate i s t h a t the f i r s t alternative w i l l not have any ef fec ts on Mest Bench. This statement is, o f course. based an c e r t a i n assumptions: .

7 . A number o f parameters wi l l be morjitored s t a r t i n g before any Development a c t i v i t y proceeds and such nloni tor lng w i l l be conttnued through the l i f e O f the UPVclopMnt. .

2 . A l l aspects o f the Development w i l l be based on t h e concept o f water conservation. For example, a1 1 domestfc water connect4ons w i l l be metered, a l l irrigation of lawns and gardens w i l l be c a r r l e d out according t o the best water conservat ion techniques, e tc .

3. All d a t a from monitorlng will be assembled once each year and examlned for any gradual long-term changes.

4. Changes which are observed jn ( 3 ) and which can be percejued t o cause problems. will be countered by t a k i n g mitigatory action.

The bases f o r the previous statements are as follows:

1 . Data from the present and previous Investigations rhaw t h a t the amount o f n a t u r a l groundwater i n t h e %and and gravel i s not large.

- 31

MGR-11-1553 10: '15 P. 09

F i o m : PfiCIFIC HYDROLOGY CIII'4SULTQNTS PHONE No. : €847336070

w Mar. 18 1'393 4:43PM W.2

U

DRAFT

2. The northern part of t h c Inland Property i s hydraulically i so la ted from West Bench by a buried rock r i d g e which prevent?. easterly groundwater C l a w u1.rdc.i- U c s t Ucnch. CvovndwsCor rnouoniont aactword through tho t i 11.

urider- Lhe south part of Mest Bench i s considered to be 3nsignif icant-

3. lhc saturated thickness o f s f l t undcr the south p a r t of West Bench 4 6

very large and has the copability o f transmitting groundwatcr at a 1 0 W

gradient and low velocity.

4. In the event that i t I s desirable or ncccssary to control the level of groundwater i n t h e sand and gravel, the water, although i t s quallty I S

not very high, can be p u t t o beneficial use. I f necessary, there are a l t e r n a t i v e s f o r water disposal a t reasonable c o s t .

5 . The essential monitoring equipment and procedures are quite simple and very rel iable . The effort and costs required for adequate monitoring are mal 1 . The main monitoring i teins' are water l eve l measurements i n observation wells and regular readfngs o f water meters a t p o i n t 5 of production and consumption.

MRR-18-1993 16 : 38

- 32 -

6047386070 P. 02

PWR-10-1993 13: 19

APPENDIX A

ILLUSTRATIONS

6047366070

ilar. 18 1993 1:24PM P12

PJ

F. 12

APPENDIX B

1992 TEST HOLE AND TEST U€LL LITHOLOGS,

TEST WELL AND PIEZOMCTCR CONSTRUCTION

- FIGURE 9 I WEST BENCH TH 1-92 CONSTRUCTION DETAILS

j

Ele\ntim ot top of 200 mm (8") diameter woll oaLlng 7 480.9 rn (1 577 fq.

200 mm (8") dlamQcer casing extends to 6.7 m (22 ft).

Backfill.

Bdmek su- at 7.S m (24 H).

50 mm (Z} dlameter slatted WC pipe.

Test hole drilled to 10.1 m (33 fl) in bcsrlmck

Nolea: 1 . 2. s.

The sketch is not to scale. All m%aburements are belowgrcund unless otherwise Indicated. The 50 htn (2") diameter open-end piemmeter consists 01 m&ehfna-slw&d pipe with openings of 0.5 mrn pn207,

C ' I

B - 7 F. 02 MRR-I~-IFB~ 13: 31 6047366070

. . .

.I_rr On January 22.1893 prior to pump testing. atatia water

l a ~ d e 1 P.63 m (57.83 It) bvluwwel caking datum.

Tap ut type K packer at tap of screen assembly = 26.3 m (86.3 ft).

1 ,S m (5 fl) of 127 rnm (0.0W) slot screen.

plate boltom 28.0 m (91.8 A}.

Notes: 1 . 2. 3.

The sketch is not to scala. All measurements are below ground unless othetwise Indica!ed. The welt screen is 200 mtn (8") nominal diameter Johhnoon stainless steel.

MRA-10-1993 13: 32 6047386070 P. 03

. .., ... ---..-.- .

. . , . .- . ...

. ... ..-

, . . -. -. __

I I

I I I

Backfill.

sand pack.

25 mrrt (I"} diameter W C pipe stacted beween 25.0 and (82 and 05 R).

GO mm ( 2 ) diameter P'dC pipe slotted batween 83.5 and (11Oand 112ft)

Qrout sed.

Bedrock ourface at 39.6 m (1 30 n) 50 mm ( 2 ) dlamewr FWC pipe (identified as 3-.92c by a

slotted between 39.3 and 39.9 m (129 and 131 I f ) .

