Korea Sewer Pipe Trenchless Repair vs Excavation Lifecycle Cost Calculator

Compare like-for-like trenchless lining and excavation-replacement quotes across restoration, downtime, maintenance, warranty-adjusted renewal, and 10-year present value in KRW.

This calculator compares two actual proposals for the same CCTV-diagnosed reach. Zero defaults are not market averages, and a specialist must first confirm structure, gradient, collapse risk, and feasibility.

1. Diagnosed reach and analysis basis

Enter the length, diameter, horizon, and rates shared by the CCTV report and both quotes. Discount and escalation rates are your scenario assumptions.

Base year

year

Analysis horizon

years

Annual discount rate

Annual cost escalation

CCTV-diagnosed length

Pipe diameter

CCTV-reported defect type

Start with the CCTV report and recorded reach.

I confirmed the CCTV footage, report, and reach.Align date, upstream/downstream points, pipe, diameter, length, and defects.A specialist confirmed both methods are feasible.Include structure, deformation, gradient, voids, bore, laterals, and access.I aligned scope and quality requirements.Compare the same reach, laterals, testing, restoration, tax, and defects liability.I confirmed the asset boundary and payer.Confirm private drains, common pipes, parcel boundary, and public connection.

The synthetic example is fictional arithmetic data, not a market average or recommended quote.

Comparison conclusion locked

Complete diagnosis and quote checks

Scenario numbers remain visible, but no lower-cost method is named until every readiness check is complete.

Lifecycle cost comparison

Trenchless repair and excavation replacement lifecycle comparison
Metric	Trenchless repair	Excavation replacement
Initial work quote	KRW 0	KRW 0
Initial downtime cost	KRW 0	KRW 0
Initial cash required	KRW 0	KRW 0
10-year nominal lifecycle cost	KRW 0	KRW 0
10-year present value	KRW 0	KRW 0
Equivalent annual cost	KRW 0	KRW 0
Present value per metre	Length required	Length required
Total warranty recovery	KRW 0	KRW 0
Total downtime	0 days	0 days

Trenchless life break-even

None within 100 years

The first integer life at which trenchless PV is no higher, holding other inputs fixed.

Excavation restoration break-even

Cost inputs required

Current entered restoration cost is KRW 0.

Cumulative-cost crossover

Tie at year zero

The first point at which cumulative PV changes the initial ordering.

Trenchless repair · cost composition

Trenchless repair nominal and present-value cost composition
Item	Nominal	Present value
Initial work quote	KRW 0	KRW 0
Initial downtime cost	KRW 0	KRW 0
Maintenance, cleaning, and inspection	KRW 0	KRW 0
Renewal work	KRW 0	KRW 0
Renewal downtime	KRW 0	KRW 0
Warranty recovery credit	KRW 0	KRW 0

Expected renewal years: none within the horizon

Excavation replacement · cost composition

Excavation replacement nominal and present-value cost composition
Item	Nominal	Present value
Initial work quote	KRW 0	KRW 0
Initial downtime cost	KRW 0	KRW 0
Maintenance, cleaning, and inspection	KRW 0	KRW 0
Renewal work	KRW 0	KRW 0
Renewal downtime	KRW 0	KRW 0
Warranty recovery credit	KRW 0	KRW 0

Expected renewal years: none within the horizon

Show annual cash flow

Annual cumulative present-value cash flow for both methods
Year	Trenchless annual cost	Trenchless cumulative PV	Excavation annual cost	Excavation cumulative PV
2026 (0)	KRW 0	KRW 0	KRW 0	KRW 0
2027 (1)	KRW 0	KRW 0	KRW 0	KRW 0
2028 (2)	KRW 0	KRW 0	KRW 0	KRW 0
2029 (3)	KRW 0	KRW 0	KRW 0	KRW 0
2030 (4)	KRW 0	KRW 0	KRW 0	KRW 0
2031 (5)	KRW 0	KRW 0	KRW 0	KRW 0
2032 (6)	KRW 0	KRW 0	KRW 0	KRW 0
2033 (7)	KRW 0	KRW 0	KRW 0	KRW 0
2034 (8)	KRW 0	KRW 0	KRW 0	KRW 0
2035 (9)	KRW 0	KRW 0	KRW 0	KRW 0
2036 (10)	KRW 0	KRW 0	KRW 0	KRW 0

Quote-scope gaps

Trenchless repair

CCTV, cleaning, and desilting
Lining or point-repair work
Lateral reopening and reconnection
Bypass, ventilation, safety, and temporary works
Curing and pre/post-work testing
Manhole, access, and local finish restoration
Tax, haulage, other cost, and contingency

