Infiltration Test July 22 2011

8/6/2019 Infiltration Test July 22 2011

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Infiltration Test for Pervious Concrete Sidewalks at Spokane, WA

Prepared by: Liv Haselbach, Ashraful Alam

Field Visit July 21, 2011

Problem Statement

The City of Spokane was concerned about infiltration rates at their pervious concrete sidewalks

on West Broadway. The sidewalks were installed over a year ago. Magnesium chloride was used

for deicing in the sidewalk during the snow event during this period. One section was also

sanded during the winter.

Infiltration tests were performed to evaluate the functionality of these sidewalks or the need for

maintenance. The testing procedure followed was ASTM C1701/C1701M. Apart from the

infiltration test, the sidewalks were observed to evaluate the structural performance following

ASTM D6433.

Infiltration Test

On both sides of the West Broadway (Figure 1) infiltration tests were performed at three

locations. Two tests were performed on the south side of the street and one test on the north side

of the street.

(a)


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(b)

Figure 1: (a) Site Photograph, (b) Approximate Infiltration Test Location

A test setup is shown in Figure 2. A 12 inch diameter plexiglass cylindrical ring was used in the

experiment. Plumbers putty was used to seal the bottom of the ring in touch with the sidewalk to

ensure minimum to no horizontal infiltration around the ring. The water inside the ring was

maintained at aprpoximately a constant head of 0.39 inch to minimize the water pressure.

Figure 2: Infiltration test setup.

The infiltration rates of the pervious concrete sidewalks and a summary of these tests are listed inTable 1. The infiltration time was estimated for one gallon of water to pass through the vertical

depth of the pavement. Infiltration rates at the first two test locations were not significant and

after 10 minutes of observation both of these tests were terminated. Test Locations 2 and 3 were

swept with a broom before the test while Test Location 1 was not. Test Locations 1 and 2 had

received sanding in addition to street deicing maintenance over the winter.

roadway Ave

Pervious Sidewalk

Pervious Sidewalk Test 1Test 2

Test 3


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Table 1: Infiltration test summary at West Broadway

Pavement Type: SidewalkDepth of the Pavement: Unknown

Depth of Subbase: Unknown

Test No. Pavement Temperature Water Used Infiltration Time Infiltration RaterF gallon sec in/hr

1 76 -- Terminated --


3 86 1 1587.9 4.64

Additional infiltration tests were performed at another location (Figure 3). The test location was

marked specifically for future reference. At one side of the sidewalk there was a silty/sand

embankment uphill and in the other side there was fairly level grass. The side near the silty/sand

hill side had visible silt deposited on the sidewalk.

Figure 3: Test location at fair grounds site

The infiltration rates obtained for these locations are listed in Table 2. At Test Location 4 two

tests were performed. The first one (4a) was under initially dry conditions and the second test

(4b) was after pre-wetting the test location. Under the dry condition, the infiltration rate was

almost twice that of the pre-wet condition. Test Location 5 was at the silty/sand uphill side and

there were no sweeping before the test. This test was terminated after a few minutes with no

noticeable infiltration in the sidewalk. At Test Location 6, Test 6a was performed after sweeping

the area. It should be mentioned a steel wire brush was used along with a standard broom to

sweep the area. Significant infiltration was observed in the first few seconds and after than therewas no significant amount of infiltration in the sidewalk. There was a noticeable level of solids

which came off the sidewalk and became suspended in the water during the test. This test was

terminated after 34 minutes 50 seconds. For Test 6b the same area was first washed with hose

water and the test condition was therefore considered to be pre-wet. This time there was

substantial infiltration.

Pervious Sidewalk

emoryLn

Panel 1Panel 2Panel 3

48"13"

Test 4

57"15"

Test 6

23"

11"

Test 5

5'-0"15'-0"

Silt/Sand Uphill

Grass


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Table 2: Infiltration test summary at Field Site

Pavement Type: SidewalkDepth of the Pavement: Unknown

Depth of Subbase: Unknown

Test No. Pavement Temperature Water Used Infiltration Time Infiltration RaterF gallon sec in/hr

4a 87 1 185.3 39.73

4b -- 1 350.3 21.01


6a -- -- Terminated --

6b -- 1 408.0 18.04

Distress Survey

It was intended to perform a pavement distress survey to evaluate the structural performance of

the sidewalk. However, the sidewalk condition on West Broadway was excellent with no visiblelongitudinal and transverse cracks, no corner breaks or spalling, no raveling and there was no

blow up in the sidewalk; which indicates the structural performance is very good to excellent.

Discussion

The south side sidewalk of the West Broadway had the worst infiltration rate considering all the

Test Locations. This might be due to a combination of many reasons. It is recommended that

maintenance be performed at this location (vacuum or power wash) and the infiltration rate re-

evaluated.

The sidewalk at the north side of the West Broadway is still hydrologically functional

considering the annual rainfall in Spokane, WA. The average annual precipitation at Spokane,

WA is 17 inch (www.wikipedia.org), while the infiltration rate was 4.6 in/hr.

The grass side of the sidewalk at the fair grounds was in good condition in terms of infiltration

rate. The uphill side was visibly clogged due to the silt/sand transported over the sidewalk but

was rehabilitated with hose washing. It is recommended not to install pervious concrete where

upslope landscape areas might discharge large amounts of sediment onto the walk.

References

ASTM D 6433-09. Standard Practice for Roads and Parking Lots Pavement Condition Index

Surveys. ASTM International, West Conshohocken, Pennsylvania, 2009, DOI:10.1520/D6433-09.

ASTM C 1701/C1701M 09. Standard Test Method for Infiltration Rate of In Place PerviousConcrete. ASTM International, West Conshohocken, Pennsylvania, 2009,

DOI:10.1520/C1701_C1701M-09.http://en.wikipedia.org/wiki/Spokane,_Washington. Accessed July 21, 2011.

Documents

Infiltration Test July 22 2011