. . - . . . -- ---

____A*I I.,---- Notes:

I 1 The sketch is not to scale.

FIOURE 12

I I- T---]=

WEST BENCH W 4-92 WNSTRUCTION DETAILS

200 mm (8") diomatPrwell caaing stiakup = 0.7 m (2.3 ftb alavation d d n g 4R2.8 m (15n3 8).

On Jmuary 22 1993. smicwater lwd = 3.16 m (lO.38 11) blow well aasing datum.

T o p c d t y p e K p a o k e r a t ~ p c / f ~ n ~ m b l y = 2 8 . 3 5 m(D3ft).

0.6 rn (2 fl) d blank riirer pipe.

15 m (5 ft) of 1.52 mrn (0.080") slot screen.

0.g m (S ft) d blank riser pipe.

1 S m (5ft) of 2.54 mm (O.tW) slot screen,

1 .S m (5 ft) of a81 mm (0.150') dot scrw~n.

Plate bottom 34.9 m (1 1 d.5 ft)-

NQtes: 1 . 2. 3 4.

The sketch IS ndt to scale. All measurements ax8 below ground unless othscuuise indicated. The weH screen IS 200 rnm (8") mrnihzd diameter Johnson otalnless steel. The riser plpe in Iha screen assembly io 178 mm (7) L d.

.-c

B - 10

P. 05 ~ I ~ R - I 0-1 993 13 : 33 6047386070

!I&-. 1B 1993 1:38PM PI36

FIGURE t3 WEST BENCH TH 5-92 CONSTRUaION DETAtLS

Elevation af tbp af 150 m m (6") diameter well carring = 378.3 m (t2d411).

Backf 111.

On FbbruatY 22.1 B93, the static whtar level In: TH 5-921 = 35.0 m (1 14.8 e): TH 5-92b = 43.8 rn (163.5 ft).

Behtonite seal from 65.2 lo 66.5 m (23 4 to 21 8 ft).

150mm(6"}dlam~rcaslng e n d s t a 6 3 . 8 m(224 ft).

31.75 rnm (1.25") diameter sluned FVC pipe. batcorned at 73.2 m (240 It).

Backfill.

B e d d surface at 98.8 m (324 ft).

Bentonite beal from 9S,? tr~ 101,2 m (327 to 332 ft).

31 -75 mm (1.2!?) diameter slotted W C pipe.

Tes! hult drilled to 103.8 m (340 fi) tn Wmdr

Notee: 1 , 2. 3,

The sketch is not to scale. AU measurements am below ground unless bthenviee indrded. The 31.75 mrn (1 23") diamster piezometers asnnist at nsanual)yr slotted PVC pipe.

B - 11

MRR-1B-1993 13:33 6047386076 P. 06

APPENDIX C

PUMPING TEST DATA AND PLOTS,

HYDROGRAPHS OF B.C. HlGHklAYS TEST WELLS

AND DATA FOR PENTICTUN CLIMATE STATIONS

PlkR-1[3-1993 13: 34 6047386070 P. 07

ci

. ..

ri 3 ._

w .. c.1 VI

1

Figure 14. Semi-logarithmic Plot 01 Drewdomn in l W 4-92 and Wash Plant Obsenmtion Well

Tme i n Minutes Since Pumping Started

10 100 lM00

P w4-92 Wash p b m Well

b- * .

-u m m

f 10

I)

10

20

30

40

50

60

1

Flgure 15. Sarni-iogarithmit Plot of Recwey of Water Level in TW 4-92

1 o m

FiqurB 16. Semi-logarithmic Plot of Recowry of Water Lwet in Wash P~unt Observation Well

t ime in Minutes Sin- Pumpins of TW 4-92 Staned Time in Minute sib- Pclmphg Of TW 4-62 Stopped

1 10 100

C - 16

I1!4R-10-1993 13 : 35 6047386070 P. 09

.I

Figure 17. SemHogaritkrnic Plot of Changa in Water Level in John Thomas Well During Pump Testing of TW 4-32

1 TO

Time in Minutsr Since Pumping of Tw 4-92 Startcd

100 7m 5m 1 Dolm

I

1-J

k- .. L Q 3

ilar-. 18 1993 1:42PM P a l

w

Figure 18. S w m i - l o g ~ r i h m i c ~ d at Drawdawn in TW 2-92

b

!i

15

2

25

30

5 h

E.