Excavation replacement

Survey, design, filing, occupation, and traffic plan
Excavation, shoring, dewatering, and backfill
New pipe, manholes, and lateral connections
Spoil, old-pipe, and waste haulage
Buried-utility survey, protection, and relocation
Road, parking, floor, and pavement restoration
Landscape, wall, finish, and adjacent works
Flow, watertightness, CCTV, tax, and other cost

Checks and warnings

Both alternatives are still zero. Enter actual quotes for the same diagnosed reach.
Confirm the CCTV footage, report, and diagnosed reach first.
A specialist must confirm that both methods are feasible at this site.
Align length, diameter, laterals, testing, restoration, and tax scope.
Confirm the private, common, or public boundary and who pays.
Enter diagnosed length and diameter to calculate cost per metre and readiness.
One or more initial scopes are unconfirmed. Confirm even a zero as not applicable.
Actual written quotes have not been confirmed for both methods.
Confirm annual cost, life, renewal, downtime, and warranty assumptions.
Enter a service-life or renewal cycle of at least one year for both methods.
For deformation, collapse, mixed, or unclassified defects, structural, ground, and hydraulic review comes before cost.
Check Sewerage Act Articles 27 and 30, Enforcement Rule Article 23 and Schedule 7, local ordinances, and project conditions.
This result is not diagnosis, design, structural or safety approval, filing acceptance, completion approval, a warranty decision, or contractor advice.

Sources checked 2026-09-03: Sewerage Act ID 001815 / MST 276803 Articles 27 and 30, Enforcement Rule ID 008578 / MST 287447 Article 23 and Schedule 7, the March 2025 condition-rating manual, and the lifecycle comparison method in NIST HB 135e2025.

Related calculators

What this trenchless-versus-excavation calculator compares

This calculator normalises two actual proposals for the same CCTV-diagnosed sewer reach. It does not stop at the headline construction price. It lays out cleaning, lateral reopening, pavement, floor and landscape restoration, business or occupancy downtime, annual maintenance, expected renewal work, and contract-supported warranty recovery over one common analysis horizon.

Trenchless lining may reduce surface opening, but it is not feasible for every defect, geometry, host pipe, or hydraulic condition. Excavation can replace the old pipe, but shoring, buried services, spoil, traffic control, reinstatement, and downtime can dominate its full cost. The useful question is therefore not which method is universally better. It is how two technically feasible, like-for-like options compare for this particular reach.

Use it when

You have the CCTV footage, report, and identified reach.
You have both a lining or point-repair quote and an excavation-replacement quote.
Shop closure, temporary accommodation, parking closure, or access disruption has a real cost.
Service life, repeat work, and warranty scope matter as much as initial price.

Gather first

Original CCTV footage, report date, and upstream and downstream limits.
Pipe material, diameter, measured length, lateral count, and manholes.
Itemised quantities, specifications, tax basis, exclusions, and variation rates.
Pre- and post-work tests, programme, warranty wording, and handover records.

CCTV condition evidence and feasibility come first

Korea's March 2025 Standard Manual for Sewer Pipe and Manhole Investigation and Condition Rating provides a public framework for consistent inspection and recording. A camera may reveal cracks, displaced joints, infiltration, roots, or deposits, but deformation, sagging, voids, and possible ground settlement can require additional measurements and professional assessment. This calculator neither reads the footage nor assigns a defect grade, and the selected defect type never changes the cost formula automatically.

Structure and safety override the arithmetic

The model cannot establish whether the host pipe can support a liner, whether the reduced bore retains adequate flow, whether every lateral can be reopened, or whether excavation can protect adjacent structures and utilities. Use the comparison as a decision aid only after a responsible specialist confirms that both entered options are genuinely feasible.

The November 28, 2022 Korean Sewerage Design Standard says rehabilitation planning should consider purpose, site conditions, hydraulic capacity, defect condition, construction cost, and alternatives including urgent versus ordinary work, full versus local work, and excavation versus trenchless work. A lower present value cannot substitute for that engineering selection process.

Put both proposals on the same scope

Comparing only two totals can accidentally compare exclusions rather than methods. Every input row includes a scope confirmation. A zero amount is not automatically treated as not applicable: confirm whether the work is included, separately priced, or genuinely unnecessary.

