United States Department of Agriculture 630-CPS-1

NRCS, NHCP

July 2022

NRCS reviews and periodically updates conservation practice standards. To obtain the current 

version of this standard, contact your Natural Resources Conservation Service State office or 

visit the Field Office Technical Guide online by going to the NRCS website at 

https://www.nrcs.usda.gov/ and type FOTG in the search field. 

USDA is an equal opportunity provider, employer, and lender.

Natural Resources Conservation Service 

CONSERVATION PRACTICE STANDARD 

VERTICAL DRAIN 

CODE 630 

(no)

DEFINITION 

A well, pipe, pit, or bore in porous underground strata into which drainage water can be discharged

without contaminating groundwater resources. 

PURPOSE 

This practice is used to accomplish the following purpose: 

• Provide an outlet for drainage water from a surface or subsurface drainage system. 

CONDITIONS WHERE PRACTICE APPLIES 

This practice is applicable in locations where the underlying strata can receive, transmit, or store the

design drainage flow, and other drainage outlets are not available and cannot be provided at a reasonable

cost. This practice is also applicable where a natural “sinkhole” acts as the vertical drain, and erosion

control or treatment of surface runoff is needed. 

This practice is applicable only in locations where a determination has been made that it— 

• Conforms to local, State, Tribal, or Federal laws or regulations. 

• Will not contaminate groundwater resources. 

• Will not affect instream habitat by reducing surface water flows. 

• Will not negatively affect underground habitats by introducing surface water flows. 

CRITERIA 

General Criteria Applicable to All Purposes 

The number, size, and location of vertical drains must be adequate to discharge the design drainage flow

into the underlying stratum or strata. Base the capacity of the vertical drain system on a field

determination of the depth, permeability, porosity, thickness, and extent of the strata. 

Design the minimum diameter of uncased wells to be 6 inches and the minimum diameter of cased wells

to be 4 inches. Well casings must be of adequate strength and longevity to serve planned needs. 

Where planned drains will divert significant amounts of surface water underground, determine the

aggregate effect on streamflow, and take steps in the design to avoid any potential negative effects on

instream and riparian habitat. Also, provide a suitable filter system, desilting basin or other means

necessary for removing sediment and other contaminants from the water before it enters the vertical drain. 
CONSIDERATIONS 

Significant additions to subsurface water sources may raise local water tables or cause undesirable

surface discharges down-gradient from the vertical drain. 

PLANS AND SPECIFICATIONS 

Prepare plans and specifications for installing the vertical drain and include a complete description of

requirements for properly installing the practice to achieve its intended purpose. At a minimum, include— 

• Documentation of aquifer characteristics, geology, and history of site relative to sources of potential

contamination, such as nutrient and pesticide application, septic systems, chemical storage

facilities, landfills, roads, animal waste storage or treatment facilities, or naturally occurring sources

of contamination. 

OPERATION AND MAINTENANCE 

Prepare an operation and maintenance (O&M) plan that describes specific instructions for maintaining the

vertical drain. The O&M plan must include at minimum— 

• Periodic inspections of inlets to vertical drains to ensure that they are not plugged or damaged. 

• Maintenance of vegetative filters, sediment basins, and other filters per O&M requirements for each

of the respective conservation practice standards in use. 

REFERENCES 

USDA NRCS. 2017. National Engineering Handbook (Title 210), Part 633, Chapter 26, Gradation Design

of Sand and Gravel Filters. https://directives.sc.egov.usda.gov/

-CPS-2

NRCS, NHCP

630

July 2022