- f 15

P a 20

25

1

Time in Minutes Sin- Pumping Started

10 100

F'igure 1 9. Semi-iogerrthmic Plot of Recovery of Water Level in TW 2-92

Time in Minubs Sin- Pumping Starled Time In Minules Sin- Pumping Sbppbd

1 10 1M)

MRR-1B-1993 13: 38

C - 18

6047386070 P. 01

Figuto 20. Gomi-logarithmic Plot of Drawdown in John Thomas Well

Time ih Minutea Sbh- Pumping w r i e d 1 I O 1 OD 1000

0

2

4

g. s 6

10

12

14

nainlained at 8 0 USgpr

Figure 21, Semi-logarithmic Plot of Recovery of Water Level in Jahn Thomas Well

1

Time in M h t f e s Slnce Pumping Started Time in Mihutes Since PumpinQ Stopped

10 100 +2

+1.5

1.5

2

c - 19

6047385070

1500

F. 02

Figure 22. Changes in Weter Level Eisvations in Pierornetera at Weet Bench TH 3-92 Between January 11 and February 23,1993

Figure 23. Changm in Water Level Elevation in Piezometers of TW 5-92 During Februtuy end March. 1993

MRR-I 0-1 993 13 : 39

n U

0

U

6047586070 P. 03

TU- 7 i

TH- 2

--- t

c - E l

INLAND CONTRACTING LTD. CONSULTANTS

HYOROGRAPHS QF I BC HIGHWAYS TEST WELLS QROUNDWATER INVESTIGATION PENTICTON, B.C.

-1993 13:39 6047386070 P. 04

F r o m : I ' 9 C I F I C H','N?ULOGY C13NSULTQV3 PHON tlo. : €84738612174

bl

ElkR-1 0-1 993 13 : 40

APPENDIX D

GROUNDWATER QUALITV

Plat-. 1W 1993 1:43PM PO5

6041386070 P. 05

lw&huuu Colour cu conductivity u f n h 6 6 / c m Total P i r e a i v e d S o l i d 6 Hardneau CaC03 FH

Total Sucigendrd Solids Turbid i ty NTU - E l k a l i n l t y - TQtal Chloride C l Fluar de F Si1 icate si02 Su Iphat e SO4

tnAwmu - N i t r a t / pJ i t I at e P J I t r nq en N

T-AP

Cadmium T-Cd

A r s e n i c Barium T-Ba

Calcium T-Ca Chromium T-Cr

Copper T-Cll

Le8d T-Pb Iron T-Fe

Maqnsoium T-Mg !.la naaneb e T-Mn

Wtasrium T-K Sodium T-Na Z i n c T-Zn

22 .0 l l O D rr2 510 7 . 9 4

<1 3 - 4 8

325 10.0 0 686 28.2 324

CD. 009

0.0002; 0 . 0 6 5 <I) .0002 I32 co. 01s

<0.010 0.492 10.001 4 3 . 5 0 . 5 2 6

4 . 9 6 61.8 o .ai0

Remarks regarding the analyeea appear a t the beginning of t h i s report- < = Lese than the deteccfon limit i n d i c a h d . Results.are expressed us mLlligrams per l i t r e except where noted.

PIRR-I 0-1993 13 : 40 Page 2

5047386070 P. 136

APPENDIX E

PACIFIC HYDROLOGY LETTCR W JUNK 25, 1992,

"GRDUNOWATER REGIME I N THC WEST BENCH AREA AT PENTICTON"

IWR-18-1993 13: 41 6047386EI70 P. 07

cnm : P4CI F I C H'KEECJLOG'r' 33NSULT'" 'T P H O E No. : En47336DX Plat-. 1B 1993 1:46PM P88

w

APPEHDIX F

E.G- LEBRETON REPORT OF DECEMBER 13, 1976,

"Gf?OUI(DWAER STUDY - WESfEENCH/SAGE MESA AREA, PEHTICTON, B.C."

P. 08

I1a.r. 18 193 1:46PM PD9

W Deoember 13, 1976

W i n following sumrnnry ramarks are o f f o r c d Q ~ I it'ifo*rnatfOn

r a o e i v e d Novombor 16, 1'376 rrom the Knrnloopa Regional

O f f i c a , Minietry of Highwayn end Public Works. Same a d d i -

tiannl intarm~t%an w i l l ba oubmittod at a latar date.

data s u p p l i e d LR a combinak.lan af work whlch io often under-

t ~ k h n by the Mintstq of Highwayf f and Public Works and a Pe-

s u l t of' office dZscussions, end also of suggestions a f t e r a

onc-dny f l e l d trip Go the Rtudy eree July 20, 1976.

The data compsines d r i l l hole information, chemical analgflf.8

and pieeometer data.

A Fequftst was mnde that frequent informal progrn~s reports

be made as information becomes available, so that d a t a could

bo utilized 88 early as possible, This 1 8 such a progross

report .

The objectives of the study a r e r o s h t e d below, end progress

to date is evnluated in relatfon to the8e objectives.

