Laserfiche WebLink
. <br /> Exhibit C <br /> passes through interconnected pores in both PC and PA. able pavement water pathways, rendering them much <br /> Permeable interlocking concrete pavements(PICP)are less permeable. This has been anecdotally observed at <br /> available in many different shapes and sizes. When laid, several permeable pavement applications across the <br /> the blocks form patterns that create openings through U.S. (Figures 2 and 3).After the tree detritus falls on to <br /> which rainfa(1 can infiltrate. Concrete Grid Pavers the permeable pavement, it risks being ground into the <br /> (CGP)are an"older cousin"to PICP and have relatively pavement by passing vehicle tires. Large parking lots <br /> larger open areas that are filled with gravel, sand,or even that are fringed by trees have had their perimeters clog, <br /> a loamy sand top soil. Plastic reinforcement grid pav- but the middle portions did not clog(Figure 2). While <br /> ers(PG), also called geocells, consist of flexible plastic the purpose of this chapter/bulletin is not to dissuade <br /> interlocking units that allow for infiltration through large designers from incorporating vegetation in the parking <br /> gaps filled with gravel or topsoil planted with hirfgrass. lot, designers do need to be mindful that any pavement <br /> A sand bedding layer and(more frequently)gravel base underneath a tree canopy is at a much higher risk of <br /> course are often added to increase infiltration and storage clogging than pavement free and clear of vegetation. <br /> for many of these paver systems. Sediment accumulation from disturbed areas sur- <br /> All permeable pavement types must be inspected and rounding the permeable pavement is the most frequent <br /> maintained.There are certain elements of maintenance cause of permeable pavement failure. Designers must <br /> that are common among permeable pavements and other take special care to inform contractors to minimize <br /> elements that are specific to one or two pavement types. exposure of permeable pavement to sediment during <br /> construction. Permeable pavements in residential areas <br /> DESIGNING AND CONSTRUCTING WITH are particularly at risk.As one home is completed, an <br /> MAINTEN�INCE IN MIND adjoining properly may remain under construction. In <br /> Proper design can help avoid future maintenance prob- these cases,the likelihood of sediment deposition from <br /> lems.Typically,the most common permeable pavement wind, water, and tires is very high(Figure 3). <br /> performance concern is clogging. Pavements must allow LANDSCAPE MAINTENANCE ACTIVITIES: <br /> water to pass through their surface to be permeable. <br /> Designers can minimize the likelihood of clogging by AVOIDING FROBLEMS <br /> considering the two most likely clogging sources: veg- Property owners often incorporate landscape mainte- <br /> etative litter and sediment. nance as part their property upkeep. Common activities <br /> Parking lots with overhanging trees provide many inc(ude re-mulching and lawn mowing with discharge <br /> benefits: shading to cool pavement temperature and of clippings.An uninformed landscaper may deposit his <br /> improved aesthetics are obvious reasons to landscape mulch pile on the pavement immediately adjacent to the <br /> parking lots with trees and shrubs. Designers must be landscape bed he is beautifying or may discharge grass <br /> aware, however, of unintended consenuences associated clippings onto the pavement. If that pavement is perme- <br /> with a leaf canopy overhanging a permeable applica- able, a clogging source has just been introduced.An <br /> tion. Vegetation debris and detritus collect in perme- easy way to avoid this issue is either to bag clippings or <br /> place the mulch pile on <br /> �• g � � a tarp that can be care- <br /> ,f ; _ <br /> � fiilly removed to prevent <br /> ` � ���� � " �; ,�� �, � ��° clippings or mulch from <br /> `�` � � ;;x � ' g ,r 6: ' falling onto the perme- <br /> � <br /> �� ;,�� � � � able pavement. <br /> � * � ��``�� In locations with <br /> , <br /> ,,• � � �, t � . <br /> '� � `� i �� ��� r ��� -���'° snowfall,plowing is a <br /> � <br /> � . �. f���� � � ° <br /> � �� � "� �--` _� ��� �,. °� ° necessary maintenance <br /> �:. �� �� � � <br /> ',��� ��� � � -�„m,; activity that can have <br /> �� � : j � � .� � , <br /> , �� ��� > � an impact on perme- <br /> �� � � ����� � � ������ - able pavement function. <br /> ��s � �.t.�-� ��� `` . .,.�.�a�� When non-spec (un- <br /> Figure 2.Leaf and tree detritus collects in path- screened and unwashed) <br /> ways intended for water in PICP located under- sand(meant for vehicle <br /> neath a tree line outside Chicago,IL. traction, not permeable <br /> pavement infiltration) is <br /> ;t� <br /> 2 Urban Waterways <br />