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Exhibit C
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<br /> Figure 6.Mechanical sweeper bristle penetration of larger gaps associated with CGP filled with sand(left)is possible,but
<br /> pavement types with small gaps(such as PICP)is not(right,courtesy of Elgin Street Sweepers).
<br /> ,� ' `� �' sediment at their sidered insufficient for this restorative measure.
<br /> '� �� .,,'°° - '' surface. The thin Clogging depth of pervious asphalt and pervious
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<br /> 4,- _y � ���_ _-� � ��� clogged zone is concrete depends upon the contributing sediment load.
<br /> � � � ''�°�� � �� named"schmutz- Research has shown that sand collected on a pervious
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<br /> ����, `��'� � �, � ��� decke"from the concrete pavement will not penetrate the pavement more
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<br /> °°� � ��r� � � >.'��=" � � �� German word for than an inch deep.Although pervious asphalt was not
<br /> �� �� : ��- ' dirt cover or ceiling. tested, it is assumed it would function similarly. How-
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<br /> � �� � �� � ��� The thickness of the ever,when a fine fraction of soil (silts or clays)was a
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<br /> �� �� �� schmutzdecke for part of the clogging sediment,the clogged zone was
<br /> �3 .�.°--:
<br /> � CGP ranges from much deeper, often at or near the bottom of the pervious
<br /> ��. � � � 0.25 to 0.50 inches concrete section(Mata 2008). Restorative maintenance
<br /> �` � ' . (James and Gerrits of a PA or PC system clogged by fines has not yet been
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<br /> � �� �; . ' 2003, Bean et al. deemed possible. However, preventative maintenance,
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<br /> `�: ���" � � � ���� ;� �� 2007).As the gaps by way of a regenerative air street sweeper,has proven
<br /> ,��`� ��� associated with CGP to be an adequate measure and keeps PA and PC sur-
<br /> �� ���,� ��� �"� ����� - � are the largest of all faces infiltrating rainfall and run-on.
<br /> ����� ,.. ��.:�� � _ .�����_�,���_ ro �:i permeable pavement Table 1 summarizes the clogging depth of vari-
<br /> Figure 7.The clogged zone of PICP is types, CGP is the ous types of permeable pavements and the appropriate
<br /> evident toward the top portion of the easiest to maintain vehicle for prevention or restoration. Obviously, the
<br /> interlocking paver.The depth of clog- With a mechanical simplest pavement type to either maintain or restore
<br /> ging at this location outside Chicago, sweeper. By basic is concrete grid pavers filled with sand.All pave-
<br /> ��,after 6 years of neglect was 1.5 geometry,the ability ment types can remain clog-free if preventive sweeper
<br /> inches(40mm).
<br /> of bristles to pen- maintenance is reliably provided. If pavements are
<br /> etrate a large gap to a deeper depth benefits CGP(Figure neglected and allowed to clog to sometimes substantial
<br /> 6). Research has shown that a standard mechanical depths, it is uncertain whether all pavements'neces-
<br /> street sweeper can sufficiently penetrate the sand-filled sary surface infiltration rates can be restored.Also
<br /> gaps of CGP to break apart the schmutzdecke. important to note, other than for CGP filled with sand,
<br /> Dust and sediment will penetrate PICP filled with different street sweeper types are used for either pre-
<br /> gravel to a much deeper level than that of CGP filled with ventive or restorative maintenance.
<br /> sand. Field observation at a lot outside Chicago found
<br /> that a 6-year-old PICP lot that had never been main- �mpot'tanCe Of Urtderlying SOiI Type
<br /> tained had become clogged to a depth of 1.5 to 2.0 inches Bean et aL(2007)showed that even when maintenance
<br /> (Figure 7). Removing a schmutzdecke of this thickness (street sweeping)has been neglected for up to 20 years,
<br /> is clearly beyond the ability of a standard mechanical permeable pavements can still be permeable,provided the
<br /> sweeper. In fact, regenerative air street sweepers are con- underlying soils are permeable. Several tests of rela-
<br /> Maintaining Permeable Pavements 5
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