1. Present groundwater situation - magnitude and direo- tiana of flows. Particular attention to quantity

2 . W h R t effect w i l l additional water in.t;roducscl into

f l O W h g t h r O U g h 851tS.

tho gravel arees hevn on piersornetric aurfeces w l t h - in the gravols and adjacent silts. of Nasmith's report indicetes oontlnuoue grave18

(An .inspectfon

MOR-1 0-1 993 13 : 42 6047386070 P. 09

Har. 113 1993 1 : 47Fl1 P 18

U

3 - What af'feot w i l l (a) doubling (b) t;rcibling praaent dwelling rlnnalty in t h e Wea+brsnch/Sage, Mean areas have on pioeometria l e v e l s within Che ailts."

Tho study erea i a shown in figure 1.

- G 9 0 l O ~

llh~ dalll h o l e d a t n v e ~ i f i ~ ~ tho surficial goology of khe

area ( N a s m f t h , 1762) whfch $3 desarlbed a8 mainly outnaah

sands urid gravels occupying the w a a t part; of the atudg are@

and thick lacustrine s1I.l;~ occuring i n the e a a t p a r t of the

a r o ~ , Se%smIc work includes one week t o aaaii crass-section

ahowing that; the westerly gravels may d i p 60 the eask beneath

the a i l t a . Though %hiwing o u t i n an easterly direction, the

oofirae granular d e p a a i t s may Rot R R cenduiC6 for groundwater

movement; with in t h o a m a , and sometime8 RS aquifam.

The main sa18nric p m f i l s showa a steadfly. though somewhat

irregularly falling bedrock awfscer from west %o ea8 t {Figure

2). In this same directton the depth to bedrock incresses

from about 3s feet to about 4 0 f e e t and probably more. The

irregulftrity in the badrock surface i s posslbly a very i m -

portant factor hnlp4ng to d ~ ~ ~ ~ l 1 1 8 movement of poundwator,

and w a t e r l e v e l s Fn the we8. The northern seismio profi le

show a morn unifomly and atssply aloping bedrock surfaoe

w i t h depth to bedrock increasing from about 10 f e e t to m o r

200 f ee t . Again here the conf igura+ion of the bedrock Bur-

face may be important in terme o f groundwater movomont; in tha

6047386870 P. 10

t1ar. 10 1993 1:mPfI P 1 1

U

Hvd r 0 Reo l o a

?Dir eo t f on of Groundwater Movement

From the l i m i t e d d a t a available from w a t e r l e v e l measwe-

mont;a, and dryho les , i t appears that the water table may

hrond f r o m wont f;b oaet;. %is oanfarms to the established

prfnotple Chat the w a h r t,abla i n aamonly s i m i l a r Co tha t

of the topography of the l a n d surface.

However it has been pointed out that the bedrock surface ?

V' m y be an important f a c t o r conbrolling groundwabr movement

and ocmrrenoe of groundwater iri t;he area. The w a t e r tab le

(hydraulto gradient) along the msfn cra8s-aeaDian shawod

continuity through t e s t holes 7 , 6 , 3 and 2 c a t one t i m e (F igure

2 ) .

went d r y at t h e end of October 1976. It is poss ib le that

the water tab le is cwntinuoua within the sand and gravel , tho

bedrook and the silts along thia prof i le . However %his may

This continuity has since been bpoken after hole No. 3 ?

not be so, and unlsss the bedrook Pa highly fracGlrred the

quantity of water flowing through the bedrock t e r r a c e betwesn

holm 6 and 3 is e x . 8 o t e d to be very s m a l l compared to that

flowing through the sand end gravel overlying this terrace.

Permeability figures m a g b8 of the order of 1 to 10 Usgph (ft2)

(United S t a t e s gallons per day per square>foot) for the bedraak

compared to 100 to 10,000 mgpd (ft2 for sand and gravel, 1

MRR-1B-1993 13:43 h047386070 P. 11

If s,,nificant groundwater m o v e m e n t through the area i8 not

from ueaC to oaat, %hen nn alternative direatton for ground-

, wakeir discharge. muak bo ooneidered. !!!he other p o s s i b l l l W

is of groundwRtor tuovornant f i w m noz.th Co south hbrou~h the

nand end gravel8 oocurring in khe w e u t P R P ~ of the atudg m e a

(Figure 4). Though there is a slight; drop In both the kopo-

grAphic and hydraulic g r n d i e n t s f r o m north to 8011th the W a t e r

l e v e l s in two holes ( 6 and 8 ) are quite low (Figures 2 and 4). Provlded that the water l svo la aro recorded in fully ef f ic ient

piezometers then it i a conaidored f r o m analysis of tho water

l e v e l data that groundwater disdbargs from *he area may prob-

ably be controlled by channelrr out Into the bedrock surfaca

and by var ia t ions in perrnaebilfty of the surl'icial depos i t s .

T h e water t a b l e EM dram through holes 6 , 8 and 9 shows ground-

we.t;er flaw oocurs both from the north and eouth nuggesting

disoharge beneath *he eenLPal pert of the presently a e t t l o d

a rea .

n ~ y develop after further piezometer readings are obtained.

