RESIDENTIAL STORMWATER DRAINAGE TECHNIQUES

LINEBERGER CONSULTING ENGINEERS, INC.

19141 Stone Oak Parkway, Suite 104 · San Antonio, Texas 78258
(San Antonio) 210-601-1379 (Austin) 512-522-9197 (Email): [email protected]

RESIDENTIAL STORMWATER DRAINAGE TECHNIQUES

1. Residential ground surface storm drain systems must transport excess moisture away from designated areas where
excess water would otherwise prevent the safe and serviceable use of a residential property. If excess stormwater
runoff collects and saturates the foundation bearing soils, the structure may displace abnormally resulting in
structural foundation distress. Finished ground surfaces must be sloped to freely drain stormwater away from the
house perimeter and into an approved outfall location (usually a paved street or street gutter system). Perpetually
moist ground surfaces can limit the appropriate use of residential yard areas and may present a health hazard.

2. To assure the residence rear yard finished grade ground surfaces comply with (IRC) §R401.3 requirements, the
customer may consider implementing the following optional drainage techniques:
[a.] OPTION 1: Modify Existing Ground Surface Stormwater Drain Systems (ASCE, section 7.35):
i. Refer to this graphic for general guidance on overall Lot Grading Type A where stormwater drainage is
directed from the rear yard to the street: https://photos.app.goo.gl/hRtzXvhFhxD275cU2 ;
ii. Surface Grading along the Foundation perimeter: A minimum slope of 5% (6” fall per 10’) away from the
foundation perimeter shall be provided for adjacent ground areas;
iii. Ground surface swales parallel to the house walls shall have longitudinal slopes of at least 2% (6” per 25')
if practical, and 1% (3” per 25’) minimum;
iv. Eroded surfaces should be replaced with vegetated surfaces;
v. Gaps between concrete surfaces along the foundation system perimeter allowing surface water to infiltrate
into the foundation bearing soils should be eliminated;
vi. Concrete surfaces allowing water to flow towards the foundation system perimeter should be modified to
direct water away from the foundation perimeter;
vii. Erosion Control: Ground cover should be placed in areas where ground surface erosion is reasonably
anticipated.
[b.] OPTION 1A: OPTION 1 + Subsurface Solid Plastic/PVC Pipe System: Subsurface gravity stormwater
drain systems help prevent foundation bearing soil saturation by capturing and collecting excess stormwater
runoff below ground level and then conveying it to approved outfall locations. The ground surface should be
graded to slope to one or more operable subsurface solid drainpipe (plastic or PVC) single collector inlets or
continuous grate type rectangular inlets. The drain inlets should be located to drain excess water from the side
and rear yards and discharge to the approved subdivision stormwater conveyance system. Stormwater earthen
or concrete drain channels or curbed streets often serve as drain outfalls. (Note: If discharging to the street is
not feasible, the customer may consider discharging the stormwater within the yard provided such discharge
permeates into the soil and does not result in ground surface flooding or water ponding in any area, including
any adjoining property, easement, or right of way.) Subsurface drain system cleanouts should be provided at
50 feet intervals for proper maintenance. Roof rainfall gutter downspouts may be connected to the subsurface
solid pipe system provided the pipe has sufficient capacity to prevent a backwater condition. The pipe should
have a minimum slope of 1% to the daylight discharge. In any case, the ground surface slope along the
foundation perimeter must comply with local building code requirements.
[c.] OPTION 1B: OPTION 1 + Subsurface Perforated Plastic/PVC Pipe System: Subsurface gravity
stormwater drain systems help prevent foundation bearing soil saturation by collecting, capturing and
conveying excess stormwater runoff to approved outfall locations. As an additional measure to drain the
building yard areas, subsurface perforated pipes placed in an aggregate filled trench (“French Drain”) along
with an optional filter fabric to prevent pipe stoppages may be optionally considered. The pipe should have a
minimum slope of 1% to the surface outfall. Cleanouts should be provided at 50 feet intervals for

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LINEBERGER CONSULTING ENGINEERS, INC.

19141 Stone Oak Parkway, Suite 104 · San Antonio, Texas 78258
(San Antonio) 210-601-1379 (Austin) 512-522-9197 (Email): [email protected]

RESIDENTIAL STORMWATER DRAINAGE TECHNIQUES

maintenance. In any case, the ground surface slope along the foundation perimeter must comply with local
code requirements. Gutter downspouts should not be connected to a perforated pipe system.

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