Feasibility Study of Constructed Wetlands for Wastewater

Treatment and Wildlife HabitatLuna County, NM

Public Meeting

November 10, 200511:00 am

Presented by:

Luna County Planning Departmentand

Zia Engineering & Environmental Consultants, LLC

Background

• 2000-2020 Luna County Comprehensive Plan indicates that County is on the verge of an “environmental catastrophe”

• County residents outside of Deming and Columbus rely on septic tanks and domestic wells

• New NMED regulations came into effect September 1, 2005

• Border 2012 grant to explore treatment options to address these concerns

Project Scope

• Research existing information and choose a study area

• Identify alternative treatment methods• Assess alternatives to determine feasibility

– Ability to meet regulations, previous experiences, demands on community, technical considerations, flexibility, cost

– County’s stated goals: provide an alternative to septic systems; water reclamation and reuse; create outdoor recreational opportunities; aesthetic improvements; provide educational opportunities

• Prepare of a schematic system design

Interstate 10

Deming City Limits

County ETZ Zone

Study Location

• T24S R9W Section 24 SW quarter (La Hacienda Estates)– 94 septic systems – 74 domestic wells– Growing area of subdivisions– Property nearby that could serve as treatment

site (state land and gravel pits)

Alternative Treatment Methods

• LagoonEarthen reservoirs with an impervious liner that can be

used alone or in combination with other processes to provide complete wastewater treatment

Alternatives (continued)

• Small Treatment Plant Smaller version of the typical wastewater treatment

plants that most large communities use for the treatment of their wastewater (two options: custom design or pre-packaged)

Alternatives (continued)

• De-centralized Treatment SystemsAn alternative that utilizes more than one location

throughout the study site to implement treatment (two options: on-lot or cluster)

Alternatives (continued)

• Treatment WetlandAttempt to mimic natural wetland processes to treat

wastewater

Advantages and DisadvantagesTreatment Lagoon

Advantages DisadvantagesMinimum operation and maintenanceLow technological demandsCan design to store sludge

Land use intensiveNot flexibleDifficult to upgrade Difficulty in consistently reducing nitrogen levelsAlgal growth can be extensiveOdor production may be a problem at headworksEventual sludge removal may be difficultRequires a NMED groundwater discharge permitRequires a collection systemRequires groundwater monitoringRequires a certified operator

Advantages and DisadvantagesSmall Treatment Plant

Advantages Disadvantages•Flexible•Able to meet all regulated effluent levels•Proven effective in the region•Easy to upgrade

•Cost•Frequent sludge disposal required•Requires a NMED groundwater discharge permit•Requires a collection system •Requires an Advanced Licensed Wastewater Operator

Advantages and DisadvantagesDe-centralized Treatment Systems

Advantages Disadvantages•No or minimal collection system required•Low maintenance requirements•Proven effective in the region•Contract out O&M services•No NMED groundwater discharge permit required•Easy to upgrade

•Numerous maintenance locations •Difficult to ensure current maintenance is done•Maintenance of septic systems may be necessary•Use of individual homeowners’ property

Advantages and DisadvantagesTreatment Wetland

Advantages Disadvantages•Aesthetically pleasing•Habitat creation

•Land use intensive•Extensive pre-treatment required•Regional systems have not been effective•Not flexible•Requires a NMED groundwater discharge permit•Requires a collection system

Summary Matrix of Treatment Alternatives

(1 = Low Desirability; 3 = High Desirability)

Treatment Lagoon

Small PlantPre-

Packaged Plant

On-lot Treatment

Cluster Systems

Meets County’s Goals

2 3 3 3 3

Complexity 3 1 2 3 3

Flexibility 1 3 3 1 1

Reliability 2 3 3 2 2

O&M Requirements

3 1 2 3 3

Cost 2 1 2 1 3

Ability to be Upgraded

1 2 2 3 3

Total 14 14 17 16 18

Effluent Alternatives

• Constructed Wetlandscan be successfully used as a final polishing and

effluent disposal step • Agricultural

use treated wastewater to irrigate an existing agriculture operation or to develop a new one

• Residentialtreated wastewater may be used to irrigate residential

landscaping• Discharge

release the water into a leach field and discharge to the groundwater table

Wetland Agriculture Residential Discharge

Meets County’s Goals

3 2 3 1

Additional Treatment

3 3 2 1

Quantitative Cost 1 3 2 2

Total 7 8 7 4

Summary Matrix of Effluent Alternatives(1 = Low Desirability; 3 = High Desirability)

Recommendation

• Meets all the criteria and goals• Lowest cost option* – no collection system required• Puts the responsibility in the hands of the homeowner* Costs calculated without grants or other funding considered

De-centralized cluster treatment with residential sub-surface irrigation

Estimated Costs for Recommendation

Capital Cost Annual O&M

4-Home Cluster System $24,100 $1,650

Irrigation System (4 homes) $8,000 ---

Total $32,100 $1,650

Capital Cost Annual O&M

Cluster Systems for La Hacienda Estates $872,600 $59,000

Irrigation System for La Hacienda Estates $200,000 ---

Total $1,072,000 $59,000

Questions?