A b e t t e r understanding on direction o f groundwater flow

Mtignibudo of CSroundwateP Flow

The pertnoability of the d e p o s i t a and the quantity of ground-

hr~ter f l o w oannat be determined From the avai lable d a t a , It

is cansfdersd this a m only be ss t ie f 'actor i ly determined f r o m

pumping t e a t s canductcd on t e a t w e l l s accompanied by obeervation

wells, P a r t i o u l n r at tadt ion i n requested aonoerning quantity

o f groundwa%er Plowing thPough the s i l t s .

PIFIR-1(3-1993 13: 44 P. 12

Before attempting I;u datermine quantiCy of' gPXandWater E law,

findings of p z b e s e n t data roquire furehar emphRRi 8 . Prum this

aat;u i t is hewn that; wa.t;er levo'ls are quite deep in t;ha a l + ~ ~

paptloularly within the slltsr There aro no eigns af sprlng

disohar&$e f r o m the a l l t dapoaits Rnd t w o k e s i t hales are d r y ,

Evidence sup;aeet;a probably only deep groundwater f l a w in khs

BFea JUS% above and poasibly nibhtln the uppep part of the bed-

rock. In some parts o f bhm area tha n i Z t a m a g be dpy to thR

bedrock uurface. Because of the th in zone of saiiurebion near

the baae of the silt d e p o s l t s and of posatbly dry sections,

not muoh grounduater 1s considered Lo f l o w thrawh the a i l t ~

In the 8t;udy t?~rea.

Though no calculations have been made a t this stage of the

study, the effects of doubling or trebling the dwelllng den-

s i t y fire not ant ic ipated to have much ef fect upon raising the

water l e v e l surface. The imported water haa to percolate to

depths ranging f r o m 30 to 130 F e e t and more before it; can Pe-

s u l t In raising the l e v e l o f the water table.

Erosional processes aa an indicator af Rrpundwster f l o w

A n a d d l t i o m l factol, concerning possible groundueter movement withln

the w a t u X t a t e d zone (between %he land surface and above the

water t s b l o mu8C be considered. fn this raepeet reference w i l l

fPrst be made to 2 stereograms (Mallard, 1973, phot68 6-10,

anti 11.2Sa). B-Jr ooincidenoe Chose photographe Oover OF f a l l

I

10-1993 13: 44 6047386070 P. 13

within the c n t i r e 3*udg area and Q V , ~ aoaompanimd hy m m m e n t a

very p e r t h e r i t to t h i a study.

lacuotrine silt find vary f i n o nand sedtmwxtB are l e s a highly

k e t t l e d but Rrh highly disaeotd.

depression^ juct w e e t of the lake ( . . . I are ool lapae f t s R t W 0 8

CaUaed by p ip ing phenomena." From 11.250 " S m a l l pinhala-like

dt5prCJ8SfQn8 on the upland ad jotn3-W aCeap laka-slde bluffe,

and On the s i d e s of ravines and gullies, R P ~ I col'lapee features

a s a o c i a t a d with punding of B U P ~ A O Q W E 4 h 3 F g , downwwd drainege

of the Wnded waters, and piping in the thick mainly s i l l ; and

very f lne aand depos i ta conEaining s o m e s h y and fine nand

From h.lOb ''. . . . . the l a m h a t e d

V e r y 8-11 funnel-ah~pad

seams. "

h atudy of the a i r photos discussed above showa the ksndtsncy

for llnear development o f shallow pfnhole depressions.

depth of their development may cosrespnd to the depth of the

less compact upper zone in the sllts deteminad from the seismic

pFOgrammed 'Phe shallow cavernc)~~ f i n e f'ea*mes which m e B O ~ Q -

times observed to develop in a i l t deparrita in bhe Kmloops region

may be due i n part to 8 0 1 U ~ f . O n of m a k e r i a l s d u r i n g horfeonbal

mdvemen~ of water possibly associated w i t h temporary saturRtian

af the upper zone fallowing auffialent preoipitatian. The samo process 5.

pected to oacub fa the study area. A bantoal ly rect;angular areek

and Valley pattePn 5s deve loped I n bhese s l l t a , It may be

inferred to be due to the resulks of mechanical erosional for006

(surfaca runoff ) u l t i m a t e l y joining dapreasiom ( k e t t l e hole8 7)

The

ex-

I

PIFIR-1 0-1 9 3 13 : 45 6(3473866370 P. 14

of g 7 R a i t r l origin, The rogulnr and p a r a l l e l nIignment of

those featurue 8eetns to Lnvolve t;oo hfgh a demea of coin-

cidonoe for all. of' theae to be enbirel7 of g l a a i a l origftn.

file 0&9723-A) +he w r i t e r suefgmatod Chat chemiaal weathnr-

In& mag be used bo explain col lapaa atructuroa end aeverno~s

a role in t h e erosion of the l and aurfaoe in the etudy area.

