A stormwater discharge is defined by the US Environment Protection Agency
(EPA) as rainwater or snowmelt runoff. These fresh waters become polluted
as they flow over modern manmade structures like roads, parking lots,
industrial sites, roofs, suburban lawns, farm land, etc. An abundance
of suspended pollutants can easily ride piggyback on sediment particles
in such water flows. These polluted waters are a known contributor to
poor water quality levels in receiving streams that suffer fish kills,
and other environmentally harmful side effects.
To better control non-point source stormwater runoff
pollution, the EPA has extended its rules to cover any parcel of disturbed
land of three acres or more. The initial runoff of stormwater contains
highly concentrated road salts, calcium chloride, motor oil, fuel and
other corrosive chemicals that effect storm sewer pipes according to
the water’s acidity or alkalinity. Crumpler’s inert HDPE
corrugated plastic pipes will not react with this potent “first-flush” stormwater.
The chemical resistance of CPP’s Single Wall and Dual Wall Smooth
Core/n-10 pipes makes them ideal for the use in Saltwater environments
and other stormwater systems as they not only eliminate internal pipe wall
corrosion, but also eliminate the exterior pipe wall corrosion caused
by corrosive soils. The need to remove untreated, corrosive natural
soils from the pipe trench site, and import non-corrosive offsite backfill
Labor is the largest cost component in any buried pipe system.Extra
labor caused by the removal of corrosive trench site soil can make
contract bid work in these areas a non-option. CPP pipes also meet the corrosion
needs in snow-belt areas that must endure much winter road and parking lot
|| CPP pipes have been used in conjunction with culverts and structures
of other raw material bases since 1985 to engineer longer lasting pipe
For Stormwater runoff drainage control and Stormwater treatment polishing
systems, CPP's inert HDPE raw material based pipes offer both Corrosion
Resistances as well as H-20 (32,000 lbs/axle) Traffic Live Loadbearing
CPP traffic load culvert pipes have been used on Industrial Roads,
Airports, Private Development Communities and Farm Roads for since
1985. From 1989 forward a number of state DOT's have approved it for
driveway culvert and catch basin/slope-median drains. State DOT HDPE
pipes have been shown to give satisfactory service when installed at
depths as Shallow As Twelve Inches (12") and As Deep As One Hundred
And Four Feet (104') in H-20 traffic bearing live load situations.
This wide range of depths is facilitated by burying the pipe in a
Good Quality Soil Bearing Envelope that eliminates soft voids around
the pipe so the pipe will not be prone to shift when traffic loads
are applied. When traffic is applied, the flexible corrugated plastic
design can utilize the stable compacted sidewall backfill for loadbearing
Both CPP Dual Wall Smooth Core and CPP Single Wall corrugated meet the
same AASHTO plastic pipe standards that cover corrugated HDPE plastic
pipes. The two styles are differentiated by the addition of the letter "S" or
the letter "C" to the end of the appropriate AASHTO pipe size
spec. The "S" indicates a smooth interior wall, and the "C" indicates
a corrugated interior wall. AASHTO-M-242 cover sizes 3" to 10",
and AASHTO-M-294 covers 12" to 48". The AASHTO standards are
based on the ASTM-F-405 (3" - 6") and ASTM-F-667 (8" -
24") single-wall corrugated HDPE pipe specs.
|| Equal compaction on each side in layers
will prevent pipe from shifting during the
construction phase. By extending compaction
fully to the firm and undisturbed sidewall,
the lateral stiffness needed to prevent
pipe side shifting under traffic loads is assured.
To meet AASHTO live load H-20 culvert burial standards, CPP pipes
should be buried in a loadbearing envelope of Class
I, Class II or Class III compacted soil. If a Class I stone of no more
than 1¼" diameter is used, 100% standard proctor density
compaction can be obtained upon Feather Dumping and hand leveling.
However, Class II and Class III soils should be Feather Dumped in layers
so 95% compaction can be assured. Many knowledgeable pipe installers
economized both labor cost and imported soil envelope cost at Class
III clay soil sites by importing a Class II sand soil to mix 50/50
with the site native Class III clay. The Class III clay will generally
provide enough moisture when mixed with the Class II sand to obtain
a quick maximum compaction job with minimum effort.
For installation with minimum effort, it is especially
important to compact on the sides at the bottom 180 degrees of the
pipe to assure elimination of all voids. A compacted foundation bed
6" below the pipe trench grade is also needed for good longitudinal
support to prevent sagging and reverse grades.
To protect CPP pipes from H-25/H-30 construction loads
prior to paving, a Mounding Ramp of 3 feet of compacted soil over the
pipe should be utilized. The Mounding Ramp should extend to each side
of the pipe for a distance of 1½ times the diameter of the pipe.
This precaution should be taken at all construction crossover sites.
Both asphalt and concrete greatly reduce the deflection potential on
shallow buried CPP pipes to virtually zero deflection. Because paving
does make it possible to use corrugated HDPE pipes at shallow or deep
depths, CPP corrosion resistant pipes fill a multitude of cost saving
needs on large paving jobs like shopping mall parking lots and airport runway
stormwater control systems.
|| Labor is always the largest
cost component in any buried
pipe system. Easy handling
allows up to twice as much
CPP pipe installed per day compared to pipes made from
heavier raw materials.
The following table gives the Minimum soil cover requirements
for 12" to 36" diameter pipe as a function of H-Truck live
loading. The cover depths shown have been tabulated for two soil conditions:
(1) Fair, which represents a Class III soil compacted to 85% proctor
density; and (2) Good, which represents a Class III soil compacted
to 95%. The accompanying CANDE graft shows pipe deflection decreasing
as compaction or depth increase.