Scope checks for trenchless repair and excavation replacement proposals
Stage	Trenchless repair	Excavation replacement	Evidence
Preparation	CCTV, jetting, cleaning, and desilting	Survey, design, filing, occupation, and traffic plan	Footage, drawings, filing list
Main work	Liner or point repair, curing, and finishing	Excavation, shoring, pipe, manholes, and backfill	Specification and quantities
Connections	Lateral reopening, bypass, and ventilation	Utility protection, relocation, and temporary drainage	Lateral count and work plan
Restoration	Manholes and local access finishes	Road, parking, floor, landscape, wall, and finish	Required width, layers, materials, and photos
Testing	Curing record, thickness, watertightness, and final CCTV	Gradient, flow, watertightness, and final CCTV	Certificates, footage, and warranty

Do not double count downtime

A trading property might use contribution margin lost during closure rather than total revenue. A residence might use supported temporary accommodation or access costs. Do not add two measures of the same loss, and use each contractor's actual work programme rather than giving both methods the same arbitrary duration.

Lifecycle cost, warranty, and present-value formulas

1. Initial cash

Initial cash equals the itemised work quote plus initial downtime days multiplied by cost per day. Do not deduct an uncertain insurance payment, subsidy, or warranty recovery.

Initial cash = work quote + downtime days × daily cost

2. Annual and renewal cash flow

Annual maintenance occurs at each year end and grows with the entered escalation rate. A five-year service life creates renewal events in years 5 and 10 within a ten-year horizon. The event at the final horizon year is included.

3. Warranty recovery

If a renewal event falls on or before the warranty term, the entered warranty percentage reduces renewal work cost only. Downtime and annual maintenance remain payable in the model. Translate the actual exclusions, claim process, tests, and restoration boundary before entering a percentage.

4. Present value and EAC

Each cost in year t is divided by `(1 + discount rate)^t`. Present value adds those discounted future costs to initial cash. Equivalent annual cost converts that total into one level annual amount over the same horizon. Compare EAC only when the scope and horizon are aligned.

Three break-even signals

Minimum trenchless life is the first whole-year life from 1 to 100 at which trenchless PV is no higher than excavation PV, with all other inputs held fixed.
Excavation restoration break-even is the combined road, floor, landscape, and finish restoration amount at which the two PV totals tie.
Cumulative crossover is the first year when cumulative PV changes the ordering established by initial cash.
These are arithmetic thresholds, not a certified technical life, approved budget, or method recommendation.

Step-by-step workflow

Freeze the diagnosed reach. Match CCTV date, limits, pipe material, diameter, length, laterals, and manholes across both requests.
Screen technical alternatives first. Ask the responsible specialist whether both methods are feasible and identify any excluded or separately treated reach.
Transcribe every initial scope. Enter amounts and confirm whether each line is included, separate, or not applicable.
Separate downtime and recurring cost. Use each programme, supported daily loss, annual cleaning or inspection, renewal cost, and service-life evidence.
Translate the warranty. Record term, covered defect, exclusions, percentage, testing, reinstatement, and claim process rather than relying on the headline term.
Read readiness before ranking. Review missing scopes and then vary life, restoration, discount, and escalation assumptions to see how robust the result is.

Synthetic 30 m worked example

The built-in example is fictional arithmetic data, not a Korean market price, standard service life, or preferred method. It uses a 30 m, 200 mm reach with mixed defects, a ten-year horizon, a 3% discount rate, and 2% annual cost escalation.

Synthetic 30 metre lifecycle result for trenchless repair and excavation replacement
Metric	Trenchless repair	Excavation replacement
Initial cash required	KRW 19,900,000	KRW 43,000,000
Ten-year nominal lifecycle cost	KRW 40,173,977	KRW 44,642,458
Ten-year present value	KRW 36,099,932	KRW 44,394,305
Present value per metre	KRW 1,203,331	KRW 1,479,810
Renewals inside horizon	One, in year 8	None

Reading the example

With these fictional entries, trenchless PV is lower by KRW 8,294,373. The calculated minimum trenchless life is four years. Entered excavation restoration is KRW 10,000,000, while its tie threshold is about KRW 1,705,627, showing how strongly restoration drives this example. The trenchless renewal occurs in year 8, after the entered five-year warranty, so warranty recovery is zero. Real results change with the diagnosed scope, quantities, programme, service life, and contract.

Site-specific ways to use the model

Detached-house yard

Check paving, walls, planting, tanks, and manhole surrounds. Limit residential downtime to supportable temporary accommodation, access, or sanitation cost.

Trading premises

Take closure days from each programme and use contribution loss rather than gross revenue. If night work and bypass cost reduce closure, do not count the same benefit twice.

Road or car park

Use the authority-required restoration width, pavement layers, line marking, traffic control, and occupation. Trenchless work can still need vehicles, manhole access, bypass, and traffic management.