%f.m downward drainage s t a t e d by Mollcard is considered by the

writer, Lo be eocomspnied by aomo solution of the silt depo-

B i t s . Initial thoughts would porhflps be b h t t e r modified to

suggest the chemical yeathering p ~ o c e a s by solutfon of carbonato m a t e r i a l s

occurs along l'racture-aontral2ad patterns within the silt

!t%e accurrenc~ uf more compact s l l t a (forming a le58 permeable

eone) at shallow depths would aeegat in creating a attuatfon

tn which temporary water tab19 conditions could oocm in the

upper treaehered less compact zone, Thus lateral poundwater

flow could OCOUP in which l i n e a l l y arranged depressions could

eventually become comeoted by subsequent erosion to form s m a l ~

MQR-10-1393 13 : 45 P. 15

- 8 -

Soma impaote OF h a u a i w developments

Development as planned 1s to be accompanied by incraReed

a d d i t i o n a l effluent disposal v i a septlo Canks, 'Ph%& will

lend to some Y C R ~ round discharge of w a t e r within *s uppap

( w e a t h a r o d ) EODO of tho s i l k s . In the lieht of eaIrl%eP P8m

marks %hi8 would only halp to inapeaae the natural e,ato of

eroafaii. I canrmt look f awuurnbly upon auch development,

aould be accompanied by sc~tnra lmter p r o b l n m s far h o m e

owners, However engineering deeign might tako ca re o f those

problems, and on0 way to a l l e v i a t e one problem would be ko

insist on the installation of a publio sewerage system.

Further sttention 3.8 again drawn to a comment of Mollmrdfs (197.3, pa 11.2Sa), ( I These deposies are highly auaceptiblo to

oroalon, a fact that should be considsred in munici_ua3. devel -

opment and road design."

Cano.lusions

Tho objoctlvs of this study oould be sunnnarlzed a s an aktempt

t o determine the effeats upon the graundwater regime of increased

w a t e r U l j e i n the study area which would be incurred bs iiicreasiLng

the d w e l l i w denflity.

The geology of the ~ P B B consister mainly of senda and grnvela

in the we8C part and of all+, depoait;s in t h e east p a ~ C of Ghe ~ W A .

MRR-10-1993 13: 46 60473B6070 P. 16

The t h f C k n a a Y of' those deposita and the dspth k~ bgdronk in*

e m .ea from went to east, The dept;h. to *;he water l e v e l In..

c reases f r o m w e s t to eaat and born0 of the sedtmerska are prob-

ably unsaturated ( d r y ) ,

clnd from the area is liowerd the taert, but gIcoundwnter diseharga

may OOGUY mainly w i t h i n buried bedroak nhnnnals .

The movemont of groundwater withgn

'Ilia erosional pattern i s bkralicvad to be a combination of' me-

c h m i o a l and chemical weathering r e l a t e d to exieting deprose-

Ions ( k e t t l e holes) due t;o d a g l ~ c i a t i o n and pinhole l i k e

dePreaaions of pos t glacial o r i ~ h a being joined togeeher, with

furGhar erosion creating deep creek and valley features.

It is assumed that though an increased use of water Rnd its

disposal may not s igni f icant ly r a i a e the piezometric (OF water

t ab l a ) aurface beneath the W R A , effeots possibly oreated (s inl l lar

to Chat which may be brought; about by sufficient precipitation) of

development of a temporary water t a b l a in the upper Less campact

zone of silt shvuld be considerod, Increased developmenh may l ead

to the occurrence of R water t a b l o within the88 silts addPng to

the n a t u r e l r a t e of erosion. The miter does not look fnvaurably

upon housing development OP fncraased housing development in &reas

auch as these. In a comment; on one particular csterogram (Mallard,

1973) the reader is reminded to oonaider tho Paot that the silt

deposita ape highly suacspt$ble to erosion and that this should be

conzidered in munioipal devolapment.

MQR-1 I3-1 993 13 1 47 6047366070 P. 17

E.G. Le Bre.t;on Soniar Ueologioaf Engineer 6roundwater SeoDion Hydrolorn D5vi.aion Waker rnveetigatians Branch

MRR-10-1993 13:48 60473€360?0 P. 02

I- .. cri W a 3:

3

I 0 I +

U3 1.0 W

w li

w W .. E

m m P -.I W W m m -I 0

TI m P

. .

. .

. . . . . . . . . . . . . . . . ' I . !

I . . . . . . . . . . . , . i

. . . :: . . . . - . .

. . .

I

. . . I

I

. . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . , .~ . . - .......

. . . : . . - . . ~-

, . . . , . . , . ,

. , . I . . . . . . I .

. . . , .

. , . I

i

. I

~.

. .

. . . . . .

. . . . . . . .

. . .

