This document is a design review checklist for a permeable pavement project in three alleys in Dubuque, Iowa. It provides details on the project location, drainage area characteristics, stormwater calculations, pavement and base materials, subgrade and foundation protection, construction details, and erosion control measures. Key information includes the project will treat runoff from 3.05 acres of 60% impervious area, include interlocking concrete pavers over gravel bases totaling over 21,000 cubic feet of storage, and tie into existing storm intakes with overflow draining longitudinally down the alleys.

1. Permeable Pavement Design Review Check List
Applicant: _City of Dubuque___________________________________ Date: 3/11/2015____________
Submitted By: _Jon Dienst, P.E._____________ Project Location: __3 Alleys – City of Dubuque________
1) Drainage Area (DA) shedding to Permeable Pavement _133,103__SF and __3.05______Ac
2) Percent of DA shedding to the Permeable Pavement that is Impervious __60__% (if soil quality
restoration is done or if soils investigations indicate green space is capable of absorbing the WQv the
green space can be eliminated from the DA for WQv calculation. If neither applies, assume ½ of the
green space is equivalent to impervious surface.)
3) WQv __________________CF (show calculations below or attach)
WQv = (Rv) x (P) x (DA) x 43,560 SF/ac x (1 ft/12in)
Rv = 0.05 + 0.009(60) = .59
WQv = 0.59 x 1.25” x 3.05 ac x 43,560 SF/ac x 1ft/12” = 8,165.23 CF
4) Surface Area of Permeable Pavement __8,775______SF
5) Describe the type of pavement (i.e. type of paver, manufacturer, etc) ___Interlocking concrete pavers
– County Materials, H2O Pro Pavers ______________________________________________________
6) Pore space storage of rock base __8465.6_____ CF (Length 814_ft x width _13_ ft x depth 2__ ft of
rock base x 40%).
7) Discuss soils investigation findings (i.e. texture, degree of compaction, percolation potentials, depth to
water table, contamination etc) __From previous experience in this area, we expect the soils
to be silty clay. The water table is below 14’ in depth. The top 6” of the subgrade below
the rock is amended with grading to break up the soil a little bit. This is subgrade
preparation. We assume the percolation rate will be less than 0.1 in/hr. ________
8) Describe the aggregate used (depth of layer / quantities / size / AASHTO or ASTM No. classification);
a. __2” of ASTM # 8, 1,492 CF________________________________________
b. __4” of ASTM # 57, 3,527 CF___________________________________________
c. __24” of ASTM # 2, 21,164 CF________________________________________
9) Provide calculations of aggregate quantities or attach a copy of the calculations:
ASTM #8 – 814’ x 11’ x 2”/12” = 1,492 CF
ASTM #57 – 814’ x 13’ x 4”/12” = 3,527 CF
ASTM #2 – 814’ x 13’ x 2’ = 21,164 CF
10) If permeable pavement is less than 10 ft from a foundation describe water proofing methods: _City
will either use a 20 mil plastic liner placed vertically and 1 foot horizontally under the
storage layer of ASTM #2 stone or a 2lb closed cell expanding foam spray followed up
by a poly urea spray coating is used. The poly urea and leveling foam is typically used
on limestone foundations. Either way, the liner is placed to a depth of 2 feet below the
lowest elevation of ASTM #2 stone._____________
11) What is the maximum slope of the finished surface of the permeable pavement_5_%?

2. 12) What is the slope of the bottom of the rock base __0.5 – 15.0%
13) If the bottom of the rock base is greater than 0.5% slope describe how slope at the bottom of the rock
base will be modified to maximize storage (i.e. installation of sheet piling to stair step the rock base
down gradient). __On steep grades the bottom of the base will have rock dikes
constructed with a 20 mil poly liner over the dike to prevent the water from seeping
down the subgrade and maximize the infiltration. We have one alley with steep grades
where it connects to another alley with flat grades. We’ll evaluate the need for dikes in
the field.
14) Size of perforated drain tile ___6_____inch
15) Depth of tile from surface of the pavement ___21___inches
16) How many inches is the tile above the bottom of the rock base ___12_______inches
17) Describe the outlet for the perforated drain tile __We will try and tie the perforated drain into a
storm intake if possible. We tie the subdrain into an intake on Merz Street. The other
short alley will have excess water bubble out of the sampling port if it needs to.
18) If fabric is used, describe the material and flow through rate ____Fabric must conform with IA
DOT Section 4196 Subsurface Drainage___________________________________
19) Describe overflow (i.e. what provisions are provided should the system plug – where would water flow,
how would it be conveyed)__Alleys are designed with an inverted crown so water would
drain longitudinally from alley to street.___________________________________
20) Describe Erosion and Sediment Control measures used to protect permeable pavement if active
construction will be taking place in the drainage area after installation:
_Silt fence or compost logs along the project extents would be required if construction
occurred next to the project. All abutting intakes will be required to be protected with
compost logs or silt fence under the grate. The City also sweeps the alleys 2 to 3 times
a year as needed to maintain the porosity of the pavers.______________________
21) Please attach a map of the drainage area.
22) Please attach a plan view, profile and cross sectional drawing
FOR REVIEWERS USE ONLY
Design appears to comply with the standards in the Iowa Stormwater Management Manual.
Design does not appear to comply with the standards in the Iowa Stormwater Management Manual.
Comments: ____________________________________________________________________
______________________________________________________________________________
_____________________________________________________________________________________
Name of Reviewer: __________________________________________ Date: _____________________
Signature: ____________________________________________________________________________