Korean legal and technical boundary

The current Sewerage Act was checked on September 3, 2026: law ID 001815, MST 276803, effective October 1, 2025. Article 27 addresses drainage installation, filing, completion inspection, structural-change notices, and maintenance responsibility, while delegating important details to local ordinances. Article 27(2)(2) refers to maintenance work such as cleaning and repair that does not obstruct public-sewer function. Article 30 allows the authority to order installation, replacement, removal, repair, or other action when installation, maintenance, or structural requirements are not met.

The current Enforcement Rule was checked on the same date: law ID 008578, MST 287447, effective June 22, 2026. Article 23 and Schedule 7, schedule serial 18199451, connect drainage work to durable and corrosion-resistant materials, watertight construction, separate foul and storm flow where applicable, and a connection that does not obstruct or damage the public sewer. These provisions do not let this calculator determine ownership, a filing duty, acceptance, contractor eligibility, or compliance for a particular site.

Questions for the authority and responsible contractor

Who maintains and pays for the private drain, common pipe, parcel-boundary reach, and public connection?
Does the proposed repair or replacement require a structural-change filing or completion inspection?
What road occupation, excavation, utility attendance, traffic, and pavement restoration rules apply?
Who accepts curing, thickness, watertightness, gradient, flow, and final CCTV records?
Which defects, exclusions, tests, reinstatement, response times, and losses does the warranty cover?

Practical cautions

Build a defensible comparison

Send the same quantities and questions to at least two bidders.
Document included, separate, or not-applicable status even for a zero line.
Support life with site-applicable design, validation, and warranty evidence.
Save short-life, base, and long-life cases rather than one optimistic result.
Write final CCTV and test deliverables into the contract.

Avoid these interpretations

Do not compare cost per metre across different diameters, laterals, or restoration reaches.
Do not treat a ten-year warranty as a ten-year life or 100% cover for every loss.
Do not treat lower PV as proof of feasibility, safety, approval, or workmanship.
Do not call a quote complete if tax, bypass, waste, night work, or retesting is excluded.
Do not copy the synthetic prices or lives into a real project.

Frequently asked questions

Is trenchless repair always cheaper?

No. Cleaning, laterals, bypass, curing tests, local reinstatement, shorter life, and repeat work can narrow or reverse the initial saving. Conversely, excavation shoring, utilities, full reinstatement, and downtime can make trenchless work much less costly on a particular site.

Which lining service life should I enter?

There is no national default in this calculator. Use evidence applicable to the material, thickness, curing method, host pipe, diameter, load, flow, workmanship, inspection, and warranty. Calculate a conservative, base, and favourable case separately.

Where should recurring blockage cost go?

Put routine cleaning or inspection in annual maintenance. Put full relining or pipe replacement at the service-life interval. If you convert irregular blockages into an annual expected amount, document both the assumed probability and the cost per event.

Is renewal in the final analysis year included?

Yes. A five-year cycle over ten years includes events in years 5 and 10. The model does not add a residual value automatically, so document a different horizon or residual assumption separately if it is relevant.

Can I use it for an apartment common sewer?

The arithmetic can be used, but establish the private-unit, common-property, development-drain, and public-sewer boundary first. This tool does not decide ownership, reserve-plan treatment, approvals, insurance, or who must pay.

Can I contract the lower-PV method immediately?

No. Present value compares the cash-flow assumptions you entered. CCTV interpretation, structure, hydraulics, ground, buried services, constructability, filings, permits, completion tests, contract terms, warranty, and contractor capability remain separate decisions.

Official sources and update boundary

Korean Sewerage Act Article 27 and Article 30, law ID 001815, MST 276803, effective October 1, 2025.
Sewerage Act Enforcement Rule Article 23 and Schedule 7, schedule serial 18199451, law ID 008578, MST 287447, effective June 22, 2026.
Standard Manual for Sewer Pipe and Manhole Investigation and Condition Rating, March 2025.
Sewer Pipeline Construction Standard Specification, Ministry of Environment Notice 2022-271, revised December 28, 2022.
Korean Sewerage Design Standard, revised November 28, 2022, Sections 18.7 and 18.8.
NIST Handbook 135e2025, used only for the general lifecycle and present-value method.

Sources were checked on September 3, 2026. Recheck statutes, local ordinances, technical standards, method validation, warranty wording, and every quote at the actual decision date. No nationwide construction price, service life, recurrence rate, or approved discount rate is embedded.

Compare the footage, quantities, and two complete proposals

Confirm included, separate, or not-applicable status for every work item, then enter supported downtime, service life, renewal, and warranty terms. Use the output as a structured question sheet for the Korean authority, inspector, designer, and contractors—not as engineering approval or an automatic method selection.