. . . . . . . . . . ! . . ~

' !

i . . . . . . .

. . . . I

, . . I . .

t I : \

I '

; . '

, . : .

. . . , .

. . . . . .

1500-

1400 -

. 1300-

L

1200-

, .

TQACCCMPAMT & h R f bH 1 SCALE:MRT: J " . p / P Q I PATE ........................... MINISTRY OF fE ENVIRONMENT

WATER IN VESTSATION S BRANC H

i e

L

. . . . /r *dfo' . f N@b4J0?6 m. . . .................................................. rJgs?-&cy +& &&&wFS . I

z 2 -1300

,3 5 - w

MOO

. . . . . . . .... . . . . . . . . . . " . . . - . . . . .

. . ...

. . . . .

. . . . . . . . . . . . . . . . . . . .

. . .~

t

MINISTRY OF THE ENVIRONMENT

WATER INVESTlGATIONS BRANCH

- I 1500-

1400

13OC

h

k w W Lr E Y

0 t > Irl -1 w

MINISTRY OF THE ENVIRONMENT

WATER INVESTfGATIONS BRANCH

c

a m m

APPEISDI'X G

WEST BENCH SILT - R MEMORANDUM BY H. I W S O N - IlDT AGRA LTD-

MRR-113-1Y93 13: 51 50473860713 P.07

Our Ref: VG-06246 DATE; March 3, 1333

To: Inland Contracting Ltd. Review Committee

m0M: H. H ~ w M ~ - HBT AGRA Ltd;

Re: QmtcchnicaJ Review, Dmhpmont of Inland Contracting Ltd. Pmpcrty, Wesl Bench Area - Penticton. B.C.

This memorandum contains geotechnical engineating comments on the results of the reoent

borehole data obtained over the last few months at the Inland Contracting property. This p.W is located on sand and gavel deposits above and west af the silr bench lands adjacent to Okanagan Lake near Penticton, B.C.

The purpose of the recenl drilling and review was ta establish the wgional groundwater conditions so that it would be possible to a s ~ s the effect that development of the Inlhd

Contracting property might have on the adjacent sift bench lands.

1.1 RELEVANTHISTOaY

Mlt bench land i s present in the Interior of B.C. throughout r)le Thornpin and Okanagan

Valleys. Prior to the early 1950’s this land was not greatly developed because of the availability of less expensive land elsewhere in the region. However, in the last 30 years, the pressure of

community growth has resulted in development encroaching on to these lands. During the late 1970’s it became apparent in several communities that them w m problems arising from the haphazard random dwelopent. At that time many of the mmmunities were uninwrpcmted and deveJopment approval was obtained frmi the B.C. Ministry of Transportation and Highways WOTH). Foundation problems were occurring in these propcrtics and MOTH decided at thai time to carry out enginocring studies to investigate the unique pmprcies of the

- : L

1

M-10-1993 13: 52

A G R A Earth R Environmental Group

6047386070 P. 08

soils and prwidc somc guidclincs for development. One such area investigated in 1977 was the

West Bcnch arca near Pcnticmn. The MO"H repoft prepared for the West Bend1 &YSI was

zLuttmi'B6 by D. Nyland and 0, M i l k (Background document 2} which is froqucnlly rdcrrcd to

as the NylanflMi1lt.r report. This report oantaind the results of testing of the soil that made up thc sit1 benches, the stability of the Soils as thcy might affixt dmelopmmlt as well as

ammpting io dctcrmhe the groundwater regime in the area. Guidelines for possible pmperty subdivision and development of the lands wcrc also prcamted md wefe subsequently adOpWd by the Regional District. Becatlse of increased development pressure in the late 1980's and 199O's, the Regional District commissioned a reevaluation of the NylancWMiller tefxm in the

light of new technologies, techniques and experience. This reassessment was canid out by

Klohn Leonoff Ltd. and a report was submitted in August of 1992. This rcporl raised wncern that dcvdopincnt of the Inland Contracting Ltd. property on sand and gravel land west of and above the silt knch land, would increase the regional gmundwacer lcvcl and thcreby initiatC instability in the silt b m h land to the east. As a result of this conern . Inland Contracting was

unable to obtain a permit for dmdopment. Consequently. a revim cornmitt= consisting of E Livingston, of Pacific Hydmlogy Consultants Lld., A. Dakin of Piteau Associates

Engineering Ltd. and H.Hawson of HBT Agra Ltd. was commissioned by Inland Contracting to investigate the conditions throughout the region and t h d y to assess the likelihood that

development on the upper sand and gmvei areas would cause problems on the lower silt kwh

land,

1.2. SILT BlENCH SOIL CONDITIONS

me geology of the area and the pmperlie of the si!; bench sediments have been discussed in

several publications (Background Documents) and have also b m tlaboratocl irr dctaiI in both the Nyland/Miller and Klohn Lconoff reparts. Thc reader is referred to these reports for a detailed description of the depositional history and soil pmperties. For complctencss, the following summary of the site conditions is presented.

