1

General Design Principles

Chapter 4

Layout/Grade/Slope

Part of SystemSupports trafficAllows water to pass

Water should flow verticallyMinimize horizontal flowStorage in gravel baseCan use pavement and ponding zoneFlat system offers the maximum storage

2

Pervious Pavement Profile Sandy Soil Subgrade

Subgrade permeability should be at least 0.5 inches per hour

6”

6”

6”

Pervious Concrete

Aggregate Base

Subgrade

Stormwater

Curb

Pervious Pavement Profile Silty or Clayey Subgrade Soils

Permeable subgrade compacted to 92-95% Modified Proctor

Filter Fabric

6”

6”

6” +

Pervious Concrete

Aggregate Base

Subgrade

Stormwater

Curb

3

Filter Fabric

Curbs

4

Transition to Asphalt

Header Curb

5

Decorative Curb

Prevent Debris from Clogging Slab

6

Slope Grade Away from Pavement

SWALE

Grade Pavement High

7

No Adjacent Dirt Parking

Islands/Vegetation

8

Pavement Grades

0% slope is best for detention

Filter Fabric may be Required to Stabilize Base

Base/Subgrade

COMPACT TO 92 - 95% OF MODIFIED PROCTOR

9

Base Thickness

Typically 6 inchesGreater than 6 inches to increase storageGreater than 6 inches for freeze-thawNot required in some cases

Minimize root damageNative soils highly permeable

Freeze-thaw Resistance

Store water in aggregate baseDry Freeze

4 – 8 in. of aggregate baseWet Freeze

4 – 8 in. of aggregate baseHard Wet Freeze

8 – 24 in. of crushed rock drainage baseAir-entraining admixturePerforated drainage pipe

10

Pavement Thickness

Minimums6” Parking lots6” Residential Driveways8” Streets8” Commercial Driveways

Consider Conventional Concrete Pavement

Heavy truck trafficHigh volume traffic

Storage Capacity

Storage capacity typically governs designDepends on porosity of pavement and subbase1” of pavement with 20% porosity can store 0.20”1” of #67 stone base with 40% porosity can store 0.40”6” pavement on 6” subbase can store 3.6” of rain

(20%) 6 in. + (40%) 6 in. = 3.6 in.

11

Proper Joints

15’ typical20 ‘ max.Square panelsIsolation joints as appropriateAlign with joints in plain concreteNo need to seal

Isolation Joint

12

Do not Seal Joints

Signage

13

Aesthetic Design

A Good Idea…

14

Colored Concrete

Striping

15

Design Aids

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