The sih hench lands are reninants of lacustrine sediments deposited in a lakc eflV~I'Onlnent

during the last glaciation period. The sediments are comprised of interlayered silrs, clays and fine sands.

MW-10-1993 13:53 6047386070

@ A G R A Eanh & Environmental Gfoup

P. 09

0

s

0

Subsequent mclting of icc dams in the histork Ohnagan Lake c a u d lake levels lo dmp

dramatidl y . Thc drop in lake l c v d rcsultod in thc groundwater level dropping and desiccation of the

acdimena whkh produced the bench lands. The wakr levcls in the sediments we low within the bmch land. Thc desiccated si1b are dry, jointed and frssurt?A. The desiccation of the soil has crcated SoiI strengths capable of supporthg steep cscarpmcnt slopcs adjncent ln the lake and within step eroSiond gullies. The

landslides 8s a result of changes in water conditions in the s lop . Laboratory testing has indicated that the fine grained sifts and clays contain sodium salts and a significant percentages of swelling clay minerals. Thcsc materials are dispersive and can erode i n t d l y as a result of water seepage. Colluvial fine ghncd foils are also present within thc gullies and elsewhere in thebench arcas. These malesials are derived from the parent lacustrine soils by weathcrhg processes Mlch as slope wash, wind action and soil slumping.

"he colluvial soils are extremely loose and subject to large settlements due to structure collapse on saturation.

slopes on the s i b an? c3sentidly marginally stable but are susospdble to

2.0 ISC CUSS ION

Rccent drilling Ihrwughout lhc West k n c h area has allwed a much more &tailed interpretadan of the regional groundwatcr regime. It is evident from this m n t data that the Inland Contracting property is separated hydraulically from the si& batch lands by a buried bedrock ridge and that the pundwaker level through the silt bench. land is located at considerable depth below the invert of the Large wesUeast trending gullies. In addition, the bedrock maintains the gibundwater flaw 1x1 a general north to south direction rather than emwards towards Okanagan lake as was originally thought. Of major concern fur dwdopmcnt of the Inland Contracting property was the possibility that a rise in the groundwater levei would bring about internal soil erosion, growth of the head of the gullies and acceleration of gulley slope failure. The Kldin Leonoff report recomiilended n ~ f u r t h e ~ dewlopmew . . , in the calchmcnl area withoul suirable macures to con~ml r h increme in groundwaicr Irwls. The results of the recent study

A G R A Enrlh & Environmental G r ~ u p

IWR-10-1993 13 : 53 6047386070 P. 18

Mar. l l r3 1993 1:5EPM P11

x catried out by the Review Committee ihdicotc that watcr infiltration into the sand and gravel materials undarfyirrg the Innland Canttacting property will only margillally iocrmc the general groundwater level. This is bemuse the prcscncc of the bedrock tends to hydiaulidly restrkt

groundwater movement in an easbrly direction. Conqucnct~ increase in rcgicmal groundwater level as a result of development if the Inland ConLmcting pqxxty will have minimal impact on the stability of the silt soils in the si& bcnck areas.

Mormver and as dimussod above, the prablems in the silt bcnclr lands are c o n s i c i d to be associated with water infiltration from the surfsoe. This is also discussed in detail in the Nyland/Miller (Background Document 2) and Klahn hmf f reprts as wcll as dsewhm. JA

Brelon (Background Document 6) in fiis memo to MOTH also concurred with this assessment. It ia wident that pmblcms in the si& kmh area are a ssociated with development over the area

itsdf and surficial hfiltratkm rather than any groundwater flow. However, my surface nmoff fmm the hntand Contracting pmperty discharged onto the si& bench b ultimately infiltrate into the silty mils m y exacerbate these problems. Surface runoff from the lnland Contracting

property must be controlled to prevent discharge on to the silt b m h lands.

4.0

1 .

2.

3. 4.

5 .

6.

-us1ontg

The new borehole and well information indicate that a buried bedrack ridge hydraulically separates tbt Inland Contracting sand and gravel property from h e sllr bench land. The regional groundwater i s located 8t depth below the invert of the large west/easl trending gullies. The groundwater flow i s predominantly in a nwth to south direction. The increase in regional groundwater level under the wurst case scenario due to developmat o* the lnland Contracting property will .be minor. The $.oil problems on the silt bench lands arc a rcsult of sutface water infilmtion from septic tanks, leaking pipes and concentrated runot'focxurring from loctll development.

Thc cffect of devciopment of the Inland Contracting property on the adjacent silt bench lands will be minimal pmvided surface: runoff is controlled and not discharged onto lhw lands.

A G R A

Earth $ Envirunrnenlal Group 4

P. 11 MRR-113-1993 13: 54 6047386070